import contextlib
import errno
import itertools
import logging
import os
import re
import signal
import subprocess
import sys
import tempfile
import time
import unicodedata
from enum import Enum
from types import FrameType, TracebackType
from typing import (
    Any,
    Iterable,
    Dict,
    List,
    Optional,
    Sequence,
    Tuple,
    Type,
    Union,
)
from .._typing_compat import Literal

import greenlet
from curtsies import (
    FSArray,
    fmtstr,
    FmtStr,
    Termmode,
    fmtfuncs,
    events,
    __version__ as curtsies_version,
)
from curtsies.configfile_keynames import keymap as key_dispatch
from curtsies.input import is_main_thread
from curtsies.window import CursorAwareWindow
from cwcwidth import wcswidth
from pygments import format as pygformat
from pygments.formatters import TerminalFormatter
from pygments.lexers import Python3Lexer

from . import events as bpythonevents, sitefix, replpainter as paint
from ..config import Config
from .coderunner import (
    CodeRunner,
    FakeOutput,
)
from .filewatch import ModuleChangedEventHandler
from .interaction import StatusBar
from .interpreter import (
    Interp,
    code_finished_will_parse,
)
from .manual_readline import (
    edit_keys,
    cursor_on_closing_char_pair,
    AbstractEdits,
)
from .parse import parse as bpythonparse, func_for_letter, color_for_letter
from .preprocess import preprocess
from .. import __version__
from ..config import getpreferredencoding
from ..formatter import BPythonFormatter
from ..pager import get_pager_command
from ..repl import (
    Repl,
    SourceNotFound,
)
from ..translations import _
from ..line import CHARACTER_PAIR_MAP

logger = logging.getLogger(__name__)

INCONSISTENT_HISTORY_MSG = "#<---History inconsistent with output shown--->"
CONTIGUITY_BROKEN_MSG = "#<---History contiguity broken by rewind--->"
EXAMPLE_CONFIG_URL = "https://raw.githubusercontent.com/bpython/bpython/master/bpython/sample-config"
EDIT_SESSION_HEADER = """### current bpython session - make changes and save to reevaluate session.
### lines beginning with ### will be ignored.
### To return to bpython without reevaluating make no changes to this file
### or save an empty file.
"""

# more than this many events will be assumed to be a true paste event,
# i.e. control characters like '<Ctrl-a>' will be stripped
MAX_EVENTS_POSSIBLY_NOT_PASTE = 20


class SearchMode(Enum):
    NO_SEARCH = 0
    INCREMENTAL_SEARCH = 1
    REVERSE_INCREMENTAL_SEARCH = 2


class LineType(Enum):
    """Used when adding a tuple to all_logical_lines, to get input / output values
    having to actually type/know the strings"""

    INPUT = "input"
    OUTPUT = "output"


class FakeStdin:
    """The stdin object user code will reference

    In user code, sys.stdin.read() asks the user for interactive input,
    so this class returns control to the UI to get that input."""

    def __init__(
        self,
        coderunner: CodeRunner,
        repl: "BaseRepl",
        configured_edit_keys: Optional[AbstractEdits] = None,
    ):
        self.coderunner = coderunner
        self.repl = repl
        self.has_focus = False  # whether FakeStdin receives keypress events
        self.current_line = ""
        self.cursor_offset = 0
        self.old_num_lines = 0
        self.readline_results: List[str] = []
        if configured_edit_keys is not None:
            self.rl_char_sequences = configured_edit_keys
        else:
            self.rl_char_sequences = edit_keys

    def process_event(self, e: Union[events.Event, str]) -> None:
        assert self.has_focus

        logger.debug("fake input processing event %r", e)
        if isinstance(e, events.Event):
            if isinstance(e, events.PasteEvent):
                for ee in e.events:
                    if ee not in self.rl_char_sequences:
                        self.add_input_character(ee)
            elif isinstance(e, events.SigIntEvent):
                self.coderunner.sigint_happened_in_main_context = True
                self.has_focus = False
                self.current_line = ""
                self.cursor_offset = 0
                self.repl.run_code_and_maybe_finish()
        elif e in self.rl_char_sequences:
            self.cursor_offset, self.current_line = self.rl_char_sequences[e](
                self.cursor_offset, self.current_line
            )
        elif e == "<Ctrl-d>":
            if not len(self.current_line):
                self.repl.send_to_stdin("\n")
                self.has_focus = False
                self.current_line = ""
                self.cursor_offset = 0
                self.repl.run_code_and_maybe_finish(for_code="")
        elif e in ("\n", "\r", "<Ctrl-j>", "<Ctrl-m>"):
            line = f"{self.current_line}\n"
            self.repl.send_to_stdin(line)
            self.has_focus = False
            self.current_line = ""
            self.cursor_offset = 0
            self.repl.run_code_and_maybe_finish(for_code=line)
        elif e != "<ESC>":  # add normal character
            self.add_input_character(e)

        if not self.current_line.endswith(("\n", "\r")):
            self.repl.send_to_stdin(self.current_line)

    def add_input_character(self, e: str) -> None:
        if e == "<SPACE>":
            e = " "
        if e.startswith("<") and e.endswith(">"):
            return
        assert len(e) == 1, "added multiple characters: %r" % e
        logger.debug("adding normal char %r to current line", e)

        self.current_line = (
            self.current_line[: self.cursor_offset]
            + e
            + self.current_line[self.cursor_offset :]
        )
        self.cursor_offset += 1

    def readline(self, size: int = -1) -> str:
        if not isinstance(size, int):
            raise TypeError(
                f"'{type(size).__name__}' object cannot be interpreted as an integer"
            )
        elif size == 0:
            return ""
        self.has_focus = True
        self.repl.send_to_stdin(self.current_line)
        value = self.coderunner.request_from_main_context()
        assert isinstance(value, str)
        self.readline_results.append(value)
        return value if size <= -1 else value[:size]

    def readlines(self, size: Optional[int] = -1) -> List[str]:
        if size is None:
            # the default readlines implementation also accepts None
            size = -1
        if not isinstance(size, int):
            raise TypeError("argument should be integer or None, not 'str'")
        if size <= 0:
            # read as much as we can
            return list(iter(self.readline, ""))

        lines = []
        while size > 0:
            line = self.readline()
            lines.append(line)
            size -= len(line)
        return lines

    def __iter__(self):
        return iter(self.readlines())

    def isatty(self) -> bool:
        return True

    def flush(self) -> None:
        """Flush the internal buffer. This is a no-op. Flushing stdin
        doesn't make any sense anyway."""

    def write(self, value):
        # XXX IPython expects sys.stdin.write to exist, there will no doubt be
        # others, so here's a hack to keep them happy
        raise OSError(errno.EBADF, "sys.stdin is read-only")

    def close(self) -> None:
        # hack to make closing stdin a nop
        # This is useful for multiprocessing.Process, which does work
        # for the most part, although output from other processes is
        # discarded.
        pass

    @property
    def encoding(self) -> str:
        return sys.__stdin__.encoding

    # TODO write a read() method?


class ReevaluateFakeStdin:
    """Stdin mock used during reevaluation (undo) so raw_inputs don't have to
    be reentered"""

    def __init__(self, fakestdin: FakeStdin, repl: "BaseRepl"):
        self.fakestdin = fakestdin
        self.repl = repl
        self.readline_results = fakestdin.readline_results[:]

    def readline(self):
        if self.readline_results:
            value = self.readline_results.pop(0)
        else:
            value = "no saved input available"
        self.repl.send_to_stdouterr(value)
        return value


class ImportLoader:
    """Wrapper for module loaders to watch their paths with watchdog."""

    def __init__(self, watcher, loader):
        self.watcher = watcher
        self.loader = loader

    def __getattr__(self, name):
        if name == "create_module" and hasattr(self.loader, name):
            return self._create_module
        return getattr(self.loader, name)

    def _create_module(self, spec):
        module_object = self.loader.create_module(spec)
        if (
            getattr(spec, "origin", None) is not None
            and spec.origin != "builtin"
        ):
            self.watcher.track_module(spec.origin)
        return module_object


class ImportFinder:
    """Wrapper for finders in sys.meta_path to wrap all loaders with ImportLoader."""

    def __init__(self, watcher, finder):
        self.watcher = watcher
        self.finder = finder

    def __getattr__(self, name):
        if name == "find_spec" and hasattr(self.finder, name):
            return self._find_spec
        return getattr(self.finder, name)

    def _find_spec(self, fullname, path, target=None):
        # Attempt to find the spec
        spec = self.finder.find_spec(fullname, path, target)
        if spec is not None:
            if getattr(spec, "loader", None) is not None:
                # Patch the loader to enable reloading
                spec.loader = ImportLoader(self.watcher, spec.loader)
        return spec


def _process_ps(ps, default_ps: str):
    """Replace ps1/ps2 with the default if the user specified value contains control characters."""
    if not isinstance(ps, str):
        return ps

    return ps if wcswidth(ps) >= 0 else default_ps


class BaseRepl(Repl):
    """Python Repl

    Reacts to events like
     - terminal dimensions and change events
     - keystrokes
    Behavior altered by
     - number of scroll downs that were necessary to render array after each
       display
     - initial cursor position
    outputs:
     - 2D array to be rendered

    BaseRepl is mostly view-independent state of Repl - but self.width and
    self.height are important for figuring out how to wrap lines for example.
    Usually self.width and self.height should be set by receiving a window
    resize event, not manually set to anything - as long as the first event
    received is a window resize event, this works fine.

    Subclasses are responsible for implementing several methods.
    """

    def __init__(
        self,
        config: Config,
        window: CursorAwareWindow,
        locals_: Optional[Dict[str, Any]] = None,
        banner: Optional[str] = None,
        interp: Optional[Interp] = None,
        orig_tcattrs: Optional[List[Any]] = None,
    ):
        """
        locals_ is a mapping of locals to pass into the interpreter
        config is a bpython config.Struct with config attributes
        banner is a string to display briefly in the status bar
        interp is an interpreter instance to use
        original terminal state, useful for shelling out with normal terminal
        """

        logger.debug("starting init")
        self.window = window

        # If creating a new interpreter on undo would be unsafe because initial
        # state was passed in
        self.weak_rewind = bool(locals_ or interp)

        if interp is None:
            interp = Interp(locals=locals_)
            interp.write = self.send_to_stdouterr  # type: ignore
        if banner is None:
            if config.help_key:
                banner = (
                    _("Welcome to bpython!")
                    + " "
                    + _("Press <%s> for help.") % config.help_key
                )
            else:
                banner = None
        if config.cli_suggestion_width <= 0 or config.cli_suggestion_width > 1:
            config.cli_suggestion_width = 1

        self.reevaluating = False
        self.fake_refresh_requested = False

        self.status_bar = StatusBar(
            config,
            "",
            request_refresh=self.request_refresh,
            schedule_refresh=self.schedule_refresh,
        )
        self.edit_keys = edit_keys.mapping_with_config(config, key_dispatch)
        logger.debug("starting parent init")
        # interp is a subclass of repl.Interpreter, so it definitely,
        # implements the methods of Interpreter!
        super().__init__(interp, config)

        self.formatter = BPythonFormatter(config.color_scheme)

        # overwriting what bpython.Repl put there
        # interact is called to interact with the status bar,
        # so we're just using the same object
        self.interact = self.status_bar

        # logical line currently being edited, without ps1 (usually '>>> ')
        self._current_line = ""

        # current line of output - stdout and stdin go here
        self.current_stdouterr_line: Union[str, FmtStr] = ""

        # this is every line that's been displayed (input and output)
        # as with formatting applied. Logical lines that exceeded the terminal width
        # at the time of output are split across multiple entries in this list.
        self.display_lines: List[FmtStr] = []

        # this is every line that's been executed; it gets smaller on rewind
        self.history = []

        # This is every logical line that's been displayed, both input and output.
        # Like self.history, lines are unwrapped, uncolored, and without prompt.
        # Entries are tuples, where
        #   - the first element the line (string, not fmtsr)
        #   - the second element is one of 2 global constants: "input" or "output"
        #     (use LineType.INPUT or LineType.OUTPUT to avoid typing these strings)
        self.all_logical_lines: List[Tuple[str, LineType]] = []

        # formatted version of lines in the buffer kept around so we can
        # unhighlight parens using self.reprint_line as called by bpython.Repl
        self.display_buffer: List[FmtStr] = []

        # how many times display has been scrolled down
        # because there wasn't room to display everything
        self.scroll_offset = 0

        # cursor position relative to start of current_line, 0 is first char
        self._cursor_offset = 0

        self.orig_tcattrs: Optional[List[Any]] = orig_tcattrs

        self.coderunner = CodeRunner(self.interp, self.request_refresh)

        # filenos match the backing device for libs that expect it,
        # but writing to them will do weird things to the display
        self.stdout = FakeOutput(
            self.coderunner,
            self.send_to_stdouterr,
            real_fileobj=sys.__stdout__,
        )
        self.stderr = FakeOutput(
            self.coderunner,
            self.send_to_stdouterr,
            real_fileobj=sys.__stderr__,
        )
        self.stdin = FakeStdin(self.coderunner, self, self.edit_keys)

        # next paint should clear screen
        self.request_paint_to_clear_screen = False

        self.request_paint_to_pad_bottom = 0

        # offscreen command yields results different from scrollback buffer
        self.inconsistent_history = False

        # history error message has already been displayed
        self.history_already_messed_up = False

        # some commands act differently based on the prev event
        # this list doesn't include instances of event.Event,
        # only keypress-type events (no refresh screen events etc.)
        self.last_events: List[Optional[str]] = [None] * 50

        # displays prev events in a column on the right hand side
        self.presentation_mode = False

        self.paste_mode = False
        self.current_match = None
        self.list_win_visible = False
        # whether auto reloading active
        self.watching_files = config.default_autoreload

        self.incr_search_mode = SearchMode.NO_SEARCH
        self.incr_search_target = ""

        self.original_modules = set(sys.modules.keys())

        # as long as the first event received is a window resize event,
        # this works fine...
        try:
            self.width, self.height = os.get_terminal_size()
        except OSError:
            # this case will trigger during unit tests when stdout is redirected
            self.width = -1
            self.height = -1

        self.status_bar.message(banner)

        self.watcher = ModuleChangedEventHandler([], self.request_reload)
        if self.watcher and config.default_autoreload:
            self.watcher.activate()

    # The methods below should be overridden, but the default implementations
    # below can be used as well.

    def get_cursor_vertical_diff(self):
        """Return how the cursor moved due to a window size change"""
        return 0

    def get_top_usable_line(self):
        """Return the top line of display that can be rewritten"""
        return 0

    def get_term_hw(self):
        """Returns the current width and height of the display area."""
        return (50, 10)

    def _schedule_refresh(self, when: float):
        """Arrange for the bpython display to be refreshed soon.

        This method will be called when the Repl wants the display to be
        refreshed at a known point in the future, and as such it should
        interrupt a pending request to the user for input.

        Because the worst-case effect of not refreshing
        is only having an out of date UI until the user enters input, a
        default NOP implementation is provided."""

    # The methods below must be overridden in subclasses.

    def _request_refresh(self):
        """Arrange for the bpython display to be refreshed soon.

        This method will be called when the Repl wants to refresh the display,
        but wants control returned to it afterwards. (it is assumed that simply
        returning from process_event will cause an event refresh)

        The very next event received by process_event should be a
        RefreshRequestEvent."""
        raise NotImplementedError

    def _request_reload(self, files_modified: Sequence[str]) -> None:
        """Like request_refresh, but for reload requests events."""
        raise NotImplementedError

    def request_undo(self, n=1):
        """Like request_refresh, but for undo request events."""
        raise NotImplementedError

    def on_suspend(self):
        """Will be called on sigtstp.

        Do whatever cleanup would allow the user to use other programs."""
        raise NotImplementedError

    def after_suspend(self):
        """Will be called when process foregrounded after suspend.

        See to it that process_event is called with None to trigger a refresh
        if not in the middle of a process_event call when suspend happened."""
        raise NotImplementedError

    # end methods that should be overridden in subclass

    def request_refresh(self):
        """Request that the bpython display to be refreshed soon."""
        if self.reevaluating or self.paste_mode:
            self.fake_refresh_requested = True
        else:
            self._request_refresh()

    def request_reload(self, files_modified: Sequence[str] = ()) -> None:
        """Request that a ReloadEvent be passed next into process_event"""
        if self.watching_files:
            self._request_reload(files_modified)

    def schedule_refresh(self, when: float = 0) -> None:
        """Schedule a ScheduledRefreshRequestEvent for when.

        Such a event should interrupt if blocked waiting for keyboard input"""
        if self.reevaluating or self.paste_mode:
            self.fake_refresh_requested = True
        else:
            self._schedule_refresh(when=when)

    def __enter__(self):
        self.orig_stdout = sys.stdout
        self.orig_stderr = sys.stderr
        self.orig_stdin = sys.stdin
        sys.stdout = self.stdout
        sys.stderr = self.stderr
        sys.stdin = self.stdin
        self.orig_sigwinch_handler = signal.getsignal(signal.SIGWINCH)
        self.orig_sigtstp_handler = signal.getsignal(signal.SIGTSTP)

        if is_main_thread():
            # This turns off resize detection and ctrl-z suspension.
            signal.signal(signal.SIGWINCH, self.sigwinch_handler)
            signal.signal(signal.SIGTSTP, self.sigtstp_handler)

        self.orig_meta_path = sys.meta_path
        if self.watcher:
            meta_path = []
            for finder in sys.meta_path:
                meta_path.append(ImportFinder(self.watcher, finder))
            sys.meta_path = meta_path

        sitefix.monkeypatch_quit()
        return self

    def __exit__(
        self,
        exc_type: Optional[Type[BaseException]],
        exc_val: Optional[BaseException],
        exc_tb: Optional[TracebackType],
    ) -> Literal[False]:
        sys.stdin = self.orig_stdin
        sys.stdout = self.orig_stdout
        sys.stderr = self.orig_stderr

        if is_main_thread():
            # This turns off resize detection and ctrl-z suspension.
            signal.signal(signal.SIGWINCH, self.orig_sigwinch_handler)
            signal.signal(signal.SIGTSTP, self.orig_sigtstp_handler)

        sys.meta_path = self.orig_meta_path
        return False

    def sigwinch_handler(self, signum: int, frame: Optional[FrameType]) -> None:
        old_rows, old_columns = self.height, self.width
        self.height, self.width = self.get_term_hw()
        cursor_dy = self.get_cursor_vertical_diff()
        self.scroll_offset -= cursor_dy
        logger.info(
            "sigwinch! Changed from %r to %r",
            (old_rows, old_columns),
            (self.height, self.width),
        )
        logger.info(
            "decreasing scroll offset by %d to %d",
            cursor_dy,
            self.scroll_offset,
        )

    def sigtstp_handler(self, signum: int, frame: Optional[FrameType]) -> None:
        self.scroll_offset = len(self.lines_for_display)
        self.__exit__(None, None, None)
        self.on_suspend()
        os.kill(os.getpid(), signal.SIGTSTP)
        self.after_suspend()
        self.__enter__()

    def clean_up_current_line_for_exit(self):
        """Called when trying to exit to prep for final paint"""
        logger.debug("unhighlighting paren for exit")
        self.cursor_offset = -1
        self.unhighlight_paren()

    # Event handling
    def process_event(self, e: Union[events.Event, str]) -> Optional[bool]:
        """Returns True if shutting down, otherwise returns None.
        Mostly mutates state of Repl object"""

        logger.debug("processing event %r", e)
        if isinstance(e, events.Event):
            return self.process_control_event(e)
        else:
            self.last_events.append(e)
            self.last_events.pop(0)
            self.process_key_event(e)
            return None

    def process_control_event(self, e: events.Event) -> Optional[bool]:
        if isinstance(e, bpythonevents.ScheduledRefreshRequestEvent):
            # This is a scheduled refresh - it's really just a refresh (so nop)
            pass

        elif isinstance(e, bpythonevents.RefreshRequestEvent):
            logger.info("received ASAP refresh request event")
            if self.status_bar.has_focus:
                self.status_bar.process_event(e)
            else:
                assert self.coderunner.code_is_waiting
                self.run_code_and_maybe_finish()

        elif self.status_bar.has_focus:
            self.status_bar.process_event(e)

        # handles paste events for both stdin and repl
        elif isinstance(e, events.PasteEvent):
            ctrl_char = compress_paste_event(e)
            if ctrl_char is not None:
                return self.process_event(ctrl_char)
            with self.in_paste_mode():
                # Might not really be a paste, UI might just be lagging
                if len(e.events) <= MAX_EVENTS_POSSIBLY_NOT_PASTE and any(
                    not is_simple_event(ee) for ee in e.events
                ):
                    for ee in e.events:
                        if self.stdin.has_focus:
                            self.stdin.process_event(ee)
                        else:
                            self.process_event(ee)
                else:
                    simple_events = just_simple_events(e.events)
                    source = preprocess(
                        "".join(simple_events), self.interp.compile
                    )
                    for ee in source:
                        if self.stdin.has_focus:
                            self.stdin.process_event(ee)
                        else:
                            self.process_simple_keypress(ee)

        elif isinstance(e, bpythonevents.RunStartupFileEvent):
            try:
                self.startup()
            except OSError as err:
                self.status_bar.message(
                    _("Executing PYTHONSTARTUP failed: %s") % (err,)
                )

        elif isinstance(e, bpythonevents.UndoEvent):
            self.undo(n=e.n)

        elif self.stdin.has_focus:
            self.stdin.process_event(e)

        elif isinstance(e, events.SigIntEvent):
            logger.debug("received sigint event")
            self.keyboard_interrupt()

        elif isinstance(e, bpythonevents.ReloadEvent):
            if self.watching_files:
                self.clear_modules_and_reevaluate()
                self.status_bar.message(
                    _("Reloaded at %s because %s modified.")
                    % (time.strftime("%X"), " & ".join(e.files_modified))
                )

        else:
            raise ValueError("Don't know how to handle event type: %r" % e)
        return None

    def process_key_event(self, e: str) -> None:
        # To find the curtsies name for a keypress, try
        # python -m curtsies.events
        if self.status_bar.has_focus:
            return self.status_bar.process_event(e)
        if self.stdin.has_focus:
            return self.stdin.process_event(e)

        if (
            e
            in (
                key_dispatch[self.config.right_key]
                + key_dispatch[self.config.end_of_line_key]
                + ("<RIGHT>",)
            )
            and self.config.curtsies_right_arrow_completion
            and self.cursor_offset == len(self.current_line)
            # if at end of current line and user presses RIGHT (to autocomplete)
        ):
            # then autocomplete
            self.current_line += self.current_suggestion
            self.cursor_offset = len(self.current_line)
        elif e in ("<UP>",) + key_dispatch[self.config.up_one_line_key]:
            self.up_one_line()
        elif e in ("<DOWN>",) + key_dispatch[self.config.down_one_line_key]:
            self.down_one_line()
        elif e == "<Ctrl-d>":
            self.on_control_d()
        elif e == "<Ctrl-o>":
            self.operate_and_get_next()
        elif e == "<Esc+.>":
            self.get_last_word()
        elif e in key_dispatch[self.config.reverse_incremental_search_key]:
            self.incremental_search(reverse=True)
        elif e in key_dispatch[self.config.incremental_search_key]:
            self.incremental_search()
        elif (
            e in (("<BACKSPACE>",) + key_dispatch[self.config.backspace_key])
            and self.incr_search_mode != SearchMode.NO_SEARCH
        ):
            self.add_to_incremental_search(self, backspace=True)
        elif e in self.edit_keys.cut_buffer_edits:
            self.readline_kill(e)
        elif e in self.edit_keys.simple_edits:
            self.cursor_offset, self.current_line = self.edit_keys.call(
                e,
                cursor_offset=self.cursor_offset,
                line=self.current_line,
                cut_buffer=self.cut_buffer,
            )
        elif e in key_dispatch[self.config.cut_to_buffer_key]:
            self.cut_to_buffer()
        elif e in key_dispatch[self.config.reimport_key]:
            self.clear_modules_and_reevaluate()
        elif e in key_dispatch[self.config.toggle_file_watch_key]:
            self.toggle_file_watch()
        elif e in key_dispatch[self.config.clear_screen_key]:
            self.request_paint_to_clear_screen = True
        elif e in key_dispatch[self.config.show_source_key]:
            self.show_source()
        elif e in key_dispatch[self.config.help_key]:
            self.pager(self.help_text())
        elif e in key_dispatch[self.config.exit_key]:
            raise SystemExit()
        elif e in ("\n", "\r", "<PADENTER>", "<Ctrl-j>", "<Ctrl-m>"):
            self.on_enter()
        elif e == "<TAB>":  # tab
            self.on_tab()
        elif e == "<Shift-TAB>":
            self.on_tab(back=True)
        elif e in key_dispatch[self.config.undo_key]:  # ctrl-r for undo
            self.prompt_undo()
        elif e in key_dispatch[self.config.redo_key]:  # ctrl-g for redo
            self.redo()
        elif e in key_dispatch[self.config.save_key]:  # ctrl-s for save
            greenlet.greenlet(self.write2file).switch()
        elif e in key_dispatch[self.config.pastebin_key]:  # F8 for pastebin
            greenlet.greenlet(self.pastebin).switch()
        elif e in key_dispatch[self.config.copy_clipboard_key]:
            greenlet.greenlet(self.copy2clipboard).switch()
        elif e in key_dispatch[self.config.external_editor_key]:
            self.send_session_to_external_editor()
        elif e in key_dispatch[self.config.edit_config_key]:
            greenlet.greenlet(self.edit_config).switch()
        # TODO add PAD keys hack as in bpython.cli
        elif e in key_dispatch[self.config.edit_current_block_key]:
            self.send_current_block_to_external_editor()
        elif e == "<ESC>":
            self.incr_search_mode = SearchMode.NO_SEARCH
        elif e == "<SPACE>":
            self.add_normal_character(" ")
        elif e in CHARACTER_PAIR_MAP.keys():
            if e in ["'", '"']:
                if self.is_closing_quote(e):
                    self.insert_char_pair_end(e)
                else:
                    self.insert_char_pair_start(e)
            else:
                self.insert_char_pair_start(e)
        elif e in CHARACTER_PAIR_MAP.values():
            self.insert_char_pair_end(e)
        else:
            self.add_normal_character(e)

    def is_closing_quote(self, e: str) -> bool:
        char_count = self._current_line.count(e)
        return (
            char_count % 2 == 0
            and cursor_on_closing_char_pair(
                self._cursor_offset, self._current_line, e
            )[0]
        )

    def insert_char_pair_start(self, e):
        """Accepts character which is a part of CHARACTER_PAIR_MAP
        like brackets and quotes, and appends it to the line with
        an appropriate character pair ending. Closing character can only be inserted
        when the next character is either a closing character or a space

        e.x. if you type "(" (lparen) , this will insert "()"
        into the line
        """
        self.add_normal_character(e)
        if self.config.brackets_completion:
            start_of_line = len(self._current_line) == 1
            end_of_line = len(self._current_line) == self._cursor_offset
            can_lookup_next = len(self._current_line) > self._cursor_offset
            next_char = (
                None
                if not can_lookup_next
                else self._current_line[self._cursor_offset]
            )
            if (
                start_of_line
                or end_of_line
                or (next_char is not None and next_char in "})] ")
            ):
                self.add_normal_character(
                    CHARACTER_PAIR_MAP[e], narrow_search=False
                )
                self._cursor_offset -= 1

    def insert_char_pair_end(self, e):
        """Accepts character which is a part of CHARACTER_PAIR_MAP
        like brackets and quotes, and checks whether it should be
        inserted to the line or overwritten

        e.x. if you type ")" (rparen) , and your cursor is directly
        above another ")" (rparen) in the cmd, this will just skip
        it and move the cursor.
        If there is no same character underneath the cursor, the
        character will be printed/appended to the line
        """
        if self.config.brackets_completion:
            if self.cursor_offset < len(self._current_line):
                if self._current_line[self.cursor_offset] == e:
                    self.cursor_offset += 1
                    return
        self.add_normal_character(e)

    def get_last_word(self):

        previous_word = _last_word(self.rl_history.entry)
        word = _last_word(self.rl_history.back())
        line = self.current_line
        self._set_current_line(
            line[: len(line) - len(previous_word)] + word,
            reset_rl_history=False,
        )
        self._set_cursor_offset(
            self.cursor_offset - len(previous_word) + len(word),
            reset_rl_history=False,
        )

    def incremental_search(self, reverse=False, include_current=False):
        if self.incr_search_mode == SearchMode.NO_SEARCH:
            self.rl_history.enter(self.current_line)
            self.incr_search_target = ""
        else:
            if self.incr_search_target:
                line = (
                    self.rl_history.back(
                        False,
                        search=True,
                        target=self.incr_search_target,
                        include_current=include_current,
                    )
                    if reverse
                    else self.rl_history.forward(
                        False,
                        search=True,
                        target=self.incr_search_target,
                        include_current=include_current,
                    )
                )
                self._set_current_line(
                    line, reset_rl_history=False, clear_special_mode=False
                )
                self._set_cursor_offset(
                    len(self.current_line),
                    reset_rl_history=False,
                    clear_special_mode=False,
                )
        if reverse:
            self.incr_search_mode = SearchMode.REVERSE_INCREMENTAL_SEARCH
        else:
            self.incr_search_mode = SearchMode.INCREMENTAL_SEARCH

    def readline_kill(self, e):
        func = self.edit_keys[e]
        self.cursor_offset, self.current_line, cut = func(
            self.cursor_offset, self.current_line
        )
        if self.last_events[-2] == e:  # consecutive kill commands accumulative
            if func.kills == "ahead":
                self.cut_buffer += cut
            elif func.kills == "behind":
                self.cut_buffer = cut + self.cut_buffer
            else:
                raise ValueError("cut value other than 'ahead' or 'behind'")
        else:
            self.cut_buffer = cut

    def on_enter(self, new_code=True, reset_rl_history=True):
        # so the cursor isn't touching a paren TODO: necessary?
        if new_code:
            self.redo_stack = []

        self._set_cursor_offset(-1, update_completion=False)
        if reset_rl_history:
            self.rl_history.reset()

        self.history.append(self.current_line)
        self.all_logical_lines.append((self.current_line, LineType.INPUT))
        self.push(self.current_line, insert_into_history=new_code)

    def on_tab(self, back=False):
        """Do something on tab key
        taken from bpython.cli

        Does one of the following:
        1) add space to move up to the next %4==0 column
        2) complete the current word with characters common to all completions
        3) select the first or last match
        4) select the next or previous match if already have a match
        """

        def only_whitespace_left_of_cursor():
            """returns true if all characters before cursor are whitespace"""
            return not self.current_line[: self.cursor_offset].strip()

        logger.debug("self.matches_iter.matches: %r", self.matches_iter.matches)
        if only_whitespace_left_of_cursor():
            front_ws = len(self.current_line[: self.cursor_offset]) - len(
                self.current_line[: self.cursor_offset].lstrip()
            )
            to_add = 4 - (front_ws % self.config.tab_length)
            for unused in range(to_add):
                self.add_normal_character(" ")
            return
        # if cursor on closing character from pair,
        # moves cursor behind it on tab
        # ? should we leave it here as default?
        if self.config.brackets_completion:
            on_closing_char, _ = cursor_on_closing_char_pair(
                self._cursor_offset, self._current_line
            )
            if on_closing_char:
                self._cursor_offset += 1
        # run complete() if we don't already have matches
        if len(self.matches_iter.matches) == 0:
            self.list_win_visible = self.complete(tab=True)

        # 3. check to see if we can expand the current word
        if self.matches_iter.is_cseq():
            cursor_and_line = self.matches_iter.substitute_cseq()
            self._cursor_offset, self._current_line = cursor_and_line
            # using _current_line so we don't trigger a completion reset
            if not self.matches_iter.matches:
                self.list_win_visible = self.complete()
        elif self.matches_iter.matches:
            self.current_match = (
                back and self.matches_iter.previous() or next(self.matches_iter)
            )
            cursor_and_line = self.matches_iter.cur_line()
            self._cursor_offset, self._current_line = cursor_and_line
            # using _current_line so we don't trigger a completion reset
            self.list_win_visible = True
        if self.config.brackets_completion:
            # appends closing char pair if completion is a callable
            if self.is_completion_callable(self._current_line):
                self._current_line = self.append_closing_character(
                    self._current_line
                )

    def is_completion_callable(self, completion):
        """Checks whether given completion is callable (e.x. function)"""
        completion_end = completion[-1]
        return completion_end in CHARACTER_PAIR_MAP

    def append_closing_character(self, completion):
        """Appends closing character/bracket to the completion"""
        completion_end = completion[-1]
        if completion_end in CHARACTER_PAIR_MAP:
            completion = f"{completion}{CHARACTER_PAIR_MAP[completion_end]}"
        return completion

    def on_control_d(self):
        if self.current_line == "":
            raise SystemExit()
        else:
            self.current_line = (
                self.current_line[: self.cursor_offset]
                + self.current_line[(self.cursor_offset + 1) :]
            )

    def cut_to_buffer(self):
        self.cut_buffer = self.current_line[self.cursor_offset :]
        self.current_line = self.current_line[: self.cursor_offset]

    def yank_from_buffer(self):
        pass

    def operate_and_get_next(self):
        # If we have not navigated back in history
        # ctrl+o will have the same effect as enter
        self.on_enter(reset_rl_history=False)

    def up_one_line(self):
        self.rl_history.enter(self.current_line)
        self._set_current_line(
            tabs_to_spaces(
                self.rl_history.back(
                    False, search=self.config.curtsies_right_arrow_completion
                )
            ),
            update_completion=False,
            reset_rl_history=False,
        )
        self._set_cursor_offset(len(self.current_line), reset_rl_history=False)

    def down_one_line(self):
        self.rl_history.enter(self.current_line)
        self._set_current_line(
            tabs_to_spaces(
                self.rl_history.forward(
                    False, search=self.config.curtsies_right_arrow_completion
                )
            ),
            update_completion=False,
            reset_rl_history=False,
        )
        self._set_cursor_offset(len(self.current_line), reset_rl_history=False)

    def process_simple_keypress(self, e: str):
        # '\n' needed for pastes
        if e in ("<Ctrl-j>", "<Ctrl-m>", "<PADENTER>", "\n", "\r"):
            self.on_enter()
            while self.fake_refresh_requested:
                self.fake_refresh_requested = False
                self.process_event(bpythonevents.RefreshRequestEvent())
        elif isinstance(e, events.Event):
            pass  # ignore events
        elif e == "<SPACE>":
            self.add_normal_character(" ")
        else:
            self.add_normal_character(e)

    def send_current_block_to_external_editor(self, filename=None):
        """
        Sends the current code block to external editor to be edited. Usually bound to C-x.
        """
        text = self.send_to_external_editor(self.get_current_block())
        lines = [line for line in text.split("\n")]
        while lines and not lines[-1].split():
            lines.pop()
        events = "\n".join(lines + ([""] if len(lines) == 1 else ["", ""]))
        self.clear_current_block()
        with self.in_paste_mode():
            for e in events:
                self.process_simple_keypress(e)
        self.cursor_offset = len(self.current_line)

    def send_session_to_external_editor(self, filename=None):
        """
        Sends entire bpython session to external editor to be edited. Usually bound to F7.
        """
        for_editor = EDIT_SESSION_HEADER
        for_editor += self.get_session_formatted_for_file()

        text = self.send_to_external_editor(for_editor)
        if text == for_editor:
            self.status_bar.message(
                _("Session not reevaluated because it was not edited")
            )
            return
        lines = text.split("\n")
        if len(lines) and not lines[-1].strip():
            lines.pop()  # strip last line if empty
        if len(lines) and lines[-1].startswith("### "):
            current_line = lines[-1][4:]
        else:
            current_line = ""
        from_editor = [
            line for line in lines if line[:6] != "# OUT:" and line[:3] != "###"
        ]
        if all(not line.strip() for line in from_editor):
            self.status_bar.message(
                _("Session not reevaluated because saved file was blank")
            )
            return

        source = preprocess("\n".join(from_editor), self.interp.compile)
        lines = source.split("\n")
        self.history = lines
        self.reevaluate(new_code=True)
        self.current_line = current_line
        self.cursor_offset = len(self.current_line)
        self.status_bar.message(_("Session edited and reevaluated"))

    def clear_modules_and_reevaluate(self):
        if self.watcher:
            self.watcher.reset()
        cursor, line = self.cursor_offset, self.current_line
        for modname in set(sys.modules.keys()) - self.original_modules:
            del sys.modules[modname]
        self.reevaluate(new_code=False)
        self.cursor_offset, self.current_line = cursor, line
        self.status_bar.message(
            _("Reloaded at %s by user.") % (time.strftime("%X"),)
        )

    def toggle_file_watch(self):
        if self.watcher:
            if self.watching_files:
                msg = _("Auto-reloading deactivated.")
                self.status_bar.message(msg)
                self.watcher.deactivate()
                self.watching_files = False
            else:
                msg = _("Auto-reloading active, watching for file changes...")
                self.status_bar.message(msg)
                self.watching_files = True
                self.watcher.activate()
        else:
            self.status_bar.message(
                _(
                    "Auto-reloading not available because "
                    "watchdog not installed."
                )
            )

    # Handler Helpers
    def add_normal_character(self, char, narrow_search=True):
        if len(char) > 1 or is_nop(char):
            return
        if self.incr_search_mode != SearchMode.NO_SEARCH:
            self.add_to_incremental_search(char)
        else:
            self._set_current_line(
                (
                    self.current_line[: self.cursor_offset]
                    + char
                    + self.current_line[self.cursor_offset :]
                ),
                update_completion=False,
                reset_rl_history=False,
                clear_special_mode=False,
            )
            if narrow_search:
                self.cursor_offset += 1
            else:
                self._cursor_offset += 1
        if self.config.cli_trim_prompts and self.current_line.startswith(
            self.ps1
        ):
            self.current_line = self.current_line[4:]
            if narrow_search:
                self.cursor_offset = max(0, self.cursor_offset - 4)
            else:
                self._cursor_offset += max(0, self.cursor_offset - 4)

    def add_to_incremental_search(self, char=None, backspace=False):
        """Modify the current search term while in incremental search.

        The only operations allowed in incremental search mode are
        adding characters and backspacing."""
        if backspace:
            self.incr_search_target = self.incr_search_target[:-1]
        elif char is not None:
            self.incr_search_target += char
        else:
            raise ValueError("must provide a char or set backspace to True")
        if self.incr_search_mode == SearchMode.REVERSE_INCREMENTAL_SEARCH:
            self.incremental_search(reverse=True, include_current=True)
        elif self.incr_search_mode == SearchMode.INCREMENTAL_SEARCH:
            self.incremental_search(include_current=True)
        else:
            raise ValueError("add_to_incremental_search not in a special mode")

    def update_completion(self, tab=False):
        """Update visible docstring and matches and box visibility"""
        # Update autocomplete info; self.matches_iter and self.funcprops
        # Should be called whenever the completion box might need to appear
        # or disappear; whenever current line or cursor offset changes,
        # unless this happened via selecting a match
        self.current_match = None
        self.list_win_visible = self.complete(tab)

    def predicted_indent(self, line):
        # TODO get rid of this! It's repeated code! Combine with Repl.
        logger.debug("line is %r", line)
        indent = len(re.match(r"[ ]*", line).group())
        if line.endswith(":"):
            indent = max(0, indent + self.config.tab_length)
        elif line and line.count(" ") == len(line):
            indent = max(0, indent - self.config.tab_length)
        elif (
            line
            and ":" not in line
            and line.strip().startswith(
                ("return", "pass", "...", "raise", "yield", "break", "continue")
            )
        ):
            indent = max(0, indent - self.config.tab_length)
        logger.debug("indent we found was %s", indent)
        return indent

    def push(self, line, insert_into_history=True):
        """Push a line of code onto the buffer, start running the buffer

        If the interpreter successfully runs the code, clear the buffer
        """
        # Note that push() overrides its parent without calling it, unlike
        # urwid and cli which implement custom behavior and call repl.Repl.push
        if self.paste_mode:
            self.saved_indent = 0
        else:
            self.saved_indent = self.predicted_indent(line)

        if self.config.syntax:
            display_line = bpythonparse(
                pygformat(self.tokenize(line), self.formatter)
            )
            # self.tokenize requires that the line not be in self.buffer yet

            logger.debug(
                "display line being pushed to buffer: %r -> %r",
                line,
                display_line,
            )
            self.display_buffer.append(display_line)
        else:
            self.display_buffer.append(fmtstr(line))

        if insert_into_history:
            self.insert_into_history(line)
        self.buffer.append(line)

        code_to_run = "\n".join(self.buffer)

        logger.debug("running %r in interpreter", self.buffer)
        c, code_will_parse = code_finished_will_parse(
            "\n".join(self.buffer), self.interp.compile
        )
        self.saved_predicted_parse_error = not code_will_parse
        if c:
            logger.debug("finished - buffer cleared")
            self.cursor_offset = 0
            self.display_lines.extend(self.display_buffer_lines)
            self.display_buffer = []
            self.buffer = []

        self.coderunner.load_code(code_to_run)
        self.run_code_and_maybe_finish()

    def run_code_and_maybe_finish(self, for_code=None):
        r = self.coderunner.run_code(for_code=for_code)
        if r:
            logger.debug("----- Running finish command stuff -----")
            logger.debug("saved_indent: %r", self.saved_indent)
            err = self.saved_predicted_parse_error
            self.saved_predicted_parse_error = False

            indent = self.saved_indent
            if err:
                indent = 0

            if self.rl_history.index == 0:
                self._set_current_line(" " * indent, update_completion=True)
            else:
                self._set_current_line(
                    self.rl_history.entries[-self.rl_history.index],
                    reset_rl_history=False,
                )
            self.cursor_offset = len(self.current_line)

    def keyboard_interrupt(self):
        # TODO factor out the common cleanup from running a line
        self.cursor_offset = -1
        self.unhighlight_paren()
        self.display_lines.extend(self.display_buffer_lines)
        self.display_lines.extend(
            paint.display_linize(self.current_cursor_line, self.width)
        )
        self.display_lines.extend(
            paint.display_linize("KeyboardInterrupt", self.width)
        )
        self.clear_current_block(remove_from_history=False)

    def unhighlight_paren(self):
        """Modify line in self.display_buffer to unhighlight a paren if
        possible.

        self.highlighted_paren should be a line in ?
        """
        if self.highlighted_paren is not None and self.config.syntax:
            lineno, saved_tokens = self.highlighted_paren
            if lineno == len(self.display_buffer):
                # then this is the current line, so don't worry about it
                return
            self.highlighted_paren = None
            logger.debug("trying to unhighlight a paren on line %r", lineno)
            logger.debug("with these tokens: %r", saved_tokens)
            new = bpythonparse(pygformat(saved_tokens, self.formatter))
            self.display_buffer[lineno] = self.display_buffer[
                lineno
            ].setslice_with_length(
                0, len(new), new, len(self.display_buffer[lineno])
            )

    def clear_current_block(self, remove_from_history=True):
        self.display_buffer = []
        if remove_from_history:
            del self.history[-len(self.buffer) :]
            del self.all_logical_lines[-len(self.buffer) :]
        self.buffer = []
        self.cursor_offset = 0
        self.saved_indent = 0
        self.current_line = ""
        self.cursor_offset = len(self.current_line)

    def get_current_block(self):
        """
        Returns the current code block as string (without prompts)
        """
        return "\n".join(self.buffer + [self.current_line])

    def send_to_stdouterr(self, output):
        """Send unicode strings or FmtStr to Repl stdout or stderr

        Must be able to handle FmtStrs because interpreter pass in
        tracebacks already formatted."""
        lines = output.split("\n")
        logger.debug("display_lines: %r", self.display_lines)
        self.current_stdouterr_line += lines[0]
        if len(lines) > 1:
            self.display_lines.extend(
                paint.display_linize(
                    self.current_stdouterr_line, self.width, blank_line=True
                )
            )
            self.display_lines.extend(
                sum(
                    (
                        paint.display_linize(line, self.width, blank_line=True)
                        for line in lines[1:-1]
                    ),
                    [],
                )
            )
            # These can be FmtStrs, but self.all_logical_lines only wants strings
            for line in itertools.chain(
                (self.current_stdouterr_line,), lines[1:-1]
            ):
                if isinstance(line, FmtStr):
                    self.all_logical_lines.append((line.s, LineType.OUTPUT))
                else:
                    self.all_logical_lines.append((line, LineType.OUTPUT))

            self.current_stdouterr_line = lines[-1]
        logger.debug("display_lines: %r", self.display_lines)

    def send_to_stdin(self, line):
        if line.endswith("\n"):
            self.display_lines.extend(
                paint.display_linize(self.current_output_line, self.width)
            )
            self.current_output_line = ""

    # formatting, output
    @property
    def done(self):
        """Whether the last block is complete - which prompt to use, ps1 or
        ps2"""
        return not self.buffer

    @property
    def current_line_formatted(self):
        """The colored current line (no prompt, not wrapped)"""
        if self.config.syntax:
            fs = bpythonparse(
                pygformat(self.tokenize(self.current_line), self.formatter)
            )
            if self.incr_search_mode != SearchMode.NO_SEARCH:
                if self.incr_search_target in self.current_line:
                    fs = fmtfuncs.on_magenta(self.incr_search_target).join(
                        fs.split(self.incr_search_target)
                    )
            elif (
                self.rl_history.saved_line
                and self.rl_history.saved_line in self.current_line
            ):
                if (
                    self.config.curtsies_right_arrow_completion
                    and self.rl_history.index != 0
                ):
                    fs = fmtfuncs.on_magenta(self.rl_history.saved_line).join(
                        fs.split(self.rl_history.saved_line)
                    )
            logger.debug("Display line %r -> %r", self.current_line, fs)
        else:
            fs = fmtstr(self.current_line)
        if hasattr(self, "old_fs") and str(fs) != str(self.old_fs):
            pass
        self.old_fs = fs
        return fs

    @property
    def lines_for_display(self):
        """All display lines (wrapped, colored, with prompts)"""
        return self.display_lines + self.display_buffer_lines

    @property
    def display_buffer_lines(self):
        """The display lines (wrapped, colored, +prompts) of current buffer"""
        lines = []
        for display_line in self.display_buffer:
            prompt = func_for_letter(self.config.color_scheme["prompt"])
            more = func_for_letter(self.config.color_scheme["prompt_more"])
            display_line = (
                more(self.ps2) if lines else prompt(self.ps1)
            ) + display_line
            for line in paint.display_linize(display_line, self.width):
                lines.append(line)
        return lines

    @property
    def display_line_with_prompt(self):
        """colored line with prompt"""
        prompt = func_for_letter(self.config.color_scheme["prompt"])
        more = func_for_letter(self.config.color_scheme["prompt_more"])
        if self.incr_search_mode == SearchMode.REVERSE_INCREMENTAL_SEARCH:
            return (
                prompt(f"(reverse-i-search)`{self.incr_search_target}': ")
                + self.current_line_formatted
            )
        elif self.incr_search_mode == SearchMode.INCREMENTAL_SEARCH:
            return prompt(f"(i-search)`%s': ") + self.current_line_formatted
        return (
            prompt(self.ps1) if self.done else more(self.ps2)
        ) + self.current_line_formatted

    @property
    def current_cursor_line_without_suggestion(self):
        """
        Current line, either output/input or Python prompt + code

        :returns: FmtStr
        """
        value = self.current_output_line + (
            "" if self.coderunner.running else self.display_line_with_prompt
        )
        logger.debug("current cursor line: %r", value)
        return value

    @property
    def current_cursor_line(self):
        if self.config.curtsies_right_arrow_completion:
            suggest = func_for_letter(
                self.config.color_scheme["right_arrow_suggestion"]
            )
            return self.current_cursor_line_without_suggestion + suggest(
                self.current_suggestion
            )
        else:
            return self.current_cursor_line_without_suggestion

    @property
    def current_suggestion(self):
        if self.current_line:
            for entry in reversed(self.rl_history.entries):
                if entry.startswith(self.current_line):
                    return entry[len(self.current_line) :]
        return ""

    @property
    def current_output_line(self):
        """line of output currently being written, and stdin typed"""
        return self.current_stdouterr_line + self.stdin.current_line

    @current_output_line.setter
    def current_output_line(self, value):
        self.current_stdouterr_line = ""
        self.stdin.current_line = "\n"

    def number_of_padding_chars_on_current_cursor_line(self):
        """To avoid cutting off two-column characters at the end of lines where
        there's only one column left, curtsies adds a padding char (u' ').
        It's important to know about these for cursor positioning.

        Should return zero unless there are fullwidth characters."""
        full_line = self.current_cursor_line_without_suggestion
        line_with_padding_len = sum(
            len(line.s)
            for line in paint.display_linize(
                self.current_cursor_line_without_suggestion.s, self.width
            )
        )

        # the difference in length here is how much padding there is
        return line_with_padding_len - len(full_line)

    def paint(
        self,
        about_to_exit=False,
        user_quit=False,
        try_preserve_history_height=30,
        min_infobox_height=5,
    ) -> Tuple[FSArray, Tuple[int, int]]:
        """Returns an array of min_height or more rows and width columns, plus
        cursor position

        Paints the entire screen - ideally the terminal display layer will take
        a diff and only write to the screen in portions that have changed, but
        the idea is that we don't need to worry about that here, instead every
        frame is completely redrawn because less state is cool!

        try_preserve_history_height is the the number of rows of content that
        must be visible before the suggestion box scrolls the terminal in order
        to display more than min_infobox_height rows of suggestions, docs etc.
        """
        # The hairiest function in the curtsies
        if about_to_exit:
            # exception to not changing state!
            self.clean_up_current_line_for_exit()

        width, min_height = self.width, self.height
        show_status_bar = (
            bool(self.status_bar.should_show_message)
            or self.status_bar.has_focus
        ) and not self.request_paint_to_pad_bottom
        if show_status_bar:
            # because we're going to tack the status bar on at the end, shoot
            # for an array one less than the height of the screen
            min_height -= 1

        current_line_start_row = len(self.lines_for_display) - max(
            0, self.scroll_offset
        )
        # TODO how is the situation of self.scroll_offset < 0 possible?
        # or show_status_bar and about_to_exit ?
        if self.request_paint_to_clear_screen:
            self.request_paint_to_clear_screen = False
            arr = FSArray(min_height + current_line_start_row, width)
        elif self.request_paint_to_pad_bottom:
            # min_height - 1 for startup banner with python version
            height = min(self.request_paint_to_pad_bottom, min_height - 1)
            arr = FSArray(height, width)
            self.request_paint_to_pad_bottom = 0
        else:
            arr = FSArray(0, width)
        # TODO test case of current line filling up the whole screen (there
        # aren't enough rows to show it)

        current_line = paint.paint_current_line(
            min_height, width, self.current_cursor_line
        )
        # needs to happen before we calculate contents of history because
        # calculating self.current_cursor_line has the side effect of
        # unhighlighting parens in buffer

        def move_screen_up(current_line_start_row):
            # move screen back up a screen minus a line
            while current_line_start_row < 0:
                logger.debug(
                    "scroll_offset was %s, current_line_start_row " "was %s",
                    self.scroll_offset,
                    current_line_start_row,
                )
                self.scroll_offset = self.scroll_offset - self.height
                current_line_start_row = len(self.lines_for_display) - max(
                    -1, self.scroll_offset
                )
                logger.debug(
                    "scroll_offset changed to %s, "
                    "current_line_start_row changed to %s",
                    self.scroll_offset,
                    current_line_start_row,
                )
            return current_line_start_row

        if self.inconsistent_history and not self.history_already_messed_up:
            logger.debug(INCONSISTENT_HISTORY_MSG)
            self.history_already_messed_up = True
            msg = INCONSISTENT_HISTORY_MSG
            arr[0, 0 : min(len(msg), width)] = [msg[:width]]
            current_line_start_row += 1  # for the message

            # to make up for the scroll that will be received after the
            # scrolls are rendered down a line
            self.scroll_offset -= 1

            current_line_start_row = move_screen_up(current_line_start_row)
            logger.debug("current_line_start_row: %r", current_line_start_row)

            history = paint.paint_history(
                max(0, current_line_start_row - 1),
                width,
                self.lines_for_display,
            )
            arr[1 : history.height + 1, : history.width] = history

            if arr.height <= min_height:
                # force scroll down to hide broken history message
                arr[min_height, 0] = " "

        elif current_line_start_row < 0:
            # if current line trying to be drawn off the top of the screen
            logger.debug(CONTIGUITY_BROKEN_MSG)
            msg = CONTIGUITY_BROKEN_MSG
            arr[0, 0 : min(len(msg), width)] = [msg[:width]]

            current_line_start_row = move_screen_up(current_line_start_row)

            history = paint.paint_history(
                max(0, current_line_start_row - 1),
                width,
                self.lines_for_display,
            )
            arr[1 : history.height + 1, : history.width] = history

            if arr.height <= min_height:
                # force scroll down to hide broken history message
                arr[min_height, 0] = " "

        else:
            assert current_line_start_row >= 0
            logger.debug("no history issues. start %i", current_line_start_row)
            history = paint.paint_history(
                current_line_start_row, width, self.lines_for_display
            )
            arr[: history.height, : history.width] = history

        self.inconsistent_history = False

        if user_quit:  # quit() or exit() in interp
            current_line_start_row = (
                current_line_start_row - current_line.height
            )
        logger.debug(
            "---current line row slice %r, %r",
            current_line_start_row,
            current_line_start_row + current_line.height,
        )
        logger.debug("---current line col slice %r, %r", 0, current_line.width)
        arr[
            current_line_start_row : (
                current_line_start_row + current_line.height
            ),
            0 : current_line.width,
        ] = current_line

        if current_line.height > min_height:
            return arr, (0, 0)  # short circuit, no room for infobox

        lines = paint.display_linize(self.current_cursor_line + "X", width)
        # extra character for space for the cursor
        current_line_end_row = current_line_start_row + len(lines) - 1
        current_line_height = current_line_end_row - current_line_start_row

        if self.stdin.has_focus:
            logger.debug(
                "stdouterr when self.stdin has focus: %r %r",
                type(self.current_stdouterr_line),
                self.current_stdouterr_line,
            )
            # mypy can't do ternary type guards yet
            stdouterr = self.current_stdouterr_line
            if isinstance(stdouterr, FmtStr):
                stdouterr_width = stdouterr.width
            else:
                stdouterr_width = len(stdouterr)
            cursor_row, cursor_column = divmod(
                stdouterr_width
                + wcswidth(
                    self.stdin.current_line, max(0, self.stdin.cursor_offset)
                ),
                width,
            )
            assert cursor_row >= 0 and cursor_column >= 0, (
                cursor_row,
                cursor_column,
                self.current_stdouterr_line,
                self.stdin.current_line,
            )
        elif self.coderunner.running:  # TODO does this ever happen?
            cursor_row, cursor_column = divmod(
                len(self.current_cursor_line_without_suggestion)
                + self.cursor_offset,
                width,
            )
            assert cursor_row >= 0 and cursor_column >= 0, (
                cursor_row,
                cursor_column,
                len(self.current_cursor_line),
                len(self.current_line),
                self.cursor_offset,
            )
        else:  # Common case for determining cursor position
            cursor_row, cursor_column = divmod(
                wcswidth(self.current_cursor_line_without_suggestion.s)
                - wcswidth(self.current_line)
                + wcswidth(self.current_line, max(0, self.cursor_offset))
                + self.number_of_padding_chars_on_current_cursor_line(),
                width,
            )
            assert cursor_row >= 0 and cursor_column >= 0, (
                cursor_row,
                cursor_column,
                self.current_cursor_line_without_suggestion.s,
                self.current_line,
                self.cursor_offset,
            )
        cursor_row += current_line_start_row

        if self.list_win_visible and not self.coderunner.running:
            logger.debug("infobox display code running")
            visible_space_above = history.height
            potential_space_below = min_height - current_line_end_row - 1
            visible_space_below = (
                potential_space_below - self.get_top_usable_line()
            )

            if self.config.curtsies_list_above:
                info_max_rows = max(visible_space_above, visible_space_below)
            else:
                # Logic for determining size of completion box
                # smallest allowed over-full completion box
                preferred_height = max(
                    # always make infobox at least this height
                    min_infobox_height,
                    # use this value if there's so much space that we can
                    # preserve this try_preserve_history_height rows history
                    min_height - try_preserve_history_height,
                )

                info_max_rows = min(
                    max(visible_space_below, preferred_height),
                    min_height - current_line_height - 1,
                )
            infobox = paint.paint_infobox(
                info_max_rows,
                int(width * self.config.cli_suggestion_width),
                self.matches_iter.matches,
                self.funcprops,
                self.arg_pos,
                self.current_match,
                self.docstring,
                self.config,
                self.matches_iter.completer.format
                if self.matches_iter.completer
                else None,
            )

            if (
                visible_space_below >= infobox.height
                or not self.config.curtsies_list_above
            ):
                arr[
                    current_line_end_row
                    + 1 : (current_line_end_row + 1 + infobox.height),
                    0 : infobox.width,
                ] = infobox
            else:
                arr[
                    current_line_start_row
                    - infobox.height : current_line_start_row,
                    0 : infobox.width,
                ] = infobox
                logger.debug(
                    "infobox of shape %r added to arr of shape %r",
                    infobox.shape,
                    arr.shape,
                )

        logger.debug("about to exit: %r", about_to_exit)
        if show_status_bar:
            statusbar_row = (
                min_height if arr.height == min_height else arr.height
            )
            if about_to_exit:
                arr[statusbar_row, :] = FSArray(1, width)
            else:
                arr[statusbar_row, :] = paint.paint_statusbar(
                    1, width, self.status_bar.current_line, self.config
                )

        if self.presentation_mode:
            rows = arr.height
            columns = arr.width
            last_key_box = paint.paint_last_events(
                rows,
                columns,
                [events.pp_event(x) for x in self.last_events if x],
                self.config,
            )
            arr[
                arr.height - last_key_box.height : arr.height,
                arr.width - last_key_box.width : arr.width,
            ] = last_key_box

        if self.config.color_scheme["background"] not in ("d", "D"):
            for r in range(arr.height):
                bg = color_for_letter(self.config.color_scheme["background"])
                arr[r] = fmtstr(arr[r], bg=bg)
        logger.debug("returning arr of size %r", arr.shape)
        logger.debug("cursor pos: %r", (cursor_row, cursor_column))
        return arr, (cursor_row, cursor_column)

    @contextlib.contextmanager
    def in_paste_mode(self):
        orig_value = self.paste_mode
        self.paste_mode = True
        yield
        self.paste_mode = orig_value
        if not self.paste_mode:
            self.update_completion()

    def __repr__(self):
        return f"""<{type(self)}
  cursor_offset: {self.cursor_offset}
  num display lines: {len(self.display_lines)}
  lines scrolled down: {self.scroll_offset}
>"""

    def _get_current_line(self) -> str:
        """The current line"""
        return self._current_line

    def _set_current_line(
        self,
        line: str,
        update_completion=True,
        reset_rl_history=True,
        clear_special_mode=True,
    ):
        if self._current_line == line:
            return
        self._current_line = line
        if self.paste_mode:
            return
        if update_completion:
            self.update_completion()
        if reset_rl_history:
            self.rl_history.reset()
        if clear_special_mode:
            self.special_mode = None
        self.unhighlight_paren()

    def _get_cursor_offset(self) -> int:
        """The current cursor offset from the front of the "line"."""
        return self._cursor_offset

    def _set_cursor_offset(
        self,
        offset: int,
        update_completion=True,
        reset_rl_history=False,
        clear_special_mode=True,
    ):
        if self._cursor_offset == offset:
            return
        if self.paste_mode:
            self._cursor_offset = offset
            self.unhighlight_paren()
            return
        if reset_rl_history:
            self.rl_history.reset()
        if clear_special_mode:
            self.incr_search_mode = SearchMode.NO_SEARCH
        self._cursor_offset = offset
        if update_completion:
            self.update_completion()
        self.unhighlight_paren()

    def echo(self, msg, redraw=True):
        """
        Notification that redrawing the current line is necessary (we don't
        care, since we always redraw the whole screen)

        Supposed to parse and echo a formatted string with appropriate
        attributes. It's not supposed to update the screen if it's reevaluating
        the code (as it does with undo)."""
        logger.debug("echo called with %r" % msg)

    @property
    def cpos(self):
        "many WATs were had - it's the pos from the end of the line back"
        return len(self.current_line) - self.cursor_offset

    def reprint_line(self, lineno, tokens):
        logger.debug("calling reprint line with %r %r", lineno, tokens)
        if self.config.syntax:
            self.display_buffer[lineno] = bpythonparse(
                pygformat(tokens, self.formatter)
            )

    def take_back_buffer_line(self):
        assert len(self.buffer) > 0
        if len(self.buffer) == 1:
            self._cursor_offset = 0
            self.current_line = ""
        else:
            line = self.buffer[-1]
            indent = self.predicted_indent(line)
            self._current_line = indent * " "
            self.cursor_offset = len(self.current_line)
        self.display_buffer.pop()
        self.buffer.pop()
        self.history.pop()
        self.all_logical_lines.pop()

    def take_back_empty_line(self):
        assert self.history and not self.history[-1]
        self.history.pop()
        self.display_lines.pop()
        self.all_logical_lines.pop()

    def prompt_undo(self):
        if self.buffer:
            return self.take_back_buffer_line()
        if self.history and not self.history[-1]:
            return self.take_back_empty_line()

        def prompt_for_undo():
            n = super(BaseRepl, self).prompt_undo()
            if n > 0:
                self.request_undo(n=n)

        greenlet.greenlet(prompt_for_undo).switch()

    def redo(self) -> None:
        if self.redo_stack:
            temp = self.redo_stack.pop()
            self.history.append(temp)
            self.all_logical_lines.append((temp, LineType.INPUT))
            self.push(temp)
        else:
            self.status_bar.message("Nothing to redo.")

    def reevaluate(self, new_code=False):
        """bpython.Repl.undo calls this"""
        if self.watcher:
            self.watcher.reset()
        old_logical_lines = self.history
        old_display_lines = self.display_lines
        self.history = []
        self.display_lines = []
        self.all_logical_lines = []

        if not self.weak_rewind:
            self.interp = self.interp.__class__()
            self.interp.write = self.send_to_stdouterr
            self.coderunner.interp = self.interp
            self.initialize_interp()

        self.buffer = []
        self.display_buffer = []
        self.highlighted_paren = None

        self.process_event(bpythonevents.RunStartupFileEvent())
        self.reevaluating = True
        sys.stdin = ReevaluateFakeStdin(self.stdin, self)
        for line in old_logical_lines:
            self._current_line = line
            self.on_enter(new_code=new_code)
            while self.fake_refresh_requested:
                self.fake_refresh_requested = False
                self.process_event(bpythonevents.RefreshRequestEvent())
        sys.stdin = self.stdin
        self.reevaluating = False

        num_lines_onscreen = len(self.lines_for_display) - max(
            0, self.scroll_offset
        )
        display_lines_offscreen = self.display_lines[
            : len(self.display_lines) - num_lines_onscreen
        ]
        old_display_lines_offscreen = old_display_lines[
            : (len(self.display_lines) - num_lines_onscreen)
        ]
        logger.debug(
            "old_display_lines_offscreen %s",
            "|".join(str(x) for x in old_display_lines_offscreen),
        )
        logger.debug(
            "    display_lines_offscreen %s",
            "|".join(str(x) for x in display_lines_offscreen),
        )
        if (
            old_display_lines_offscreen[: len(display_lines_offscreen)]
            != display_lines_offscreen
        ) and not self.history_already_messed_up:
            self.inconsistent_history = True
        logger.debug(
            "after rewind, self.inconsistent_history is %r",
            self.inconsistent_history,
        )

        self._cursor_offset = 0
        self.current_line = ""

    def initialize_interp(self) -> None:
        self.coderunner.interp.locals["_repl"] = self
        self.coderunner.interp.runsource(
            "from bpython.curtsiesfrontend._internal import _Helper\n"
        )
        self.coderunner.interp.runsource("help = _Helper(_repl)\n")
        self.coderunner.interp.runsource("del _Helper\n")

        del self.coderunner.interp.locals["_repl"]

    def getstdout(self) -> str:
        """
        Returns a string of the current bpython session, wrapped, WITH prompts.
        """
        lines = self.lines_for_display + [self.current_line_formatted]
        s = (
            "\n".join(x.s if isinstance(x, FmtStr) else x for x in lines)
            if lines
            else ""
        )
        return s

    def focus_on_subprocess(self, args):
        prev_sigwinch_handler = signal.getsignal(signal.SIGWINCH)
        try:
            signal.signal(signal.SIGWINCH, self.orig_sigwinch_handler)
            with Termmode(self.orig_stdin, self.orig_tcattrs):
                terminal = self.window.t
                with terminal.fullscreen():
                    sys.__stdout__.write(terminal.save)
                    sys.__stdout__.write(terminal.move(0, 0))
                    sys.__stdout__.flush()
                    p = subprocess.Popen(
                        args,
                        stdin=self.orig_stdin,
                        stderr=sys.__stderr__,
                        stdout=sys.__stdout__,
                    )
                    p.wait()
                    sys.__stdout__.write(terminal.restore)
                    sys.__stdout__.flush()
        finally:
            signal.signal(signal.SIGWINCH, prev_sigwinch_handler)

    def pager(self, text: str) -> None:
        """Runs an external pager on text

        text must be a str"""
        command = get_pager_command()
        with tempfile.NamedTemporaryFile() as tmp:
            tmp.write(text.encode(getpreferredencoding()))
            tmp.flush()
            self.focus_on_subprocess(command + [tmp.name])

    def show_source(self) -> None:
        try:
            source = self.get_source_of_current_name()
        except SourceNotFound as e:
            self.status_bar.message(f"{e}")
        else:
            if self.config.highlight_show_source:
                source = pygformat(
                    Python3Lexer().get_tokens(source), TerminalFormatter()
                )
            self.pager(source)

    def help_text(self) -> str:
        return self.version_help_text() + "\n" + self.key_help_text()

    def version_help_text(self) -> str:
        help_message = _(
            """
Thanks for using bpython!

See http://bpython-interpreter.org/ for more information and http://docs.bpython-interpreter.org/ for docs.
Please report issues at https://github.com/bpython/bpython/issues

Features:
Try using undo ({config.undo_key})!
Edit the current line ({config.edit_current_block_key}) or the entire session ({config.external_editor_key}) in an external editor. (currently {config.editor})
Save sessions ({config.save_key}) or post them to pastebins ({config.pastebin_key})! Current pastebin helper: {config.pastebin_helper}
Reload all modules and rerun session ({config.reimport_key}) to test out changes to a module.
Toggle auto-reload mode ({config.toggle_file_watch_key}) to re-execute the current session when a module you've imported is modified.

bpython -i your_script.py runs a file in interactive mode
bpython -t your_script.py pastes the contents of a file into the session

A config file at {config.config_path} customizes keys and behavior of bpython.
You can also set which pastebin helper and which external editor to use.
See {example_config_url} for an example config file.
Press {config.edit_config_key} to edit this config file.
"""
        ).format(example_config_url=EXAMPLE_CONFIG_URL, config=self.config)

        return f"bpython-curtsies version {__version__} using curtsies version {curtsies_version}\n{help_message}"

    def key_help_text(self) -> str:
        NOT_IMPLEMENTED = (
            "suspend",
            "cut to buffer",
            "search",
            "last output",
            "yank from buffer",
            "cut to buffer",
        )
        pairs = [
            ["complete history suggestion", "right arrow at end of line"],
            ["previous match with current line", "up arrow"],
        ]
        for functionality, key in (
            (attr[:-4].replace("_", " "), getattr(self.config, attr))
            for attr in self.config.__dict__
            if attr.endswith("key")
        ):
            if functionality in NOT_IMPLEMENTED:
                key = "Not Implemented"
            if key == "":
                key = "Disabled"

            pairs.append([functionality, key])

        max_func = max(len(func) for func, key in pairs)
        return "\n".join(
            f"{func.rjust(max_func)} : {key}" for func, key in pairs
        )

    def get_session_formatted_for_file(self) -> str:
        def process():
            for line, lineType in self.all_logical_lines:
                if lineType == LineType.INPUT:
                    yield line
                elif line.rstrip():
                    yield "# OUT: %s" % line
            yield "### %s" % self.current_line

        return "\n".join(process())

    @property
    def ps1(self):
        return _process_ps(super().ps1, ">>> ")

    @property
    def ps2(self):
        return _process_ps(super().ps2, "... ")


def is_nop(char: str) -> bool:
    return unicodedata.category(char) == "Cc"


def tabs_to_spaces(line: str) -> str:
    return line.replace("\t", "    ")


def _last_word(line: str) -> str:
    split_line = line.split()
    return split_line.pop() if split_line else ""


def compress_paste_event(paste_event):
    """If all events in a paste event are identical and not simple characters,
    returns one of them

    Useful for when the UI is running so slowly that repeated keypresses end up
    in a paste event.  If we value not getting delayed and assume the user is
    holding down a key to produce such frequent key events, it makes sense to
    drop some of the events.
    """
    if not all(paste_event.events[0] == e for e in paste_event.events):
        return None
    event = paste_event.events[0]
    # basically "is there a special curtsies names for this key?"
    if len(event) > 1:
        return event
    else:
        return None


def just_simple_events(
    event_list: Iterable[Union[str, events.Event]]
) -> List[str]:
    simple_events = []
    for e in event_list:
        if isinstance(e, events.Event):
            continue  # ignore events
        # '\n' necessary for pastes
        elif e in ("<Ctrl-j>", "<Ctrl-m>", "<PADENTER>", "\n", "\r"):
            simple_events.append("\n")
        elif e == "<SPACE>":
            simple_events.append(" ")
        elif len(e) > 1:
            continue  # get rid of <Ctrl-a> etc.
        else:
            simple_events.append(e)
    return simple_events


def is_simple_event(e: Union[str, events.Event]) -> bool:
    if isinstance(e, events.Event):
        return False
    return (
        e in ("<Ctrl-j>", "<Ctrl-m>", "<PADENTER>", "\n", "\r", "<SPACE>")
        or len(e) <= 1
    )