import ast
import json
import logging
import traceback
from datetime import datetime
from typing import Any, Dict, List

import pyarrow as pa
import pyarrow.flight as fl

from feast import FeatureStore, FeatureView, utils
from feast.feature_logging import FeatureServiceLoggingSource
from feast.feature_view import DUMMY_ENTITY_NAME
from feast.infra.offline_stores.offline_utils import get_offline_store_from_config
from feast.saved_dataset import SavedDatasetStorage

logger = logging.getLogger(__name__)


class OfflineServer(fl.FlightServerBase):
    def __init__(self, store: FeatureStore, location: str, **kwargs):
        super(OfflineServer, self).__init__(location, **kwargs)
        self._location = location
        # A dictionary of configured flights, e.g. API calls received and not yet served
        self.flights: Dict[str, Any] = {}
        self.store = store
        self.offline_store = get_offline_store_from_config(store.config.offline_store)

    @classmethod
    def descriptor_to_key(self, descriptor: fl.FlightDescriptor):
        return (
            descriptor.descriptor_type.value,
            descriptor.command,
            tuple(descriptor.path or tuple()),
        )

    def _make_flight_info(self, key: Any, descriptor: fl.FlightDescriptor):
        endpoints = [fl.FlightEndpoint(repr(key), [self._location])]
        # TODO calculate actual schema from the given features
        schema = pa.schema([])

        return fl.FlightInfo(schema, descriptor, endpoints, -1, -1)

    def get_flight_info(
        self, context: fl.ServerCallContext, descriptor: fl.FlightDescriptor
    ):
        key = OfflineServer.descriptor_to_key(descriptor)
        if key in self.flights:
            return self._make_flight_info(key, descriptor)
        raise KeyError("Flight not found.")

    def list_flights(self, context: fl.ServerCallContext, criteria: bytes):
        for key, table in self.flights.items():
            if key[1] is not None:
                descriptor = fl.FlightDescriptor.for_command(key[1])
            else:
                descriptor = fl.FlightDescriptor.for_path(*key[2])

            yield self._make_flight_info(key, descriptor)

    # Expects to receive request parameters and stores them in the flights dictionary
    # Indexed by the unique command
    def do_put(
        self,
        context: fl.ServerCallContext,
        descriptor: fl.FlightDescriptor,
        reader: fl.MetadataRecordBatchReader,
        writer: fl.FlightMetadataWriter,
    ):
        key = OfflineServer.descriptor_to_key(descriptor)
        command = json.loads(key[1])
        if "api" in command:
            data = reader.read_all()
            logger.debug(f"do_put: command is{command}, data is {data}")
            self.flights[key] = data

            self._call_api(command, key)
        else:
            logger.warning(f"No 'api' field in command: {command}")

    def _call_api(self, command: dict, key: str):
        remove_data = False
        try:
            api = command["api"]
            if api == OfflineServer.offline_write_batch.__name__:
                self.offline_write_batch(command, key)
                remove_data = True
            elif api == OfflineServer.write_logged_features.__name__:
                self.write_logged_features(command, key)
                remove_data = True
            elif api == OfflineServer.persist.__name__:
                self.persist(command["retrieve_func"], command, key)
                remove_data = True
        except Exception as e:
            remove_data = True
            logger.exception(e)
            traceback.print_exc()
            raise e
        finally:
            if remove_data:
                # Get service is consumed, so we clear the corresponding flight and data
                del self.flights[key]

    def get_feature_view_by_name(
        self, fv_name: str, name_alias: str, project: str
    ) -> FeatureView:
        """
        Retrieves a feature view by name, including all subclasses of FeatureView.

        Args:
            fv_name: Name of feature view
            name_alias: Alias to be applied to the projection of the registered view
            project: Feast project that this feature view belongs to

        Returns:
            Returns either the specified feature view, or raises an exception if
            none is found
        """
        try:
            fv = self.store.registry.get_feature_view(name=fv_name, project=project)
            if name_alias is not None:
                for fs in self.store.registry.list_feature_services(project=project):
                    for p in fs.feature_view_projections:
                        if p.name_alias == name_alias:
                            logger.debug(
                                f"Found matching FeatureService {fs.name} with projection {p}"
                            )
                            fv = fv.with_projection(p)
            return fv
        except Exception:
            try:
                return self.store.registry.get_stream_feature_view(
                    name=fv_name, project=project
                )
            except Exception as e:
                logger.error(
                    f"Cannot find any FeatureView by name {fv_name} in project {project}"
                )
                raise e

    def list_feature_views_by_name(
        self, feature_view_names: List[str], name_aliases: List[str], project: str
    ) -> List[FeatureView]:
        return [
            remove_dummies(
                self.get_feature_view_by_name(
                    fv_name=fv_name, name_alias=name_aliases[index], project=project
                )
            )
            for index, fv_name in enumerate(feature_view_names)
        ]

    # Extracts the API parameters from the flights dictionary, delegates the execution to the FeatureStore instance
    # and returns the stream of data
    def do_get(self, context: fl.ServerCallContext, ticket: fl.Ticket):
        key = ast.literal_eval(ticket.ticket.decode())
        if key not in self.flights:
            logger.error(f"Unknown key {key}")
            return None

        command = json.loads(key[1])
        api = command["api"]
        logger.debug(f"get command is {command}")
        logger.debug(f"requested api is {api}")
        try:
            if api == OfflineServer.get_historical_features.__name__:
                table = self.get_historical_features(command, key).to_arrow()
            elif api == OfflineServer.pull_all_from_table_or_query.__name__:
                table = self.pull_all_from_table_or_query(command).to_arrow()
            elif api == OfflineServer.pull_latest_from_table_or_query.__name__:
                table = self.pull_latest_from_table_or_query(command).to_arrow()
            else:
                raise NotImplementedError
        except Exception as e:
            logger.exception(e)
            traceback.print_exc()
            raise e

        # Get service is consumed, so we clear the corresponding flight and data
        del self.flights[key]
        return fl.RecordBatchStream(table)

    def offline_write_batch(self, command: dict, key: str):
        feature_view_names = command["feature_view_names"]
        assert (
            len(feature_view_names) == 1
        ), "feature_view_names list should only have one item"
        name_aliases = command["name_aliases"]
        assert len(name_aliases) == 1, "name_aliases list should only have one item"
        project = self.store.config.project
        feature_views = self.list_feature_views_by_name(
            feature_view_names=feature_view_names,
            name_aliases=name_aliases,
            project=project,
        )

        assert len(feature_views) == 1
        table = self.flights[key]
        self.offline_store.offline_write_batch(
            self.store.config, feature_views[0], table, command["progress"]
        )

    def write_logged_features(self, command: dict, key: str):
        table = self.flights[key]
        feature_service = self.store.get_feature_service(
            command["feature_service_name"]
        )

        assert feature_service.logging_config is not None

        self.offline_store.write_logged_features(
            config=self.store.config,
            data=table,
            source=FeatureServiceLoggingSource(
                feature_service, self.store.config.project
            ),
            logging_config=feature_service.logging_config,
            registry=self.store.registry,
        )

    def pull_all_from_table_or_query(self, command: dict):
        return self.offline_store.pull_all_from_table_or_query(
            self.store.config,
            self.store.get_data_source(command["data_source_name"]),
            command["join_key_columns"],
            command["feature_name_columns"],
            command["timestamp_field"],
            utils.make_tzaware(datetime.fromisoformat(command["start_date"])),
            utils.make_tzaware(datetime.fromisoformat(command["end_date"])),
        )

    def pull_latest_from_table_or_query(self, command: dict):
        return self.offline_store.pull_latest_from_table_or_query(
            self.store.config,
            self.store.get_data_source(command["data_source_name"]),
            command["join_key_columns"],
            command["feature_name_columns"],
            command["timestamp_field"],
            command["created_timestamp_column"],
            utils.make_tzaware(datetime.fromisoformat(command["start_date"])),
            utils.make_tzaware(datetime.fromisoformat(command["end_date"])),
        )

    def list_actions(self, context):
        return [
            (
                OfflineServer.offline_write_batch.__name__,
                "Writes the specified arrow table to the data source underlying the specified feature view.",
            ),
            (
                OfflineServer.write_logged_features.__name__,
                "Writes logged features to a specified destination in the offline store.",
            ),
            (
                OfflineServer.persist.__name__,
                "Synchronously executes the underlying query and persists the result in the same offline store at the "
                "specified destination.",
            ),
        ]

    def get_historical_features(self, command: dict, key: str):
        # Extract parameters from the internal flights dictionary
        entity_df_value = self.flights[key]
        entity_df = pa.Table.to_pandas(entity_df_value)
        feature_view_names = command["feature_view_names"]
        name_aliases = command["name_aliases"]
        feature_refs = command["feature_refs"]
        project = command["project"]
        full_feature_names = command["full_feature_names"]
        feature_views = self.list_feature_views_by_name(
            feature_view_names=feature_view_names,
            name_aliases=name_aliases,
            project=project,
        )
        retJob = self.offline_store.get_historical_features(
            config=self.store.config,
            feature_views=feature_views,
            feature_refs=feature_refs,
            entity_df=entity_df,
            registry=self.store.registry,
            project=project,
            full_feature_names=full_feature_names,
        )
        return retJob

    def persist(self, retrieve_func: str, command: dict, key: str):
        try:
            if retrieve_func == OfflineServer.get_historical_features.__name__:
                ret_job = self.get_historical_features(command, key)
            elif (
                retrieve_func == OfflineServer.pull_latest_from_table_or_query.__name__
            ):
                ret_job = self.pull_latest_from_table_or_query(command)
            elif retrieve_func == OfflineServer.pull_all_from_table_or_query.__name__:
                ret_job = self.pull_all_from_table_or_query(command)
            else:
                raise NotImplementedError

            data_source = self.store.get_data_source(command["data_source_name"])
            storage = SavedDatasetStorage.from_data_source(data_source)
            ret_job.persist(storage, command["allow_overwrite"], command["timeout"])
        except Exception as e:
            logger.exception(e)
            traceback.print_exc()
            raise e

    def do_action(self, context: fl.ServerCallContext, action: fl.Action):
        pass

    def do_drop_dataset(self, dataset):
        pass


def remove_dummies(fv: FeatureView) -> FeatureView:
    """
    Removes dummmy IDs from FeatureView instances created with FeatureView.from_proto
    """
    if DUMMY_ENTITY_NAME in fv.entities:
        fv.entities = []
        fv.entity_columns = []
    return fv


def start_server(
    store: FeatureStore,
    host: str,
    port: int,
):
    location = "grpc+tcp://{}:{}".format(host, port)
    server = OfflineServer(store, location)
    logger.info(f"Offline store server serving on {location}")
    server.serve()