#!/usr/bin/env python3

# pylint: disable=C0111, C0103, W0703, R0902, R0903, R0912, R0913, R0914, R0915, C0413, W0122

"""Handles parsing trigger plugin files and running them.

The plugin file must be a python file which contains either a function called 'trigger'

or a class called 'Trigger'. It's also recommended to specify a '__apiversion__' (which is just an int)

for backward compatibility if api changes are made in the future.

If specifying a 'trigger' function, the trigger can take the args specified by default_trigger, and should

always take a catch-all **kwargs for future compatibility.

Likewise, if specifying a 'Trigger' class, that class must define a '__call__' method, which takes

a subset of the kwargs specified by 'default_trigger', and should always contain a catch-all **kwargs

for future compatibility.

plugin_config is a dict of config passed to Trigger as kwargs.

Note that this plugin system is not sandboxed, so if the code in trigger_path brakes something,

the host program will break (unless it is explicitly handling any errors).

Last, a trigger can override any config parameters with the __config__ param.

"""

import ast

import json

from .common import TJException

CURRENT_TRIGGER_API_VERSION = 1

def parse_trigger_plugin(trigger_path, plugin_config, parse_only=False):

"""Parse plugin file and return the trigger config."""

# Open and exec plugin definitions

with open(trigger_path, 'r') as f:

trigger_code = f.read()

trigger_vars = {}

exec(trigger_code, trigger_vars)

# Get trigger data

api_version = trigger_vars.get('__apiversion__', CURRENT_TRIGGER_API_VERSION)

config = trigger_vars.get('__config__', {})

trigger = trigger_vars.get('trigger', None)

trigger_class = trigger_vars.get('Trigger', None)

if parse_only:

trigger = None

else:

if trigger_class:

# Pass optional plugin_config to trigger class

plugin_config = parse_plugin_config(plugin_config)

# Instantiate class. Note that only a trigger function or class can be defined (and class takes priority)

# Assume the class is called 'Trigger'

try:

trigger = trigger_class(**plugin_config)

except Exception as e:

raise TJException('Error loading plugin ({}): {}'.format(trigger_path, e))

if not trigger:

raise TJException('Plugin file must specify a "trigger" function or a "Trigger" class')

return {'trigger': trigger, 'api_version': api_version, 'config': config}

def parse_plugin_config(plugin_config_str):

"""Attempt to parse the config as ast or json."""

if not plugin_config_str:

return {}

try:

return ast.literal_eval(plugin_config_str)

except SyntaxError:

pass

try:

return json.loads(plugin_config_str)

except json.decoder.JSONDecodeError:

pass

return {}