from datetime import datetime
from flask import current_app
from .. import db, mail, socketio
from ..email import create_message
from ..models import Corpus, CorpusFile, Job, JobInput, JobResult, QueryResult


###############################################################################
# SQLAlchemy event handlers                                                   #
###############################################################################
@db.event.listens_for(Corpus, 'after_delete')
@db.event.listens_for(CorpusFile, 'after_delete')
@db.event.listens_for(Job, 'after_delete')
@db.event.listens_for(JobInput, 'after_delete')
@db.event.listens_for(JobResult, 'after_delete')
@db.event.listens_for(QueryResult, 'after_delete')
def ressource_after_delete(mapper, connection, ressource):
    jsonpatch = [{'op': 'remove', 'path': ressource.jsonpatch_path}]
    room = f'users.{ressource.user_hashid}'
    socketio.emit('users.patch', jsonpatch, room=room)


@db.event.listens_for(Corpus, 'after_insert')
@db.event.listens_for(CorpusFile, 'after_insert')
@db.event.listens_for(Job, 'after_insert')
@db.event.listens_for(JobInput, 'after_insert')
@db.event.listens_for(JobResult, 'after_insert')
@db.event.listens_for(QueryResult, 'after_insert')
def ressource_after_insert_handler(mapper, connection, ressource):
    value = ressource.to_dict(backrefs=False, relationships=False)
    if isinstance(ressource, Job):
        value['inputs'] = {}
        value['results'] = {}
    elif isinstance(ressource, Corpus):
        value['files'] = {}
    jsonpatch = [
        {'op': 'add', 'path': ressource.jsonpatch_path, 'value': value}
    ]
    room = f'users.{ressource.user_hashid}'
    socketio.emit('users.patch', jsonpatch, room=room)


@db.event.listens_for(Corpus, 'after_update')
@db.event.listens_for(CorpusFile, 'after_update')
@db.event.listens_for(Job, 'after_update')
@db.event.listens_for(JobInput, 'after_update')
@db.event.listens_for(JobResult, 'after_update')
@db.event.listens_for(QueryResult, 'after_update')
def ressource_after_update_handler(mapper, connection, ressource):
    jsonpatch = []
    for attr in db.inspect(ressource).attrs:
        # We don't want to handle changes in relationship fields
        # TODO: Find a way to handle this without a hardcoded list
        if attr.key in ['files', 'inputs', 'results']:
            continue
        history = attr.load_history()
        if not history.has_changes():
            continue
        new_value = history.added[0]
        # In order to be JSON serializable, DateTime attributes must be
        # converted to a string
        if isinstance(new_value, datetime):
            new_value = new_value.isoformat() + 'Z'
        jsonpatch.append(
            {
                'op': 'replace',
                'path': f'{ressource.jsonpatch_path}/{attr.key}',
                'value': new_value
            }
        )
        # Job status update notification if it changed and wanted by the user
        if isinstance(ressource, Job) and attr.key == 'status':
            if ressource.user.setting_job_status_mail_notifications == 'none':  # noqa
                pass
            elif (ressource.user.setting_job_status_mail_notifications == 'end'  # noqa
                  and ressource.status not in ['complete', 'failed']):
                pass
            else:
                msg = create_message(
                    ressource.user.email,
                    f'Status update for your Job "{ressource.title}"',
                    'tasks/email/notification',
                    job=ressource
                )
                mail.send(msg)
    if jsonpatch:
        room = f'users.{ressource.user_hashid}'
        socketio.emit('users.patch', jsonpatch, room=room)