from app import db, mail, socketio
from app.email import create_message
from app.models import (
    Corpus,
    CorpusFile,
    Job,
    JobInput,
    JobResult,
    JobStatus,
    JobStatusMailNotificationLevel
)
from datetime import datetime


###############################################################################
# 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')
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')
def ressource_after_insert_handler(mapper, connection, ressource):
    value = ressource.to_dict(backrefs=False, relationships=False)
    for relationship in mapper.relationships:
        value[relationship.key] = {}
    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')
def ressource_after_update_handler(mapper, connection, ressource):
    jsonpatch = []
    for attr in db.inspect(ressource).attrs:
        # Don't handle changes in relationship fields
        if attr.key in mapper.relationships:
            continue
        # Check if their are changes for the current field
        history = attr.load_history()
        if not history.has_changes():
            continue
        if isinstance(history.added[0], datetime):
            # In order to be JSON serializable, DateTime attributes must be
            # converted to a string
            attr_name = attr.key
            value = history.added[0].isoformat() + 'Z'
        elif attr.key.endswith('_enum_value'):
            # Handling fake enum attributes
            attr_name = attr.key[:-11]
            value = getattr(ressource, attr_name).name
        else:
            attr_name = attr.key
            value = history.added[0]
        jsonpatch.append(
            {
                'op': 'replace',
                'path': f'{ressource.jsonpatch_path}/{attr_name}',
                'value': value
            }
        )
        # Job status update notification if it changed and wanted by the user
        if isinstance(ressource, Job) and attr_name == 'status':
            if ressource.user.setting_job_status_mail_notification_level == JobStatusMailNotificationLevel.NONE:  # noqa
                pass
            elif (
                ressource.user.setting_job_status_mail_notification_level == JobStatusMailNotificationLevel.END  # noqa
                and ressource.status not in [JobStatus.COMPLETED, JobStatus.FAILED]  # noqa
            ):
                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)