from datetime import datetime
from .. import db, socketio
from ..models import Corpus, CorpusFile, Job, JobInput, JobResult


###############################################################################
# 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):
    if isinstance(ressource, Corpus):
        user_id = ressource.creator.id
        path = '/corpora/{}'.format(ressource.id)
    elif isinstance(ressource, CorpusFile):
        user_id = ressource.corpus.creator.id
        path = '/corpora/{}/files/{}'.format(ressource.corpus.id, ressource.id)
    elif isinstance(ressource, Job):
        user_id = ressource.creator.id
        path = '/jobs/{}'.format(ressource.id)
    elif isinstance(ressource, JobInput):
        user_id = ressource.job.creator.id
        path = '/jobs/{}/inputs/{}'.format(ressource.job.id, ressource.id)
    elif isinstance(ressource, JobResult):
        user_id = ressource.job.creator.id
        path = '/jobs/{}/results/{}'.format(ressource.job.id, ressource.id)
    event = 'user_{}_patch'.format(user_id)
    jsonpatch = [{'op': 'remove', 'path': path}]
    room = 'user_{}'.format(user_id)
    socketio.emit(event, 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):
    if isinstance(ressource, Corpus):
        user_id = ressource.creator.id
        path = '/corpora/{}'.format(ressource.id)
    elif isinstance(ressource, CorpusFile):
        user_id = ressource.corpus.creator.id
        path = '/corpora/{}/files/{}'.format(ressource.corpus.id, ressource.id)
    elif isinstance(ressource, Job):
        user_id = ressource.creator.id
        path = '/jobs/{}'.format(ressource.id)
    elif isinstance(ressource, JobInput):
        user_id = ressource.job.creator.id
        path = '/jobs/{}/inputs/{}'.format(ressource.job.id, ressource.id)
    elif isinstance(ressource, JobResult):
        user_id = ressource.job.creator.id
        path = '/jobs/{}/results/{}'.format(ressource.job.id, ressource.id)
    event = 'user_{}_patch'.format(user_id)
    jsonpatch = [
        {
            'op': 'add',
            'path': path,
            'value': ressource.to_dict(include_relationships=False)
        }
    ]
    room = 'user_{}'.format(user_id)
    socketio.emit(event, 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):
    if isinstance(ressource, Corpus):
        user_id = ressource.creator.id
        base_path = '/corpora/{}'.format(ressource.id)
    elif isinstance(ressource, CorpusFile):
        user_id = ressource.corpus.creator.id
        base_path = '/corpora/{}/files/{}'.format(ressource.corpus.id,
                                                  ressource.id)
    elif isinstance(ressource, Job):
        user_id = ressource.creator.id
        base_path = '/jobs/{}'.format(ressource.id)
    elif isinstance(ressource, JobInput):
        user_id = ressource.job.creator.id
        base_path = '/jobs/{}/inputs/{}'.format(ressource.job.id, ressource.id)
    elif isinstance(ressource, JobResult):
        user_id = ressource.job.creator.id
        base_path = '/jobs/{}/results/{}'.format(ressource.job.id,
                                                 ressource.id)
    jsonpatch = []
    for attr in db.inspect(ressource).attrs:
        # We don't want to emit changes about relationship fields
        if attr.key in ['files', 'inputs', 'results']:
            continue
        history = attr.load_history()
        if not history.has_changes():
            continue
        new_value = history.added[0]
        # DateTime attributes must be converted to a string
        if isinstance(new_value, datetime):
            new_value = new_value.isoformat()
        jsonpatch.append(
            {
                'op': 'replace',
                'path': '{}/{}'.format(base_path, attr.key),
                'value': new_value
            }
        )
    if jsonpatch:
        event = 'user_{}_patch'.format(user_id)
        room = 'user_{}'.format(user_id)
        socketio.emit(event, jsonpatch, room=room)