# -*- coding: utf-8 -*-
from __future__ import unicode_literals

from django.db import migrations


def event_to_gestion(apps, schema_editor):
    # Fetching the models that have be moved from cof to gestion
    OldEvent = apps.get_model('cof', 'Event')
    NewEvent = apps.get_model('gestion', 'Event')
    Location = apps.get_model('gestion', 'Location')
    Association = apps.get_model('gestion', 'Association')

    # The old Event.location field becomes a table: we need to create an entry
    # in this table for each value of the old `location` field.
    locations = set()  # A set to prevent duplicate entries
    old_events = OldEvent.objects.values()
    new_events = []
    for event in old_events:
        locations.add(event["location"])
        new_events.append(event)
    Location.objects.bulk_create([Location(name=name) for name in locations])
    map_loc = {
        loc.name: loc
        for loc in Location.objects.all()
    }
    for event in new_events:
        event["location"] = map_loc[event["location"]]
    NewEvent.objects.bulk_create([
        NewEvent(**event)
        for event in new_events
    ])

    # Do not forget to link all the existing event to the COF association
    cof_assoc = Association.objects.get(name="COF")
    cof_assoc.events.add(*NewEvent.objects.all())

    # Migrating the other models is straightforward.
    # Keep care to the ordering. A change can lead to DB error because of
    # failed checks on foreignkey constraints. The dependencies between these
    # models give the following constraints:
    # - EventRegistration must precede EventCommentField and EventOption,
    # - EventCommentField must precede EventCommentValue,
    # - EventOption must precede EventOptionChoice.
    model_names = [
        'EventRegistration', 'EventCommentField', 'EventCommentValue',
        'EventOption', 'EventOptionChoice',
    ]

    cls_models = [
        (apps.get_model('cof', name), apps.get_model('gestion', name))
        for name in model_names
    ]

    for FromModel, ToModel in cls_models:
        ToModel.objects.bulk_create([
            ToModel(**values)
            for values in FromModel.objects.values()
        ])


class Migration(migrations.Migration):

    dependencies = [
        ('cof', '0015_move_club'),
        ('gestion', '0002_create_cof_bds'),
    ]

    operations = [
        migrations.RunPython(event_to_gestion),
        migrations.RemoveField(
            model_name='eventcommentfield',
            name='event',
        ),
        migrations.RemoveField(
            model_name='eventcommentvalue',
            name='commentfield',
        ),
        migrations.RemoveField(
            model_name='eventcommentvalue',
            name='registration',
        ),
        migrations.RemoveField(
            model_name='eventoption',
            name='event',
        ),
        migrations.RemoveField(
            model_name='eventoptionchoice',
            name='event_option',
        ),
        migrations.AlterUniqueTogether(
            name='eventregistration',
            unique_together=set([]),
        ),
        migrations.RemoveField(
            model_name='eventregistration',
            name='event',
        ),
        migrations.RemoveField(
            model_name='eventregistration',
            name='filledcomments',
        ),
        migrations.RemoveField(
            model_name='eventregistration',
            name='options',
        ),
        migrations.RemoveField(
            model_name='eventregistration',
            name='user',
        ),
        migrations.DeleteModel(
            name='Event',
        ),
        migrations.DeleteModel(
            name='EventCommentField',
        ),
        migrations.DeleteModel(
            name='EventCommentValue',
        ),
        migrations.DeleteModel(
            name='EventOption',
        ),
        migrations.DeleteModel(
            name='EventOptionChoice',
        ),
        migrations.DeleteModel(
            name='EventRegistration',
        ),
    ]