"""
Add contributed_by field to Event and backfill from overloaded source field.

The admin dashboard stores community contributor identifiers (EVT-XXXXXXXX or email)
in the source field. This migration:
1. Adds a dedicated contributed_by CharField
2. Copies user identifiers from source → contributed_by
3. Normalizes source back to its intended choices ('eventify', 'community', 'partner')
"""

from django.db import migrations, models


def backfill_contributed_by(apps, schema_editor):
    """Move user identifiers from source to contributed_by."""
    Event = apps.get_model('events', 'Event')

    STANDARD_SOURCES = {'eventify', 'community', 'partner', 'eventify_team', 'official', ''}

    for event in Event.objects.all().iterator():
        source_val = (event.source or '').strip()
        changed = False

        # User identifier: contains @ (email) or starts with EVT- (eventifyId)
        if source_val and source_val not in STANDARD_SOURCES and not source_val.startswith('partner:'):
            event.contributed_by = source_val
            event.source = 'community'
            changed = True

        # Normalize eventify_team → eventify
        elif source_val == 'eventify_team':
            event.source = 'eventify'
            changed = True

        # Normalize official → eventify
        elif source_val == 'official':
            event.source = 'eventify'
            changed = True

        if changed:
            event.save(update_fields=['source', 'contributed_by'])


def reverse_backfill(apps, schema_editor):
    """Reverse: move contributed_by back to source."""
    Event = apps.get_model('events', 'Event')
    for event in Event.objects.exclude(contributed_by__isnull=True).exclude(contributed_by='').iterator():
        event.source = event.contributed_by
        event.contributed_by = None
        event.save(update_fields=['source', 'contributed_by'])


class Migration(migrations.Migration):

    dependencies = [
        ('events', '0010_merge_20260324_1443'),
    ]

    operations = [
        # Step 1: Add the field
        migrations.AddField(
            model_name='event',
            name='contributed_by',
            field=models.CharField(
                blank=True,
                help_text='Eventify ID (EVT-XXXXXXXX) or email of the community contributor',
                max_length=100,
                null=True,
            ),
        ),
        # Step 2: Backfill data
        migrations.RunPython(backfill_contributed_by, reverse_backfill),
    ]