# Generated by Django 5.1.10 on 2025-08-07 16:14

import logging

from django.conf import settings
from django.db import migrations

from core.redis import start_job_async_or_sync
from core.models import AsyncMigrationStatus
from core.utils.common import btree_gin_migration_operations

logger = logging.getLogger(__name__)

IS_SQLITE = settings.DJANGO_DB == settings.DJANGO_DB_SQLITE

migration_name = "0056_prediction_result_proj_gin_idx_async"

SQL_CREATE_INDEX = (
    "CREATE INDEX CONCURRENTLY IF NOT EXISTS tasks_predictions_result_proj_gin "
    "ON prediction USING GIN (project_id, CAST(result AS text) gin_trgm_ops);"
)

SQL_DROP_INDEX = "DROP INDEX CONCURRENTLY IF EXISTS tasks_predictions_result_proj_gin;"

def _forward(migration_name: str, db_alias: str):
    """Create the GIN index inside a dedicated job."""
    # If the migration has already been executed, do nothing
    migration, created = AsyncMigrationStatus.objects.using(db_alias).get_or_create(
        name=migration_name,
        defaults={"status": AsyncMigrationStatus.STATUS_STARTED},
    )
    if not created:
        logger.info("Migration %s already executed", migration_name)
        return

    logger.info("Starting async migration %s", migration_name)
    from django.db import connections

    with connections[db_alias].cursor() as cursor:
        cursor.execute(SQL_CREATE_INDEX)
    migration.status = AsyncMigrationStatus.STATUS_FINISHED
    migration.save(using=db_alias)
    logger.info("Async migration %s complete", migration_name)


def _backward(migration_name: str, db_alias: str):
    """Revert the GIN index creation."""
    migration = AsyncMigrationStatus.objects.using(db_alias).create(
        name=migration_name,
        status=AsyncMigrationStatus.STATUS_STARTED,
    )
    logger.info("Reverting async migration %s", migration_name)
    from django.db import connections

    with connections[db_alias].cursor() as cursor:
        cursor.execute(SQL_DROP_INDEX)
    migration.status = AsyncMigrationStatus.STATUS_FINISHED
    migration.save(using=db_alias)
    logger.info("Revert of async migration %s complete", migration_name)


def forwards(apps, schema_editor):
    if IS_SQLITE:
        logger.info("SQLite detected; skipping GIN index creation")
        return

    # Only run on PostgreSQL
    if not schema_editor.connection.vendor.startswith("postgres"):
        logger.info("Database vendor: %s. Skipping index creation", schema_editor.connection.vendor)
        return

    db_alias = schema_editor.connection.alias
    start_job_async_or_sync(_forward, migration_name=migration_name, db_alias=db_alias)


def backwards(apps, schema_editor):
    if IS_SQLITE:
        logger.info("SQLite detected; skipping GIN index drop")
        return

    if not schema_editor.connection.vendor.startswith("postgres"):
        logger.info("Database vendor: %s. Skipping index drop", schema_editor.connection.vendor)
        return

    db_alias = schema_editor.connection.alias
    start_job_async_or_sync(_backward, migration_name=migration_name, db_alias=db_alias)



class Migration(migrations.Migration):
    atomic = False

    dependencies = [
        ("tasks", "0055_task_proj_octlen_idx_async"),
    ]

    operations = btree_gin_migration_operations(migrations.RunPython(forwards, backwards))