"""Migration script to add public-booking-link slug support to properties.

Idempotent (safe to run multiple times):
- Adds `slug` (VARCHAR, nullable) and `list_on_landing` (BOOLEAN NOT NULL
  DEFAULT 0) columns to `properties` if missing.
- Creates a UNIQUE INDEX on `slug` if missing.
- Backfills NULL slugs deterministically from each property's name.
"""
import sys
import os

# Add backend to path
sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))

from sqlalchemy import inspect, text

from app.core.slug import generate_unique_slug
from app.db.session import SessionLocal, engine
from app.models.property import Property

SLUG_INDEX_NAME = "ix_properties_slug_unique"


def migrate() -> None:
    """Run migration to add slug + list_on_landing support to properties."""
    inspector = inspect(engine)
    columns = [col["name"] for col in inspector.get_columns("properties")]

    print("Starting property slug migration...")

    with engine.connect() as conn:
        if "slug" not in columns:
            print("1. Adding slug column to properties...")
            conn.execute(text("ALTER TABLE properties ADD COLUMN slug VARCHAR"))
            conn.commit()
            print("   Column added.")
        else:
            print("1. slug column already exists.")

        if "list_on_landing" not in columns:
            print("2. Adding list_on_landing column to properties...")
            conn.execute(
                text("ALTER TABLE properties ADD COLUMN list_on_landing BOOLEAN DEFAULT 0 NOT NULL")
            )
            conn.commit()
            print("   Column added.")
        else:
            print("2. list_on_landing column already exists.")

    # Recompute indexes after potentially adding the slug column.
    inspector = inspect(engine)
    index_names = {ix["name"] for ix in inspector.get_indexes("properties")}
    if SLUG_INDEX_NAME not in index_names:
        print("3. Creating unique index on slug...")
        with engine.connect() as conn:
            conn.execute(
                text(f"CREATE UNIQUE INDEX {SLUG_INDEX_NAME} ON properties (slug)")
            )
            conn.commit()
        print("   Index created.")
    else:
        print("3. Unique index on slug already exists.")

    # Backfill: deterministic unique slug for every property missing one.
    print("4. Backfilling missing slugs...")
    db = SessionLocal()
    try:
        properties_without_slug = (
            db.query(Property)
            .filter(Property.slug.is_(None))
            .order_by(Property.id)
            .all()
        )
        for prop in properties_without_slug:
            prop.slug = generate_unique_slug(db, prop.name, exclude_id=prop.id)
            db.flush()
        db.commit()
        print(f"   Backfilled {len(properties_without_slug)} propert(y/ies).")
    except Exception:
        db.rollback()
        raise
    finally:
        db.close()

    print("Migration completed successfully!")


if __name__ == "__main__":
    migrate()