"""Migrate player_user table to remove player_id and make user_code unique globally.

Idempotent and data-preserving: the table is only rebuilt when the legacy
``player_id`` column is actually present. Existing code/name pairs are carried
over into the new schema, and on a fresh or already-migrated database this
script is a no-op.

The rebuild uses a temporary table rather than a bare ``DROP TABLE`` so that
user data is never lost.
"""
import sys
sys.path.insert(0, '/app')

from app.app import create_app
from app.extensions import db
from sqlalchemy import text

app = create_app('production')

with app.app_context():
    print("Migrating player_user table...")

    inspector = db.inspect(db.engine)

    if 'player_user' not in inspector.get_table_names():
        # Fresh database — just create the current schema.
        db.create_all()
        print("✓ player_user table created with current schema.")
        sys.exit(0)

    columns = [col['name'] for col in inspector.get_columns('player_user')]

    if 'player_id' not in columns:
        # Already migrated — running the migration again must not destroy data.
        db.create_all()
        print("✓ player_user table already migrated, skipping.")
        sys.exit(0)

    # Legacy schema detected: rebuild it, preserving user_code/user_name.
    print("  Legacy schema detected (player_id present) — rebuilding...")
    with db.engine.connect() as conn:
        conn.execute(text(
            'CREATE TABLE player_user_new ('
            '  id INTEGER PRIMARY KEY,'
            '  user_code VARCHAR(255) NOT NULL UNIQUE,'
            '  user_name VARCHAR(255),'
            '  created_at DATETIME NOT NULL,'
            '  updated_at DATETIME NOT NULL'
            ')'
        ))

        # De-duplicate on user_code (the new schema makes it globally unique).
        conn.execute(text(
            'INSERT OR IGNORE INTO player_user_new '
            '(id, user_code, user_name, created_at, updated_at) '
            'SELECT id, user_code, user_name, created_at, updated_at '
            'FROM player_user '
            'WHERE user_code IS NOT NULL'
        ))

        conn.execute(text('DROP TABLE player_user'))
        conn.execute(text('ALTER TABLE player_user_new RENAME TO player_user'))
        conn.commit()

    print("✓ player_user table migrated successfully!")
    print("  - Removed player_id foreign key")
    print("  - Made user_code unique globally")
    print("  - user_name is now nullable")
    print("  - Existing user_code/user_name rows preserved")