"""Migration: Add custom_fields column to customers table.

Sprint 6.6: Enable dynamic WordPress field synchronization.

This migration adds a TEXT column for storing JSON-encoded custom fields
from WordPress booking forms, enabling automatic synchronization without
schema changes.

Usage:
    python -m customer_portal.migrations.001_add_custom_fields
"""

import os
import sys

from sqlalchemy import create_engine, inspect, text


def get_database_url() -> str:
    """Get database URL from environment."""
    return os.getenv(
        "DATABASE_URL",
        os.getenv(
            "SQLALCHEMY_DATABASE_URI",
            "sqlite:///customer_portal.db",
        ),
    )


def migrate():
    """Add custom_fields column to customers table."""
    database_url = get_database_url()
    engine = create_engine(database_url)

    inspector = inspect(engine)
    columns = [col["name"] for col in inspector.get_columns("customers")]

    if "custom_fields" in columns:
        print("Column 'custom_fields' already exists. Skipping.")
        return True

    print("Adding 'custom_fields' column to customers table...")

    # Detect database type for appropriate SQL
    dialect = engine.dialect.name

    with engine.begin() as conn:
        if dialect in {"sqlite", "postgresql"}:
            conn.execute(
                text("ALTER TABLE customers ADD COLUMN custom_fields TEXT DEFAULT '{}'")
            )
        elif dialect == "mysql":
            conn.execute(text("ALTER TABLE customers ADD COLUMN custom_fields TEXT"))
            conn.execute(
                text(
                    "UPDATE customers SET custom_fields = '{}' WHERE custom_fields IS NULL"
                )
            )
        else:
            # Generic SQL
            conn.execute(
                text("ALTER TABLE customers ADD COLUMN custom_fields TEXT DEFAULT '{}'")
            )

    print("Migration completed successfully.")
    return True


def rollback():
    """Remove custom_fields column (if needed)."""
    database_url = get_database_url()
    engine = create_engine(database_url)

    inspector = inspect(engine)
    columns = [col["name"] for col in inspector.get_columns("customers")]

    if "custom_fields" not in columns:
        print("Column 'custom_fields' does not exist. Skipping rollback.")
        return True

    print("WARNING: Rolling back will DELETE all custom field data!")

    dialect = engine.dialect.name

    with engine.begin() as conn:
        if dialect == "sqlite":
            # SQLite doesn't support DROP COLUMN directly
            print("SQLite does not support DROP COLUMN. Manual migration required.")
            return False
        else:
            conn.execute(text("ALTER TABLE customers DROP COLUMN custom_fields"))

    print("Rollback completed.")
    return True


if __name__ == "__main__":
    if len(sys.argv) > 1 and sys.argv[1] == "--rollback":
        success = rollback()
    else:
        success = migrate()

    sys.exit(0 if success else 1)