/**
 * Migration: Prepare UUID migration - Add new UUID columns
 *
 * Phase 1 of 3 for migrating Serial primary keys to UUID
 * This migration adds new UUID columns and generates values
 *
 * Affected tables:
 * - analysis_results
 * - weather_stations
 * - weather_forecasts
 * - weather_observations
 * - subscription_plans
 * - user_subscriptions
 * - subscription_history
 * - payment_records
 * - camera_devices
 *
 * @type {import('node-pg-migrate').ColumnDefinitions | undefined}
 */
export const shorthands = undefined;

/**
 * Tables with serial primary keys that need UUID migration
 */
const TABLES_TO_MIGRATE = [
  'analysis_results',
  'weather_stations',
  'weather_forecasts',
  'weather_observations',
  'subscription_plans',
  'user_subscriptions',
  'subscription_history',
  'payment_records',
  'camera_devices',
];

/**
 * @param pgm {import('node-pg-migrate').MigrationBuilder}
 * @param run {() => void | undefined}
 * @returns {Promise<void> | void}
 */
export const up = (pgm) => {
  console.log('Phase 1: Adding new UUID columns to tables with Serial primary keys...');

  // Ensure pgcrypto extension is available for gen_random_uuid()
  pgm.sql('CREATE EXTENSION IF NOT EXISTS pgcrypto;');

  // Add new_id UUID column to each table
  TABLES_TO_MIGRATE.forEach((table) => {
    console.log(`  Adding new_id to ${table}...`);

    pgm.addColumn(table, {
      new_id: {
        type: 'uuid',
        notNull: false,
        comment: 'Temporary UUID column for migration from serial ID',
      },
    });

    // Generate UUID for all existing rows
    pgm.sql(`UPDATE ${table} SET new_id = gen_random_uuid() WHERE new_id IS NULL;`);

    // Create index on new_id for faster lookups during migration
    pgm.createIndex(table, 'new_id', {
      name: `idx_${table}_new_id`,
      unique: true,
      where: 'new_id IS NOT NULL',
    });
  });

  // Create mapping tables to preserve old_id -> new_id relationships
  // This is crucial for data migration and rollback
  pgm.sql(`
    -- Create mapping table for ID lookups during migration
    CREATE TABLE IF NOT EXISTS _migration_id_mapping (
      table_name VARCHAR(100) NOT NULL,
      old_id INTEGER NOT NULL,
      new_id UUID NOT NULL,
      created_at TIMESTAMPTZ DEFAULT CURRENT_TIMESTAMP,
      PRIMARY KEY (table_name, old_id)
    );

    CREATE INDEX IF NOT EXISTS idx_migration_mapping_new_id
    ON _migration_id_mapping(table_name, new_id);
  `);

  // Populate mapping table
  TABLES_TO_MIGRATE.forEach((table) => {
    pgm.sql(`
      INSERT INTO _migration_id_mapping (table_name, old_id, new_id)
      SELECT '${table}', id, new_id FROM ${table}
      ON CONFLICT (table_name, old_id) DO UPDATE SET new_id = EXCLUDED.new_id;
    `);
  });

  console.log('Phase 1 complete: UUID columns added and populated.');
};

/**
 * @param pgm {import('node-pg-migrate').MigrationBuilder}
 * @param run {() => void | undefined}
 * @returns {Promise<void> | void}
 */
export const down = (pgm) => {
  console.log('Rolling back Phase 1: Removing UUID columns...');

  // Drop mapping table
  pgm.sql('DROP TABLE IF EXISTS _migration_id_mapping CASCADE;');

  // Remove new_id columns from all tables
  TABLES_TO_MIGRATE.forEach((table) => {
    console.log(`  Removing new_id from ${table}...`);

    pgm.dropIndex(table, 'new_id', {
      name: `idx_${table}_new_id`,
      ifExists: true,
    });

    pgm.dropColumn(table, 'new_id', {
      ifExists: true,
    });
  });

  console.log('Phase 1 rollback complete.');
};