/**
 * Migration: Update foreign key references to use new UUID columns
 *
 * Phase 2 of 3 for migrating Serial primary keys to UUID
 * This migration adds UUID foreign key columns and migrates the data
 *
 * Foreign Key Relationships to Update:
 * - weather_forecasts.station_id -> weather_stations.id
 * - weather_observations.weather_station_id -> weather_stations.id
 * - user_subscriptions.subscription_plan_id -> subscription_plans.id
 * - subscription_history.user_subscription_id -> user_subscriptions.id
 * - payment_records.user_subscription_id -> user_subscriptions.id
 *
 * @type {import('node-pg-migrate').ColumnDefinitions | undefined}
 */
export const shorthands = undefined;

/**
 * @param pgm {import('node-pg-migrate').MigrationBuilder}
 * @param run {() => void | undefined}
 * @returns {Promise<void> | void}
 */
export const up = (pgm) => {
  console.log('Phase 2: Updating foreign key references to use UUID...');

  // =====================================================
  // 1. weather_forecasts.station_id -> weather_stations
  // =====================================================
  console.log('  Updating weather_forecasts.station_id...');

  pgm.addColumn('weather_forecasts', {
    new_station_id: {
      type: 'uuid',
      notNull: false,
      comment: 'Temporary UUID FK for migration',
    },
  });

  pgm.sql(`
    UPDATE weather_forecasts wf
    SET new_station_id = ws.new_id
    FROM weather_stations ws
    WHERE wf.station_id = ws.id;
  `);

  // =====================================================
  // 2. weather_observations.weather_station_id -> weather_stations
  // =====================================================
  console.log('  Updating weather_observations.weather_station_id...');

  pgm.addColumn('weather_observations', {
    new_weather_station_id: {
      type: 'uuid',
      notNull: false,
      comment: 'Temporary UUID FK for migration',
    },
  });

  pgm.sql(`
    UPDATE weather_observations wo
    SET new_weather_station_id = ws.new_id
    FROM weather_stations ws
    WHERE wo.weather_station_id = ws.id;
  `);

  // =====================================================
  // 3. user_subscriptions.subscription_plan_id -> subscription_plans
  // =====================================================
  console.log('  Updating user_subscriptions.subscription_plan_id...');

  pgm.addColumn('user_subscriptions', {
    new_subscription_plan_id: {
      type: 'uuid',
      notNull: false,
      comment: 'Temporary UUID FK for migration',
    },
  });

  pgm.sql(`
    UPDATE user_subscriptions us
    SET new_subscription_plan_id = sp.new_id
    FROM subscription_plans sp
    WHERE us.subscription_plan_id = sp.id;
  `);

  // =====================================================
  // 4. subscription_history.user_subscription_id -> user_subscriptions
  // =====================================================
  console.log('  Updating subscription_history.user_subscription_id...');

  pgm.addColumn('subscription_history', {
    new_user_subscription_id: {
      type: 'uuid',
      notNull: false,
      comment: 'Temporary UUID FK for migration',
    },
  });

  pgm.sql(`
    UPDATE subscription_history sh
    SET new_user_subscription_id = us.new_id
    FROM user_subscriptions us
    WHERE sh.user_subscription_id = us.id;
  `);

  // =====================================================
  // 5. payment_records.user_subscription_id -> user_subscriptions
  // =====================================================
  console.log('  Updating payment_records.user_subscription_id...');

  pgm.addColumn('payment_records', {
    new_user_subscription_id: {
      type: 'uuid',
      notNull: false,
      comment: 'Temporary UUID FK for migration',
    },
  });

  pgm.sql(`
    UPDATE payment_records pr
    SET new_user_subscription_id = us.new_id
    FROM user_subscriptions us
    WHERE pr.user_subscription_id = us.id;
  `);

  // Create indexes on new FK columns for validation
  pgm.createIndex('weather_forecasts', 'new_station_id', {
    name: 'idx_weather_forecasts_new_station_id',
  });

  pgm.createIndex('weather_observations', 'new_weather_station_id', {
    name: 'idx_weather_observations_new_station_id',
  });

  pgm.createIndex('user_subscriptions', 'new_subscription_plan_id', {
    name: 'idx_user_subscriptions_new_plan_id',
  });

  pgm.createIndex('subscription_history', 'new_user_subscription_id', {
    name: 'idx_subscription_history_new_sub_id',
  });

  pgm.createIndex('payment_records', 'new_user_subscription_id', {
    name: 'idx_payment_records_new_sub_id',
  });

  console.log('Phase 2 complete: Foreign key references updated.');
};

/**
 * @param pgm {import('node-pg-migrate').MigrationBuilder}
 * @param run {() => void | undefined}
 * @returns {Promise<void> | void}
 */
export const down = (pgm) => {
  console.log('Rolling back Phase 2: Removing UUID FK columns...');

  // Drop indexes
  const indexes = [
    { table: 'weather_forecasts', name: 'idx_weather_forecasts_new_station_id' },
    { table: 'weather_observations', name: 'idx_weather_observations_new_station_id' },
    { table: 'user_subscriptions', name: 'idx_user_subscriptions_new_plan_id' },
    { table: 'subscription_history', name: 'idx_subscription_history_new_sub_id' },
    { table: 'payment_records', name: 'idx_payment_records_new_sub_id' },
  ];

  indexes.forEach(({ table, name }) => {
    pgm.dropIndex(table, [], { name, ifExists: true });
  });

  // Drop columns
  pgm.dropColumn('weather_forecasts', 'new_station_id', { ifExists: true });
  pgm.dropColumn('weather_observations', 'new_weather_station_id', { ifExists: true });
  pgm.dropColumn('user_subscriptions', 'new_subscription_plan_id', { ifExists: true });
  pgm.dropColumn('subscription_history', 'new_user_subscription_id', { ifExists: true });
  pgm.dropColumn('payment_records', 'new_user_subscription_id', { ifExists: true });

  console.log('Phase 2 rollback complete.');
};