/**
 * Migration: Add language_code column to email template tables
 * This migration adds language support to email templates for i18n
 * Citus-compatible: unique constraints include tenant column for distributed tables
 */

const ensureSequentialMode = async (knex) => {
  await knex.raw(`
    DO $$
    BEGIN
      IF EXISTS (
        SELECT 1 FROM pg_extension WHERE extname = 'citus'
      ) THEN
        EXECUTE 'SET citus.multi_shard_modify_mode TO ''sequential''';
      END IF;
    END $$;
  `);
};

exports.up = async function (knex) {
  await ensureSequentialMode(knex);

  // Check if language_code already exists in system_email_templates
  const systemHasLanguageCode = await knex.raw(`
    SELECT EXISTS (
      SELECT 1 FROM information_schema.columns
      WHERE table_name = 'system_email_templates'
      AND column_name = 'language_code'
    )
  `);

  if (!systemHasLanguageCode.rows[0].exists) {
    // Add language_code to system_email_templates (reference table in Citus)
    await knex.schema.alterTable('system_email_templates', (table) => {
      table.string('language_code', 10);
    });

    await knex('system_email_templates').update({ language_code: 'en' });
    await knex.raw("ALTER TABLE system_email_templates ALTER COLUMN language_code SET DEFAULT 'en'");
    await knex.raw('ALTER TABLE system_email_templates ALTER COLUMN language_code SET NOT NULL');
  }

  // Create index after column is added
  await knex.raw('CREATE INDEX IF NOT EXISTS idx_system_email_templates_name_language ON system_email_templates(name, language_code)');

  // Check if language_code already exists in tenant_email_templates
  const tenantHasLanguageCode = await knex.raw(`
    SELECT EXISTS (
      SELECT 1 FROM information_schema.columns
      WHERE table_name = 'tenant_email_templates'
      AND column_name = 'language_code'
    )
  `);

  if (!tenantHasLanguageCode.rows[0].exists) {
    // Add language_code to tenant_email_templates (distributed table in Citus)
    await knex.schema.alterTable('tenant_email_templates', (table) => {
      table.string('language_code', 10);
    });

    await ensureSequentialMode(knex);
    await knex('tenant_email_templates').update({ language_code: 'en' });
    await knex.raw("ALTER TABLE tenant_email_templates ALTER COLUMN language_code SET DEFAULT 'en'");
    await knex.raw('ALTER TABLE tenant_email_templates ALTER COLUMN language_code SET NOT NULL');
  }

  // Create index including tenant column for Citus compatibility
  await knex.raw('CREATE INDEX IF NOT EXISTS idx_tenant_email_templates_tenant_name_language ON tenant_email_templates(tenant, name, language_code)');

  // Drop existing unique constraints if they exist
  await knex.raw('ALTER TABLE system_email_templates DROP CONSTRAINT IF EXISTS system_email_templates_name_key');
  await knex.raw('ALTER TABLE tenant_email_templates DROP CONSTRAINT IF EXISTS tenant_email_templates_tenant_name_key');

  // Add new unique constraints including language_code (only if not already exist)
  await knex.raw('ALTER TABLE system_email_templates DROP CONSTRAINT IF EXISTS system_email_templates_name_language_key');
  await knex.raw('ALTER TABLE system_email_templates ADD CONSTRAINT system_email_templates_name_language_key UNIQUE (name, language_code)');

  // For Citus distributed tables, unique constraints must include the distribution column (tenant)
  await knex.raw('ALTER TABLE tenant_email_templates DROP CONSTRAINT IF EXISTS tenant_email_templates_tenant_name_language_key');
  await knex.raw('ALTER TABLE tenant_email_templates ADD CONSTRAINT tenant_email_templates_tenant_name_language_key UNIQUE (tenant, name, language_code)');

  // Note: user_preferences uses a key-value pattern (setting_name, setting_value)
  // Locale will be stored as: setting_name = 'locale', setting_value = '"en"' or '"fr"'
  // No schema change needed, but add index for better performance
  await knex.raw(`
    CREATE INDEX IF NOT EXISTS idx_user_preferences_locale_setting
    ON user_preferences(tenant, setting_name)
    WHERE setting_name = 'locale'
  `);

  // Note: tenant_settings uses a generic 'settings' JSONB column
  // Locale settings will be stored in settings.clientPortal.defaultLocale and settings.clientPortal.enabledLocales
  // Add comment to document the expected structure
  await knex.raw(`
    COMMENT ON COLUMN tenant_settings.settings IS
    'General tenant settings as JSONB. Expected structure includes:
    {
      "clientPortal": {
        "defaultLocale": "en",
        "enabledLocales": ["en", "fr"],
        "branding": {...},
        "theme": {...}
      },
      "defaultLocale": "en",  -- Tenant-wide default locale
      ...other settings...
    }'
  `);

  // Add comment for companies.properties to document language preference
  await knex.raw(`
    COMMENT ON COLUMN companies.properties IS
    'Company properties as JSONB. Expected structure includes:
    {
      "defaultLocale": "en",  -- Company-wide default locale for all contacts
      ...other properties...
    }'
  `);
};

exports.down = async function (knex) {
  await ensureSequentialMode(knex);

  // Remove unique constraints with language_code
  await knex.raw('ALTER TABLE system_email_templates DROP CONSTRAINT IF EXISTS system_email_templates_name_language_key');
  await knex.raw('ALTER TABLE tenant_email_templates DROP CONSTRAINT IF EXISTS tenant_email_templates_tenant_name_language_key');

  // Restore original unique constraints (if they existed)
  // Note: These may fail if constraints already exist, which is fine
  try {
    await knex.raw('ALTER TABLE system_email_templates ADD CONSTRAINT system_email_templates_name_key UNIQUE (name)');
  } catch (e) {
    // Constraint might already exist
  }

  try {
    // For Citus, unique constraint must include distribution column
    await knex.raw('ALTER TABLE tenant_email_templates ADD CONSTRAINT tenant_email_templates_tenant_name_key UNIQUE (tenant, name)');
  } catch (e) {
    // Constraint might already exist
  }

  // Remove indexes
  await knex.raw('DROP INDEX IF EXISTS idx_system_email_templates_name_language');
  await knex.raw('DROP INDEX IF EXISTS idx_tenant_email_templates_tenant_name_language');
  await knex.raw('DROP INDEX IF EXISTS idx_user_preferences_locale_setting');

  // Check if columns exist before dropping them
  const systemHasLanguageCode = await knex.raw(`
    SELECT EXISTS (
      SELECT 1 FROM information_schema.columns
      WHERE table_name = 'system_email_templates'
      AND column_name = 'language_code'
    )
  `);

  if (systemHasLanguageCode.rows[0].exists) {
    await knex.schema.alterTable('system_email_templates', (table) => {
      table.dropColumn('language_code');
    });
  }

  const tenantHasLanguageCode = await knex.raw(`
    SELECT EXISTS (
      SELECT 1 FROM information_schema.columns
      WHERE table_name = 'tenant_email_templates'
      AND column_name = 'language_code'
    )
  `);

  if (tenantHasLanguageCode.rows[0].exists) {
    await knex.schema.alterTable('tenant_email_templates', (table) => {
      table.dropColumn('language_code');
    });
  }
};

exports.config = { transaction: false };