<?php

declare(strict_types=1);

namespace Yatra\Services;

/**
 * Installer Service
 * 
 * Handles plugin installation and default settings setup
 * Ensures proper default configuration on fresh installation
 */
class InstallerService
{
    /**
     * Run installation tasks
     * 
     * @return void
     */
    public static function install(): void
    {
        // Create all database tables (one-time action)
        self::createDatabaseTables();
        
        // Set all default options for fresh installation
        self::setDefaultOptions();
    }
    
    /**
     * Create all database tables (centralized table creation)
     * 
     * @return void
     */
    public static function createDatabaseTables(): void
    {
        if (class_exists('\Yatra\Core\Database')) {
            \Yatra\Core\Database::createTables();
        }

    }
    
    /**
     * Set all default options for fresh installation
     * Only Book Now Pay Later should be enabled by default
     * Uses SettingsService keys to ensure consistency
     * 
     * @return void
     */
    private static function setDefaultOptions(): void
    {
        // Whether this is a brand-new install vs. a reactivation/upgrade.
        // Captured before version/date are stamped below so it reflects the
        // pre-activation state.
        $isFreshInstall = self::isFreshInstallation();

        // Seed a default only when the option is absent. add_option() is a
        // no-op when the option already exists (existence is keyed on the
        // option NAME, so values legitimately stored as false/0/'' are still
        // preserved). This makes activation idempotent: a deactivate ->
        // reactivate, or a plugin update, can never overwrite an operator's
        // saved settings, while a fresh install (and any newly-introduced
        // default on upgrade) is still seeded.
        $seed = static function (string $name, $value): void {
            add_option($name, $value);
        };

        // Payment Gateway Settings - Only enable Pay Later by default
        // These match SettingsService defaults exactly
        $seed('yatra_payment_gateways', ['pay_later']);
        $seed('yatra_payment_methods', []);
        $seed('yatra_payment_test_mode', true);
        $seed('yatra_auto_confirm_pay_later', true);
        $seed('yatra_partial_payment', false);
        // Set gateway configs with proper structure - only enable pay_later by default
        $gateway_configs = [
            'pay_later' => [
                'enabled' => true,
                'title' => 'Book Now, Pay Later',
                'description' => 'Allow customers to reserve now and pay before the trip',
            ],
            // Explicitly disable all other gateways
            'stripe' => [
                'enabled' => false,
                'title' => 'Stripe',
                'description' => 'Accept credit and debit cards',
                'api_key' => '',
                'api_secret' => '',
                'webhook_secret' => '',
            ],
            'paypal' => [
                'enabled' => false,
                'title' => 'PayPal',
                'description' => 'Accept PayPal payments',
                'api_key' => '',
                'api_secret' => '',
            ],
            'razorpay' => [
                'enabled' => false,
                'title' => 'Razorpay',
                'description' => 'Accept payments via Razorpay',
                'api_key' => '',
                'api_secret' => '',
            ],
            'square' => [
                'enabled' => false,
                'title' => 'Square',
                'description' => 'Accept payments via Square',
                'api_key' => '',
                'api_secret' => '',
            ],
            'authorize_net' => [
                'enabled' => false,
                'title' => 'Authorize.net',
                'description' => 'Accept payments via Authorize.net',
                'api_key' => '',
                'api_secret' => '',
            ],
            'bank_transfer' => [
                'enabled' => false,
                'title' => 'Bank Transfer',
                'description' => 'Accept manual bank transfer payments',
                'api_key' => '',
                'api_secret' => '',
            ]
        ];
        $seed('yatra_gateway_configs', $gateway_configs);
        $seed('yatra_gateway_order', []);
        
        // Currency Settings - Match SettingsService defaults
        $seed('yatra_currency', 'USD');
        $seed('yatra_currency_position', 'before');
        $seed('yatra_thousand_separator', ',');
        $seed('yatra_decimal_separator', '.');
        $seed('yatra_decimal_places', 2);
        
        // Flexible Payment Settings - Match SettingsService defaults
        $seed('yatra_enable_deposit', false);
        $seed('yatra_deposit_type', 'percentage');
        $seed('yatra_deposit_amount', 20);
        $seed('yatra_deposit_required', false);
        $seed('yatra_deposit_percentage', 20);
        $seed('yatra_partial_payment_percentage', 30);
        
        $seed('yatra_allow_save_payment_methods', false);
        
        // Trip Settings - Match SettingsService defaults
        $seed('yatra_trip_base', 'trip');
        $seed('yatra_trips_per_page', 12);
        $seed('yatra_enable_wishlist', false);
        $seed('yatra_enable_comparison', false);
        $seed('yatra_show_sold_out', true);
        
        // Customer Settings - Match SettingsService defaults
        $seed('yatra_enable_customer_accounts', true);
        $seed('yatra_enable_customer_registration', true);
        
        // Booking Settings - Match SettingsService defaults
        $seed('yatra_booking_base', 'book');
        $seed('yatra_use_booking_page', false);
        $seed('yatra_booking_page_id', 0);
        $seed('yatra_enable_guest_booking', true);
        $seed('yatra_booking_confirmation', true);
        $seed('yatra_auto_confirm_bookings', false);
        $seed('yatra_require_login', false);
        $seed('yatra_allow_guest_checkout', true);
        // cancellation_policy / cancellation_days / refund_policy
        // intentionally not seeded — these are removed settings (see
        // SettingsController::$default_settings comment). Existing
        // sites that already have orphan values stored will keep
        // them in wp_options; new sites won't acquire them.
        $seed('yatra_booking_expiry_hours', 24);
        $seed('yatra_booking_reminder_days', 3);
        $seed('yatra_allow_waitlist', true);
        
        // Email identity: canonical keys (REST / EmailService) + legacy keys for older code paths
        $wpAdminEmail = (string) get_option('admin_email', '');
        $blogName = (string) get_bloginfo('name');
        $seed('yatra_from_email', $wpAdminEmail);
        $seed('yatra_from_name', $blogName);
        $seed('yatra_admin_email', $wpAdminEmail);
        $seed('yatra_email_from_name', $blogName);
        $seed('yatra_email_from_address', $wpAdminEmail);
        $seed('yatra_enable_admin_notifications', true);
        $seed('yatra_enable_customer_notifications', true);

        // Default transactional template HTML + subjects (Email → Templates / settings API)
        foreach (EmailTemplateDefaults::settingsOptionDefaults() as $optionKey => $value) {
            $seed('yatra_' . $optionKey, $value);
        }
        $seed('yatra_email_template_booking', true);
        $seed('yatra_email_template_confirmation', true);
        $seed('yatra_email_template_cancellation', true);
        $seed('yatra_email_template_reminder', true);
        $seed('yatra_email_template_admin_new_booking', true);
        $seed('yatra_email_template_admin_payment', true);
        $seed('yatra_email_template_admin_cancellation', true);
        $seed('yatra_email_template_trip_consent', true);
        $seed('yatra_email_template_customer_verification', true);
        $seed('yatra_email_template_guest_verification', true);
        $seed('yatra_email_template_booking_completed', true);
        $seed('yatra_email_template_booking_expired_customer', true);
        $seed('yatra_email_template_admin_booking_expired', true);
        $seed('yatra_email_template_scheduled_payment_reminder', true);
        $seed('yatra_email_template_scheduled_payment_succeeded', true);
        $seed('yatra_email_template_scheduled_payment_failed', true);
        $seed('yatra_email_template_admin_scheduled_payment_failed', true);
        $seed('yatra_email_template_enquiry_received', true);
        $seed('yatra_email_template_enquiry_admin', true);
        $seed('yatra_email_template_enquiry_response', true);
        $seed('yatra_email_template_review_request', true);
        $seed('yatra_email_template_abandoned_booking_recovery_first', true);
        $seed('yatra_email_template_abandoned_booking_recovery_second', true);
        $seed('yatra_email_template_abandoned_booking_recovery_final', true);

        // Clear pre-existing legacy Stripe/PayPal settings, but only on a
        // brand-new install. On a reactivation these may hold the operator's
        // configured gateway data, so deleting them would be destructive.
        if ($isFreshInstall) {
            delete_option('yatra_stripe_settings');
            delete_option('yatra_paypal_settings');
        }
        
        // Installation tracking: stamp the date once (seed); keep the
        // version current so upgrade routines can detect version changes.
        $seed('yatra_installation_date', current_time('mysql'));
        update_option('yatra_version', defined('YATRA_VERSION') ? YATRA_VERSION : '3.0.3');
        

    }
    
    /**
     * Get all required database tables using Table classes
     * 
     * @return array
     */
    public static function getRequiredTables(): array
    {
        // Must match \Yatra\Core\Database::createTables() — used for activation, migrations, and targeted checks.
        $table_classes = [
            \Yatra\Database\Tables\TripsTable::class,
            \Yatra\Database\Tables\BookingsTable::class,
            \Yatra\Database\Tables\BookingPaymentsTable::class,
            \Yatra\Database\Tables\CustomersTable::class,
            \Yatra\Database\Tables\BookingTravellersTable::class,
            \Yatra\Database\Tables\BookingTravellerMetaTable::class,
            \Yatra\Database\Tables\BookingDeparturesTable::class,
            \Yatra\Database\Tables\ReviewsTable::class,
            \Yatra\Database\Tables\DiscountsTable::class,
            \Yatra\Database\Tables\EnquiriesTable::class,
            \Yatra\Database\Tables\TripAvailabilityDatesTable::class,
            \Yatra\Database\Tables\TripAvailabilityRulesTable::class,
            \Yatra\Database\Tables\TripRevisionsTable::class,
            \Yatra\Database\Tables\DeparturesTable::class,
            \Yatra\Database\Tables\TripItineraryDaysTable::class,
            \Yatra\Database\Tables\TripItineraryDayEntryTable::class,
            \Yatra\Database\Tables\ClassificationsTable::class,
            \Yatra\Database\Tables\TripClassificationsTable::class,
            \Yatra\Database\Tables\TripContentTable::class,
        ];

        $table_names = [];
        foreach ($table_classes as $table_class) {
            if (class_exists($table_class)) {
                $table_names[] = $table_class::getTableName();
            }
        }

        return $table_names;
    }

    /**
     * Whether a prefixed table exists. Uses esc_like() because SQL LIKE treats "_" as a wildcard.
     */
    public static function databaseTableExists(string $fullTableName): bool
    {
        global $wpdb;
        if ($fullTableName === '') {
            return false;
        }
        $pattern = $wpdb->esc_like($fullTableName);
        $found = $wpdb->get_var($wpdb->prepare('SHOW TABLES LIKE %s', $pattern));

        return $found === $fullTableName;
    }
    
    /**
     * Check if this is a fresh installation
     * 
     * @return bool
     */
    public static function isFreshInstallation(): bool
    {
        // Check if Yatra version exists in database
        $installed_version = get_option('yatra_version');
        
        // If no version is set, it's a fresh installation
        if ($installed_version === false) {
            return true;
        }
        
        // Check installation date
        $installation_date = get_option('yatra_installation_date');
        if ($installation_date === false) {
            return true;
        }
        
        // Additional check: if core tables don't exist, it's fresh
        $required_tables = self::getRequiredTables();
        if (!empty($required_tables)) {
            $trips_table = $required_tables[0]; // Use first table (already has prefix)
            if (!self::databaseTableExists($trips_table)) {
                return true;
            }
        }
        
        return false;
    }

    /**
     * One-time: coupon migration incorrectly stored status "active"; 3.x uses "publish" (admin + checkout).
     */
    public static function maybeNormalizeMigratedCouponDiscountStatuses(): void
    {
        if (get_option('yatra_discount_active_status_normalized_v1')) {
            return;
        }

        if (!class_exists('Yatra\\Database\\Tables\\DiscountsTable')) {
            return;
        }

        $table = \Yatra\Database\Tables\DiscountsTable::getTableName();
        if (!self::databaseTableExists($table)) {
            return;
        }

        global $wpdb;
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from schema helper
        $wpdb->query("UPDATE `{$table}` SET `status` = 'publish' WHERE `status` = 'active'");

        update_option('yatra_discount_active_status_normalized_v1', '1', false);
    }

    /**
     * One-time normalization of recurring availability rules created against the
     * legacy schema (only `recurrence_type`, `capacity_value`, `interval`, etc.
     * were written) so the new admin React UI — which reads `rule_type`,
     * `seats_total`, `interval_days`, `interval_start_date` — can render and
     * edit them without showing phantom "1 on All / Active" badges or empty
     * "Every " patterns.
     *
     * What this fixes:
     *  - Sample-data and pre-3.x rows landed with `rule_type` defaulted to
     *    'weekly' regardless of the actual `recurrence_type`, and with
     *    `seats_total` left NULL (the new capacity column). Daily and monthly
     *    rules therefore appeared as broken weekly rows in the new UI.
     *  - The /counts endpoint correctly reported 1 active rule, but the list
     *    table couldn't render it cleanly, leading users to read the API
     *    response as "ghost data".
     *
     * Invariants:
     *  - Idempotent — every UPDATE filters rows whose new columns are still
     *    unset, so re-running is a no-op once the data is healed.
     *  - Read-only on rows already authored by the new UI (`rule_type` already
     *    matches the recurrence intent), so user edits are never overwritten.
     *  - No-ops cleanly when the rules table doesn't exist yet (fresh install
     *    before {@see \Yatra\Core\Database::createTables()} has run).
     */
    public static function maybeNormalizeAvailabilityRulesLegacyData(): void
    {
        if (get_option('yatra_availability_rules_legacy_normalized_v1')) {
            return;
        }

        if (!class_exists('Yatra\\Database\\Tables\\TripAvailabilityRulesTable')) {
            return;
        }

        $table = \Yatra\Database\Tables\TripAvailabilityRulesTable::getTableName();
        if (!self::databaseTableExists($table)) {
            return;
        }

        global $wpdb;

        // 1. Daily-recurrence rows whose `rule_type` defaulted to 'weekly':
        //    map to the new "interval" rule type and copy the legacy `interval`
        //    + `start_date` into the new columns the React form binds to.
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from schema helper
        $wpdb->query("UPDATE `{$table}`
            SET `rule_type` = 'interval',
                `interval_days` = COALESCE(`interval_days`, NULLIF(`interval`, 0), 1),
                `interval_start_date` = COALESCE(`interval_start_date`, `start_date`)
            WHERE `recurrence_type` = 'daily'
              AND (`rule_type` IS NULL OR `rule_type` = '' OR `rule_type` = 'weekly')");

        // 2. Monthly-recurrence rows whose `rule_type` defaulted to 'weekly':
        //    relabel to 'monthly'. The new UI uses (week_of_month, day_of_week)
        //    rather than `day_of_month`, so we leave those NULL for the user
        //    to set in the form rather than guess from the legacy day_of_month.
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from schema helper
        $wpdb->query("UPDATE `{$table}`
            SET `rule_type` = 'monthly'
            WHERE `recurrence_type` = 'monthly'
              AND (`rule_type` IS NULL OR `rule_type` = '' OR `rule_type` = 'weekly')");

        // 3. Weekly-recurrence rows: ensure `rule_type` is set explicitly
        //    (most already match the default; this catches any NULL/empty).
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from schema helper
        $wpdb->query("UPDATE `{$table}`
            SET `rule_type` = 'weekly'
            WHERE `recurrence_type` = 'weekly'
              AND (`rule_type` IS NULL OR `rule_type` = '')");

        // 4. seats_total backfill from `capacity_value` for fixed-capacity rows
        //    so CapacityService and the React table both surface the right
        //    seat cap without falling through hydrate-time fallbacks.
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from schema helper
        $wpdb->query("UPDATE `{$table}`
            SET `seats_total` = `capacity_value`
            WHERE `seats_total` IS NULL
              AND `capacity_value` IS NOT NULL
              AND `capacity_value` > 0
              AND (`capacity_type` IS NULL OR `capacity_type` = 'fixed')");

        update_option('yatra_availability_rules_legacy_normalized_v1', '1', false);
    }

    /**
     * Ensure `wp_yatra_bookings.status` accepts `pending_verification`.
     *
     * The 3.0.5 guest email-verification feature introduced a new holding
     * status (`pending_verification`) but the production ENUM only listed
     * the legacy values. Until the column is widened, MySQL non-strict
     * mode silently coerces the value to `''` on insert — which makes
     * every booking placed with verification enabled appear broken:
     *
     *   1. The admin booking list renders an empty status badge (the
     *      React status map has no entry for `''` so the row falls into
     *      the default branch with an empty label).
     *   2. `BookingService::createBooking` sees the in-memory
     *      `$data['status'] === 'pending_verification'` and defers
     *      firing `yatra_booking_created`, so the customer never gets
     *      the booking-confirmation email.
     *   3. `verify_email` reads the persisted status (now `''`),
     *      decides the booking is "already verified", skips the deferred
     *      fan-out — so neither the status flip nor the booking email
     *      ever fires.
     *
     * Doing the widening here (runIdempotentMaintenance — every admin
     * pageview) instead of a pure version-gated upgrade step means it
     * heals installs whose stored yatra_version was already bumped to
     * 3.0.5 by an earlier failed upgrade attempt. Cheap: one
     * INFORMATION_SCHEMA query gated by a one-shot option flag, ALTER
     * runs at most once per install.
     *
     * Also backfills any rows whose status was silently coerced to `''`
     * by the pre-widening insert path: those bookings *should* have
     * landed in `pending_verification`, so we restore them there. The
     * original verify-email magic link still works because the HMAC
     * token is bound to booking_id + email, not status.
     */
    public static function maybeAddPendingVerificationBookingStatus(): void
    {
        if (get_option('yatra_booking_status_pending_verification_v1')) {
            return;
        }

        if (!class_exists('Yatra\\Database\\Tables\\BookingsTable')) {
            return;
        }

        $table = \Yatra\Database\Tables\BookingsTable::getTableName();
        if (!self::databaseTableExists($table)) {
            return;
        }

        global $wpdb;

        $columnInfo = $wpdb->get_row(
            $wpdb->prepare(
                "SELECT COLUMN_TYPE FROM INFORMATION_SCHEMA.COLUMNS
                 WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s AND COLUMN_NAME = %s",
                DB_NAME,
                $table,
                'status'
            )
        );

        $columnType = is_object($columnInfo) ? (string) ($columnInfo->COLUMN_TYPE ?? '') : '';
        $needsAlter = $columnType !== '' && strpos($columnType, 'pending_verification') === false;

        if ($needsAlter) {
            // Match the original column shape exactly minus the new enum
            // value — nullable, default 'pending', no NOT NULL.
            // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name escaped, enum literal is static.
            $wpdb->query(
                'ALTER TABLE `' . esc_sql($table) . "` "
                . "MODIFY COLUMN `status` "
                . "enum('pending','pending_verification','confirmed','processing','completed','cancelled','refunded','failed','on_hold','waitlist') "
                . "DEFAULT 'pending'"
            );
        }

        // Backfill: bookings whose insert hit the old ENUM during a
        // verification flow ended up with status='' (silent coerce).
        // Now that the enum accepts pending_verification, restore them.
        // Filtered to a narrow signal (status='' AND payment_status='pending')
        // so we don't accidentally re-stamp unrelated edge cases.
        // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name from schema helper, literal values only.
        $wpdb->query(
            "UPDATE `{$table}` SET `status` = 'pending_verification' "
            . "WHERE `status` = '' AND `payment_status` = 'pending'"
        );

        update_option('yatra_booking_status_pending_verification_v1', '1', false);
    }

    /**
     * Add the `duration_hours` column to the trips table for hour-based
     * (single-day) tours. Purely additive and nullable — existing trips get
     * NULL and behave exactly as before (day-based via `duration_days`). Only
     * tours that later set a positive `duration_hours` change behaviour.
     *
     * Idempotent: guarded by a one-shot option AND an INFORMATION_SCHEMA check,
     * so it runs its ALTER at most once and is a no-op when the column already
     * exists (fresh installs get it from TripsTable::getSchema()).
     */
    public static function maybeAddTripDurationHoursColumn(): void
    {
        if (get_option('yatra_trip_duration_hours_v1')) {
            return;
        }

        if (!class_exists('Yatra\\Database\\Tables\\TripsTable')) {
            return;
        }

        $table = \Yatra\Database\Tables\TripsTable::getTableName();
        if (!self::databaseTableExists($table)) {
            return;
        }

        global $wpdb;

        $columnExists = $wpdb->get_var(
            $wpdb->prepare(
                "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
                 WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s AND COLUMN_NAME = %s",
                DB_NAME,
                $table,
                'duration_hours'
            )
        );

        if (!$columnExists) {
            // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- table name escaped, static column definition.
            $wpdb->query(
                'ALTER TABLE `' . esc_sql($table) . '` '
                . "ADD COLUMN `duration_hours` smallint(5) UNSIGNED DEFAULT NULL "
                . "COMMENT 'Duration in hours for hour-based (single-day) tours; NULL = day-based' "
                . 'AFTER `duration_nights`'
            );

            // Re-check so we only mark this done when the column really exists.
            // If the ALTER failed (e.g. a restrictive host), leave the one-shot
            // flag unset so it retries on the next admin load rather than
            // disabling the feature permanently.
            $columnExists = $wpdb->get_var(
                $wpdb->prepare(
                    "SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
                     WHERE TABLE_SCHEMA = %s AND TABLE_NAME = %s AND COLUMN_NAME = %s",
                    DB_NAME,
                    $table,
                    'duration_hours'
                )
            );
        }

        if ($columnExists) {
            update_option('yatra_trip_duration_hours_v1', '1', false);
        }
    }

    /**
     * Fill canonical + legacy email identity options when empty (upgrades, partial installs, or empty strings in DB).
     * Idempotent; safe to run on each admin load via maybeBackfillEmailTemplateDefaults().
     */
    public static function maybeBackfillEmailDeliveryIdentity(): void
    {
        $wpAdmin = trim((string) get_option('admin_email', ''));
        $wpName = trim((string) get_bloginfo('name'));

        $isUnsetOrEmpty = static function ($v): bool {
            return $v === false || $v === null || $v === '' || (is_string($v) && trim($v) === '');
        };

        if ($wpAdmin !== '') {
            foreach (['yatra_admin_email', 'yatra_from_email', 'yatra_email_from_address'] as $opt) {
                if ($isUnsetOrEmpty(get_option($opt, false))) {
                    update_option($opt, $wpAdmin);
                }
            }
        }
        if ($wpName !== '') {
            foreach (['yatra_from_name', 'yatra_email_from_name'] as $opt) {
                if ($isUnsetOrEmpty(get_option($opt, false))) {
                    update_option($opt, $wpName);
                }
            }
        }
    }

    /**
     * One-time: persist default HTML subjects/bodies when options exist but are empty (pre-template-defaults installs).
     */
    public static function maybeBackfillEmailTemplateDefaults(): void
    {
        self::maybeBackfillEmailDeliveryIdentity();

        // Default-on for new option on existing sites (add_option no-ops if already present).
        add_option('yatra_email_template_admin_new_booking', 1);
        add_option('yatra_email_template_admin_payment', 1);
        add_option('yatra_email_template_admin_cancellation', 1);

        self::maybeBackfillCustomerEmailVerificationTemplate();
        self::maybeBackfillExtendedTransactionalEmailOptionsV2();

        if (!get_option('yatra_email_identity_synced_v1')) {
            $from = get_option('yatra_from_email', '');
            if (($from === false || $from === '') && ($legacy = get_option('yatra_email_from_address', '')) && is_string($legacy) && $legacy !== '') {
                update_option('yatra_from_email', $legacy);
            }
            $fname = get_option('yatra_from_name', '');
            if (($fname === false || $fname === '') && ($legacy = get_option('yatra_email_from_name', '')) && is_string($legacy) && $legacy !== '') {
                update_option('yatra_from_name', $legacy);
            }
            update_option('yatra_email_identity_synced_v1', '1');
        }

        if (get_option('yatra_email_tpl_defaults_backfill_1')) {
            return;
        }

        foreach (EmailTemplateDefaults::settingsOptionDefaults() as $key => $defaultValue) {
            $name = 'yatra_' . $key;
            $current = get_option($name, false);
            $isEmpty = $current === false || $current === '' || (is_string($current) && trim($current) === '');
            if ($isEmpty) {
                update_option($name, $defaultValue);
            }
        }

        update_option('yatra_email_tpl_defaults_backfill_1', '1');
    }

    /**
     * One-time: customer email verification template (Email → Templates) for existing installs.
     */
    private static function maybeBackfillCustomerEmailVerificationTemplate(): void
    {
        if (get_option('yatra_email_customer_verification_tpl_v1')) {
            return;
        }

        add_option('yatra_email_template_customer_verification', true);
        add_option('yatra_email_template_guest_verification', true);

        $defaults = EmailTemplateDefaults::settingsOptionDefaults();
        foreach (['email_tpl_customer_verification_subject', 'email_tpl_customer_verification_body'] as $key) {
            if (!isset($defaults[$key])) {
                continue;
            }
            $name = 'yatra_' . $key;
            $current = get_option($name, false);
            $isEmpty = $current === false || $current === '' || (is_string($current) && trim($current) === '');
            if ($isEmpty) {
                update_option($name, $defaults[$key]);
            }
        }

        update_option('yatra_email_customer_verification_tpl_v1', '1');
    }

    /**
     * One-time: enable flags + default HTML for extended transactional templates (completed, expiry, scheduled, enquiry, review, abandoned).
     * Only writes options that are still empty so existing customized HTML in the database is preserved on plugin update.
     */
    private static function maybeBackfillExtendedTransactionalEmailOptionsV2(): void
    {
        if (get_option('yatra_email_tpl_extended_v2')) {
            return;
        }

        $boolFlags = [
            'email_template_booking_completed',
            'email_template_booking_expired_customer',
            'email_template_admin_booking_expired',
            'email_template_scheduled_payment_reminder',
            'email_template_scheduled_payment_succeeded',
            'email_template_scheduled_payment_failed',
            'email_template_admin_scheduled_payment_failed',
            'email_template_enquiry_received',
            'email_template_enquiry_admin',
            'email_template_enquiry_response',
            'email_template_review_request',
            'email_template_abandoned_booking_recovery_first',
            'email_template_abandoned_booking_recovery_second',
            'email_template_abandoned_booking_recovery_final',
        ];
        foreach ($boolFlags as $flag) {
            add_option('yatra_' . $flag, true);
        }

        $extendedContentKeys = [
            'email_tpl_booking_completed_subject',
            'email_tpl_booking_completed_body',
            'email_tpl_booking_expired_customer_subject',
            'email_tpl_booking_expired_customer_body',
            'email_tpl_admin_booking_expired_subject',
            'email_tpl_admin_booking_expired_body',
            'email_tpl_scheduled_payment_reminder_subject',
            'email_tpl_scheduled_payment_reminder_body',
            'email_tpl_scheduled_payment_succeeded_subject',
            'email_tpl_scheduled_payment_succeeded_body',
            'email_tpl_scheduled_payment_failed_subject',
            'email_tpl_scheduled_payment_failed_body',
            'email_tpl_admin_scheduled_payment_failed_subject',
            'email_tpl_admin_scheduled_payment_failed_body',
            'email_tpl_enquiry_admin_subject',
            'email_tpl_enquiry_admin_body',
            'email_tpl_enquiry_received_subject',
            'email_tpl_enquiry_received_body',
            'email_tpl_enquiry_response_subject',
            'email_tpl_enquiry_response_body',
            'email_tpl_review_request_subject',
            'email_tpl_review_request_body',
            'email_tpl_abandoned_booking_recovery_first_subject',
            'email_tpl_abandoned_booking_recovery_first_body',
            'email_tpl_abandoned_booking_recovery_second_subject',
            'email_tpl_abandoned_booking_recovery_second_body',
            'email_tpl_abandoned_booking_recovery_final_subject',
            'email_tpl_abandoned_booking_recovery_final_body',
        ];

        $defaults = EmailTemplateDefaults::settingsOptionDefaults();
        foreach ($extendedContentKeys as $key) {
            if (!isset($defaults[$key])) {
                continue;
            }
            $name = 'yatra_' . $key;
            $current = get_option($name, false);
            $isEmpty = $current === false || $current === '' || (is_string($current) && trim($current) === '');
            if ($isEmpty) {
                update_option($name, $defaults[$key]);
            }
        }

        update_option('yatra_email_tpl_extended_v2', '1');
    }
}