<?php
/**
 * AKSRT Settings Migration
 *
 * Handles AKSRT's own schema evolution.
 * This migration layer no longer backfills or mirrors deprecated option aliases.
 *
 * @package AKSRT
 */

defined('ABSPATH') || exit;

class AKSRT_Settings_Migration {

    private static $instance = null;

    /**
     * Current migration schema version.
     */
    const MIGRATION_VERSION = '1.3.0';

    /**
     * Option key that stores the current migration version.
     */
    const VERSION_KEY = 'aksrt_settings_migration_version';

    /**
     * Option key that stores migration log entries.
     */
    const LOG_KEY = 'aksrt_settings_migration_log';

    public static function get_instance(): self {
        if (null === self::$instance) self::$instance = new self();
        return self::$instance;
    }

    /**
     * Run pending migrations.
     * Called on theme activation and admin_init.
     */
    public function maybe_migrate(): void {
        $current = get_option(self::VERSION_KEY, '0.0.0');

        if (version_compare($current, self::MIGRATION_VERSION, '>=')) {
            return; // Already up to date
        }

        $log = $this->get_log();
        $schema_provider = AKSRT_Admin_Schema_Provider::get_instance();

        // Run migrations in order
        $this->migrate_v1_0_0($schema_provider, $log);
        $this->migrate_v1_2_0($log);
        $this->migrate_v1_3_0($log);

        // Update version
        update_option(self::VERSION_KEY, self::MIGRATION_VERSION);
        $log[] = [
            'version'   => self::MIGRATION_VERSION,
            'timestamp' => gmdate('Y-m-d H:i:s'),
            'action'    => 'migration_complete',
        ];
        update_option(self::LOG_KEY, $log);
    }

    /**
     * Get the migration log.
     *
     * @return array
     */
    public function get_log(): array {
        $log = get_option(self::LOG_KEY, []);
        return is_array($log) ? $log : [];
    }

    /**
     * Get current migration version.
     *
     * @return string
     */
    public function get_version(): string {
        return get_option(self::VERSION_KEY, '0.0.0');
    }

    /* ------------------------------------------------------------------ */
    /*  Migration: v1.0.0                                                  */
    /*  Maps old option keys to new schema-managed domains.                */
    /* ------------------------------------------------------------------ */

    private function migrate_v1_0_0(AKSRT_Admin_Schema_Provider $schema_provider, array &$log): void {
        // 1. Migrate aksrt_basic_settings fields into the new global domain
        $this->migrate_basic_to_global($schema_provider, $log);

        // 2. Migrate aksrt_seo_settings to the new seo domain (already a standalone key)
        //    No action needed — it's already stored under aksrt_seo_settings.

        // 3. Ensure all domain options exist with defaults
        foreach ($schema_provider->get_domain_keys() as $domain) {
            $option_key = $schema_provider->get_option_key($domain);
            $existing = get_option($option_key);
            if ($existing === false) {
                $defaults = $schema_provider->get_defaults($domain);
                if (!empty($defaults)) {
                    add_option($option_key, $defaults);
                    $log[] = [
                        'version' => '1.0.0',
                        'action'  => 'created_domain_defaults',
                        'domain'  => $domain,
                    ];
                }
            }
        }
    }

    /**
     * Migrate fields from aksrt_basic_settings to the new global domain.
     *
     * The old aksrt_basic_settings contains many fields from different domains
     * (auth, comment, avatar, etc.). We selectively map them to the new structure
     * without deleting the original option.
     */
    private function migrate_basic_to_global(AKSRT_Admin_Schema_Provider $schema_provider, array &$log): void {
        $old = get_option('aksrt_basic_settings', []);
        if (!is_array($old) || empty($old)) return;

        // Map old keys to new global domain keys
        $field_map = [
            'comment_enabled'             => 'comment_enabled',
            'comments_per_page'           => 'comments_per_page',
            'comment_requires_registration' => 'comment_requires_registration',
            'lazy_load'                   => 'lazy_load',
            'avatar_source'               => 'avatar_source',
            'icp_filing'                  => 'icp_filing',
            'footer_text'                 => 'footer_text',
            'copyright_year'              => 'copyright_year',
            'registration_enabled'        => 'registration_enabled',
            'email_verification'          => 'email_verification',
        ];

        $new_data = [];
        foreach ($field_map as $old_key => $new_key) {
            if (isset($old[$old_key])) {
                $new_data[$new_key] = $old[$old_key];
            }
        }

        if (!empty($new_data)) {
            $existing = get_option('aksrt_basic_settings', []);
            if (!is_array($existing)) $existing = [];
            // Merge: new mapped values take precedence only if not already set
            $merged = wp_parse_args($existing, $new_data);
            update_option('aksrt_basic_settings', $merged);

            $log[] = [
                'version'  => '1.0.0',
                'action'   => 'migrated_basic_to_global',
                'fields'   => array_keys($new_data),
                'migrated' => count($new_data),
            ];
        }
    }

    private function migrate_v1_2_0(array &$log): void {
        $settings = get_option('aksrt_settings', []);
        if (!is_array($settings) || empty($settings)) {
            return;
        }

        $map = [
            'header_slider_search' => 'header_components_search_enabled',
            'header_slider_cards' => 'header_components_cards_enabled',
            'header_slider_nav_color' => 'header_components_nav_color',
            'header_slider_show' => 'header_components_show_on',
            'header_slider_show_type' => 'header_components_device_visibility',
            'header_slider_filter_blur' => 'header_components_filter_blur_devices',
            'header_slider_card_show' => 'header_components_card_show_devices',
            'header_card_shared_bg' => 'header_components_card_shared_bg',
            'header_card_blur' => 'header_components_card_blur',
            'header_card_icon_shape' => 'header_components_card_icon_shape',
            'header_icon_cards' => 'header_components_icon_cards',
            'header_slider_search_pc' => 'header_components_search_pc',
            'header_slider_search_mobile' => 'header_components_search_mobile',
            'header_slider_search_show_keywords' => 'header_components_search_show_keywords',
            'header_slider_search_popular_limit' => 'header_components_search_popular_limit',
            'header_slider_search_show_input_cat' => 'header_components_search_show_input_cat',
            'header_slider_search_show_type' => 'header_components_search_show_type',
        ];

        $migrated = [];
        foreach ($map as $old_key => $new_key) {
            if (array_key_exists($old_key, $settings) && !array_key_exists($new_key, $settings)) {
                $settings[$new_key] = $settings[$old_key];
                $migrated[] = $old_key;
            }
            if (array_key_exists($old_key, $settings)) {
                unset($settings[$old_key]);
            }
        }

        if (!empty($migrated)) {
            update_option('aksrt_settings', $settings);
            $log[] = [
                'version'  => '1.2.0',
                'action'   => 'renamed_header_components_keys',
                'migrated' => $migrated,
            ];
        }
    }

    private function migrate_v1_3_0(array &$log): void {
        $settings = get_option('aksrt_settings', []);
        if (!is_array($settings) || empty($settings)) {
            return;
        }

        $map = [
            'homepage_hero_enabled' => 'homepage_module_hero_enabled',
            'homepage_banner_enabled' => 'homepage_module_banner_enabled',
        ];

        $migrated = [];
        foreach ($map as $old_key => $new_key) {
            if (array_key_exists($old_key, $settings) && !array_key_exists($new_key, $settings)) {
                $settings[$new_key] = $settings[$old_key];
                $migrated[] = $old_key;
            }
            if (array_key_exists($old_key, $settings)) {
                unset($settings[$old_key]);
            }
        }

        if (!empty($migrated)) {
            update_option('aksrt_settings', $settings);
            $log[] = [
                'version'  => '1.3.0',
                'action'   => 'renamed_homepage_module_toggle_keys',
                'migrated' => $migrated,
            ];
        }
    }

    public function map_legacy_key(string $option_key): ?array {
        $map = [
            'aksrt_basic_settings'     => ['domain' => 'global', 'key' => 'aksrt_basic_settings'],
            'aksrt_seo_settings'       => ['domain' => 'seo', 'key' => 'aksrt_seo_settings'],
            'aksrt_mail_smtp'          => ['domain' => 'global', 'key' => 'aksrt_mail_smtp'],
            'aksrt_oauth'              => ['domain' => 'users', 'key' => 'aksrt_oauth'],
            'aksrt_moderation_config'  => ['domain' => 'permissions', 'key' => 'aksrt_moderation_config'],
            'aksrt_captcha_config'     => ['domain' => 'permissions', 'key' => 'aksrt_captcha_config'],
            'aksrt_credit_settings'    => ['domain' => 'users', 'key' => 'aksrt_credit_settings'],
            'aksrt_notification_settings' => ['domain' => 'users', 'key' => 'aksrt_notification_settings'],
            'aksrt_footer_settings'    => ['domain' => 'page_display', 'key' => 'aksrt_footer_settings'],
            'aksrt_footer_tabbar'      => ['domain' => 'page_display', 'key' => 'aksrt_footer_tabbar'],
            'aksrt_floating_buttons'   => ['domain' => 'global', 'key' => 'aksrt_floating_buttons'],
            'aksrt_friend_links'       => ['domain' => 'page_display', 'key' => 'aksrt_friend_links'],
            'aksrt_banners'            => ['domain' => 'page_display', 'key' => 'aksrt_banners'],
            'aksrt_category_recommend' => ['domain' => 'page_display', 'key' => 'aksrt_category_recommend'],
        ];

        return $map[$option_key] ?? null;
    }
}