<?php
/**
 * Detects active source SEO plugins and migrates their data into
 * ABDS SEO's own meta keys, per TZ §2.2.
 *
 * Compatibility mode: while a source plugin is still active and migration
 * hasn't been confirmed, ABDS SEO must not output its own meta
 * tags/schema (see ABDS_SEO_Frontend, not part of this MVP phase) to
 * avoid duplicate title/canonical/OG tags on the page.
 *
 * @package ABDS_SEO
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Orchestrates preview, migration, and completion tracking across all
 * registered source-plugin adapters.
 */
class ABDS_SEO_Migration_Manager {

	/**
	 * Option name the plugin's settings (including migration state) are stored under.
	 */
	const SETTINGS_OPTION = 'abds_seo_settings';

	/**
	 * Own meta key prefix the migrated values are written under.
	 */
	const META_PREFIX = '_abds_seo_';

	/**
	 * Returns every known migration adapter, regardless of whether its
	 * source plugin is currently active.
	 *
	 * @return ABDS_SEO_Migration_Adapter[]
	 */
	public function get_adapters(): array {
		return array(
			new ABDS_SEO_Adapter_Yoast(),
			new ABDS_SEO_Adapter_RankMath(),
			new ABDS_SEO_Adapter_AIOSEO(),
		);
	}

	/**
	 * Returns only adapters whose source plugin is currently active.
	 *
	 * @return ABDS_SEO_Migration_Adapter[]
	 */
	public function get_active_adapters(): array {
		return array_values( array_filter( $this->get_adapters(), fn( $adapter ) => $adapter->is_active() ) );
	}

	/**
	 * Whether any known source SEO plugin is currently active.
	 *
	 * @return bool
	 */
	public function has_active_source_plugin(): bool {
		return ! empty( $this->get_active_adapters() );
	}

	/**
	 * Dry-run preview: how many pages/fields would be affected, without writing anything.
	 *
	 * @param ABDS_SEO_Migration_Adapter $adapter Adapter to preview.
	 * @return array{adapter: string, pages_found: int}
	 */
	public function preview( ABDS_SEO_Migration_Adapter $adapter ): array {
		return array(
			'adapter'     => $adapter->get_name(),
			'pages_found' => $adapter->count_migratable_pages(),
		);
	}

	/**
	 * Migrates all public post types' SEO data from the given adapter into
	 * ABDS SEO's own postmeta, logging progress to wp_abds_seo_migration_log.
	 *
	 * @param ABDS_SEO_Migration_Adapter $adapter Adapter to migrate from.
	 * @return array{log_id: int, pages_total: int, pages_migrated: int}
	 */
	public function migrate( ABDS_SEO_Migration_Adapter $adapter ): array {
		global $wpdb;

		$log_table = $wpdb->prefix . 'abds_seo_migration_log';

		$post_ids = get_posts(
			array(
				'post_type'      => 'any',
				'post_status'    => 'publish',
				'posts_per_page' => -1,
				'fields'         => 'ids',
			)
		);

		$pages_total = count( $post_ids );

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- $log_table is built only from $wpdb->prefix plus a hardcoded literal, never user input; $wpdb->insert() safely escapes its values via the format array. Runs once per explicit, admin-triggered migration, not a cacheable read path.
		$wpdb->insert(
			$log_table,
			array(
				'source_plugin' => $adapter->get_slug(),
				'started_at'    => current_time( 'mysql' ),
				'pages_total'   => $pages_total,
				'status'        => 'running',
			),
			array( '%s', '%s', '%d', '%s' )
		);
		$log_id = (int) $wpdb->insert_id;

		$pages_migrated = 0;

		foreach ( $post_ids as $post_id ) {
			if ( $this->migrate_single_post( $adapter, (int) $post_id ) ) {
				++$pages_migrated;
			}
		}

		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching -- $log_table is built only from $wpdb->prefix plus a hardcoded literal, never user input; $wpdb->update() safely escapes its values via the format array. Runs once per explicit, admin-triggered migration, not a cacheable read path.
		$wpdb->update(
			$log_table,
			array(
				'finished_at'    => current_time( 'mysql' ),
				'pages_migrated' => $pages_migrated,
				'status'         => 'completed',
			),
			array( 'id' => $log_id ),
			array( '%s', '%d', '%s' ),
			array( '%d' )
		);

		$settings                        = get_option( self::SETTINGS_OPTION, array() );
		$settings['migration_completed'] = true;
		$settings['migration_source']    = $adapter->get_slug();
		update_option( self::SETTINGS_OPTION, $settings );

		return array(
			'log_id'         => $log_id,
			'pages_total'    => $pages_total,
			'pages_migrated' => $pages_migrated,
		);
	}

	/**
	 * Copies one post's fields from the source adapter into ABDS SEO's
	 * own meta keys. Returns false if the source had nothing to migrate.
	 *
	 * @param ABDS_SEO_Migration_Adapter $adapter Adapter to read from.
	 * @param int                        $post_id Post ID to migrate.
	 * @return bool True if at least one field was migrated.
	 */
	protected function migrate_single_post( ABDS_SEO_Migration_Adapter $adapter, int $post_id ): bool {
		$title       = $adapter->get_meta_title( $post_id );
		$description = $adapter->get_meta_description( $post_id );
		$canonical   = $adapter->get_canonical( $post_id );
		$robots      = $adapter->get_robots( $post_id );
		$og_title    = $adapter->get_og_title( $post_id );
		$og_desc     = $adapter->get_og_description( $post_id );
		$focus_kw    = $adapter->get_focus_keyword( $post_id );

		$has_data = $title || $description || $canonical || $og_title || $og_desc || $focus_kw;

		if ( ! $has_data ) {
			return false;
		}

		if ( $title ) {
			update_post_meta( $post_id, self::META_PREFIX . 'title', sanitize_text_field( $title ) );
		}
		if ( $description ) {
			update_post_meta( $post_id, self::META_PREFIX . 'description', sanitize_text_field( $description ) );
		}
		if ( $canonical ) {
			update_post_meta( $post_id, self::META_PREFIX . 'canonical', esc_url_raw( $canonical ) );
		}
		update_post_meta( $post_id, self::META_PREFIX . 'noindex', ! empty( $robots['noindex'] ) ? '1' : '' );
		update_post_meta( $post_id, self::META_PREFIX . 'nofollow', ! empty( $robots['nofollow'] ) ? '1' : '' );
		if ( $og_title ) {
			update_post_meta( $post_id, self::META_PREFIX . 'og_title', sanitize_text_field( $og_title ) );
		}
		if ( $og_desc ) {
			update_post_meta( $post_id, self::META_PREFIX . 'og_description', sanitize_text_field( $og_desc ) );
		}
		if ( $focus_kw ) {
			update_post_meta( $post_id, self::META_PREFIX . 'focus_keyword', sanitize_text_field( $focus_kw ) );
		}

		return true;
	}

	/**
	 * Whether a migration has ever completed on this site.
	 *
	 * @return bool
	 */
	public function is_migration_completed(): bool {
		$settings = get_option( self::SETTINGS_OPTION, array() );
		return ! empty( $settings['migration_completed'] );
	}
}