<?php
/**
 * TMDO_Shadow_Diff_Logger - Shadow-read 差異偵測與記錄
 *
 * 當 bridge 為 shadow_read 模式時,每次讀取都會:
 *   1. 從 UAE flat table 取值
 *   2. 從 wp_*meta 原生表取值
 *   3. 比對
 *   4. 若不一致 → 記錄到 wp_wpdo_uni_shadow_diffs 表
 *
 * 這個表是**持久化**的(不像 AEAV 原本用 transient — 會被 flush 掉),
 * 因為驗證期可能跨多日,不能丟失。
 *
 * 寫入有 rate limit(同 entity+key 在 5 分鐘內只記一筆),防止熱門欄位寫爆。
 *
 * @package WP_Data_Optimizer
 */

declare(strict_types=1);

// phpcs:disable Squiz.Commenting,Generic.Commenting,WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.PreparedSQLPlaceholders.ReplacementsWrongNumber,Generic.CodeAnalysis.UnusedFunctionParameter,Generic.CodeAnalysis.EmptyStatement,Squiz.PHP.DisallowMultipleAssignments,Squiz.PHP.DisallowSizeFunctionsInLoops,WordPress.WP.I18n.MissingTranslatorsComment,WordPress.PHP.NoSilencedErrors,WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents,Squiz.PHP.CommentedOutCode,Universal.NamingConventions.NoReservedKeywordParameterNames,WordPress.PHP.YodaConditions,Squiz.Commenting.InlineComment.InvalidEndChar -- PR-1 ported from UAE; cleanup PR scheduled.


defined( 'ABSPATH' ) || exit;

final class TMDO_Shadow_Diff_Logger {

	/** 保留最近 N 筆 diffs(超過就 rolling delete)。防止表爆炸。 */
	public const MAX_ROWS = 5000;

	/** Rate limit 視窗(秒)— 同 entity+key 在此視窗內重複 diff 不重記 */
	public const RATELIMIT_WINDOW = 300;

	public static function table_name(): string {
		global $wpdb;
		return $wpdb->prefix . 'wpdo_shadow_diffs';
	}

	/**
	 * 比對並記錄差異
	 *
	 * @param string $entity_type
	 * @param int    $entity_id
	 * @param string $meta_key
	 * @param mixed  $wpdo_value  從 UAE flat table 取得的值(已型別轉換)
	 * @param array  $field_def  field definition(含 type)
	 */
	public static function compare_and_log(
		string $entity_type,
		int $entity_id,
		string $meta_key,
		$wpdo_value,
		array $field_def
	): void {
		// 直接從 native meta 表取(繞過 UAE filter 避免無限迴圈)
		$eav_raw = self::get_eav_value_raw( $entity_type, $entity_id, $meta_key );

		// 兩邊都無 → 一致
		if ( $eav_raw === null && ( $wpdo_value === null || $wpdo_value === '' ) ) {
			return;
		}

		$type    = $field_def['type'] ?? 'text';
		$eav_val = self::cast_eav( $eav_raw, $type );

		// 比對
		if ( self::values_equal( $eav_val, $wpdo_value, $type ) ) {
			return;  // 一致
		}

		// 不一致 → 檢查 rate limit
		if ( self::is_rate_limited( $entity_type, $entity_id, $meta_key ) ) {
			return;
		}

		// 寫入 diff log
		self::record(
			$entity_type,
			$entity_id,
			$meta_key,
			self::stringify_for_log( $eav_val ),
			self::stringify_for_log( $wpdo_value ),
			$type
		);

		// Trim 舊 rows
		self::maybe_trim();
	}

	/**
	 * 從 wp_*meta 直接取值(繞過 UAE filter)
	 */
	private static function get_eav_value_raw( string $entity_type, int $entity_id, string $meta_key ): ?string {
		global $wpdb;

		$adapter = TMDO_Entity_Registry::get_adapter( $entity_type );
		if ( ! $adapter ) {
			return null;
		}

		$table  = $adapter->get_native_meta_table();
		$id_col = $adapter->get_entity_id_column();

		// 直接 SQL 繞過 get_metadata 系列 filter
		$value = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT meta_value FROM `{$table}` WHERE `{$id_col}` = %d AND meta_key = %s LIMIT 1",
				$entity_id,
				$meta_key
			)
		);

		return $value === null ? null : (string) $value;
	}

	/**
	 * 把 EAV 原始字串轉為該型別的值(用來比對)
	 */
	private static function cast_eav( ?string $raw, string $type ) {
		if ( $raw === null ) {
			return null;
		}
		// v2.13.3: object-injection-safe unserialize (fixes L-DESER-1).
		// Mirrors WP's maybe_unserialize but with allowed_classes=false.
		$raw = TMDO_Safe_Unserialize::run( $raw );

		switch ( $type ) {
			case 'integer':
				return is_numeric( $raw ) ? (int) $raw : null;
			case 'decimal':
				return is_numeric( $raw ) ? (float) $raw : null;
			case 'boolean':
				return (bool) $raw;
			case 'json':
				if ( is_array( $raw ) || is_object( $raw ) ) {
					return $raw;
				}
				$decoded = json_decode( (string) $raw, true );
				return $decoded !== null ? $decoded : $raw;
			default:
				return $raw;
		}
	}

	/**
	 * 兩值是否一致(依型別做合適比對)
	 */
	private static function values_equal( $a, $b, string $type ): bool {
		if ( $a === $b ) {
			return true;
		}

		// JSON / array 比對:用 canonical JSON
		if ( $type === 'json' || is_array( $a ) || is_array( $b ) ) {
			return wp_json_encode( $a ) === wp_json_encode( $b );
		}

		// Numeric:比數值
		if ( in_array( $type, array( 'integer', 'decimal' ), true ) ) {
			return is_numeric( $a ) && is_numeric( $b )
				? (float) $a === (float) $b
				: $a === $b;
		}

		// Boolean:寬鬆
		if ( $type === 'boolean' ) {
			return (bool) $a === (bool) $b;
		}

		// Default:鬆散字串比較(EAV 字串 vs casted)
		return (string) $a === (string) $b;
	}

	/**
	 * Rate limit 判斷(同 entity+key 在 300 秒內只記一次)
	 */
	private static function is_rate_limited( string $entity_type, int $entity_id, string $meta_key ): bool {
		$key = 'wpdo_sd_rl_' . md5( "{$entity_type}:{$entity_id}:{$meta_key}" );
		if ( get_transient( $key ) !== false ) {
			return true;
		}
		set_transient( $key, 1, self::RATELIMIT_WINDOW );
		return false;
	}

	/**
	 * 寫入 diff row
	 *
	 * v2.1.6 fix: aligned to actual `wpdo_shadow_diffs` schema installed by
	 * TMDO_Installer. The columns are: ts / entity_type / entity_id / meta_key /
	 * postmeta_value / zone_value / diff_hash. Logger code previously assumed
	 * eav_value / wpdo_value / created_at / field_type — schema-vs-code drift
	 * that silently no-op'd every diff INSERT (wpdb returns 0, no exception).
	 *
	 * `field_type` is consumed only as input to diff_hash so the same
	 * (entity_type, entity_id, meta_key) tuple records distinct rows when the
	 * field's interpreted type changes (rare; mostly a defence-in-depth bucket).
	 */
	private static function record(
		string $entity_type,
		int $entity_id,
		string $meta_key,
		string $eav_value,
		string $wpdo_value,
		string $field_type
	): void {
		global $wpdb;
		$table = self::table_name();

		$diff_hash = sha1( $entity_type . '|' . $meta_key . '|' . $field_type . '|' . $eav_value . '|' . $wpdo_value );

		$wpdb->insert(
			$table,
			array(
				'ts'             => current_time( 'mysql', true ),
				'entity_type'    => $entity_type,
				'entity_id'      => $entity_id,
				'meta_key'       => $meta_key,
				'postmeta_value' => $eav_value,
				'zone_value'     => $wpdo_value,
				'diff_hash'      => $diff_hash,
			),
			array( '%s', '%s', '%d', '%s', '%s', '%s', '%s' )
		);

		TMDO_Logger::warning(
			'shadow_read_diff',
			array(
				'entity_type' => $entity_type,
				'entity_id'   => $entity_id,
				'meta_key'    => $meta_key,
			)
		);
	}

	/**
	 * 轉為 log 字串
	 */
	private static function stringify_for_log( $value ): string {
		if ( is_scalar( $value ) || $value === null ) {
			return (string) $value;
		}
		return (string) wp_json_encode( $value, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES );
	}

	/**
	 * 超過 MAX_ROWS 時 trim 最舊的(chance 1% 才執行,不用每次都跑)
	 */
	private static function maybe_trim(): void {
		if ( wp_rand( 1, 100 ) !== 1 ) {
			return;
		}

		global $wpdb;
		$table = self::table_name();

		$count = (int) $wpdb->get_var( "SELECT COUNT(*) FROM `{$table}`" );
		if ( $count <= self::MAX_ROWS ) {
			return;
		}

		$to_delete = $count - self::MAX_ROWS;
		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM `{$table}` ORDER BY id ASC LIMIT %d",
				$to_delete
			)
		);
	}

	// ─────────────────────────────────────────────────────────
	// Read API (for admin UI + CLI)
	// ─────────────────────────────────────────────────────────

	/**
	 * 取得最近 N 筆 diffs
	 */
	public static function recent( int $limit = 100, ?string $entity_type = null ): array {
		global $wpdb;
		$table = self::table_name();

		if ( $entity_type ) {
			$sql = $wpdb->prepare(
				"SELECT * FROM `{$table}` WHERE entity_type = %s ORDER BY id DESC LIMIT %d",
				$entity_type,
				$limit
			);
		} else {
			$sql = $wpdb->prepare(
				"SELECT * FROM `{$table}` ORDER BY id DESC LIMIT %d",
				$limit
			);
		}

		$rows = $wpdb->get_results( $sql, ARRAY_A );
		return is_array( $rows ) ? $rows : array();
	}

	/**
	 * 統計:按 entity / meta_key 聚合
	 */
	public static function stats_by_key( int $limit = 20 ): array {
		global $wpdb;
		$table = self::table_name();

		// v2.1.6: column is `ts`, not `created_at` (matches installer schema).
		$rows = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT entity_type, meta_key, COUNT(*) AS c, MAX(ts) AS last_seen
			 FROM `{$table}`
			 GROUP BY entity_type, meta_key
			 ORDER BY c DESC LIMIT %d",
				$limit
			),
			ARRAY_A
		);

		return is_array( $rows ) ? $rows : array();
	}

	/**
	 * 全部 diff 總數
	 */
	public static function total_count(): int {
		global $wpdb;
		return (int) $wpdb->get_var( 'SELECT COUNT(*) FROM `' . self::table_name() . '`' );
	}

	/**
	 * 按 entity type 統計
	 */
	public static function count_by_entity(): array {
		global $wpdb;
		$rows   = $wpdb->get_results(
			'SELECT entity_type, COUNT(*) AS c FROM `' . self::table_name() . '` GROUP BY entity_type',
			ARRAY_A
		);
		$result = array();
		foreach ( $rows ?: array() as $r ) {
			$result[ $r['entity_type'] ] = (int) $r['c'];
		}
		return $result;
	}

	/**
	 * 清空所有 diffs(admin confirmed)
	 */
	public static function clear_all(): int {
		global $wpdb;
		$table = self::table_name();
		$count = (int) $wpdb->get_var( "SELECT COUNT(*) FROM `{$table}`" );
		$wpdb->query( "TRUNCATE TABLE `{$table}`" );
		TMDO_Logger::info(
			'shadow_diffs_cleared',
			array(
				'count'   => $count,
				'user_id' => get_current_user_id(),
			)
		);
		return $count;
	}

	/**
	 * 清除特定 entity 的 diffs
	 */
	public static function clear_entity( string $entity_type ): int {
		global $wpdb;
		return (int) $wpdb->query(
			$wpdb->prepare(
				'DELETE FROM `' . self::table_name() . '` WHERE entity_type = %s',
				$entity_type
			)
		);
	}

	// ─────────────────────────────────────────────────────────
	// Schema
	// ─────────────────────────────────────────────────────────

	public static function install_table(): void {
		global $wpdb;
		require_once ABSPATH . 'wp-admin/includes/upgrade.php';

		$table   = self::table_name();
		$charset = $wpdb->get_charset_collate();

		$sql = "CREATE TABLE {$table} (
			id           BIGINT UNSIGNED NOT NULL AUTO_INCREMENT,
			entity_type  VARCHAR(20) NOT NULL,
			entity_id    BIGINT UNSIGNED NOT NULL,
			meta_key     VARCHAR(255) NOT NULL,
			field_type   VARCHAR(20) NOT NULL DEFAULT 'text',
			eav_value    LONGTEXT NULL,
			wpdo_value    LONGTEXT NULL,
			created_at   DATETIME NOT NULL,
			PRIMARY KEY (id),
			KEY idx_entity (entity_type, entity_id),
			KEY idx_key (entity_type, meta_key(191)),
			KEY idx_created (created_at)
		) {$charset};";

		dbDelta( $sql );
	}

	public static function drop_table(): void {
		global $wpdb;
		$wpdb->query( 'DROP TABLE IF EXISTS ' . self::table_name() );
	}
}