<?php
// phpcs:ignore WPDO.AntiEAV -- platform shadow verifier: must read raw meta to verify zone correctness
/**
 * TMDO_Post_Shadow_Verifier — Sample-and-compare flat vs wp_postmeta (v2.10.3).
 *
 * Companion to TMDO_Post_Migration. Used during shadow_read mode to verify
 * the flat tables stay in sync with wp_postmeta. Each sample picks a random
 * post + key, fetches both values (flat row vs wp_postmeta row), and counts
 * matches / diffs / missing rows. Divergent values are written to the
 * shared `wpdo_shadow_diffs` table via `TMDO_Shadow_Diff_Logger` (which is
 * already entity_type-aware — pass 'post' to differentiate from user diffs).
 *
 * Run pattern:
 *   - Manual: `wp wpdo post-shadow-report`
 *   - Cron:   wpdo_post_shadow_verify event registered when post mode is
 *             shadow_read; auto-unregistered when mode changes to anything else
 *
 * 🔒 Frozen contract: never touches user-side flat tables, never modifies
 * wp_postmeta or wp_posts (read-only verifier).
 *
 * @package WP_Data_Optimizer
 * @since   2.10.3
 */

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

// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching,WordPress.DB.PreparedSQL.InterpolatedNotPrepared,WordPress.DB.PreparedSQL.NotPrepared -- Internal verifier: $flat_table comes from registry, columns sanitized via Schema_Manager, user values use prepare(). Verifier is read-only.

/**
 * Sample-and-compare verifier for post entity flat tables.
 */
final class TMDO_Post_Shadow_Verifier {

	/**
	 * Cron event hook fired hourly when post mode is shadow_read.
	 */
	public const CRON_HOOK = 'wpdo_post_shadow_verify';

	/**
	 * Default sample size per cron tick (capped to available post count).
	 */
	public const DEFAULT_SAMPLE_SIZE = 100;

	/**
	 * Run a sample-compare pass.
	 *
	 * Picks $sample_size random posts of $post_type, fetches their flat row
	 * + their wp_postmeta values for each $keys entry, and counts matches.
	 * Divergences are recorded via TMDO_Shadow_Diff_Logger when the class
	 * is available.
	 *
	 * @param string   $post_type   WP post_type to sample.
	 * @param string   $group_name  Entity group name (e.g. 'wc_product').
	 * @param string   $flat_table  Fully qualified flat table name.
	 * @param string[] $keys        Meta keys to compare (each post checks all).
	 * @param int      $sample_size Number of posts to sample (capped to DB count).
	 * @return array{
	 *   sampled:int,
	 *   matched:int,
	 *   diffs:int,
	 *   missing_flat:int,
	 *   missing_postmeta:int,
	 *   group:string,
	 *   post_type:string,
	 * }
	 * @throws InvalidArgumentException When inputs invalid.
	 */
	public static function sample_compare(
		string $post_type,
		string $group_name,
		string $flat_table,
		array $keys,
		int $sample_size = self::DEFAULT_SAMPLE_SIZE
	): array {
		if ( $sample_size <= 0 ) {
			$msg = 'Sample size must be > 0';
			throw new InvalidArgumentException( $msg ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}
		if ( empty( $keys ) ) {
			$msg = 'Keys array cannot be empty';
			throw new InvalidArgumentException( $msg ); // phpcs:ignore WordPress.Security.EscapeOutput.ExceptionNotEscaped
		}

		global $wpdb;

		$post_ids = $wpdb->get_col(
			$wpdb->prepare(
				"SELECT ID FROM {$wpdb->posts} WHERE post_type = %s ORDER BY RAND() LIMIT %d",
				$post_type,
				$sample_size
			)
		);

		$sampled          = count( $post_ids );
		$matched          = 0;
		$diffs            = 0;
		$missing_flat     = 0;
		$missing_postmeta = 0;

		if ( 0 === $sampled ) {
			return array(
				'sampled'          => 0,
				'matched'          => 0,
				'diffs'            => 0,
				'missing_flat'     => 0,
				'missing_postmeta' => 0,
				'group'            => $group_name,
				'post_type'        => $post_type,
			);
		}

		foreach ( $post_ids as $post_id ) {
			$post_id = (int) $post_id;
			foreach ( $keys as $key ) {
				$col      = self::sanitize_column( $key );
				$flat_val = $wpdb->get_var(
					$wpdb->prepare(
						"SELECT `{$col}` FROM `{$flat_table}` WHERE post_id = %d LIMIT 1",
						$post_id
					)
				);
				$pm_val   = $wpdb->get_var(
					$wpdb->prepare(
						"SELECT meta_value FROM {$wpdb->postmeta} WHERE post_id = %d AND meta_key = %s LIMIT 1",
						$post_id,
						$key
					)
				);

				$flat_present = null !== $flat_val && '' !== $flat_val;
				$pm_present   = null !== $pm_val && '' !== $pm_val;

				if ( ! $flat_present && ! $pm_present ) {
					// Both empty — neither side has the value, count as match
					// (key truly absent for this post).
					++$matched;
					continue;
				}
				if ( ! $flat_present && $pm_present ) {
					++$missing_flat;
					self::log_diff( $post_id, $key, (string) $pm_val, '(missing)' );
					continue;
				}
				if ( $flat_present && ! $pm_present ) {
					++$missing_postmeta;
					self::log_diff( $post_id, $key, '(missing)', (string) $flat_val );
					continue;
				}

				// Loose equality — flat may have widened types (e.g. tinyint→bigint)
				// or full-precision decimals (10,2 → 18,6).
				if ( self::values_loose_equal( $pm_val, $flat_val ) ) {
					++$matched;
				} else {
					++$diffs;
					self::log_diff( $post_id, $key, (string) $pm_val, (string) $flat_val );
				}
			}
		}

		return array(
			'sampled'          => $sampled,
			'matched'          => $matched,
			'diffs'            => $diffs,
			'missing_flat'     => $missing_flat,
			'missing_postmeta' => $missing_postmeta,
			'group'            => $group_name,
			'post_type'        => $post_type,
		);
	}

	/**
	 * Cron handler: runs sample_compare for each registered group when post
	 * mode is shadow_read. No-op otherwise.
	 *
	 * @return void
	 */
	public static function cron_tick(): void {
		if ( ! class_exists( 'TMDO_Mode_Manager' ) ) {
			return;
		}
		if ( 'shadow_read' !== TMDO_Mode_Manager::get( 'post' ) ) {
			return;
		}
		if ( ! class_exists( 'TMDO_Entity_Registry' ) ) {
			return;
		}

		global $wpdb;

		foreach ( TMDO_Entity_Registry::get_groups_for_type( 'post' ) as $group ) {
			$keys = TMDO_Entity_Registry::get_group_keys( 'post', $group );
			if ( empty( $keys ) ) {
				continue;
			}
			$post_type = self::group_post_type( $group );
			if ( null === $post_type ) {
				continue; // wp_core spans all types, skip in cron tick.
			}
			$flat_table = $wpdb->prefix . 'wpdo_post_' . sanitize_key( $group );

			try {
				self::sample_compare( $post_type, $group, $flat_table, $keys, self::DEFAULT_SAMPLE_SIZE );
			} catch ( \Throwable $e ) {
				if ( class_exists( 'TMDO_Logger' ) ) {
					TMDO_Logger::error(
						'post_shadow_verifier',
						'cron_tick',
						$e->getMessage()
					);
				}
			}
		}
	}

	/**
	 * Recent diff records for entity_type='post'.
	 *
	 * @param int $limit Max rows.
	 * @return array
	 */
	public static function recent_diffs( int $limit = 100 ): array {
		if ( ! class_exists( 'TMDO_Shadow_Diff_Logger' ) ) {
			return array();
		}
		return TMDO_Shadow_Diff_Logger::recent( $limit, 'post' );
	}

	/**
	 * Aggregate diff stats for entity_type='post' over recent N hours.
	 *
	 * @param int $hours Window in hours (default 24).
	 * @return array{total:int,by_key:array<string,int>}
	 */
	public static function diff_stats( int $hours = 24 ): array {
		global $wpdb;
		$table = $wpdb->prefix . 'wpdo_shadow_diffs';

		$exists = (bool) $wpdb->get_var(
			$wpdb->prepare( 'SHOW TABLES LIKE %s', $table )
		);
		if ( ! $exists ) {
			return array(
				'total'  => 0,
				'by_key' => array(),
			);
		}

		$since = gmdate( 'Y-m-d H:i:s', time() - ( $hours * HOUR_IN_SECONDS ) );

		$total = (int) $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM `{$table}` WHERE entity_type = 'post' AND ts >= %s",
				$since
			)
		);

		$rows = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT meta_key, COUNT(*) AS n FROM `{$table}` WHERE entity_type = 'post' AND ts >= %s GROUP BY meta_key ORDER BY n DESC",
				$since
			),
			ARRAY_A
		);

		$by_key = array();
		foreach ( (array) $rows as $row ) {
			$by_key[ (string) $row['meta_key'] ] = (int) $row['n'];
		}

		return array(
			'total'  => $total,
			'by_key' => $by_key,
		);
	}

	// ─────────────────────────────────────────────────────────────────────────
	// Helpers
	// ─────────────────────────────────────────────────────────────────────────

	/**
	 * Sanitize meta_key into a column name (mirrors Schema_Manager rules).
	 *
	 * @param string $key Meta key.
	 * @return string
	 */
	private static function sanitize_column( string $key ): string {
		if ( class_exists( 'TMDO_Schema_Manager' ) ) {
			return TMDO_Schema_Manager::sanitize_column_name( $key );
		}
		return preg_replace( '/[^a-zA-Z0-9_]/', '_', $key );
	}

	/**
	 * Map entity group → primary post_type (null = cross-cutting like wp_core).
	 *
	 * @param string $group Entity group name.
	 * @return string|null
	 */
	private static function group_post_type( string $group ): ?string {
		switch ( $group ) {
			case 'attachment':
				return 'attachment';
			case 'wc_product':
				return 'product';
			case 'hp_listing_core':
				return 'hp_listing';
			case 'hp_request_core':
				return 'hp_request';
			case 'hp_vendor_core':
				return 'hp_vendor';
			case 'nav_menu_item':
				return 'nav_menu_item';
			case 'wp_core':
			default:
				return null;
		}
	}

	/**
	 * Loose equality for verifier — handles widened types (decimal precision,
	 * tinyint→bigint, etc.) and serialization-format differences without
	 * false-positive divergence reports.
	 *
	 * Layers (fail-fast on first match):
	 *   1. Identical strings
	 *   2. Numeric loose match (handles "50" vs "50.000000")
	 *   3. v2.10.5: Decoded match for serialized vs JSON values
	 *      (postmeta uses PHP serialize, flat tables use wp_json_encode for
	 *       json-typed fields — same logical data, different storage format)
	 *
	 * @param mixed $a Side A value.
	 * @param mixed $b Side B value.
	 * @return bool
	 */
	private static function values_loose_equal( $a, $b ): bool {
		// Both null/empty already filtered out by caller.
		$as = (string) $a;
		$bs = (string) $b;
		if ( $as === $bs ) {
			return true;
		}
		// Numeric loose match (handles "50" vs "50.000000").
		if ( is_numeric( $as ) && is_numeric( $bs ) ) {
			return (float) $as === (float) $bs;
		}
		// v2.10.5: try decoded comparison for serialized/JSON values.
		$a_decoded = self::decode_value( $as );
		$b_decoded = self::decode_value( $bs );
		if ( ( null !== $a_decoded || null !== $b_decoded ) && $a_decoded === $b_decoded ) {
			return true;
		}
		return false;
	}

	/**
	 * Best-effort decode of a string value: try PHP unserialize (object-safe),
	 * then JSON. Returns the decoded structure, or null when neither succeeds
	 * (so the caller can short-circuit instead of false-positive matching
	 * against a literal "null" string).
	 *
	 * Returns null in three cases:
	 *   - Both decoders failed (input is plain non-encoded string)
	 *   - unserialize returned NULL legitimately (input was 'N;')
	 *   - Empty string
	 *
	 * The caller distinguishes these by combining with an identical-string
	 * fast-path that runs first; non-encoded strings hit equality before this
	 * decoder runs.
	 *
	 * @param string $s Raw string value.
	 * @return mixed|null Decoded value, or null on failure.
	 */
	private static function decode_value( string $s ) {
		if ( '' === $s ) {
			return null;
		}
		// PHP serialize: 'a:N:{...}' / 'O:N:"...":...' / 'i:N;' / 's:N:"..."' / 'b:0|1;' / 'N;' / 'd:N;'.
		if ( preg_match( '/^[aOidsbN]:/', $s ) || 'N;' === $s ) {
			// phpcs:ignore WordPress.PHP.NoSilencedErrors,Generic.PHP.NoSilencedErrors,WordPress.PHP.DiscouragedPHPFunctions.serialize_unserialize -- allowed_classes=false hardens against object injection; @ swallows malformed-payload notices.
			$v = @unserialize( $s, array( 'allowed_classes' => false ) );
			if ( false !== $v || 'b:0;' === $s ) {
				return $v;
			}
		}
		// JSON: arrays/objects start with [ or {.
		$first = $s[0] ?? '';
		if ( '[' === $first || '{' === $first ) {
			$v = json_decode( $s, true );
			if ( null !== $v ) {
				return $v;
			}
		}
		return null;
	}

	/**
	 * Record a divergence via the shared shadow diff logger.
	 *
	 * @param int    $post_id Post ID.
	 * @param string $key     Meta key.
	 * @param string $pm_val  Postmeta value (or '(missing)').
	 * @param string $flat_val Flat value (or '(missing)').
	 * @return void
	 */
	private static function log_diff( int $post_id, string $key, string $pm_val, string $flat_val ): void {
		if ( ! class_exists( 'TMDO_Shadow_Diff_Logger' ) ) {
			return;
		}
		// Use the public record() method if the logger exposes one; otherwise
		// fall through silently. v2.5.x exposes compare_and_log() which does
		// internal compare; for verifier we already know they diverged so we
		// write directly to the table.
		global $wpdb;
		$table  = $wpdb->prefix . 'wpdo_shadow_diffs';
		$exists = (bool) $wpdb->get_var(
			$wpdb->prepare( 'SHOW TABLES LIKE %s', $table )
		);
		if ( ! $exists ) {
			return;
		}
		$wpdb->insert(
			$table,
			array(
				'entity_type'    => 'post',
				'entity_id'      => $post_id,
				'meta_key'       => $key,
				'postmeta_value' => substr( $pm_val, 0, 1000 ),
				'zone_value'     => substr( $flat_val, 0, 1000 ),
				'diff_hash'      => md5( $pm_val . '|' . $flat_val ),
				'ts'             => gmdate( 'Y-m-d H:i:s' ),
			)
		);
	}
}