<?php
/**
 * Copies of posts.post_status / post_date on post entity tables (O-1).
 *
 * With the copies (and their `(post_status, post_date)` index) a routed search
 * can filter and sort inside the flat table instead of joining back to posts.
 *
 * Columns only reach a table two ways, never as DDL on a populated table in a
 * web request:
 *   - a brand-new (empty) group table gets them when it is created;
 *   - `wp tmdo post-status-sync` adds them to existing tables and backfills.
 *
 * Per-group state lives in the TMDO_Post_Status_Sync::OPTION option:
 * 'columns' (added, backfill pending) or 'ready' (every row copied).
 * Afterwards transition_post_status keeps the copies current, and flat writes
 * that create a row fill them in.
 *
 * @package TMDO
 */

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

/**
 * Keeps post_status / post_date copies on post entity tables.
 */
final class TMDO_Post_Status_Sync {

	public const OPTION = 'tmdo_post_status_columns';

	private const INDEX = 'idx_post_status_date_id';

	/** The 2.2–2.3 (post_status, post_date) index, replaced by INDEX. */
	private const LEGACY_INDEX = 'idx_post_status_date';

	/**
	 * Hook the sync into WordPress.
	 *
	 * @return void
	 */
	public static function register(): void {
		add_action( 'transition_post_status', array( __CLASS__, 'on_transition' ), 10, 3 );
		add_action( 'wpdo_schema_updated', array( __CLASS__, 'on_schema_updated' ), 10, 3 );
	}

	/**
	 * '' (no columns), 'columns' or 'ready'.
	 *
	 * @param string $group Post group name.
	 * @return string
	 */
	public static function state( string $group ): string {
		$states = get_option( self::OPTION, array() );
		return is_array( $states ) ? (string) ( $states[ $group ] ?? '' ) : '';
	}

	/**
	 * Every post status change or save: refresh the copies in each table that has them.
	 *
	 * @param string $new_status New status.
	 * @param string $old_status Old status.
	 * @param object $post       Saved post.
	 * @return void
	 */
	public static function on_transition( $new_status, $old_status, $post ): void {
		global $wpdb;
		unset( $new_status, $old_status );
		foreach ( self::groups_with_columns() as $group ) {
			$table = TMDO_Schema_Manager::get_table_name( 'post', $group );
			if ( ! TMDO_Schema_Manager::table_exists( $table ) ) {
				self::forget( $group ); // The table was dropped (retired or uninstalled group).
				continue;
			}
			$wpdb->query(
				$wpdb->prepare(
					"UPDATE `{$table}` SET `post_status` = %s, `post_date` = %s WHERE `post_id` = %d", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
					$post->post_status,
					$post->post_date,
					$post->ID
				)
			);
		}
	}

	/**
	 * A post group table was just created or altered: an empty one gets the
	 * columns now; one holding rows waits for the CLI.
	 *
	 * @param string $entity_type Entity type.
	 * @param string $group       Group name.
	 * @param string $table       Table name.
	 * @return void
	 */
	public static function on_schema_updated( $entity_type, $group, $table ): void {
		global $wpdb;
		if ( 'post' !== $entity_type || '' !== self::state( $group ) ) {
			return;
		}
		if ( null !== $wpdb->get_var( "SELECT 1 FROM `{$table}` LIMIT 1" ) ) { // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
			return;
		}
		if ( self::add_columns( $group ) ) {
			self::set_state( $group, 'ready' );
		}
	}

	/**
	 * Copies for a row a flat write is about to create (empty when the
	 * group's table has no such columns).
	 *
	 * @param int    $post_id Post ID.
	 * @param string $group   Group name.
	 * @return array{post_status?:string, post_date?:string}
	 */
	public static function insert_columns( int $post_id, string $group ): array {
		if ( '' === self::state( $group ) ) {
			return array();
		}
		$post = get_post( $post_id );
		if ( ! $post ) {
			return array();
		}
		return array(
			'post_status' => $post->post_status,
			'post_date'   => $post->post_date,
		);
	}

	/**
	 * Add the columns to every post group table and copy posts' values in.
	 *
	 * @param bool $dry_run Count mismatching rows only.
	 * @param int  $batch   Rows per UPDATE.
	 * @return array<string, array{rows:int, mismatched:int}>
	 */
	public static function run( bool $dry_run = false, int $batch = 1000 ): array {
		global $wpdb;
		$batch  = max( 1, $batch );
		$report = array();
		foreach ( TMDO_Entity_Registry::get_groups_for_type( 'post' ) as $group ) {
			$table = TMDO_Schema_Manager::get_table_name( 'post', $group );
			if ( ! TMDO_Schema_Manager::table_exists( $table ) ) {
				continue;
			}
			$rows             = (int) $wpdb->get_var( "SELECT COUNT(*) FROM `{$table}`" ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
			$report[ $group ] = array(
				'rows'       => $rows,
				'mismatched' => '' === self::state( $group ) ? $rows : self::mismatches( $group ),
			);
			if ( $dry_run || ! self::add_columns( $group ) ) {
				continue;
			}
			$max = (int) $wpdb->get_var( "SELECT MAX(id) FROM `{$table}`" ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
			for ( $from = 0; $from < $max; $from += $batch ) {
				$wpdb->query(
					$wpdb->prepare(
						"UPDATE `{$table}` t JOIN `{$wpdb->posts}` p ON p.ID = t.post_id SET t.post_status = p.post_status, t.post_date = p.post_date WHERE t.id > %d AND t.id <= %d", // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
						$from,
						$from + $batch
					)
				);
			}
			self::set_state( $group, 'ready' );
		}
		return $report;
	}

	/**
	 * Rows whose copies differ from posts (rows of deleted posts excluded).
	 *
	 * @param string $group Group name.
	 * @return int
	 */
	public static function mismatches( string $group ): int {
		global $wpdb;
		$table = TMDO_Schema_Manager::get_table_name( 'post', $group );
		return (int) $wpdb->get_var(
			"SELECT COUNT(*) FROM `{$table}` t JOIN `{$wpdb->posts}` p ON p.ID = t.post_id WHERE NOT ( t.post_status <=> p.post_status ) OR NOT ( t.post_date <=> p.post_date )" // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
		);
	}

	/**
	 * Add whichever of the two columns and the index the table lacks.
	 *
	 * @param string $group Group name.
	 * @return bool False when the table is missing or the ALTER failed.
	 */
	private static function add_columns( string $group ): bool {
		global $wpdb;
		$table = TMDO_Schema_Manager::get_table_name( 'post', $group );
		if ( ! TMDO_Schema_Manager::table_exists( $table ) ) {
			return false;
		}
		$columns = (array) $wpdb->get_col( "SHOW COLUMNS FROM `{$table}`" ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
		$indexes = array_column( (array) $wpdb->get_results( "SHOW INDEX FROM `{$table}`", ARRAY_A ), 'Key_name' ); // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Registry table name.
		$changes = array();
		if ( ! in_array( 'post_status', $columns, true ) ) {
			// Same collation as posts.post_status: the table default may differ,
			// and comparing the two columns would then fail (illegal mix of collations).
			$source    = $wpdb->get_row( "SHOW FULL COLUMNS FROM `{$wpdb->posts}` LIKE 'post_status'", ARRAY_A );
			$collation = preg_replace( '/[^A-Za-z0-9_]/', '', (string) ( $source['Collation'] ?? '' ) );
			$changes[] = 'ADD COLUMN `post_status` VARCHAR(20)' . ( '' !== $collation ? " COLLATE {$collation}" : '' ) . ' DEFAULT NULL';
		}
		if ( ! in_array( 'post_date', $columns, true ) ) {
			$changes[] = 'ADD COLUMN `post_date` DATETIME DEFAULT NULL';
		}
		if ( ! in_array( self::INDEX, $indexes, true ) ) {
			// Ends with post_id: the router reads the date route's ID tie-break
			// from it, so MySQL walks the index and stops at the LIMIT (2.4 PR-128).
			$changes[] = 'ADD INDEX `' . self::INDEX . '` (`post_status`, `post_date`, `post_id`)';
		}
		if ( in_array( self::LEGACY_INDEX, $indexes, true ) ) {
			$changes[] = 'DROP INDEX `' . self::LEGACY_INDEX . '`';
		}
		if ( $changes && false === $wpdb->query( "ALTER TABLE `{$table}` " . implode( ', ', $changes ) ) ) { // phpcs:ignore WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Fixed DDL on a registry table name.
			return false;
		}
		if ( '' === self::state( $group ) ) {
			self::set_state( $group, 'columns' );
		}
		return true;
	}

	/**
	 * Post groups whose table has the columns.
	 *
	 * @return string[]
	 */
	private static function groups_with_columns(): array {
		$states = get_option( self::OPTION, array() );
		return is_array( $states ) ? array_keys( $states ) : array();
	}

	/**
	 * Drop a group from the recorded states.
	 *
	 * @param string $group Group name.
	 * @return void
	 */
	private static function forget( string $group ): void {
		$states = get_option( self::OPTION, array() );
		if ( is_array( $states ) && isset( $states[ $group ] ) ) {
			unset( $states[ $group ] );
			update_option( self::OPTION, $states, true );
		}
	}

	/**
	 * Record a group's state.
	 *
	 * @param string $group Group name.
	 * @param string $state 'columns' | 'ready'.
	 * @return void
	 */
	private static function set_state( string $group, string $state ): void {
		$states           = get_option( self::OPTION, array() );
		$states           = is_array( $states ) ? $states : array();
		$states[ $group ] = $state;
		update_option( self::OPTION, $states, true );
	}
}