<?php
/**
 * Translation groups in {prefix}blocklingo_translations.
 *
 * One row per translated object: object_type + object_id -> lang, group_id.
 * Objects sharing a group_id are translations of each other; an object
 * without a row counts as the default language. No foreign keys (WordPress
 * convention): deleting a post removes only its own row.
 */

declare( strict_types = 1 );

namespace AddBlack\Lang\Translation;

defined( 'ABSPATH' ) || exit;

use AddBlack\Lang\Install\Schema;
use WP_Error;

final class TranslationRepository {

	private const CACHE_GROUP = 'blocklingo';

	public function __construct(
		private readonly \wpdb $db,
		private readonly Schema $schema
	) {}

	public function table(): string {
		return $this->schema->translations();
	}

	/**
	 * Language and group of an object, or null when it has no row.
	 *
	 * @return array{lang: string, group_id: string}|null
	 */
	public function find( int $object_id, string $type = 'post' ): ?array {
		$key = $this->cache_key( $type, $object_id );
		$row = wp_cache_get( $key, self::CACHE_GROUP );
		if ( false === $row ) {
			$row = $this->db->get_row(
				$this->db->prepare(
					'SELECT lang, group_id FROM %i WHERE object_type = %s AND object_id = %d',
					$this->table(),
					$type,
					$object_id
				),
				ARRAY_A
			);
			$row = $row ? $row : 'none';
			wp_cache_set( $key, $row, self::CACHE_GROUP );
		}
		return 'none' === $row ? null : $row;
	}

	/**
	 * Set an object's language. Keeps its group unless $group_id is given.
	 * Refused when the group already has another object in that language.
	 *
	 * @return true|WP_Error
	 */
	public function assign( int $object_id, string $lang, ?int $group_id = null, string $type = 'post' ): bool|WP_Error {
		$row = $this->find( $object_id, $type );
		if ( null === $group_id ) {
			$group_id = $row ? (int) $row['group_id'] : $object_id;
		}

		$taken = $this->db->get_var(
			$this->db->prepare(
				'SELECT object_id FROM %i WHERE object_type = %s AND group_id = %d AND lang = %s AND object_id <> %d',
				$this->table(),
				$type,
				$group_id,
				$lang,
				$object_id
			)
		);
		if ( $taken ) {
			return new WP_Error( 'blocklingo_lang_taken', sprintf( /* translators: 1: language code, 2: post ID. */ __( 'Translation group already has a "%1$s" version (ID %2$d).', 'blocklingo' ), $lang, (int) $taken ) );
		}

		$this->db->replace(
			$this->table(),
			array(
				'object_type' => $type,
				'object_id'   => $object_id,
				'lang'        => $lang,
				'group_id'    => $group_id,
			),
			array( '%s', '%d', '%s', '%d' )
		);
		wp_cache_delete( $this->cache_key( $type, $object_id ), self::CACHE_GROUP );
		return true;
	}

	/**
	 * Detach an object from its group: it becomes a group of its own.
	 *
	 * @return true|WP_Error
	 */
	public function unlink( int $object_id, string $type = 'post' ): bool|WP_Error {
		$row = $this->find( $object_id, $type );
		return $row ? $this->assign( $object_id, $row['lang'], $object_id, $type ) : true;
	}

	/**
	 * The object's group, itself included. An untagged object is a group of one
	 * in $fallback_lang.
	 *
	 * @return array<string, int> lang => object_id
	 */
	public function group( int $object_id, string $fallback_lang, string $type = 'post' ): array {
		$row = $this->find( $object_id, $type );
		if ( ! $row ) {
			return array( $fallback_lang => $object_id );
		}
		$rows = $this->db->get_results(
			$this->db->prepare(
				'SELECT lang, object_id FROM %i WHERE object_type = %s AND group_id = %d',
				$this->table(),
				$type,
				$row['group_id']
			),
			ARRAY_A
		);
		$out  = array();
		foreach ( (array) $rows as $r ) {
			$out[ (string) $r['lang'] ] = (int) $r['object_id'];
		}
		return $out;
	}

	public function delete( int $object_id, string $type = 'post' ): void {
		$this->db->delete(
			$this->table(),
			array(
				'object_type' => $type,
				'object_id'   => $object_id,
			)
		);
		wp_cache_delete( $this->cache_key( $type, $object_id ), self::CACHE_GROUP );
	}

	/**
	 * Tag every untagged post of the given types with $lang, each as its own group.
	 *
	 * @param string[] $post_types
	 */
	public function tag_untagged_posts( array $post_types, string $lang ): void {
		if ( ! $post_types ) {
			return;
		}
		$in = implode( ',', array_fill( 0, count( $post_types ), '%s' ) );
		// phpcs:disable WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare, WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- $in is a list of %s placeholders.
		$this->db->query(
			$this->db->prepare(
				"INSERT IGNORE INTO %i (object_type, object_id, lang, group_id)
				 SELECT 'post', ID, %s, ID FROM %i
				 WHERE post_type IN ({$in}) AND post_status NOT IN ('auto-draft','inherit')",
				array_merge( array( $this->table(), $lang, $this->db->posts ), $post_types )
			)
		);
		// phpcs:enable
		// Many rows changed at once: invalidate every cached lookup.
		wp_cache_set_last_changed( self::CACHE_GROUP );
	}

	/**
	 * Published posts of $post_types in the default language (tagged with it,
	 * or not tagged at all), per type: how many there are and how many have a
	 * version in $lang (any status). One query, however big the site.
	 *
	 * @param string[] $post_types
	 * @return array<string, array{total: int, done: int}>
	 */
	public function coverage_counts( array $post_types, string $default_lang, string $lang ): array {
		if ( ! $post_types ) {
			return array();
		}
		$in = implode( ',', array_fill( 0, count( $post_types ), '%s' ) );
		// phpcs:disable WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery -- $in is a list of %s placeholders; live counts.
		$rows = $this->db->get_results(
			$this->db->prepare(
				"SELECT p.post_type, COUNT(*) AS total, SUM( t.object_id IS NOT NULL ) AS done
				 FROM %i p
				 LEFT JOIN %i s ON s.object_type = 'post' AND s.object_id = p.ID
				 LEFT JOIN %i t ON t.object_type = 'post' AND t.group_id = s.group_id AND t.lang = %s
				 WHERE p.post_status = 'publish' AND p.post_type IN ({$in}) AND ( s.lang = %s OR s.lang IS NULL )
				 GROUP BY p.post_type",
				array_merge( array( $this->db->posts, $this->table(), $this->table(), $lang ), $post_types, array( $default_lang ) )
			),
			ARRAY_A
		);
		// phpcs:enable
		$out = array();
		foreach ( (array) $rows as $row ) {
			$out[ (string) $row['post_type'] ] = array(
				'total' => (int) $row['total'],
				'done'  => (int) $row['done'],
			);
		}
		return $out;
	}

	/**
	 * IDs of published default-language posts with no version in $lang,
	 * ordered by type (page before post), menu order and ID.
	 *
	 * @param string[] $post_types
	 * @return int[]
	 */
	public function missing_ids( array $post_types, string $default_lang, string $lang, int $limit ): array {
		if ( ! $post_types || $limit < 1 ) {
			return array();
		}
		$in = implode( ',', array_fill( 0, count( $post_types ), '%s' ) );
		// phpcs:disable WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, WordPress.DB.DirectDatabaseQuery -- $in is a list of %s placeholders; live list.
		$ids = $this->db->get_col(
			$this->db->prepare(
				"SELECT p.ID
				 FROM %i p
				 LEFT JOIN %i s ON s.object_type = 'post' AND s.object_id = p.ID
				 LEFT JOIN %i t ON t.object_type = 'post' AND t.group_id = s.group_id AND t.lang = %s
				 WHERE p.post_status = 'publish' AND p.post_type IN ({$in}) AND ( s.lang = %s OR s.lang IS NULL ) AND t.object_id IS NULL
				 ORDER BY p.post_type ASC, p.menu_order ASC, p.ID ASC
				 LIMIT %d",
				array_merge( array( $this->db->posts, $this->table(), $this->table(), $lang ), $post_types, array( $default_lang, $limit ) )
			)
		);
		// phpcs:enable
		return array_map( 'intval', (array) $ids );
	}

	/** Cache key for one object; changes whenever many rows change at once. */
	private function cache_key( string $type, int $object_id ): string {
		return $type . '_' . $object_id . ':' . wp_cache_get_last_changed( self::CACHE_GROUP );
	}
}