<?php
/**
 * TMDO_Query_Compiler - 跨實體查詢編譯器
 *
 * 將 wpdo_meta_query 編譯為高效 SQL：
 * - 單次 JOIN UAE 表（而非原生 meta_query 多次 JOIN wp_*meta）
 * - 型別正確的比較（避免 CAST 開銷）
 * - 命中索引
 *
 * @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_Query_Compiler {

	/** @var array 合法的 SQL 比較運算子 */
	private const VALID_OPERATORS = array(
		'=',
		'!=',
		'<>',
		'>',
		'>=',
		'<',
		'<=',
		'LIKE',
		'NOT LIKE',
		'IN',
		'NOT IN',
		'BETWEEN',
		'NOT BETWEEN',
		'EXISTS',
		'NOT EXISTS',
	);

	/**
	 * 注入 wpdo_meta_query 至 WP_Query（post 實體）
	 *
	 * @param WP_Query $query
	 * @param array    $wpdo_meta_query 結構同 meta_query
	 */
	public static function inject_into_wp_query( WP_Query $query, array $wpdo_meta_query ): void {

		$post_type = $query->get( 'post_type' );
		if ( is_array( $post_type ) ) {
			$post_type = $post_type[0] ?? 'post';
		}
		if ( empty( $post_type ) || $post_type === 'any' ) {
			$post_type = 'post';
		}

		// 編譯 JOIN 與 WHERE
		$compiled = self::compile( 'post', $wpdo_meta_query );

		if ( empty( $compiled['joins'] ) && empty( $compiled['where'] ) ) {
			return;
		}

		// 注入 posts_clauses filter
		add_filter(
			'posts_clauses',
			function ( $clauses ) use ( $compiled ) {
				global $wpdb;

				if ( ! empty( $compiled['joins'] ) ) {
					$clauses['join'] .= ' ' . implode( ' ', $compiled['joins'] );
				}

				if ( ! empty( $compiled['where'] ) ) {
					$clauses['where'] .= ' AND (' . implode( ' AND ', $compiled['where'] ) . ')';
				}

				return $clauses;
			},
			10,
			1
		);

		// wpdo_orderby 支援
		$wpdo_orderby = $query->get( 'wpdo_orderby' );
		if ( $wpdo_orderby ) {
			$order_dir = strtoupper( $query->get( 'order' ) ?: 'DESC' );
			if ( ! in_array( $order_dir, array( 'ASC', 'DESC' ), true ) ) {
				$order_dir = 'DESC';
			}

			$wpdo_col = TMDO_Schema_Manager::sanitize_column_name( $wpdo_orderby );

			// 找出該欄位所在的群組
			$field_def = TMDO_Entity_Registry::get_field( 'post', $wpdo_orderby );
			if ( $field_def ) {
				$alias = 'wpdo_' . $field_def['group'];
				add_filter(
					'posts_orderby',
					function ( $orderby ) use ( $alias, $wpdo_col, $order_dir ) {
						return "`{$alias}`.`{$wpdo_col}` {$order_dir}";
					},
					10,
					1
				);
			}
		}
	}

	/**
	 * 注入至 WP_User_Query
	 */
	public static function inject_into_user_query( WP_User_Query $query, array $wpdo_meta_query ): void {

		$compiled = self::compile( 'user', $wpdo_meta_query );

		if ( empty( $compiled['joins'] ) && empty( $compiled['where'] ) ) {
			return;
		}

		global $wpdb;

		// 透過 reflection 存取 WP_User_Query 的 query_vars 來注入
		$query_orderby = &$query->query_orderby;
		$query_where   = &$query->query_where;
		$query_from    = &$query->query_from;

		if ( ! empty( $compiled['joins'] ) ) {
			$query_from .= ' ' . implode( ' ', $compiled['joins'] );
		}

		if ( ! empty( $compiled['where'] ) ) {
			$query_where .= ' AND (' . implode( ' AND ', $compiled['where'] ) . ')';
		}

		// wpdo_orderby
		$wpdo_orderby = $query->get( 'wpdo_orderby' );
		if ( $wpdo_orderby ) {
			$field_def = TMDO_Entity_Registry::get_field( 'user', $wpdo_orderby );
			if ( $field_def ) {
				$order_dir = strtoupper( $query->get( 'order' ) ?: 'DESC' );
				if ( ! in_array( $order_dir, array( 'ASC', 'DESC' ), true ) ) {
					$order_dir = 'DESC';
				}
				$alias         = 'wpdo_' . $field_def['group'];
				$col           = TMDO_Schema_Manager::sanitize_column_name( $wpdo_orderby );
				$query_orderby = "ORDER BY `{$alias}`.`{$col}` {$order_dir}";
			}
		}
	}

	/**
	 * 注入至 get_terms() 的 clauses
	 */
	public static function inject_into_terms_clauses( array $clauses, array $wpdo_meta_query ): array {

		$compiled = self::compile( 'term', $wpdo_meta_query );

		if ( empty( $compiled['joins'] ) && empty( $compiled['where'] ) ) {
			return $clauses;
		}

		if ( ! empty( $compiled['joins'] ) ) {
			$clauses['join'] .= ' ' . implode( ' ', $compiled['joins'] );
		}

		if ( ! empty( $compiled['where'] ) ) {
			$clauses['where'] .= ' AND (' . implode( ' AND ', $compiled['where'] ) . ')';
		}

		return $clauses;
	}

	/**
	 * 核心編譯邏輯
	 *
	 * @param string $entity_type
	 * @param array  $meta_query 結構範例：
	 *               [
	 *                 'relation' => 'AND',
	 *                 [ 'key' => 'price', 'value' => [100, 500], 'compare' => 'BETWEEN' ],
	 *                 [ 'key' => 'stock', 'value' => 'instock' ],
	 *               ]
	 * @return array{joins: array<string>, where: array<string>}
	 */
	public static function compile( string $entity_type, array $meta_query ): array {

		$adapter = TMDO_Entity_Registry::get_adapter( $entity_type );
		if ( ! $adapter ) {
			return array(
				'joins' => array(),
				'where' => array(),
			);
		}

		$relation = strtoupper( $meta_query['relation'] ?? 'AND' );
		if ( ! in_array( $relation, array( 'AND', 'OR' ), true ) ) {
			$relation = 'AND';
		}
		unset( $meta_query['relation'] );

		$needed_groups = array();  // group → true
		$where_clauses = array();

		foreach ( $meta_query as $clause ) {
			if ( ! is_array( $clause ) || empty( $clause['key'] ) ) {
				continue;
			}

			$field_def = TMDO_Entity_Registry::get_field( $entity_type, $clause['key'] );
			if ( ! $field_def ) {
				// 非 UAE 管理的欄位，跳過（讓原生 meta_query 接手）
				continue;
			}

			$group                   = $field_def['group'];
			$needed_groups[ $group ] = true;

			$compare = strtoupper( $clause['compare'] ?? '=' );
			if ( ! in_array( $compare, self::VALID_OPERATORS, true ) ) {
				$compare = '=';
			}

			$alias = 'wpdo_' . $group;
			$col   = TMDO_Schema_Manager::sanitize_column_name( $clause['key'] );
			$value = $clause['value'] ?? null;

			$where_clauses[] = self::build_comparison( $alias, $col, $compare, $value, $field_def );
		}

		// 建立 JOIN
		$joins      = array();
		$prim_table = $adapter->get_primary_table();
		$prim_id    = $adapter->get_primary_id_column();
		$id_col     = $adapter->get_entity_id_column();

		foreach ( array_keys( $needed_groups ) as $group ) {
			$wpdo_table = TMDO_Schema_Manager::get_table_name( $entity_type, $group );

			if ( ! TMDO_Schema_Manager::table_exists( $wpdo_table ) ) {
				continue;
			}

			$alias   = 'wpdo_' . $group;
			$joins[] = "LEFT JOIN `{$wpdo_table}` `{$alias}` ON `{$prim_table}`.`{$prim_id}` = `{$alias}`.`{$id_col}`";
		}

		// 組合 where，依 relation 連接
		$where_sql = array();
		if ( ! empty( $where_clauses ) ) {
			$where_sql[] = implode( " {$relation} ", $where_clauses );
		}

		return array(
			'joins' => $joins,
			'where' => $where_sql,
		);
	}

	/**
	 * 產生單一比較子句
	 */
	private static function build_comparison(
		string $alias,
		string $col,
		string $compare,
		$value,
		array $field_def
	): string {
		global $wpdb;

		$col_ref = "`{$alias}`.`{$col}`";

		switch ( $compare ) {
			case 'EXISTS':
				return "{$col_ref} IS NOT NULL";

			case 'NOT EXISTS':
				return "{$col_ref} IS NULL";

			case 'BETWEEN':
			case 'NOT BETWEEN':
				if ( ! is_array( $value ) || count( $value ) !== 2 ) {
					return '1=1';
				}
				$v1 = self::escape_value( $value[0], $field_def );
				$v2 = self::escape_value( $value[1], $field_def );
				return "{$col_ref} {$compare} {$v1} AND {$v2}";

			case 'IN':
			case 'NOT IN':
				if ( ! is_array( $value ) ) {
					$value = array( $value );
				}
				if ( empty( $value ) ) {
					return $compare === 'IN' ? '1=0' : '1=1';
				}
				$escaped = array_map( fn( $v ) => self::escape_value( $v, $field_def ), $value );
				return "{$col_ref} {$compare} (" . implode( ',', $escaped ) . ')';

			case 'LIKE':
			case 'NOT LIKE':
				$like_val = '%' . $wpdb->esc_like( (string) $value ) . '%';
				return "{$col_ref} {$compare} '" . esc_sql( $like_val ) . "'";

			default:
				$escaped = self::escape_value( $value, $field_def );
				return "{$col_ref} {$compare} {$escaped}";
		}
	}

	/**
	 * 型別安全地轉義值
	 */
	private static function escape_value( $value, array $field_def ): string {
		$type = $field_def['type'] ?? 'text';

		return match ( $type ) {
			'integer', 'boolean' => (string) (int) $value,
			'decimal'            => (string) (float) $value,
			default              => "'" . esc_sql( (string) $value ) . "'",
		};
	}
}