<?php
/**
 * TMDO_Post_Query_Router — Post entity meta_query → flat table JOIN rewriter (v2.10.1).
 *
 * Companion to legacy TMDO_Query_Router (which targets zone hot tables).
 * Independent class — does NOT modify the user side path or the legacy zone
 * router. Both routers can coexist on the same WP_Query without conflict
 * because they extract clauses on disjoint criteria:
 *
 *   - TMDO_Query_Router         → only zone-registered keys with feature_flag query_active
 *   - TMDO_Post_Query_Router    → only entity-registered keys with mode=reads_from_flat
 *
 * Mode-gated: only rewrites when post mode is `shadow_read` or `aeav_only`.
 * In `disabled` / `dual_write` modes the router is a no-op.
 *
 * Hook order:
 *   1. pre_get_posts  — strip registered keys from meta_query, store in
 *                       $query->set( 'wpdo_post_clauses', $routed )
 *   2. posts_join     — LEFT JOIN wp_wpdo_post_<group> per routed post_type
 *   3. posts_where    — append WHERE conditions targeting flat columns
 *   4. posts_groupby  — ensure GROUP BY posts.ID to dedup join multiplication
 *
 * 🔒 v2.9.x → v2.10.x frozen contract: never touches user entity. Routes
 * only entity_type='post'.
 *
 * @package WP_Data_Optimizer
 * @since   2.10.1
 */

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

// phpcs:disable WordPress.DB.PreparedSQL.NotPrepared,WordPress.DB.PreparedSQL.InterpolatedNotPrepared -- Internal query rewriter: table names go through Schema_Manager::sanitize_column_name, column names go through esc_sql, user-controlled values use $wpdb->prepare() in build_condition().

/**
 * Rewrites WP_Query meta_query clauses to JOIN against post entity flat tables.
 */
class TMDO_Post_Query_Router {

	/** Query var key for capturing routed clauses (consumed by posts_join/where). */
	private const QUERY_VAR = 'wpdo_post_clauses';

	/**
	 * Map post_type → entity group (mirror of TMDO_Post_Migration::group_post_type
	 * but inverted; a post_type may map to multiple groups eventually, currently
	 * we route to the most-specific *_core group plus the cross-cutting wp_core
	 * group when the key is in wp_core).
	 *
	 * @var array<string,string>
	 */
	private const POST_TYPE_GROUP_MAP = array(
		'product'       => 'wc_product',
		'hp_listing'    => 'hp_listing_core',
		'hp_request'    => 'hp_request_core',
		'hp_vendor'     => 'hp_vendor_core',
		'attachment'    => 'attachment',
		'nav_menu_item' => 'nav_menu_item',
	);

	/**
	 * Register all WP_Query hooks.
	 *
	 * @return void
	 */
	public function register_hooks(): void {
		add_action( 'pre_get_posts', array( $this, 'pre_get_posts' ), 10, 1 );
		add_filter( 'posts_join', array( $this, 'posts_join' ), 10, 2 );
		add_filter( 'posts_where', array( $this, 'posts_where' ), 10, 2 );
		add_filter( 'posts_groupby', array( $this, 'posts_groupby' ), 10, 2 );
	}

	/**
	 * Strip Entity-Registry-managed meta_query keys; store routed clauses.
	 *
	 * @param \WP_Query $query Current WP_Query.
	 * @return void
	 */
	public function pre_get_posts( \WP_Query $query ): void {
		// Mode gate: only run when post mode is reads_from_flat.
		if ( ! self::is_router_active() ) {
			return;
		}

		// is_admin guard (matches legacy TMDO_Query_Router behavior).
		if ( is_admin() && ! wp_doing_ajax() ) {
			return;
		}

		$post_types = (array) $query->get( 'post_type' );
		if ( empty( $post_types ) ) {
			return;
		}

		$raw_meta_query = (array) $query->get( 'meta_query' );
		if ( empty( $raw_meta_query ) ) {
			return;
		}

		$routed    = array(); // Keyed by post_type.
		$remaining = array();

		foreach ( $raw_meta_query as $k => $clause ) {
			if ( 'relation' === $k || ! is_array( $clause ) || ! isset( $clause['key'] ) ) {
				$remaining[ $k ] = $clause;
				continue;
			}

			$matched = false;
			foreach ( $post_types as $pt ) {
				$field = TMDO_Entity_Registry::get_field( 'post', $clause['key'] );
				if ( ! $field ) {
					continue;
				}
				// Confirm the field's group is appropriate for this post_type:
				// either cross-cutting wp_core (any) or the post_type-specific group.
				$group          = $field['group'] ?? '';
				$expected_grp   = self::POST_TYPE_GROUP_MAP[ $pt ] ?? null;
				$is_appropriate = ( 'wp_core' === $group ) || ( null !== $expected_grp && $expected_grp === $group );
				if ( ! $is_appropriate ) {
					continue;
				}

				$column = TMDO_Schema_Manager::sanitize_column_name( $clause['key'] );

				$routed[ $pt ][] = array(
					'group'   => $group,
					'column'  => $column,
					'value'   => $clause['value'] ?? '',
					'compare' => strtoupper( trim( (string) ( $clause['compare'] ?? '=' ) ) ),
					'type'    => strtoupper( trim( (string) ( $clause['type'] ?? 'CHAR' ) ) ),
				);
				$matched         = true;
				break;
			}

			if ( ! $matched ) {
				$remaining[ $k ] = $clause;
			}
		}

		if ( empty( $routed ) ) {
			return;
		}

		// Preserve relation if surviving clauses still have it.
		if ( isset( $raw_meta_query['relation'] ) && ! isset( $remaining['relation'] ) ) {
			$remaining['relation'] = $raw_meta_query['relation'];
		}

		$query->set( 'meta_query', $remaining );
		$query->set( self::QUERY_VAR, $routed );
	}

	/**
	 * LEFT JOIN flat tables for each routed post_type.
	 *
	 * @param string|null $join  Current JOIN SQL.
	 * @param \WP_Query   $query Current WP_Query.
	 * @return string Modified JOIN SQL.
	 */
	public function posts_join( ?string $join, \WP_Query $query ): string {
		$join   = (string) ( $join ?? '' );
		$routed = $query->get( self::QUERY_VAR );
		if ( empty( $routed ) || ! is_array( $routed ) ) {
			return $join;
		}

		global $wpdb;

		foreach ( $routed as $post_type => $clauses ) {
			// Each routed clause carries its group; use the first clause's group
			// (all clauses for a given post_type currently target one group).
			$group = $clauses[0]['group'] ?? '';
			if ( '' === $group ) {
				continue;
			}
			$table = $wpdb->prefix . 'wpdo_post_' . sanitize_key( $group );
			$alias = self::table_alias( $post_type, $group );

			// Don't double-join.
			if ( false !== strpos( $join, "`{$alias}`" ) ) {
				continue;
			}

			$join .= " LEFT JOIN `{$table}` AS `{$alias}` "
				. "ON (`{$wpdb->posts}`.`ID` = `{$alias}`.`post_id`)";
		}

		return $join;
	}

	/**
	 * Append WHERE conditions for routed clauses.
	 *
	 * @param string|null $where Current WHERE SQL.
	 * @param \WP_Query   $query Current WP_Query.
	 * @return string Modified WHERE SQL.
	 */
	public function posts_where( ?string $where, \WP_Query $query ): string {
		$where  = (string) ( $where ?? '' );
		$routed = $query->get( self::QUERY_VAR );
		if ( empty( $routed ) || ! is_array( $routed ) ) {
			return $where;
		}

		global $wpdb;

		foreach ( $routed as $post_type => $clauses ) {
			foreach ( $clauses as $clause ) {
				$alias   = self::table_alias( $post_type, $clause['group'] );
				$col     = '`' . $alias . '`.`' . esc_sql( $clause['column'] ) . '`';
				$compare = self::sanitize_compare( $clause['compare'] );
				$value   = $clause['value'];

				$where .= self::build_condition( $col, $compare, $value );
			}
		}

		return $where;
	}

	/**
	 * Ensure GROUP BY posts.ID to deduplicate JOIN-multiplied rows.
	 *
	 * @param string|null $groupby Current GROUP BY SQL.
	 * @param \WP_Query   $query   Current WP_Query.
	 * @return string Modified GROUP BY SQL.
	 */
	public function posts_groupby( ?string $groupby, \WP_Query $query ): string {
		$groupby = (string) ( $groupby ?? '' );
		$routed  = $query->get( self::QUERY_VAR );
		if ( empty( $routed ) || ! is_array( $routed ) ) {
			return $groupby;
		}

		global $wpdb;
		if ( '' === trim( $groupby ) ) {
			$groupby = "`{$wpdb->posts}`.`ID`";
		}

		return $groupby;
	}

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

	/**
	 * Whether the router is mode-active (post mode is shadow_read or aeav_only).
	 *
	 * @return bool
	 */
	public static function is_router_active(): bool {
		if ( ! class_exists( 'TMDO_Mode_Manager' ) ) {
			return false;
		}
		return TMDO_Mode_Manager::reads_from_flat( 'post' );
	}

	/**
	 * Generate a deterministic JOIN alias for a (post_type, group) pair.
	 *
	 * @param string $post_type Post type slug.
	 * @param string $group     Entity group name.
	 * @return string SQL alias.
	 */
	private static function table_alias( string $post_type, string $group ): string {
		return 'wpdoflat_' . sanitize_key( $post_type ) . '_' . sanitize_key( $group );
	}

	/**
	 * Allow-list of comparison operators.
	 *
	 * @param string $compare Raw operator from clause.
	 * @return string Sanitized operator (defaults to '=').
	 */
	private static function sanitize_compare( string $compare ): string {
		$allowed = array( '=', '!=', '<>', '<', '<=', '>', '>=', 'IN', 'NOT IN', 'LIKE', 'NOT LIKE', 'BETWEEN', 'NOT BETWEEN', 'EXISTS', 'NOT EXISTS' );
		$compare = strtoupper( trim( $compare ) );
		return in_array( $compare, $allowed, true ) ? $compare : '=';
	}

	/**
	 * Build a single WHERE condition fragment (always prepended with " AND ").
	 *
	 * @param string $col_sql  Quoted column reference.
	 * @param string $compare  Sanitized comparison operator.
	 * @param mixed  $value    Raw value (scalar or array).
	 * @return string
	 */
	private static function build_condition( string $col_sql, string $compare, $value ): string {
		global $wpdb;

		if ( in_array( $compare, array( 'IN', 'NOT IN' ), true ) ) {
			$values = (array) $value;
			if ( empty( $values ) ) {
				return '';
			}
			$placeholders = implode( ',', array_fill( 0, count( $values ), '%s' ) );
			return ' AND ' . $col_sql . ' ' . $compare . ' (' . $wpdb->prepare( $placeholders, ...$values ) . ')';
		}

		if ( in_array( $compare, array( 'BETWEEN', 'NOT BETWEEN' ), true ) ) {
			$values = (array) $value;
			if ( count( $values ) < 2 ) {
				return '';
			}
			return ' AND ' . $col_sql . ' ' . $compare . ' '
				. $wpdb->prepare( '%s AND %s', $values[0], $values[1] );
		}

		if ( in_array( $compare, array( 'EXISTS', 'NOT EXISTS' ), true ) ) {
			$op = 'EXISTS' === $compare ? 'IS NOT NULL' : 'IS NULL';
			return ' AND ' . $col_sql . ' ' . $op;
		}

		return ' AND ' . $col_sql . ' ' . $compare . ' ' . $wpdb->prepare( '%s', (string) $value );
	}
}