<?php
/**
 * Central registry for zone field configurations.
 *
 * @package WP_Data_Optimizer
 */

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

/**
 * Central registry for zone field configurations.
 *
 * Plugins register their meta_key → zone mappings here.
 * The registry drives table creation, migration, interceptors, and query routing.
 *
 * Usage:
 *   $registry = TMDO_Schema_Registry::instance();
 *   $registry->register( 'hivepress', [
 *       'post_type' => 'hp_listing',
 *       'meta_key'  => 'hp_price',
 *       'zone'      => 'hot',
 *       'data_type' => 'decimal(10,2) NOT NULL DEFAULT 0',
 *       'column'    => 'hp_price',
 *       'indexed'   => true,
 *   ]);
 */
class TMDO_Schema_Registry {

	/**
	 * Singleton instance.
	 *
	 * @var self|null
	 */
	private static ?self $instance = null;

	/**
	 * Registered field mappings.
	 *
	 * Structure: [ 'post_type:meta_key' => field_config, ... ]
	 *
	 * @var array<string, array>
	 */
	private array $fields = array();

	/**
	 * Zone → post_type → columns map for Zone A (hot) table creation.
	 *
	 * @var array<string, array<string, array>>
	 */
	private array $hot_columns = array();

	/**
	 * Zone C (cold) fields grouped by post_type.
	 *
	 * @var array<string, string[]>
	 */
	private array $cold_fields = array();

	/**
	 * Zone B (warm) fields with TTL config.
	 *
	 * @var array<string, array>
	 */
	private array $warm_fields = array();

	/**
	 * Private constructor — use instance() to get the singleton.
	 */
	private function __construct() {}

	/**
	 * Get the singleton instance.
	 */
	public static function instance(): self {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Register a field mapping.
	 *
	 * @param string $provider Provider name (e.g. 'hivepress', 'woocommerce').
	 * @param array  $config   Field configuration:
	 *   - post_type  (string) WordPress post type.
	 *   - meta_key   (string) The wp_postmeta meta_key.
	 *   - zone       (string) hot|warm|cold|archive
	 *   - data_type  (string) SQL column type for Zone A (e.g. 'decimal(10,2) NOT NULL DEFAULT 0').
	 *   - column     (string) Column name in zone table (defaults to sanitized meta_key).
	 *   - indexed    (bool)   Whether to add an index (Zone A only).
	 *   - ttl        (int)    TTL in seconds (Zone B only, null = no expiry).
	 *   - cache_group (string) Object cache group (Zone C only).
	 *   - cache_ttl   (int)   Cache TTL in seconds (Zone C only).
	 *   - show_in_rest (bool) Whether to expose via GET /wpdo/v1/listings. Default true.
	 */
	public function register( string $provider, array $config ): void {
		$config = wp_parse_args(
			$config,
			array(
				'post_type'    => '',
				'entity_type'  => '',
				'meta_key'     => '',
				'zone'         => 'hot',
				'data_type'    => 'longtext',
				'column'       => '',
				'indexed'      => false,
				'ttl'          => null,
				'cache_group'  => '',
				'cache_ttl'    => HOUR_IN_SECONDS,
				'provider'     => $provider,
				'show_in_rest' => true,
			)
		);

		// v2.1.2 fix: normalize post_type vs entity_type. Some partner plugins
		// (e.g. 2meet-liff) register fields against entities other than posts
		// (user / term / comment) using `entity_type` instead of `post_type`.
		// Without normalization, those fields end up with empty-string post_type,
		// polluting `get_hot_post_types()` output. Use entity_type as bucket key.
		if ( empty( $config['post_type'] ) && ! empty( $config['entity_type'] ) ) {
			$config['post_type'] = sanitize_key( $config['entity_type'] );
		}

		if ( empty( $config['column'] ) ) {
			$config['column'] = sanitize_key( $config['meta_key'] );
		}

		$key                  = $config['post_type'] . ':' . $config['meta_key'];
		$config['provider']   = $provider;
		$this->fields[ $key ] = $config;

		// Index by zone for efficient lookup.
		switch ( $config['zone'] ) {
			case 'hot':
				$this->hot_columns[ $config['post_type'] ][ $config['column'] ] = $config['data_type'];
				break;

			case 'warm':
				$this->warm_fields[ $config['meta_key'] ] = $config;
				break;

			case 'cold':
				$this->cold_fields[ $config['post_type'] ][] = $config['meta_key'];
				break;
		}
	}

	/**
	 * Bulk register multiple fields.
	 *
	 * @param string $provider Provider name.
	 * @param array  $configs  Array of field configs.
	 */
	public function register_many( string $provider, array $configs ): void {
		foreach ( $configs as $config ) {
			$this->register( $provider, $config );
		}
	}

	/**
	 * Get the zone configuration for a specific field.
	 *
	 * @param string $post_type Post type.
	 * @param string $meta_key  Meta key.
	 * @return array|null Field config or null if not registered.
	 */
	public function get_field( string $post_type, string $meta_key ): ?array {
		$key = $post_type . ':' . $meta_key;
		return $this->fields[ $key ] ?? null;
	}

	/**
	 * Get all fields for a specific zone.
	 *
	 * @param string $zone Zone identifier (hot/warm/cold/archive).
	 * @return array Array of field configs.
	 */
	public function get_zone_fields( string $zone ): array {
		return array_filter( $this->fields, fn( $f ) => $f['zone'] === $zone );
	}

	/**
	 * Get all fields for a specific zone and post type.
	 *
	 * @param string $zone      Zone identifier.
	 * @param string $post_type Post type.
	 * @return array
	 */
	public function get_zone_fields_for_type( string $zone, string $post_type ): array {
		return array_filter(
			$this->fields,
			fn( $f ) => $f['zone'] === $zone && $f['post_type'] === $post_type
		);
	}

	/**
	 * Get hot column definitions for a post type (for table creation).
	 *
	 * @param string $post_type Post type.
	 * @return array<string, string> Column name => SQL type.
	 */
	public function get_hot_columns( string $post_type ): array {
		return $this->hot_columns[ $post_type ] ?? array();
	}

	/**
	 * Get all post types that have hot zone fields.
	 *
	 * @return string[]
	 */
	public function get_hot_post_types(): array {
		return array_keys( $this->hot_columns );
	}

	/**
	 * Get all post types that have cold zone fields.
	 *
	 * @return string[]
	 */
	public function get_cold_post_types(): array {
		return array_keys( $this->cold_fields );
	}

	/**
	 * Get cold field meta keys for a post type.
	 *
	 * @param string $post_type Post type.
	 * @return string[] Array of meta keys.
	 */
	public function get_cold_meta_keys( string $post_type ): array {
		return array_unique( $this->cold_fields[ $post_type ] ?? array() );
	}

	/**
	 * Returns hot column names for a post type where show_in_rest is true.
	 * Used by REST endpoints to restrict publicly exposed fields.
	 *
	 * @param string $post_type Post type.
	 * @return string[] Column names that are REST-visible.
	 */
	public function get_rest_visible_hot_columns( string $post_type ): array {
		$visible = array();
		foreach ( $this->fields as $field ) {
			if ( 'hot' === $field['zone'] && $field['post_type'] === $post_type && ! empty( $field['show_in_rest'] ) ) {
				$visible[] = $field['column'];
			}
		}
		return $visible;
	}

	/**
	 * Returns cold meta keys for a post type where show_in_rest is true.
	 * Used by REST endpoints to restrict publicly exposed fields.
	 *
	 * @param string $post_type Post type.
	 * @return string[] Meta keys that are REST-visible.
	 */
	public function get_rest_visible_cold_keys( string $post_type ): array {
		$visible = array();
		foreach ( $this->fields as $field ) {
			if ( 'cold' === $field['zone'] && $field['post_type'] === $post_type && ! empty( $field['show_in_rest'] ) ) {
				$visible[] = $field['meta_key'];
			}
		}
		return array_unique( $visible );
	}

	/**
	 * Get warm field configuration.
	 *
	 * @param string $meta_key Meta key.
	 * @return array|null
	 */
	public function get_warm_field( string $meta_key ): ?array {
		return $this->warm_fields[ $meta_key ] ?? null;
	}

	/**
	 * Check which zone a meta_key belongs to for a given post type.
	 *
	 * @param string $post_type Post type.
	 * @param string $meta_key  Meta key.
	 * @return string|null Zone name or null if not registered.
	 */
	public function get_field_zone( string $post_type, string $meta_key ): ?string {
		$field = $this->get_field( $post_type, $meta_key );
		return $field['zone'] ?? null;
	}

	/**
	 * Get all registered fields (for admin dashboard / analysis).
	 *
	 * @return array<string, array>
	 */
	public function all(): array {
		return $this->fields;
	}

	/**
	 * Get summary statistics for the admin dashboard.
	 *
	 * @return array{hot: int, warm: int, cold: int, archive: int, total: int}
	 */
	public function get_stats(): array {
		$stats = array(
			'hot'     => 0,
			'warm'    => 0,
			'cold'    => 0,
			'archive' => 0,
			'total'   => 0,
		);
		foreach ( $this->fields as $field ) {
			if ( isset( $stats[ $field['zone'] ] ) ) {
				++$stats[ $field['zone'] ];
			}
			++$stats['total'];
		}
		return $stats;
	}
}