<?php
/**
 * Connectors API
 *
 * Defines WP_Connector_Registry class.
 *
 * @package gutenberg
 * @since 7.0.0
 */

if ( ! class_exists( 'WP_Connector_Registry' ) ) {
	/**
	 * Manages the registration and lookup of connectors.
	 *
	 * @since 7.0.0
	 * @access private
	 *
	 * @phpstan-type Connector array{
	 *     name: non-empty-string,
	 *     description: non-empty-string,
	 *     logo_url?: non-empty-string,
	 *     type: non-empty-string,
	 *     authentication: array{
	 *         method: 'api_key'|'none',
	 *         credentials_url?: non-empty-string,
	 *         setting_name?: non-empty-string,
	 *         constant_name?: non-empty-string,
	 *         env_var_name?: non-empty-string
	 *     },
	 *     plugin?: array{
	 *         file: non-empty-string,
	 *         is_active?: callable(): bool
	 *     }
	 * }
	 */
	final class WP_Connector_Registry {
		/**
		 * The singleton instance of the registry.
		 *
		 * @since 7.0.0
		 */
		private static ?WP_Connector_Registry $instance = null;

		/**
		 * Holds the registered connectors.
		 *
		 * Each connector is stored as an associative array with keys:
		 * name, description, type, authentication, and optionally plugin.
		 *
		 * @since 7.0.0
		 * @var array<string, array>
		 * @phpstan-var array<string, Connector>
		 */
		private array $registered_connectors = array();

		/**
		 * Registers a new connector.
		 *
		 * Validates the provided arguments and stores the connector in the registry.
		 * For connectors with `api_key` authentication, a `setting_name` can be provided
		 * explicitly. If omitted, one is automatically generated using the pattern
		 * `connectors_{$type}_{$id}_api_key`, with hyphens in the type and ID normalized
		 * to underscores (e.g., connector type `spam_filtering` with ID `akismet` produces
		 * `connectors_spam_filtering_akismet_api_key`). This setting name is used for the
		 * Settings API registration and REST API exposure.
		 *
		 * Registering a connector with an ID that is already registered will trigger a
		 * `_doing_it_wrong()` notice and return `null`. To override an existing connector,
		 * call `unregister()` first.
		 *
		 * @since 7.0.0
		 *
		 * @see WP_Connector_Registry::unregister()
		 *
		 * @param string $id   The unique connector identifier. Must match the pattern
		 *                     `/^[a-z0-9_-]+$/` (lowercase alphanumeric, hyphens, and underscores only).
		 * @param array  $args {
		 *     An associative array of arguments for the connector.
		 *
		 *     @type string $name           Required. The connector's display name.
		 *     @type string $description    Optional. The connector's description. Default empty string.
		 *     @type string $logo_url       Optional. URL to the connector's logo image.
		 *     @type string $type           Required. The connector type, e.g. 'ai_provider'.
		 *     @type array  $authentication {
		 *         Required. Authentication configuration.
		 *
		 *         @type string $method          Required. The authentication method: 'api_key' or 'none'.
		 *         @type string $credentials_url Optional. URL where users can obtain API credentials.
		 *         @type string $setting_name    Optional. The setting name for the API key.
		 *                                       When omitted, auto-generated as
		 *                                       `connectors_{$type}_{$id}_api_key`.
		 *                                       Must be a non-empty string when provided.
		 *         @type string $constant_name   Optional. PHP constant name for the API key
		 *                                       (e.g. 'ANTHROPIC_API_KEY'). Only checked when provided.
		 *         @type string $env_var_name    Optional. Environment variable name for the API key
		 *                                       (e.g. 'ANTHROPIC_API_KEY'). Only checked when provided.
		 *     }
		 *     @type array  $plugin         {
		 *         Optional. Plugin data for install/activate UI.
		 *
		 *         @type string $file The plugin's main file path relative to the plugins
		 *                           directory (e.g. 'akismet/akismet.php' or 'hello.php').
		 *         @type callable $is_active Optional callback to determine whether the plugin
		 *                                   is active. Receives no arguments and must return bool.
		 *     }
		 * }
		 * @return array|null The registered connector data on success, null on failure.
		 *
		 * @phpstan-param Connector $args
		 * @phpstan-return Connector|null
		 */
		public function register( string $id, array $args ): ?array {
			if ( ! preg_match( '/^[a-z0-9_-]+$/', $id ) ) {
				_doing_it_wrong(
					__METHOD__,
					__(
						'Connector ID must contain only lowercase alphanumeric characters, hyphens, and underscores.'
					),
					'7.0.0'
				);
				return null;
			}

			if ( $this->is_registered( $id ) ) {
				_doing_it_wrong(
					__METHOD__,
					/* translators: %s: Connector ID. */
					sprintf( __( 'Connector "%s" is already registered.' ), esc_html( $id ) ),
					'7.0.0'
				);
				return null;
			}

			// Validate required fields.
			if ( empty( $args['name'] ) || ! is_string( $args['name'] ) ) {
				_doing_it_wrong(
					__METHOD__,
					/* translators: %s: Connector ID. */
					sprintf( __( 'Connector "%s" requires a non-empty "name" string.' ), esc_html( $id ) ),
					'7.0.0'
				);
				return null;
			}

			if ( empty( $args['type'] ) || ! is_string( $args['type'] ) ) {
				_doing_it_wrong(
					__METHOD__,
					/* translators: %s: Connector ID. */
					sprintf( __( 'Connector "%s" requires a non-empty "type" string.' ), esc_html( $id ) ),
					'7.0.0'
				);
				return null;
			}

			if ( ! isset( $args['authentication'] ) || ! is_array( $args['authentication'] ) ) {
				_doing_it_wrong(
					__METHOD__,
					/* translators: %s: Connector ID. */
					sprintf( __( 'Connector "%s" requires an "authentication" array.' ), esc_html( $id ) ),
					'7.0.0'
				);
				return null;
			}

			if ( empty( $args['authentication']['method'] ) || ! in_array( $args['authentication']['method'], array( 'api_key', 'none' ), true ) ) {
				_doing_it_wrong(
					__METHOD__,
					/* translators: %s: Connector ID. */
					sprintf( __( 'Connector "%s" authentication method must be "api_key" or "none".' ), esc_html( $id ) ),
					'7.0.0'
				);
				return null;
			}

			if ( 'ai_provider' === $args['type'] && ! class_exists( '\WordPress\AiClient\AiClient' ) ) {
				// No need for a doing_it_wrong as AI support is disabled intentionally.
				return null;
			}

			$connector = array(
				'name'           => $args['name'],
				'description'    => isset( $args['description'] ) && is_string( $args['description'] ) ? $args['description'] : '',
				'type'           => $args['type'],
				'authentication' => array(
					'method' => $args['authentication']['method'],
				),
			);

			if ( ! empty( $args['logo_url'] ) && is_string( $args['logo_url'] ) ) {
				$connector['logo_url'] = $args['logo_url'];
			}

			if ( 'api_key' === $args['authentication']['method'] ) {
				if ( ! empty( $args['authentication']['credentials_url'] ) && is_string( $args['authentication']['credentials_url'] ) ) {
					$connector['authentication']['credentials_url'] = $args['authentication']['credentials_url'];
				}
				if ( isset( $args['authentication']['setting_name'] ) ) {
					if ( ! is_string( $args['authentication']['setting_name'] ) || '' === $args['authentication']['setting_name'] ) {
						_doing_it_wrong(
							__METHOD__,
							/* translators: %s: Connector ID. */
							sprintf( __( 'Connector "%s" authentication setting_name must be a non-empty string.' ), esc_html( $id ) ),
							'7.0.0'
						);
						return null;
					}
					$connector['authentication']['setting_name'] = $args['authentication']['setting_name'];
				} else {
					$connector['authentication']['setting_name'] = str_replace( '-', '_', "connectors_{$connector['type']}_{$id}_api_key" );
				}
				if ( isset( $args['authentication']['constant_name'] ) ) {
					if ( ! is_string( $args['authentication']['constant_name'] ) || '' === $args['authentication']['constant_name'] ) {
						_doing_it_wrong(
							__METHOD__,
							/* translators: %s: Connector ID. */
							sprintf( __( 'Connector "%s" authentication constant_name must be a non-empty string.' ), esc_html( $id ) ),
							'7.0.0'
						);
						return null;
					}
					$connector['authentication']['constant_name'] = $args['authentication']['constant_name'];
				}
				if ( isset( $args['authentication']['env_var_name'] ) ) {
					if ( ! is_string( $args['authentication']['env_var_name'] ) || '' === $args['authentication']['env_var_name'] ) {
						_doing_it_wrong(
							__METHOD__,
							/* translators: %s: Connector ID. */
							sprintf( __( 'Connector "%s" authentication env_var_name must be a non-empty string.' ), esc_html( $id ) ),
							'7.0.0'
						);
						return null;
					}
					$connector['authentication']['env_var_name'] = $args['authentication']['env_var_name'];
				}
			}

			if ( ! empty( $args['plugin'] ) && is_array( $args['plugin'] ) && ! empty( $args['plugin']['file'] ) ) {
				$connector['plugin'] = array( 'file' => $args['plugin']['file'] );

				if ( isset( $args['plugin']['is_active'] ) ) {
					if ( ! is_callable( $args['plugin']['is_active'] ) ) {
						_doing_it_wrong(
							__METHOD__,
							/* translators: %s: Connector ID. */
							sprintf( __( 'Connector "%s" plugin is_active must be callable.' ), esc_html( $id ) ),
							'7.0.0'
						);
						return null;
					}

					$connector['plugin']['is_active'] = $args['plugin']['is_active'];
				}
			}

			$this->registered_connectors[ $id ] = $connector;
			return $connector;
		}

		/**
		 * Unregisters a connector.
		 *
		 * @since 7.0.0
		 *
		 * @param string $id The connector identifier.
		 * @return array|null The unregistered connector data on success, null on failure.
		 *
		 * @phpstan-return Connector|null
		 */
		public function unregister( string $id ): ?array {
			if ( ! $this->is_registered( $id ) ) {
				_doing_it_wrong(
					__METHOD__,
					/* translators: %s: Connector ID. */
					sprintf( __( 'Connector "%s" not found.' ), esc_html( $id ) ),
					'7.0.0'
				);
				return null;
			}

			$unregistered = $this->registered_connectors[ $id ];
			unset( $this->registered_connectors[ $id ] );

			return $unregistered;
		}

		/**
		 * Retrieves the list of all registered connectors.
		 *
		 * Do not use this method directly. Instead, use the `wp_get_connectors()` function.
		 *
		 * @since 7.0.0
		 *
		 * @see wp_get_connectors()
		 *
		 * @return array<string, array> The array of registered connectors keyed by connector ID.
		 *
		 * @phpstan-return array<string, Connector>
		 */
		public function get_all_registered(): array {
			return $this->registered_connectors;
		}

		/**
		 * Checks if a connector is registered.
		 *
		 * Do not use this method directly. Instead, use the `wp_is_connector_registered()` function.
		 *
		 * @since 7.0.0
		 *
		 * @see wp_is_connector_registered()
		 *
		 * @param string $id The connector identifier.
		 * @return bool True if the connector is registered, false otherwise.
		 */
		public function is_registered( string $id ): bool {
			return isset( $this->registered_connectors[ $id ] );
		}

		/**
		 * Retrieves a registered connector.
		 *
		 * Do not use this method directly. Instead, use the `wp_get_connector()` function.
		 *
		 * @since 7.0.0
		 *
		 * @see wp_get_connector()
		 *
		 * @param string $id The connector identifier.
		 * @return array|null The registered connector data, or null if it is not registered.
		 * @phpstan-return Connector|null
		 */
		public function get_registered( string $id ): ?array {
			if ( ! $this->is_registered( $id ) ) {
				_doing_it_wrong(
					__METHOD__,
					/* translators: %s: Connector ID. */
					sprintf( __( 'Connector "%s" not found.' ), esc_html( $id ) ),
					'7.0.0'
				);
				return null;
			}
			return $this->registered_connectors[ $id ];
		}

		/**
		 * Retrieves the main instance of the registry class.
		 *
		 * @since 7.0.0
		 *
		 * @return WP_Connector_Registry|null The main registry instance, or null if not yet initialized.
		 */
		public static function get_instance(): ?self {
			return self::$instance;
		}

		/**
		 * Sets the main instance of the registry class.
		 *
		 * @since 7.0.0
		 * @access private
		 *
		 * @param WP_Connector_Registry $registry The registry instance.
		 */
		public static function set_instance( WP_Connector_Registry $registry ): void {
			if ( ! doing_action( 'init' ) ) {
				_doing_it_wrong(
					__METHOD__,
					__( 'The connector registry instance must be set during the <code>init</code> action.' ),
					'7.0.0'
				);
				return;
			}

			self::$instance = $registry;
		}
	}
}
