<?php
/**
 * Settings validation that runs after every other `streamsera_save_settings` filter (core and add-ons):
 *
 * - e-mail settings registered by add-ons (`streamsera_email_setting_keys`, `streamsera_email_list_setting_keys`): invalid addresses are
 *   rejected with a settings error and the previous value is kept.
 *
 * Errors recorded with streamsera_add_settings_error() are appended to the settings REST response as
 * `_errors` ({ key: message }) so the admin app can show them next to the field.
 *
 * @package StreamSera
 */

namespace StreamSera\Modules;

use WP_REST_Request;
use WP_REST_Response;

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

/**
 * Late settings validation + error transport.
 */
class Settings_Guard {

	/**
	 * Hook in.
	 */
	public function register() {
		add_filter( 'streamsera_save_settings', array( $this, 'validate' ), 20, 2 );
		add_filter( 'rest_post_dispatch', array( $this, 'attach_errors' ), 10, 3 );
	}

	/**
	 * Validate the keys above; keep previous values on error.
	 *
	 * @param array $next  Settings about to be saved.
	 * @param array $input Raw input.
	 * @return array
	 */
	public function validate( $next, $input ) {
		$input   = is_array( $input ) ? $input : array();
		$current = (array) get_option( 'streamsera_settings', array() );

		// Never persist the error transport key if a client echoes a previous response back.
		unset( $next['_errors'] );

		/**
		 * Filter the setting keys that hold a single e-mail address.
		 *
		 * @param string[] $keys Keys.
		 */
		foreach ( (array) apply_filters( 'streamsera_email_setting_keys', array() ) as $key ) {
			if ( ! array_key_exists( $key, $input ) ) {
				continue;
			}
			$raw = is_scalar( $input[ $key ] ) ? trim( (string) $input[ $key ] ) : '';
			if ( '' === $raw ) {
				$next[ $key ] = '';
				continue;
			}
			$email = sanitize_email( $raw );
			if ( ! $email || ! is_email( $email ) ) {
				streamsera_add_settings_error(
					$key,
					sprintf( /* translators: %s: the rejected value */ __( '"%s" is not a valid e-mail address. The previous value was kept.', 'streamsera' ), sanitize_text_field( $raw ) )
				);
				$next[ $key ] = isset( $current[ $key ] ) ? $current[ $key ] : '';
				continue;
			}
			$next[ $key ] = $email;
		}

		/**
		 * Filter the setting keys that hold a list of e-mail addresses.
		 *
		 * @param string[] $keys Keys.
		 */
		foreach ( (array) apply_filters( 'streamsera_email_list_setting_keys', array() ) as $key ) {
			if ( ! array_key_exists( $key, $input ) ) {
				continue;
			}
			$raw = is_scalar( $input[ $key ] ) ? trim( (string) $input[ $key ] ) : '';
			if ( '' === $raw ) {
				$next[ $key ] = '';
				continue;
			}
			$valid = array();
			$bad   = array();
			foreach ( preg_split( '/[,;\s]+/', $raw ) as $part ) {
				if ( '' === $part ) {
					continue;
				}
				$email = sanitize_email( $part );
				if ( $email && is_email( $email ) ) {
					$valid[] = $email;
				} else {
					$bad[] = $part;
				}
			}
			if ( $bad ) {
				streamsera_add_settings_error(
					$key,
					sprintf( /* translators: %s: comma-separated rejected values */ __( 'Not a valid e-mail address: %s. The previous value was kept.', 'streamsera' ), implode( ', ', array_map( 'sanitize_text_field', $bad ) ) )
				);
				$next[ $key ] = isset( $current[ $key ] ) ? $current[ $key ] : '';
				continue;
			}
			$next[ $key ] = implode( ', ', array_unique( $valid ) );
		}

		return $next;
	}

	/**
	 * Append `_errors` to the settings save response.
	 *
	 * @param WP_REST_Response $response Response.
	 * @param mixed            $server   Server.
	 * @param WP_REST_Request  $request  Request.
	 * @return WP_REST_Response
	 */
	public function attach_errors( $response, $server, $request ) {
		unset( $server );
		if ( ! ( $response instanceof WP_REST_Response ) || ! ( $request instanceof WP_REST_Request ) ) {
			return $response;
		}
		if ( 'POST' !== $request->get_method() || '/streamsera/v1/settings' !== $request->get_route() ) {
			return $response;
		}
		$errors = streamsera_get_settings_errors();
		if ( ! $errors ) {
			return $response;
		}
		$data = $response->get_data();
		if ( is_array( $data ) ) {
			$data['_errors'] = $errors;
			$response->set_data( $data );
		}
		return $response;
	}
}