<?php
/**
 * Public REST endpoint for code checks.
 *
 * @package NovoVerify
 */

defined( 'ABSPATH' ) || exit;

/**
 * Registers POST novoverify/v1/check.
 *
 * The endpoint is public on purpose (customers are not logged in). It is protected by
 * input validation, a honeypot field and a per-visitor rate limit.
 */
final class NovoVerify_Rest {

	/**
	 * REST namespace.
	 */
	const NAMESPACE_V1 = 'novoverify/v1';

	/**
	 * Name of the honeypot field. Real visitors never fill it in.
	 */
	const HONEYPOT = 'novoverify_website';

	/**
	 * Registers hooks.
	 */
	public function __construct() {
		add_action( 'rest_api_init', array( $this, 'register_routes' ) );
	}

	/**
	 * Registers the route.
	 */
	public function register_routes() {
		register_rest_route(
			self::NAMESPACE_V1,
			'/check',
			array(
				'methods'             => WP_REST_Server::CREATABLE,
				'callback'            => array( $this, 'check' ),
				'permission_callback' => '__return_true',
				'args'                => array(
					'code'         => array(
						'type'      => 'string',
						'required'  => true,
						'minLength' => 1,
						'maxLength' => 100,
					),
					self::HONEYPOT => array(
						'type'      => 'string',
						'default'   => '',
						'maxLength' => 200,
					),
				),
			)
		);
	}

	/**
	 * Hashed request context: IP, user agent and country.
	 *
	 * @return array{ip_hash: string, user_agent_hash: string, country: string}
	 */
	public static function request_context() {
		$ip = self::client_ip( (string) NovoVerify_Settings::get( 'ip_source' ) );

		$user_agent = isset( $_SERVER['HTTP_USER_AGENT'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ) : '';

		$context = array(
			'ip_hash'         => NovoVerify_Codes::hash_value( '' !== $ip ? $ip : 'unknown' ),
			'user_agent_hash' => NovoVerify_Codes::hash_value( $user_agent ),
			'country'         => '',
		);

		/**
		 * Filters the request context stored with each check.
		 *
		 * @param array $context ip_hash, user_agent_hash, country.
		 */
		return apply_filters( 'novoverify_check_context', $context );
	}

	/**
	 * Visitor IP from the configured source, falling back to REMOTE_ADDR.
	 *
	 * Proxy headers are only trusted when the admin selected them, because anyone can
	 * send such a header when the site is not really behind that proxy.
	 *
	 * @param string $source Key from NovoVerify_Settings::ip_sources().
	 * @return string IP address, or empty string.
	 */
	public static function client_ip( $source = 'remote_addr' ) {
		$sources = NovoVerify_Settings::ip_sources();
		$ip      = '';

		if ( 'remote_addr' !== $source && isset( $sources[ $source ], $_SERVER[ $sources[ $source ] ] ) ) {
			$value = sanitize_text_field( wp_unslash( $_SERVER[ $sources[ $source ] ] ) );
			// X-Forwarded-For may hold a list: "client, proxy1, proxy2". The first entry is the visitor.
			$first = trim( (string) strtok( $value, ',' ) );
			if ( false !== filter_var( $first, FILTER_VALIDATE_IP ) ) {
				$ip = $first;
			}
		}

		if ( '' === $ip && isset( $_SERVER['REMOTE_ADDR'] ) ) {
			$remote = sanitize_text_field( wp_unslash( $_SERVER['REMOTE_ADDR'] ) );
			$ip     = false !== filter_var( $remote, FILTER_VALIDATE_IP ) ? $remote : '';
		}

		/**
		 * Filters the visitor IP used for rate limiting and repeat detection.
		 *
		 * @param string $ip     IP address.
		 * @param string $source Configured IP source.
		 */
		return (string) apply_filters( 'novoverify_client_ip', $ip, $source );
	}

	/**
	 * Handles a check request.
	 *
	 * @param WP_REST_Request $request Request.
	 * @return WP_REST_Response|WP_Error
	 */
	public function check( WP_REST_Request $request ) {
		if ( '' !== trim( (string) $request[ self::HONEYPOT ] ) ) {
			return new WP_Error( 'novoverify_rejected', __( 'Your request could not be processed. Please try again.', 'novoverify' ), array( 'status' => 400 ) );
		}

		$context     = self::request_context();
		$retry_after = NovoVerify_Rate_Limit::check( $context['ip_hash'] );

		if ( $retry_after > 0 ) {
			$error = new WP_Error(
				'novoverify_rate_limited',
				MINUTE_IN_SECONDS >= $retry_after
					? __( 'Too many checks in a short time. Please wait a minute and try again.', 'novoverify' )
					: __( 'Too many checks in a short time. Please try again in an hour.', 'novoverify' ),
				array(
					'status'      => 429,
					'retry_after' => $retry_after,
				)
			);
			return $error;
		}

		$check = NovoVerify_Codes::check( (string) $request['code'], $context );

		$response = rest_ensure_response( self::format_response( $check, (string) $request['code'] ) );
		$response->header( 'Cache-Control', 'no-store, max-age=0' );
		return $response;
	}

	/**
	 * Turns a check result into the public response.
	 *
	 * @param array  $check Result of NovoVerify_Codes::check().
	 * @param string $input Code as entered.
	 * @return array
	 */
	public static function format_response( array $check, $input ) {
		$row    = $check['code'];
		$result = $check['result'];
		$found  = is_object( $row );

		$first_date = $found ? NovoVerify_Codes::format_datetime( $check['first_checked_at'], get_option( 'date_format' ) ) : '';
		$code       = $found ? ( '' !== $row->display_code ? $row->display_code : $row->code ) : mb_substr( sanitize_text_field( $input ), 0, 64 );
		$product    = $found && NovoVerify_Codes::RESULT_AUTHENTIC === $result ? (string) $row->product_name : '';

		$texts = NovoVerify_Messages::get(
			$result,
			array(
				'code'       => $code,
				'count'      => (int) $check['previous_checks'],
				'first_date' => $first_date,
				'product'    => $found ? (string) $row->product_name : '',
			)
		);

		$response = array(
			'result'          => $result,
			'title'           => $texts['title'],
			'message'         => $texts['message'],
			'code'            => $code,
			'previous_checks' => (int) $check['previous_checks'],
			'first_checked'   => $first_date,
			'details'         => array(),
		);

		if ( '' !== $product ) {
			$response['details'][] = array(
				'label' => __( 'Product', 'novoverify' ),
				'value' => $product,
			);
		}

		/**
		 * Filters the public check response. Values are printed as text, never as HTML.
		 *
		 * @param array       $response Response data.
		 * @param array       $check    Raw check result.
		 * @param object|null $row      Code row.
		 */
		return apply_filters( 'novoverify_check_response', $response, $check, $row );
	}
}