<?php
/**
 * AIT Easy Post Customization - REST API
 *
 * Registers REST routes used by the plugin.
 * Currently provides a public, token-protected unsubscribe endpoint
 * so email recipients can opt out without logging in.
 *
 * @package AIT Easy Post Customization
 */

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

/**
 * Register plugin REST API routes.
 * Hooked on rest_api_init.
 */
function aitepc_register_rest_routes() {
	register_rest_route(
		'aitepc/v1',
		'/unsubscribe',
		array(
			'methods'             => WP_REST_Server::READABLE, // GET
			'callback'            => 'aitepc_rest_unsubscribe_callback',
			'permission_callback' => '__return_true', // Token-verified; no auth required.
			'args'                => array(
				'user_id' => array(
					'required'          => true,
					'sanitize_callback' => 'absint',
					'validate_callback' => static function ( $param ) {
						return is_numeric( $param ) && (int) $param > 0;
					},
					'description'       => __( 'The user ID to unsubscribe.', 'ait-easy-post-customization' ),
				),
				'token'   => array(
					'required'          => true,
					'sanitize_callback' => 'sanitize_text_field',
					'description'       => __( 'HMAC verification token.', 'ait-easy-post-customization' ),
				),
			),
		)
	);
}
add_action( 'rest_api_init', 'aitepc_register_rest_routes' );

/**
 * Handle an unsubscribe request.
 *
 * Validates the HMAC token derived from user ID + email (stateless —
 * no token DB table needed). Uses hash_equals() for timing-safe comparison.
 * Sets user meta 'aitepc_email_unsubscribe' = '1' on success.
 *
 * @param  WP_REST_Request $request Incoming REST request.
 * @return WP_REST_Response|WP_Error JSON response.
 */
function aitepc_rest_unsubscribe_callback( WP_REST_Request $request ) {
	$user_id = $request->get_param( 'user_id' );
	$token   = $request->get_param( 'token' );

	$user = get_userdata( $user_id );
	if ( ! $user ) {
		return new WP_Error(
			'aitepc_invalid_user',
			__( 'User not found.', 'ait-easy-post-customization' ),
			array( 'status' => 404 )
		);
	}

	// Build the expected token — same algorithm used when generating the link.
	$expected = wp_hash( $user->ID . $user->user_email );

	// Timing-safe comparison prevents brute-force token guessing.
	if ( ! hash_equals( $expected, $token ) ) {
		return new WP_Error(
			'aitepc_invalid_token',
			__( 'Invalid or expired unsubscribe token.', 'ait-easy-post-customization' ),
			array( 'status' => 403 )
		);
	}

	// Mark the user as unsubscribed.
	update_user_meta( $user_id, 'aitepc_email_unsubscribe', '1' );

	return new WP_REST_Response(
		array(
			'success' => true,
			'message' => __( 'You have been unsubscribed from expiry notifications.', 'ait-easy-post-customization' ),
		),
		200
	);
}