<?php

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

if ( ! class_exists( 'AIEO_Offer_Link', false ) ) {

	class AIEO_Offer_Link {

		const ARG        = 'aieo_offer';
		const VERSION    = 1;
		const MAX_AGE    = 60; 

		
		private static $registered = false;

		
		public static function register() {
			if ( self::$registered ) {
				return;
			}
			self::$registered = true;
			add_action( 'template_redirect', array( __CLASS__, 'handle' ) );
		}

		
		
		

		
		public static function url( $code, $email = '', $grant_id = 0, $exp_ts = 0 ) {
			$payload = array( 'c' => strtolower( (string) $code ) );
			if ( '' !== (string) $email ) {
				$payload['e'] = (string) $email;
			}
			if ( (int) $grant_id > 0 ) {
				$payload['g'] = (int) $grant_id;
			}
			
			
			
			$ceiling        = time() + self::MAX_AGE * DAY_IN_SECONDS;
			$exp            = ( (int) $exp_ts > 0 ) ? (int) $exp_ts : ( time() + 30 * DAY_IN_SECONDS );
			$payload['exp'] = min( $exp, $ceiling );
			$token          = self::sign( $payload );
			$cart  = function_exists( 'wc_get_cart_url' ) ? wc_get_cart_url() : home_url( '/cart/' );
			return add_query_arg( self::ARG, $token, $cart );
		}

		public static function sign( array $payload ) {
			$payload['v'] = self::VERSION;
			$payload['iat'] = time();
			$b64 = self::b64e( wp_json_encode( $payload ) );
			$sig = self::b64e( hash_hmac( 'sha256', $b64, self::secret(), true ) );
			return $b64 . '.' . $sig;
		}

		
		public static function verify( $token ) {
			$token = (string) $token;
			$parts = explode( '.', $token, 2 );
			if ( count( $parts ) !== 2 ) {
				return new WP_Error( 'offer_format', 'malformed token' );
			}
			list( $b64, $sig ) = $parts;
			$expected = self::b64e( hash_hmac( 'sha256', $b64, self::secret(), true ) );
			if ( ! hash_equals( $expected, (string) $sig ) ) {
				return new WP_Error( 'offer_sig', 'bad signature' );
			}
			$p = json_decode( self::b64d( $b64 ), true );
			if ( ! is_array( $p ) || (int) ( $p['v'] ?? 0 ) !== self::VERSION ) {
				return new WP_Error( 'offer_payload', 'bad payload' );
			}
			if ( empty( $p['exp'] ) || time() > (int) $p['exp'] ) {
				return new WP_Error( 'offer_expired', 'expired' );
			}
			
			if ( ! empty( $p['iat'] ) && ( time() - (int) $p['iat'] ) > self::MAX_AGE * DAY_IN_SECONDS ) {
				return new WP_Error( 'offer_stale', 'stale token' );
			}
			return $p;
		}

		
		
		

		public static function handle() {
			if ( is_admin() || ! function_exists( 'WC' ) || empty( $_GET[ self::ARG ] ) ) {
				return;
			}
			$p = self::verify( (string) wp_unslash( $_GET[ self::ARG ] ) ); 
			if ( is_wp_error( $p ) ) {
				
				
				if ( function_exists( 'wc_add_notice' ) && WC()->session ) {
					wc_add_notice( __( 'This offer link is no longer valid.', 'ai-eshop-optimizer' ), 'notice' );
				}
				return;
			}
			$code = strtolower( sanitize_text_field( (string) ( $p['c'] ?? '' ) ) );
			if ( '' === $code ) {
				return;
			}
			
			
			
			
			if ( ! is_user_logged_in() && WC()->session && method_exists( WC()->session, 'set_customer_session_cookie' ) ) {
				WC()->session->set_customer_session_cookie( true );
			}
			$cart = WC()->cart;
			if ( $cart && ! $cart->has_discount( $code ) ) {
				$cart->apply_coupon( $code ); 
			}
			
			
			
			if ( ! empty( $p['e'] ) && is_email( $p['e'] ) && ! is_user_logged_in() && WC()->customer
				&& '' === (string) WC()->customer->get_billing_email() ) {
				WC()->customer->set_billing_email( sanitize_email( (string) $p['e'] ) );
				WC()->customer->save();
			}
			
			
			$gid = (int) ( $p['g'] ?? 0 );
			if ( $gid > 0 && class_exists( 'AIEO_Coupon_Minter' ) ) {
				AIEO_Coupon_Minter::mark_clicked( $gid );
			}
			
			
			
			
			
			$cart_url = function_exists( 'wc_get_cart_url' ) ? wc_get_cart_url() : home_url( '/cart/' );
			$forward  = array();
			foreach ( array( 'utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content', 'aieo_src', 'gclid', 'fbclid', 'msclkid', 'ttclid' ) as $k ) {
				if ( isset( $_GET[ $k ] ) && '' !== $_GET[ $k ] ) { 
					$forward[ $k ] = sanitize_text_field( wp_unslash( $_GET[ $k ] ) );
				}
			}
			if ( ! empty( $forward ) ) {
				$cart_url = add_query_arg( $forward, $cart_url );
			}
			wp_safe_redirect( $cart_url );
			exit;
		}

		
		
		

		
		private static function secret() {
			return hash_hmac( 'sha256', 'aieo_offer_link_v1', wp_salt( 'auth' ) );
		}

		private static function b64e( $s ) {
			return rtrim( strtr( base64_encode( (string) $s ), '+/', '-_' ), '=' );
		}

		private static function b64d( $s ) {
			$s   = strtr( (string) $s, '-_', '+/' );
			$pad = strlen( $s ) % 4;
			if ( $pad ) {
				$s .= str_repeat( '=', 4 - $pad );
			}
			$out = base64_decode( $s, true );
			return false === $out ? '' : $out;
		}
	}
}