<?php
/**
 * The Matomo tracker in the visitor's browser.
 *
 * @package Rahkar\WP
 */

declare( strict_types = 1 );

namespace Rahkar\WP\Modules\Matomo;

use WC_Order;

defined( 'ABSPATH' ) || exit;

/**
 * Prints Matomo's standard asynchronous tracker (`_paq`) at the foot of each
 * page, with what WooCommerce knows put before the page view (PHASE-5.md M2 in
 * the rahkar-foroosh repository).
 *
 * - The tracker file and the tracking requests both go to Matomo's `js/` path,
 *   not `matomo.js` and `matomo.php`, which EasyPrivacy blocks on every host.
 * - A signed-in customer goes as their numeric user id, never a user name: an
 *   SMS sign-up's user name is the mobile number.
 * - Dimension 1 is the page type, 2 the visitor type, 3 the furthest funnel stage
 *   this visit reached, kept for 30 minutes in a cookie of the site's own.
 * - The cart goes whole after every change. The tracker watches WooCommerce's
 *   own `woocommerce_cart_hash` cookie, which every way of changing the cart
 *   updates: the AJAX button, a form post, the cart page, the blocks, a theme's
 *   own endpoint. The cart itself comes from the copy printed with the page or
 *   carried in WooCommerce's cart fragments, and only when neither is current
 *   from one small `wc-ajax` request: none on a page view, one per change at
 *   most.
 *
 * No query of its own on a page view: the user and their meta are loaded for
 * the capability check, the product and its terms are already in the object
 * cache, and the result count comes from the main query. Only the thank-you
 * page reads an order and the sale statuses.
 */
final class Tracker {

	/**
	 * Id of the element holding the cart as JSON.
	 */
	public const CART_ID = 'rahkar-matomo-cart';

	/**
	 * The `wc-ajax` action that answers with the cart.
	 */
	public const CART_AJAX = 'rahkar_matomo_cart';

	/**
	 * Funnel stages by page type; the rest are `browse`.
	 *
	 * @var array<string, int>
	 */
	private const STAGES = [
		'product'        => 1,
		'cart'           => 2,
		'checkout'       => 3,
		'order_received' => 3,
	];

	/**
	 * Print the tracker.
	 *
	 * @internal Hooked to `wp_footer`.
	 */
	public function footer(): void {
		$site = Config::site();

		if ( null === $site || self::excluded() ) {
			return;
		}

		$type     = self::pageType();
		$commands = [];
		$view     = [ 'trackPageView' ];
		$user     = get_current_user_id();

		if ( $user > 0 ) {
			$commands[] = [ 'setUserId', (string) $user ];
		}

		$commands[] = [ 'setCustomDimension', 1, $type ];
		$commands[] = [ 'setCustomDimension', 2, self::visitorType( $user ) ];

		if ( 'product' === $type ) {
			$commands = array_merge( $commands, $this->productView() );
		} elseif ( 'category' === $type && ( is_product_category() || is_product_tag() ) ) {
			$commands[] = [ 'setEcommerceView', false, false, single_term_title( '', false ) ];
		} elseif ( 'search' === $type ) {
			[ $extra, $view ] = $this->search();
			$commands         = array_merge( $commands, $extra );
		} elseif ( 'order_received' === $type ) {
			$commands = array_merge( $commands, $this->order() );
		}

		$config = [
			'a' => \WC_AJAX::get_endpoint( self::CART_AJAX ),
			'u' => $site['url'],
			's' => $site['site'],
			'p' => $type,
			'g' => self::STAGES[ $type ] ?? 0,
			'c' => $commands,
			'v' => $view,
		];

		echo self::cartTag(); // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- Built by wp_get_inline_script_tag() from JSON with HTML characters escaped.
		wp_print_inline_script_tag( '(' . self::SCRIPT . ')(' . self::json( $config ) . ');' );
	}

	/**
	 * Add the cart JSON to WooCommerce's cart fragments.
	 *
	 * @param mixed $fragments Fragments by selector.
	 *
	 * @return array<string, string>
	 *
	 * @internal Hooked to `woocommerce_add_to_cart_fragments`.
	 */
	public static function fragments( $fragments ): array {
		$fragments = is_array( $fragments ) ? $fragments : [];

		$fragments[ 'script#' . self::CART_ID ] = self::cartTag();

		return $fragments;
	}

	/**
	 * Answer the tracker with the cart, after the cart hash cookie changed.
	 *
	 * @internal Hooked to `wc_ajax_rahkar_matomo_cart`.
	 */
	public static function ajaxCart(): void {
		nocache_headers();
		wp_send_json( self::cart() );
	}

	/**
	 * Requests Matomo should not count: staff, previews and the like.
	 */
	private static function excluded(): bool {
		if ( is_preview() || is_customize_preview() || is_feed() || is_embed() || is_robots() ) {
			return true;
		}

		return is_user_logged_in() && ( current_user_can( 'manage_woocommerce' ) || current_user_can( 'edit_posts' ) ); // phpcs:ignore WordPress.WP.Capabilities.Unknown -- WooCommerce's shop manager capability.
	}

	/**
	 * Page type (dimension 1). These values never change once released.
	 */
	private static function pageType(): string {
		if ( ! function_exists( 'is_woocommerce' ) ) {
			return is_front_page() ? 'home' : ( is_search() ? 'search' : 'other' );
		}

		return match ( true ) {
			is_order_received_page()                               => 'order_received',
			is_checkout()                                          => 'checkout',
			is_cart()                                              => 'cart',
			is_product()                                           => 'product',
			is_search()                                            => 'search',
			is_shop() || is_product_category() || is_product_tag() => 'category',
			is_account_page()                                      => 'account',
			is_front_page()                                        => 'home',
			default                                                => 'other',
		};
	}

	/**
	 * Visitor type (dimension 2): `guest`, `member` or `customer`.
	 *
	 * @param int $user Current user id, 0 for a guest.
	 */
	private static function visitorType( int $user ): string {
		if ( 0 === $user ) {
			return 'guest';
		}

		return get_user_meta( $user, 'paying_customer', true ) ? 'customer' : 'member';
	}

	/**
	 * A product page as an ecommerce view.
	 *
	 * @return list<array<int, mixed>>
	 */
	private function productView(): array {
		$product = wc_get_product( get_queried_object_id() );

		if ( ! $product instanceof \WC_Product ) {
			return [];
		}

		$id       = $product->get_parent_id() > 0 ? $product->get_parent_id() : $product->get_id();
		$terms    = get_the_terms( $id, 'product_cat' );
		$category = is_array( $terms ) && isset( $terms[0] ) ? $terms[0]->name : '';

		return [
			[
				'setEcommerceView',
				(string) $id,
				$product->get_name(),
				$category,
				Parse::money( wc_get_price_to_display( $product ), get_woocommerce_currency() ),
			],
		];
	}

	/**
	 * A search result page: Matomo's site search instead of a page view, unless
	 * the term looks like a mobile number or an email. Then a plain page view
	 * goes, with the term taken out of its address and out of its title, which
	 * themes write as "results for …".
	 *
	 * @return array{0: list<array<int, mixed>>, 1: list<mixed>}
	 */
	private function search(): array {
		$term = trim( get_search_query( false ) );

		if ( '' === $term || Parse::looksPersonal( $term ) ) {
			return [
				[
					[ 'setCustomUrl', remove_query_arg( 's' ) ],
					[ 'setDocumentTitle', __( 'نتایج جست‌وجو', 'rahkar-toolkit' ) ],
				],
				[ 'trackPageView' ],
			];
		}

		$category = 'product' === get_query_var( 'post_type' ) ? 'product' : false;
		$found    = (int) ( $GLOBALS['wp_query']->found_posts ?? 0 );

		return [ [], [ 'trackSiteSearch', $term, $category, $found ] ];
	}

	/**
	 * The thank-you page: the order, once it is a sale.
	 *
	 * Matomo keeps an order id once, so a reload or the server-side send that
	 * follows cannot count it twice.
	 *
	 * @return list<array<int, mixed>>
	 */
	private function order(): array {
		$id    = absint( get_query_var( 'order-received' ) );
		$key   = isset( $_GET['key'] ) ? sanitize_text_field( wp_unslash( $_GET['key'] ) ) : ''; // phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Compared with the order's own key, as WooCommerce does on this page.
		$order = $id > 0 ? wc_get_order( $id ) : null;

		if ( ! $order instanceof WC_Order || ! $order->key_is_valid( $key ) || ! Orders::isSale( $order ) ) {
			return [];
		}

		$data     = Orders::ecommerce( $order );
		$commands = [];

		foreach ( $data['items'] as $item ) {
			$commands[] = array_merge( [ 'addEcommerceItem' ], $item );
		}

		$commands[] = [ 'trackEcommerceOrder', $data['id'], $data['total'], $data['subtotal'], $data['tax'], $data['shipping'], $data['discount'] ];

		return $commands;
	}

	/**
	 * The cart as JSON in a script tag, by id, for the tracker to read.
	 */
	private static function cartTag(): string {
		return wp_get_inline_script_tag(
			self::json( self::cart() ),
			[
				'type' => 'application/json',
				'id'   => self::CART_ID,
			]
		);
	}

	/**
	 * The cart: WooCommerce's cart hash, the items and the total.
	 *
	 * `h` is the hash WooCommerce puts in its `woocommerce_cart_hash` cookie, empty
	 * for an empty cart, so the tracker can tell whether a copy is current. Items
	 * go under their parent product id, as on the product page, so a variation in
	 * the cart is the same product Matomo saw viewed.
	 *
	 * @return array{h: string, i: list<array{0: string, 1: string, 2: string, 3: float, 4: int}>, t: float}
	 */
	private static function cart(): array {
		$cart = function_exists( 'WC' ) ? WC()->cart : null;

		if ( null === $cart || $cart->is_empty() ) {
			return [
				'h' => '',
				'i' => [],
				't' => 0.0,
			];
		}

		$currency = get_woocommerce_currency();
		$items    = [];

		foreach ( $cart->get_cart() as $line ) {
			$product  = $line['data'] ?? null;
			$quantity = max( 1, (int) ( $line['quantity'] ?? 1 ) );

			if ( ! $product instanceof \WC_Product ) {
				continue;
			}

			$items[] = [
				(string) ( (int) ( $line['product_id'] ?? 0 ) ),
				$product->get_title(),
				'',
				Parse::money( (float) ( $line['line_subtotal'] ?? 0 ) / $quantity, $currency ),
				$quantity,
			];
		}

		return [
			'h' => $cart->get_cart_hash(),
			'i' => $items,
			't' => Parse::money( $cart->get_total( 'edit' ), $currency ),
		];
	}

	/**
	 * JSON safe to print inside a script tag.
	 *
	 * @param array<string, mixed> $value Value.
	 */
	private static function json( array $value ): string {
		return (string) wp_json_encode( $value, JSON_HEX_TAG | JSON_HEX_AMP | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );
	}

	/**
	 * The tracker, called with the config above.
	 *
	 * `g` is the stage this page reaches. The stage only goes up within a visit,
	 * and adding to the cart lifts it to `cart` whatever the page. An add is
	 * found by comparing the cart with the last one sent; each product whose
	 * quantity went up gets one `rahkar` / `add_to_cart` event named by its
	 * parent id. The cart is looked at when the page loads, when WooCommerce's
	 * cart hash cookie changes (checked every two seconds and on focus), and when
	 * cart fragments arrive. The thank-you page sends no cart: the order ends it.
	 */
	private const SCRIPT = <<<'JS'
function(c){
var S=['browse','product','cart','checkout'],L='rk_mtm_cart',busy=false;
function stage(){var m=document.cookie.match(/(?:^|; )rk_mtm_stage=(\d)/);return m?+m[1]:0}
function hash(){var m=document.cookie.match(/(?:^|; )woocommerce_cart_hash=([^;]*)/);return m?decodeURIComponent(m[1]):''}
// Matomo swaps window._paq for its own object once loaded: always push to the current one.
function P(a){(window._paq=window._paq||[]).push(a)}
var st=Math.max(stage(),c.g),seen=hash();
function keepStage(){document.cookie='rk_mtm_stage='+st+';path=/;max-age=1800;SameSite=Lax'+('https:'===location.protocol?';Secure':'')}
keepStage();
P(['setTrackerUrl',c.u+'js/']);P(['setSiteId',String(c.s)]);
for(var i=0;i<c.c.length;i++){P(c.c[i])}
P(['setCustomDimension',3,S[st]]);
P(c.v);P(['enableLinkTracking']);
function send(d){
var p=null,q={},j,k,up=false;
try{p=JSON.parse(window.localStorage.getItem(L)||'null')}catch(x){}
for(j=0;j<d.i.length;j++){q[d.i[j][0]]=(q[d.i[j][0]]||0)+d.i[j][4]}
function keep(){try{window.localStorage.setItem(L,JSON.stringify({h:d.h,q:q}))}catch(x){}}
if(p&&p.h===d.h){return}
if('order_received'===c.p||(!p&&!d.i.length)){keep();return}
if(p&&p.q){for(k in q){if(q.hasOwnProperty(k)&&q[k]>(p.q[k]||0)){
if(!up){up=true;if(st<2){st=2;keepStage();P(['setCustomDimension',3,S[st]])}}
P(['trackEvent','rahkar','add_to_cart',k])}}}
P(['clearEcommerceCart']);
for(j=0;j<d.i.length;j++){P(['addEcommerceItem',d.i[j][0],d.i[j][1],d.i[j][2],d.i[j][3],d.i[j][4]])}
P(['trackEcommerceCartUpdate',d.t]);keep()}
function cart(){
var e=document.getElementById('rahkar-matomo-cart'),d=null;
seen=hash();
try{d=e?JSON.parse(e.textContent):null}catch(x){}
if(d&&d.h===seen){send(d);return}
if(busy||!window.fetch){return}
busy=true;
window.fetch(c.a,{credentials:'same-origin'}).then(function(r){return r.json()}).then(function(f){busy=false;if(f&&f.i){send(f)}},function(){busy=false})}
cart();
setInterval(function(){if(hash()!==seen){cart()}},2000);
window.addEventListener('focus',function(){if(hash()!==seen){cart()}});
if(window.jQuery){window.jQuery(document.body).on('wc_fragments_refreshed wc_fragments_loaded added_to_cart removed_from_cart updated_cart_totals',function(){setTimeout(cart,0)})}
var s=document.createElement('script'),f=document.getElementsByTagName('script')[0];s.async=true;s.src=c.u+'js/';f.parentNode.insertBefore(s,f)}
JS;
}