<?php
/**
 * Pixel Tracking for WooCommerce.
 *
 * @package AgentShop
 */

namespace AgentShop\Pixel;

defined( 'ABSPATH' ) || exit;

/**
 * Tracker class.
 */
class Tracker {

	/**
	 * Max quantity for cart rebuild (security).
	 */
	const MAX_CART_QUANTITY = 100;

	/**
	 * Constructor.
	 */
	public function __construct() {
		if ( is_admin() && ! wp_doing_ajax() ) {
			return;
		}

		if ( ! agentshop()->is_tracking_enabled() ) {
			return;
		}

		// Client-side tracking.
		add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_pixel' ), 1 );
		add_action( 'wp_enqueue_scripts', array( $this, 'inject_page_data' ), 10 );
		add_action( 'wp_enqueue_scripts', array( $this, 'inject_cart_rebuild_script' ), 20 );

		// Server-side tracking.
		add_action( 'woocommerce_add_to_cart', array( $this, 'track_add_to_cart' ), 25, 6 );
		add_action( 'woocommerce_remove_cart_item', array( $this, 'track_remove_from_cart' ), 25, 2 );
		add_action( 'woocommerce_thankyou', array( $this, 'track_order_completed' ), 10, 1 );
		add_action( 'woocommerce_checkout_update_order_review', array( $this, 'capture_checkout_email' ) );

		// Cart rebuild.
		add_action( 'init', array( $this, 'handle_cart_rebuild' ) );
	}

	/**
	 * Enqueue pixel script.
	 *
	 * Note: Cannot use 'defer' or 'async' strategy because this script uses
	 * wp_add_inline_script() in the 'after' position, which prevents deferred loading.
	 * See: https://make.wordpress.org/core/2023/07/14/registering-scripts-with-async-and-defer-attributes-in-wordpress-6-3/
	 */
	public function enqueue_pixel() {
		$options = agentshop()->get_options();

		wp_enqueue_script(
			'agentshop-pixel',
			AGENTSHOP_PLUGIN_URL . 'assets/js/pixel.js',
			array( 'jquery' ),
			AGENTSHOP_VERSION,
			array(
				'in_footer' => true,
			)
		);

		wp_localize_script(
			'agentshop-pixel',
			'agentshopConfig',
			array(
				'pixelToken'     => $options['pixel_token'] ?? '',
				'storeId'        => $options['store_id'] ?? '',
				'storeUrl'       => agentshop()->get_store_url(),
				'apiEndpoint'    => agentshop()->get_api_endpoint() . '/api/woocommerce/pixel/events',
				'customerId'     => agentshop()->get_customer_id(),
				'sessionId'      => agentshop()->get_session_id(),
				'version'        => AGENTSHOP_VERSION,
				'currency'       => get_woocommerce_currency(),
				'currencySymbol' => get_woocommerce_currency_symbol(),
			)
		);
	}

	/**
	 * Inject page data.
	 */
	public function inject_page_data() {
		$data = array(
			'pageType' => $this->get_page_type(),
		);

		if ( is_product() ) {
			$product = wc_get_product();
			if ( $product ) {
				$data['product'] = $this->build_product_data( $product );
			}
		}

		if ( is_cart() || is_checkout() ) {
			$data['cart'] = $this->build_cart_data();
		}

		if ( is_search() ) {
			$data['search'] = array(
				'query'         => get_search_query(),
				'results_count' => $GLOBALS['wp_query']->found_posts ?? 0,
			);
		}

		wp_localize_script( 'agentshop-pixel', 'agentshopPageData', $data );
	}

	/**
	 * Get page type.
	 *
	 * @return string
	 */
	private function get_page_type() {
		if ( is_front_page() ) {
			return 'home';
		}
		if ( is_product() ) {
			return 'product';
		}
		if ( is_product_category() || is_product_tag() ) {
			return 'collection';
		}
		if ( is_cart() ) {
			return 'cart';
		}
		if ( is_checkout() ) {
			return is_wc_endpoint_url( 'order-received' ) ? 'thank_you' : 'checkout';
		}
		if ( is_account_page() ) {
			return 'account';
		}
		if ( is_search() ) {
			return 'search';
		}
		if ( is_shop() ) {
			return 'shop';
		}
		return 'page';
	}

	/**
	 * Build product data.
	 *
	 * @param \WC_Product $product Product.
	 * @return array
	 */
	private function build_product_data( $product ) {
		$data = array(
			'product_id'    => $product->get_id(),
			'title'         => $product->get_name(),
			'sku'           => $product->get_sku(),
			'price'         => (float) $product->get_price(),
			'regular_price' => (float) $product->get_regular_price(),
			'sale_price'    => $product->get_sale_price() ? (float) $product->get_sale_price() : null,
			'url'           => get_permalink( $product->get_id() ),
			'image_url'     => $this->get_product_image_url( $product ),
			'categories'    => $this->get_product_categories( $product ),
			'in_stock'      => $product->is_in_stock(),
		);

		if ( $product->is_type( 'variation' ) ) {
			$data['variant_id'] = $product->get_id();
			$data['product_id'] = $product->get_parent_id();
			$data['attributes'] = $product->get_variation_attributes();
		}

		return $data;
	}

	/**
	 * Build cart data.
	 *
	 * @return array
	 */
	private function build_cart_data() {
		$cart = WC()->cart;

		if ( ! $cart || $cart->is_empty() ) {
			return array(
				'cart_total' => 0,
				'item_count' => 0,
				'line_items' => array(),
			);
		}

		$line_items = array();

		foreach ( $cart->get_cart() as $cart_item ) {
			$product = $cart_item['data'];

			$line_items[] = array(
				'product_id' => $cart_item['product_id'],
				'variant_id' => $cart_item['variation_id'] ?: $cart_item['product_id'],
				'title'      => $product->get_name(),
				'sku'        => $product->get_sku(),
				'quantity'   => $cart_item['quantity'],
				'price'      => (float) $product->get_price(),
				'line_total' => (float) $cart_item['line_total'],
				'url'        => get_permalink( $cart_item['product_id'] ),
				'image_url'  => $this->get_product_image_url( $product ),
			);
		}

		return array(
			'cart_total'       => (float) $cart->get_cart_contents_total(),
			'subtotal'         => (float) $cart->get_subtotal(),
			'shipping_total'   => (float) $cart->get_shipping_total(),
			'tax_total'        => (float) $cart->get_cart_contents_tax(),
			'discount_total'   => (float) $cart->get_discount_total(),
			'currency'         => get_woocommerce_currency(),
			'item_count'       => $cart->get_cart_contents_count(),
			'line_items'       => $line_items,
			'cart_rebuild_key' => $this->generate_cart_rebuild_key( $cart ),
		);
	}

	/**
	 * Generate cart rebuild key with HMAC signature.
	 *
	 * @param \WC_Cart $cart Cart.
	 * @return string
	 */
	private function generate_cart_rebuild_key( $cart ) {
		$items = array();

		foreach ( $cart->get_cart() as $cart_item ) {
			$items[] = array(
				'id'  => $cart_item['variation_id'] ?: $cart_item['product_id'],
				'qty' => min( $cart_item['quantity'], self::MAX_CART_QUANTITY ),
			);
		}

		$data      = wp_json_encode( $items );
		$encoded   = base64_encode( $data );
		$signature = $this->generate_signature( $encoded );

		return $encoded . '.' . $signature;
	}

	/**
	 * Generate HMAC signature.
	 *
	 * @param string $data Data to sign.
	 * @return string
	 */
	private function generate_signature( $data ) {
		$options = agentshop()->get_options();
		$secret  = isset( $options['webhook_secret'] ) ? $options['webhook_secret'] : wp_salt( 'auth' );

		$signature = hash_hmac( 'sha256', $data, $secret, true );
		return rtrim( strtr( base64_encode( $signature ), '+/', '-_' ), '=' );
	}

	/**
	 * Verify signature.
	 *
	 * @param string $data      Data.
	 * @param string $signature Signature.
	 * @return bool
	 */
	private function verify_signature( $data, $signature ) {
		$expected = $this->generate_signature( $data );
		return hash_equals( $expected, $signature );
	}

	/**
	 * Track add to cart.
	 *
	 * @param string $cart_item_key Cart item key.
	 * @param int    $product_id    Product ID.
	 * @param int    $quantity      Quantity.
	 * @param int    $variation_id  Variation ID.
	 * @param array  $variation     Variation data.
	 * @param array  $cart_item_data Cart item data.
	 */
	public function track_add_to_cart( $cart_item_key, $product_id, $quantity, $variation_id, $variation, $cart_item_data ) {
		$product = $variation_id ? wc_get_product( $variation_id ) : wc_get_product( $product_id );

		if ( ! $product ) {
			return;
		}

		$event_data = array(
			'event_type'   => 'added_to_cart',
			'event_source' => 'server',
			'event_data'   => array_merge(
				$this->build_product_data( $product ),
				array(
					'quantity'   => $quantity,
					'cart_total' => (float) WC()->cart->get_cart_contents_total(),
				)
			),
		);

		if ( ! empty( $variation ) ) {
			$event_data['event_data']['attributes'] = $variation;
		}

		$this->send_event_async( $event_data );
	}

	/**
	 * Track remove from cart.
	 *
	 * @param string   $cart_item_key Cart item key.
	 * @param \WC_Cart $cart          Cart.
	 */
	public function track_remove_from_cart( $cart_item_key, $cart ) {
		$cart_item = $cart->get_cart_item( $cart_item_key );

		if ( ! $cart_item ) {
			return;
		}

		$product = $cart_item['data'];

		$this->send_event_async(
			array(
				'event_type'   => 'removed_from_cart',
				'event_source' => 'server',
				'event_data'   => array(
					'product_id' => $cart_item['product_id'],
					'variant_id' => $cart_item['variation_id'] ?: $cart_item['product_id'],
					'title'      => $product->get_name(),
					'quantity'   => $cart_item['quantity'],
				),
			)
		);
	}

	/**
	 * Track order completed.
	 *
	 * @param int $order_id Order ID.
	 */
	public function track_order_completed( $order_id ) {
		$order = wc_get_order( $order_id );

		if ( ! $order ) {
			return;
		}

		// Check if already tracked.
		if ( $order->get_meta( '_agentshop_tracked' ) ) {
			return;
		}

		$line_items = array();
		foreach ( $order->get_items() as $item ) {
			$product = $item->get_product();
			if ( ! $product ) {
				continue;
			}

			$line_items[] = array(
				'product_id' => $item->get_product_id(),
				'variant_id' => $item->get_variation_id() ?: $item->get_product_id(),
				'title'      => $item->get_name(),
				'sku'        => $product->get_sku(),
				'quantity'   => $item->get_quantity(),
				'price'      => (float) ( $item->get_total() / max( 1, $item->get_quantity() ) ),
				'line_total' => (float) $item->get_total(),
			);
		}

		$event_data = array(
			'event_type'     => 'checkout_completed',
			'event_source'   => 'server',
			'customer_email' => $order->get_billing_email(),
			'event_data'     => array(
				'order_id'       => $order->get_id(),
				'order_number'   => $order->get_order_number(),
				'total_price'    => (float) $order->get_total(),
				'subtotal'       => (float) $order->get_subtotal(),
				'shipping_total' => (float) $order->get_shipping_total(),
				'tax_total'      => (float) $order->get_total_tax(),
				'discount_total' => (float) $order->get_discount_total(),
				'currency'       => $order->get_currency(),
				'payment_method' => $order->get_payment_method_title(),
				'customer_email' => $order->get_billing_email(),
				'customer_name'  => $order->get_formatted_billing_full_name(),
				'line_items'     => $line_items,
				'billing_address' => array(
					'city'    => $order->get_billing_city(),
					'state'   => $order->get_billing_state(),
					'country' => $order->get_billing_country(),
				),
			),
		);

		// Mark as tracked.
		$order->update_meta_data( '_agentshop_tracked', time() );
		$order->save();

		agentshop()->api->send_pixel_event( $event_data );
	}

	/**
	 * Capture checkout email.
	 *
	 * @param string $post_data Posted data.
	 */
	public function capture_checkout_email( $post_data ) {
		parse_str( $post_data, $parsed );

		if ( ! empty( $parsed['billing_email'] ) ) {
			$email = sanitize_email( $parsed['billing_email'] );

			if ( is_email( $email ) ) {
				WC()->session->set( 'agentshop_customer_email', $email );

				$this->send_event_async(
					array(
						'event_type'     => 'checkout_contact_submitted',
						'event_source'   => 'server',
						'customer_email' => $email,
						'event_data'     => array_merge(
							$this->build_cart_data(),
							array( 'customer_email' => $email )
						),
					)
				);
			}
		}
	}

	/**
	 * Handle cart rebuild.
	 */
	public function handle_cart_rebuild() {
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Uses signature verification below.
		if ( ! isset( $_GET['agentshop_rebuild'] ) ) {
			return;
		}

		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Signature verified at line 447.
		$key = sanitize_text_field( wp_unslash( $_GET['agentshop_rebuild'] ) );

		$parts = explode( '.', $key );
		if ( count( $parts ) !== 2 ) {
			agentshop()->log( 'Cart rebuild: invalid key format', 'warning' );
			return;
		}

		list( $encoded_data, $signature ) = $parts;

		// Verify signature.
		if ( ! $this->verify_signature( $encoded_data, $signature ) ) {
			agentshop()->log( 'Cart rebuild: invalid signature', 'error' );
			return;
		}

		$decoded = base64_decode( $encoded_data );
		if ( ! $decoded ) {
			return;
		}

		$items = json_decode( $decoded, true );
		if ( ! is_array( $items ) ) {
			return;
		}

		WC()->cart->empty_cart();

		foreach ( $items as $item ) {
			if ( isset( $item['id'] ) && isset( $item['qty'] ) ) {
				$product_id = absint( $item['id'] );
				$quantity   = min( absint( $item['qty'] ), self::MAX_CART_QUANTITY );

				$product = wc_get_product( $product_id );
				if ( $product && $product->is_purchasable() && $product->is_in_stock() ) {
					WC()->cart->add_to_cart( $product_id, $quantity );
				}
			}
		}

		wp_safe_redirect( wc_get_checkout_url() );
		exit;
	}

	/**
	 * Inject cart rebuild script using wp_add_inline_script.
	 */
	public function inject_cart_rebuild_script() {
		if ( ! is_checkout() || is_wc_endpoint_url( 'order-received' ) ) {
			return;
		}

		$cart_data        = $this->build_cart_data();
		$cart_rebuild_url = esc_url( home_url( '/?agentshop_rebuild=' . $cart_data['cart_rebuild_key'] ) );

		$inline_script = sprintf(
			'(function() { if (typeof agentshopConfig !== "undefined") { window.agentshopCartRebuildUrl = %s; } })();',
			wp_json_encode( $cart_rebuild_url )
		);

		wp_add_inline_script( 'agentshop-pixel', $inline_script, 'after' );
	}

	/**
	 * Send event asynchronously.
	 *
	 * @param array $event_data Event data.
	 */
	private function send_event_async( $event_data ) {
		$options = agentshop()->get_options();

		$payload = array_merge(
			array(
				'pixel_version' => AGENTSHOP_VERSION,
				'store_url'     => agentshop()->get_store_url(),
				'pixel_token'   => $options['pixel_token'] ?? '',
				'session_id'    => agentshop()->get_session_id(),
				'customer_id'   => agentshop()->get_customer_id(),
				'llm_source'    => $this->get_llm_source(),
				'timestamp'     => gmdate( 'c' ),
				'url'           => $this->get_current_url(),
				'referrer'      => wp_get_referer() ?: '',
			),
			$event_data
		);

		$url = agentshop()->get_api_endpoint() . '/api/woocommerce/pixel/events';

		wp_remote_post(
			$url,
			array(
				'method'   => 'POST',
				'timeout'  => 0.01,
				'blocking' => false,
				'headers'  => array(
					'Content-Type'       => 'application/json',
					'X-AgentShop-Token' => $options['pixel_token'] ?? '',
				),
				'body'     => wp_json_encode( $payload ),
			)
		);
	}

	/**
	 * Get LLM source from cookie.
	 *
	 * @return string|null
	 */
	private function get_llm_source() {
		if ( isset( $_COOKIE['agentshop_llm'] ) ) {
			return sanitize_text_field( wp_unslash( $_COOKIE['agentshop_llm'] ) );
		}

		$referrer = wp_get_referer();
		if ( $referrer ) {
			return agentshop()->detect_llm_source( $referrer );
		}

		return null;
	}

	/**
	 * Get product image URL.
	 *
	 * @param \WC_Product $product Product.
	 * @return string
	 */
	private function get_product_image_url( $product ) {
		$image_id = $product->get_image_id();

		if ( $image_id ) {
			$url = wp_get_attachment_image_url( $image_id, 'large' );
			if ( $url ) {
				return $url;
			}
		}

		if ( $product->is_type( 'variation' ) ) {
			$parent = wc_get_product( $product->get_parent_id() );
			if ( $parent ) {
				return $this->get_product_image_url( $parent );
			}
		}

		return wc_placeholder_img_src( 'large' );
	}

	/**
	 * Get product categories.
	 *
	 * @param \WC_Product $product Product.
	 * @return array
	 */
	private function get_product_categories( $product ) {
		if ( ! $product ) {
			return array();
		}

		$product_id = $product->is_type( 'variation' ) ? $product->get_parent_id() : $product->get_id();
		$terms      = get_the_terms( $product_id, 'product_cat' );

		if ( ! $terms || is_wp_error( $terms ) ) {
			return array();
		}

		return wp_list_pluck( $terms, 'name' );
	}

	/**
	 * Get current URL.
	 *
	 * @return string
	 */
	private function get_current_url() {
		global $wp;
		return home_url( add_query_arg( array(), $wp->request ) );
	}
}