<?php
/**
 * Attribution panel on the order screen.
 *
 * @package AdPix\Analytics
 */

declare( strict_types = 1 );

namespace AdPix\Analytics\Controller\Admin;

use AdPix\Analytics\Contracts\BootableInterface;
use AdPix\Analytics\Contracts\ReadTransportInterface;
use AdPix\Analytics\Contracts\SettingsRepositoryInterface;
use AdPix\Analytics\View\Renderer;
use WC_Order;

defined( 'ABSPATH' ) || exit;

/**
 * Shows where an order actually came from, on the order itself.
 *
 * This is the one place the plugin reads from AdPix rather than writing to it. The answer lives in
 * the collector, not in the site's database: attribution is decided by touches the site never sees,
 * across devices the site cannot join. Copying a snapshot into post meta would produce a number that
 * looks authoritative and quietly goes stale.
 */
final class OrderPanelController implements BootableInterface {

	/**
	 * Meta box id.
	 */
	private const BOX = 'adpix_analytics_attribution';

	/**
	 * Order screens the panel appears on.
	 *
	 * WooCommerce can store orders as posts or in its own tables, and the two produce different
	 * screen ids.
	 */
	private const SCREENS = array( 'shop_order', 'woocommerce_page_wc-orders' );

	/**
	 * @var ReadTransportInterface
	 */
	private $transport;

	/**
	 * @var SettingsRepositoryInterface
	 */
	private $settings;

	/**
	 * @var Renderer
	 */
	private $view;

	/**
	 * @param ReadTransportInterface      $transport Read side of the S2S client.
	 * @param SettingsRepositoryInterface $settings  Configuration source.
	 * @param Renderer                    $view      Template renderer.
	 */
	public function __construct( ReadTransportInterface $transport, SettingsRepositoryInterface $settings, Renderer $view ) {
		$this->transport = $transport;
		$this->settings  = $settings;
		$this->view      = $view;
	}

	/**
	 * Register hooks.
	 *
	 * @return void
	 */
	public function boot(): void {
		add_action( 'add_meta_boxes', array( $this, 'add_box' ), 10, 2 );
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue' ) );
	}

	/**
	 * Load the stylesheet the panel is laid out with, on the order screen only.
	 *
	 * The panel shares the plugin's one admin stylesheet. Without this it was enqueued on the
	 * settings screen alone, so the attribution table arrived on the order screen unstyled.
	 *
	 * @return void
	 */
	public function enqueue(): void {
		$screen = function_exists( 'get_current_screen' ) ? get_current_screen() : null;

		if ( null === $screen || ! in_array( $screen->id, self::SCREENS, true ) ) {
			return;
		}

		wp_enqueue_style(
			'adpix-analytics-admin',
			ADPIX_ANALYTICS_URL . 'assets/css/admin.css',
			array( 'dashicons' ),
			ADPIX_ANALYTICS_VERSION
		);
	}

	/**
	 * Add the panel to whichever order screen this site uses.
	 *
	 * Registering against the screen WooCommerce reports keeps the panel working through a migration
	 * in either direction, without the plugin having to know which storage mode is active.
	 *
	 * @param string $screen_id Current screen id.
	 * @param mixed  $object    Post or order being edited.
	 * @return void
	 */
	public function add_box( $screen_id, $object = null ): void {
		if ( ! $this->settings->load()->is_connected() ) {
			return;
		}

		if ( ! in_array( (string) $screen_id, self::SCREENS, true ) ) {
			return;
		}

		add_meta_box(
			self::BOX,
			__( 'AdPix attribution', 'adpix-analytics' ),
			array( $this, 'render' ),
			$screen_id,
			'side',
			'default'
		);
	}

	/**
	 * Render the panel.
	 *
	 * @param mixed $object Post or order being edited.
	 * @return void
	 */
	public function render( $object ): void {
		if ( ! current_user_can( 'edit_shop_orders' ) && ! current_user_can( SettingsController::CAPABILITY ) ) {
			return;
		}

		$order = $this->resolve_order( $object );
		if ( null === $order ) {
			return;
		}

		$this->view->render(
			'order-panel',
			array(
				'attribution' => $this->lookup( $order ),
			)
		);
	}

	/**
	 * The order being edited, whichever object type the screen passed us.
	 *
	 * @param mixed $object Post or order.
	 * @return WC_Order|null
	 */
	private function resolve_order( $object ): ?WC_Order {
		if ( $object instanceof WC_Order ) {
			return $object;
		}

		$id = is_object( $object ) && isset( $object->ID ) ? (int) $object->ID : 0;
		if ( $id <= 0 || ! function_exists( 'wc_get_order' ) ) {
			return null;
		}

		$order = wc_get_order( $id );

		return $order instanceof WC_Order ? $order : null;
	}

	/**
	 * Ask the collector what it knows about this order.
	 *
	 * Cached for a few minutes because the panel is rendered on every order view and the answer only
	 * changes when the snapshot is rewritten — and an admin screen should not wait on a network round
	 * trip it already made a moment ago.
	 *
	 * @param WC_Order $order Order being edited.
	 * @return array<string,mixed>|null Null when the collector has no snapshot or could not be reached.
	 */
	private function lookup( WC_Order $order ): ?array {
		$reference = (string) $order->get_order_number();
		if ( '' === $reference ) {
			return null;
		}

		$cache_key = 'adpix_attr_' . md5( $reference );
		$cached    = get_transient( $cache_key );
		if ( is_array( $cached ) ) {
			return array() !== $cached ? $cached : null;
		}

		$response = $this->transport->fetch( 'attribution', array( 'order_id' => $reference ) );

		if ( ! $response->is_ok() ) {
			// A miss is cached too, briefly: an order placed before the plugin was connected has no
			// snapshot and never will, and re-asking on every page view would not change that.
			set_transient( $cache_key, array(), $response->is_retryable() ? MINUTE_IN_SECONDS : 10 * MINUTE_IN_SECONDS );
			return null;
		}

		$data = array(
			'attribution' => is_array( $response->get( 'attribution' ) ) ? $response->get( 'attribution' ) : array(),
			'snapshot'    => is_array( $response->get( 'order_snapshot' ) ) ? $response->get( 'order_snapshot' ) : array(),
		);

		set_transient( $cache_key, $data, 5 * MINUTE_IN_SECONDS );

		return $data;
	}
}