<?php
/**
 * Site statistics screen.
 *
 * @package AdPix\Analytics
 */

declare( strict_types = 1 );

namespace AdPix\Analytics\Controller\Admin;

use AdPix\Analytics\Contracts\AdminPageInterface;
use AdPix\Analytics\Contracts\BootableInterface;
use AdPix\Analytics\Contracts\SettingsRepositoryInterface;
use AdPix\Analytics\Service\Countries;
use AdPix\Analytics\Service\StatsService;
use AdPix\Analytics\View\Renderer;

defined( 'ABSPATH' ) || exit;

/**
 * Shows what AdPix has already measured about this site.
 *
 * Nothing on this screen is computed here and nothing is stored here. Every number is read back from
 * the AdPix reporting API with a token that can do nothing but read, which is the whole reason the
 * screen could be built at all without changing anything on the platform side: the reports it needs
 * were already there.
 *
 * Six reports are fetched per view. They are fetched in sequence rather than concurrently because
 * WordPress's HTTP layer has no parallel mode worth the complexity here, and because the service
 * behind this caches for ten minutes — so the cost falls on the first person to open the screen each
 * quarter-hour, and on nobody else.
 */
final class StatsController implements BootableInterface, AdminPageInterface {

	/**
	 * Menu slug.
	 */
	public const PAGE = 'adpix-analytics-stats';

	/**
	 * admin-post action that drops the cached reports.
	 */
	public const REFRESH_ACTION = 'adpix_analytics_refresh_stats';

	/**
	 * Query argument carrying the chosen window.
	 */
	public const RANGE_ARG = 'adpix_range';

	/**
	 * Capability required. Reports describe the site's visitors, so this is the same bar as the
	 * settings — not something an author or an editor is given by default.
	 */
	public const CAPABILITY = 'manage_options';

	/**
	 * @var StatsService
	 */
	private $stats;

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

	/**
	 * @var Countries
	 */
	private $countries;

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

	/**
	 * Hook suffix WordPress assigned this screen.
	 *
	 * @var string
	 */
	private $hook = '';

	/**
	 * @param StatsService                $stats     Report source.
	 * @param SettingsRepositoryInterface $settings  Configuration source.
	 * @param Countries                   $countries Country code translator.
	 * @param Renderer                    $view      Template renderer.
	 */
	public function __construct(
		StatsService $stats,
		SettingsRepositoryInterface $settings,
		Countries $countries,
		Renderer $view
	) {
		$this->stats     = $stats;
		$this->settings  = $settings;
		$this->countries = $countries;
		$this->view      = $view;
	}

	/**
	 * Register hooks.
	 *
	 * @return void
	 */
	public function boot(): void {
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue' ) );
		add_action( 'admin_post_' . self::REFRESH_ACTION, array( $this, 'refresh' ) );
	}

	/**
	 * Title for the browser tab and the page heading.
	 *
	 * @return string
	 */
	public function page_title(): string {
		return __( 'Site statistics', 'adpix-analytics' );
	}

	/**
	 * Label in the sidebar.
	 *
	 * @return string
	 */
	public function menu_title(): string {
		return __( 'Site statistics', 'adpix-analytics' );
	}

	/**
	 * Capability required to open it.
	 *
	 * @return string
	 */
	public function capability(): string {
		return self::CAPABILITY;
	}

	/**
	 * Menu slug.
	 *
	 * @return string
	 */
	public function slug(): string {
		return self::PAGE;
	}

	/**
	 * Record the hook suffix WordPress gave this screen.
	 *
	 * @param string $hook Hook suffix.
	 * @return void
	 */
	public function set_hook( string $hook ): void {
		$this->hook = $hook;
	}

	/**
	 * Throw away the cached reports and come back.
	 *
	 * @return void
	 */
	public function refresh(): void {
		if ( ! current_user_can( self::CAPABILITY ) ) {
			wp_die( esc_html__( 'You do not have permission to do that.', 'adpix-analytics' ), '', array( 'response' => 403 ) );
		}

		check_admin_referer( self::REFRESH_ACTION );

		$this->stats->flush();

		$range = isset( $_REQUEST[ self::RANGE_ARG ] )
			? StatsService::range( sanitize_key( wp_unslash( $_REQUEST[ self::RANGE_ARG ] ) ) )
			: StatsService::DEFAULT_RANGE;

		wp_safe_redirect( $this->url( $range ) );
		exit;
	}

	/**
	 * Load the assets, on this screen only.
	 *
	 * @param string $hook Current admin page hook.
	 * @return void
	 */
	public function enqueue( $hook ): void {
		if ( '' === $this->hook || $this->hook !== $hook ) {
			return;
		}

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

		wp_enqueue_script(
			'adpix-analytics-stats',
			ADPIX_ANALYTICS_URL . 'assets/js/stats.js',
			array(),
			ADPIX_ANALYTICS_VERSION,
			true
		);
	}

	/**
	 * Render the screen.
	 *
	 * @return void
	 */
	public function render(): void {
		if ( ! current_user_can( self::CAPABILITY ) ) {
			wp_die( esc_html__( 'You do not have permission to view AdPix Analytics statistics.', 'adpix-analytics' ) );
		}

		$settings = $this->settings->load();
		$range    = $this->requested_range();

		$data = array(
			'range'          => $range,
			'ranges'         => $this->range_links( $range ),
			'can_report'     => $settings->can_report(),
			// Which of the three the setup card should tick off. A site that already sends measurements
			// has the property ID, and should be told it only needs the other two.
			'checklist'      => array(
				'property_id' => '' !== $settings->str( 'property_id' ),
				'api_token'   => '' !== $settings->str( 'api_token' ),
			),
			'settings_url'   => admin_url( 'admin.php?page=' ) . SettingsController::PAGE,
			'refresh_action' => self::REFRESH_ACTION,
			'refresh_url'    => admin_url( 'admin-post.php' ),
			'range_arg'      => self::RANGE_ARG,
			'countries'      => $this->countries,
			'logo_url'       => ADPIX_ANALYTICS_URL . 'assets/img/logo.svg',
		);

		// Only ask the API for anything once the screen knows it has somewhere to ask. Six failed
		// round trips would otherwise stand between an unconfigured site and the sentence explaining
		// what it is missing.
		if ( $settings->can_report() ) {
			$data += array(
				'overview'   => $this->stats->overview( $range ),
				'timeseries' => $this->stats->timeseries( $range ),
				'geo'        => $this->stats->breakdown( 'geo', $range, array( 'sessions', 'totalUsers' ) ),
				'channels'   => $this->stats->breakdown( 'channels', $range, array( 'sessions', 'totalUsers' ) ),
				'pages'      => $this->stats->breakdown( 'top_pages', $range, array( 'pageviews', 'sessions' ) ),
				'devices'    => $this->stats->breakdown( 'devices', $range, array( 'sessions' ) ),
			);

			// "Not found" means the token is valid but this property is outside it. Ask which properties
			// it does reach, so the screen can say whether the ID or the token is the thing to change.
			if ( ! $data['overview']->ok() && false !== strpos( $data['overview']->error(), 'NOT_FOUND' ) ) {
				$data['diagnosis']   = $this->stats->accessible_properties();
				$data['property_id'] = $settings->str( 'property_id' );
			}
		}

		$this->view->render( 'stats-page', $data );
	}

	/**
	 * The window the reader asked for.
	 *
	 * @return string
	 */
	private function requested_range(): string {
		// Read-only, changes nothing, and is whitelisted against a fixed list before it is used, so a
		// nonce here would only be ceremony — and would break the plain links the tabs are made of.
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended
		$raw = isset( $_GET[ self::RANGE_ARG ] ) ? sanitize_key( wp_unslash( $_GET[ self::RANGE_ARG ] ) ) : '';

		return StatsService::range( $raw );
	}

	/**
	 * The window switcher: every offered range with its label, link and current state.
	 *
	 * @param string $current The window in view.
	 * @return array<int,array<string,mixed>>
	 */
	private function range_links( string $current ): array {
		$links = array();

		foreach ( StatsService::RANGES as $range ) {
			$links[] = array(
				'key'     => $range,
				'label'   => StatsService::range_label( $range ),
				'url'     => $this->url( $range ),
				'current' => $range === $current,
			);
		}

		return $links;
	}

	/**
	 * This screen's address, for one window.
	 *
	 * @param string $range Range key.
	 * @return string
	 */
	private function url( string $range ): string {
		return add_query_arg(
			array(
				'page'          => self::PAGE,
				self::RANGE_ARG => $range,
			),
			admin_url( 'admin.php' )
		);
	}
}