<?php
/**
 * The app shell around every TurtleReport screen: sidebar, navigation, theme.
 *
 * @package TurtleReport
 */

namespace TurtleReport\Admin;

use TurtleReport\Access\AccessPolicy;
use TurtleReport\Access\Capabilities;
use TurtleReport\Monitoring\HealthMonitor;
use TurtleReport\Settings\Settings;
use TurtleReport\Support\Text;
use TurtleReport\Support\View;
use TurtleReport\TurtleFramework\AdminAssets;

defined( 'ABSPATH' ) || exit;

/**
 * Renders the TurtleReport app frame on its own screens and leaves every other
 * admin screen untouched.
 *
 * Two layouts:
 * - "sidebar" for managers and for anyone who can see more than one report:
 *   brand, a list of reports (the site switcher), manage links, and a footer
 *   with the guide, theme and collapse controls. The WordPress menu retains
 *   Core's user preference and responsive behavior; its state is independent
 *   of the TurtleReport sidebar.
 * - "header" for a viewer with a single report: a slim bar with the brand and
 *   theme switch, because a sidebar with one link is empty chrome.
 *
 * Theme and sidebar state are per-user preferences, applied as body classes
 * on the server so nothing flickers on load.
 */
final class Shell {

	const THEME_META   = 'turtlereport_theme';
	const SIDEBAR_META = 'turtlereport_sidebar';
	const THEMES       = array( 'light', 'dark', 'system' );
	const SIDEBARS     = array( 'expanded', 'collapsed' );

	/** Show a filter box above the report list from this many sites. */
	const FILTER_FROM = 8;

	/**
	 * Screens, in menu order.
	 *
	 * @var AdminPage[]
	 */
	private $pages;

	/**
	 * Install settings (white-label brand).
	 *
	 * @var Settings
	 */
	private $settings;

	/**
	 * Access rules (which reports the user can open).
	 *
	 * @var AccessPolicy
	 */
	private $access;

	/**
	 * Connection health, for the warning dot. Optional.
	 *
	 * @var HealthMonitor|null
	 */
	private $health;

	/**
	 * Constructor.
	 *
	 * @param Settings           $settings Install settings.
	 * @param AccessPolicy       $access   Access rules.
	 * @param HealthMonitor|null $health   Connection health.
	 * @param AdminPage          ...$pages Screens, in menu order.
	 */
	public function __construct( Settings $settings, AccessPolicy $access, ?HealthMonitor $health, AdminPage ...$pages ) {
		$this->settings = $settings;
		$this->access   = $access;
		$this->health   = $health;
		$this->pages    = $pages;
	}

	/**
	 * Hooks into WordPress.
	 *
	 * @return void
	 */
	public function register() {
		add_filter( 'admin_body_class', array( $this, 'body_class' ) );
		add_action( 'in_admin_header', array( $this, 'render' ) );
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue' ), 5 );
	}

	/**
	 * A user's theme: light (default), dark or system.
	 *
	 * @param int $user_id User ID.
	 * @return string
	 */
	public static function theme( $user_id ) {
		$theme = (string) get_user_meta( (int) $user_id, self::THEME_META, true );
		return in_array( $theme, self::THEMES, true ) ? $theme : 'light';
	}

	/**
	 * Whether a user collapsed the sidebar to its icon rail.
	 *
	 * @param int $user_id User ID.
	 * @return bool
	 */
	public static function collapsed( $user_id ) {
		return 'collapsed' === (string) get_user_meta( (int) $user_id, self::SIDEBAR_META, true );
	}

	/**
	 * The screen object being viewed, or null outside TurtleReport.
	 *
	 * @return AdminPage|null
	 */
	public function screen() {
		// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Read-only screen detection.
		$page = isset( $_GET['page'] ) ? sanitize_key( wp_unslash( $_GET['page'] ) ) : '';
		foreach ( $this->pages as $screen ) {
			if ( $screen::SLUG === $page ) {
				return $screen;
			}
		}
		return null;
	}

	/**
	 * Slug of the TurtleReport screen being viewed, or '' elsewhere.
	 *
	 * @return string
	 */
	public function current() {
		$screen = $this->screen();
		return $screen ? $screen::SLUG : '';
	}

	/**
	 * Which layout the current user gets.
	 *
	 * @return string "sidebar" or "header".
	 */
	public function layout() {
		if ( current_user_can( Capabilities::MANAGE ) ) {
			return 'sidebar';
		}
		return count( $this->access->visible_sites( get_current_user_id() ) ) > 1 ? 'sidebar' : 'header';
	}

	/**
	 * Body classes on TurtleReport screens: token scope, theme, layout and
	 * TurtleReport sidebar state. Preserve Core's menu state by default.
	 *
	 * @param string $classes Space-separated classes.
	 * @return string
	 */
	public function body_class( $classes ) {
		if ( '' === $this->current() ) {
			return $classes;
		}
		$user_id = get_current_user_id();
		$layout  = $this->layout();
		$add     = array( 'tly-shell', 'tly-theme-' . self::theme( $user_id ), 'tly-layout-' . $layout );
		if ( 'sidebar' === $layout ) {
			if ( self::collapsed( $user_id ) ) {
				$add[] = 'tly-side-collapsed';
			}
			/**
			 * Opt into folding the WordPress admin menu on TurtleReport screens.
			 * Core's user preference and responsive state are preserved by default.
			 *
			 * @param bool $fold Default false.
			 */
			if ( apply_filters( 'turtlereport_fold_admin_menu', false ) ) {
				$add[] = 'folded';
			}
		}
		return $classes . ' ' . implode( ' ', $add ) . ' ';
	}

	/**
	 * Shared styles and the shell script.
	 *
	 * @return void
	 */
	public function enqueue() {
		if ( '' === $this->current() ) {
			return;
		}
		wp_enqueue_style( 'turtlereport-tokens', TURTLEREPORT_URL . 'assets/css/tokens.css', array(), AdminPage::asset_version( 'assets/css/tokens.css' ) );
		wp_enqueue_style( 'turtlereport-shell', TURTLEREPORT_URL . 'assets/css/shell.css', array( 'turtlereport-tokens' ), AdminPage::asset_version( 'assets/css/shell.css' ) );
		AdminAssets::enqueue( 'shell', 'turtlereport-shell' );
	}

	/**
	 * Outputs the sidebar (or slim header) before the screen's content.
	 *
	 * @return void
	 */
	public function render() {
		$screen = $this->screen();
		if ( ! $screen ) {
			return;
		}
		View::render( 'shell', $this->view_data( $screen ) );
	}

	/**
	 * Everything the shell template needs.
	 *
	 * @param AdminPage $screen Current screen.
	 * @return array
	 */
	public function view_data( AdminPage $screen ) {
		$user_id = get_current_user_id();
		$sites   = $this->reports( $screen );
		$title   = $screen->nav_title();
		foreach ( $sites as $item ) {
			if ( $item['active'] ) {
				$title = $item['name'];
			}
		}
		return array(
			'layout'     => $this->layout(),
			// White-label: the agency's name when set, otherwise TurtleReport.
			'brand_name' => '' !== (string) $this->settings->get( 'brand_name' ) ? (string) $this->settings->get( 'brand_name' ) : __( 'TurtleReport', 'turtlereport' ),
			'brand_logo' => $this->settings->logo_url(),
			'home'       => ReportsPage::url(),
			'sites'      => $sites,
			'filter'     => count( $sites ) >= self::FILTER_FROM,
			'manage'     => $this->manage( $screen ),
			'guide'      => $this->guide( $screen ),
			'add_site'   => current_user_can( Capabilities::MANAGE ) ? SitesPage::url( array( 'action' => 'new' ) ) : '',
			'theme'      => self::theme( $user_id ),
			'collapsed'  => self::collapsed( $user_id ),
			'title'      => $title,
		);
	}

	/**
	 * Reports the user can open, for the switcher.
	 *
	 * @param AdminPage $screen Current screen.
	 * @return array[] Items with id, name, label, initial, url and active.
	 */
	public function reports( AdminPage $screen ) {
		$sites = $this->access->visible_sites( get_current_user_id() );
		if ( ! $sites ) {
			return array();
		}
		$active = '';
		if ( ReportsPage::SLUG === $screen::SLUG ) {
			// Same rule as the report screen: the requested site if visible, else the first (A–Z).
			// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- Read-only choice of a visible site.
			$requested = isset( $_GET['site'] ) ? sanitize_key( wp_unslash( $_GET['site'] ) ) : '';
			$active    = isset( $sites[ $requested ] ) ? $requested : (string) key( $sites );
		}
		$out = array();
		foreach ( $sites as $site ) {
			$name  = $site->display_name();
			$out[] = array(
				'id'      => $site->id,
				'name'    => $name,
				'label'   => $site->site_label(),
				'initial' => Text::upper( Text::substr( $name, 0, 1 ) ),
				'url'     => ReportsPage::url( array( 'site' => $site->id ) ),
				'active'  => $site->id === $active,
			);
		}
		return $out;
	}

	/**
	 * Manage links for administrators.
	 *
	 * @param AdminPage $screen Current screen.
	 * @return array[] Items with key, label, url, active, badge and alert.
	 */
	public function manage( AdminPage $screen ) {
		$items = array();
		foreach ( $this->pages as $page ) {
			if ( $page instanceof ReportsPage || $page instanceof GuidePage || ! current_user_can( $page->capability() ) ) {
				continue;
			}
			$item = array(
				'key'    => str_replace( 'turtlereport-', '', $page::SLUG ),
				'label'  => $page->nav_title(),
				'url'    => $page::url(),
				'active' => $page::SLUG === $screen::SLUG,
				'badge'  => '',
				'alert'  => '',
			);
			if ( $page instanceof DeliveriesPage ) {
				$waiting = $page->attention();
				if ( $waiting ) {
					/* translators: %d: number of scheduled report emails that need attention. */
					$item['alert'] = sprintf( _n( '%d report email needs attention', '%d report emails need attention', $waiting, 'turtlereport' ), $waiting );
				}
			}
			if ( $page instanceof ConnectionsPage && $this->health ) {
				$failing = count( $this->health->failing() );
				if ( $failing ) {
					/* translators: %d: number of connections that stopped working. */
					$item['alert'] = sprintf( _n( '%d connection needs attention', '%d connections need attention', $failing, 'turtlereport' ), $failing );
				}
			}
			$items[] = $item;
		}
		return $items;
	}

	/**
	 * The setup guide link, if the user may open it.
	 *
	 * @param AdminPage $screen Current screen.
	 * @return array|null Item with label, url and active.
	 */
	private function guide( AdminPage $screen ) {
		foreach ( $this->pages as $page ) {
			if ( $page instanceof GuidePage && current_user_can( $page->capability() ) ) {
				return array(
					'label'  => $page->nav_title(),
					'url'    => $page::url(),
					'active' => $page::SLUG === $screen::SLUG,
				);
			}
		}
		return null;
	}
}