<?php
/**
 * OpenStation — Progressive Web App support.
 *
 * Lets users install the WordPress site as a desktop / mobile app from
 * the openstation shell. Three concerns live here:
 *
 *   1. Web app manifest at `/openstation/manifest.webmanifest` —
 *      served via `parse_request` like the portal URL, no rewrite-rule
 *      registration. Site name, theme color, and icons assembled from
 *      the WordPress Site Icon (when set) with a wp-logo fallback. The
 *      `openstation_pwa_manifest` filter lets plugins mutate any
 *      field before encoding.
 *
 *   2. Service worker at `/openstation/sw.js`, served with the
 *      explicit `Service-Worker-Allowed: /` header so a single SW can
 *      scope across `/openstation/` AND `/wp-admin/` (their common
 *      ancestor is `/`). The plugin lives at
 *      `/wp-content/plugins/desktop-mode/`, which is NOT a parent of
 *      `/wp-admin/`, so wp-content-served SWs cannot reach admin pages.
 *      PHP delivery sidesteps that constraint cleanly.
 *
 *   3. Two REST routes scoped to the current user:
 *        - `GET/POST /desktop-mode/v1/pwa-state` — dismissal pref for
 *          the install hint, plus notification permission record.
 *        - (future) `POST /desktop-mode/v1/push-subscription` — Web
 *          Push subscription storage. Stub left here in a comment as
 *          a hint for the v2 push PR.
 *
 * @package OpenStation
 */

defined( 'ABSPATH' ) || exit;

/**
 * URL fragment for the manifest endpoint, joined onto the portal path.
 *
 * Kept as a constant so the JS-side script localisation and the
 * `parse_request` matcher cannot drift apart.
 */
const OPENSTATION_PWA_MANIFEST_FRAGMENT = 'manifest.webmanifest';

/**
 * URL fragment for the service worker.
 */
const OPENSTATION_PWA_SW_FRAGMENT = 'sw.js';

/**
 * Query var for the extensionless service-worker fallback endpoint.
 *
 * Some hosts' nginx (WordPress.com among them) short-circuits paths
 * with a static-file extension straight to the filesystem: a virtual
 * route like `/openstation/sw.js` 404s at the web server and never
 * reaches WordPress, so the pretty SW endpoint is unservable there —
 * while the extensionless manifest route works fine. The fallback
 * serves the same bytes at `/?openstation_sw=1`: no extension, so the
 * request always reaches WordPress, and the script URL's *path* is
 * `/`, which grants root scope without the `Service-Worker-Allowed`
 * header even mattering. `src/pwa/sw-register.ts` retries with this
 * URL when registering the pretty URL fails.
 */
const OPENSTATION_PWA_SW_QUERY = 'openstation_sw';

/**
 * User-meta key — JSON blob persisting per-user PWA UI state.
 *
 * Today: `installHintDismissed` (bool), `notificationsEnabled` (bool).
 * Future: `pushSubscription` (object) when phase 4 lands.
 *
 * The VALUE keeps its pre-rebrand spelling on purpose: it is a
 * persisted or externally-visible identifier, so renaming it would
 * orphan data already written by live installs (or break a live
 * URL). The mismatch between this constant's name and its value is
 * deliberate — it is NOT a half-finished rename.
 */
const OPENSTATION_PWA_USER_META = 'desktop_mode_pwa_state';

/**
 * Builds the absolute manifest URL.
 *
 * @return string
 */
function openstation_pwa_manifest_url() {
	return openstation_portal_url() . OPENSTATION_PWA_MANIFEST_FRAGMENT;
}

/**
 * Builds the absolute service-worker URL.
 *
 * @return string
 */
function openstation_pwa_sw_url() {
	return openstation_portal_url() . OPENSTATION_PWA_SW_FRAGMENT;
}

/**
 * Builds the extensionless service-worker fallback URL.
 *
 * See {@see OPENSTATION_PWA_SW_QUERY} for why this exists. Kept as a
 * home-path URL on purpose: the SW script URL's path determines the
 * default maximum scope, and the home path is exactly the scope we
 * register ({@see openstation_pwa_sw_scope()}).
 *
 * @return string
 */
function openstation_pwa_sw_fallback_url() {
	return add_query_arg( OPENSTATION_PWA_SW_QUERY, '1', home_url( '/' ) );
}

/**
 * The service worker's registration scope: the SITE's home path.
 *
 * `/` everywhere except a subdirectory network's subsites, where it is
 * the site path (`/site2/`). One scope per site is what makes the PWA
 * work across a subdirectory network at all — every site registers its
 * own worker, the browser routes each page to the longest matching
 * scope, and the worker derives its portal and admin prefixes from the
 * scope it was given (see `scopePath` in `src/pwa/sw.ts`) instead of
 * assuming it owns the origin root.
 *
 * @return string Path with a trailing slash.
 */
function openstation_pwa_sw_scope() {
	$path = wp_parse_url( home_url( '/' ), PHP_URL_PATH );
	return is_string( $path ) && '' !== $path ? $path : '/';
}

/**
 * Resolves whether openstation should usurp another root-scope SW.
 *
 * When `false` (default), `src/pwa/sw-register.ts` bails on registration
 * if another root-scope service worker is already on the origin — polite
 * behaviour for sites that intentionally use a different PWA plugin. When
 * `true`, our registration replaces the existing SW.
 *
 * Operators flip this to recover installability on sites where a foreign
 * SW (Super PWA, Jetpack Boost, etc.) is shadowing the openstation SW
 * and causing the "Install <site> as an app" tile to surface the
 * "another app is handling installs" toast.
 *
 * @return bool
 */
function openstation_pwa_force_replace_sw() {
	/**
	 * Filters whether openstation replaces an existing root-scope SW.
	 *
	 * Return `true` to take over from a foreign PWA plugin's service
	 * worker so openstation's "Install as app" affordance works on
	 * sites where another plugin's SW is already active.
	 *
	 * @param bool $force_replace Defaults to `false` (yield to existing SWs).
	 */
	return (bool) apply_filters( 'openstation_pwa_force_replace_sw', false );
}

/**
 * Resolves whether the service worker's shared admin-asset cache is on.
 *
 * When enabled, the root-scope SW serves versioned admin static assets
 * (Core CSS/JS, the `load-scripts.php` / `load-styles.php` concat
 * blobs, plugin/theme assets carrying a `ver` query) from one
 * origin-wide Cache Storage bucket — so an asset fetched by any window
 * (shell or chromeless iframe) is answered locally for every later
 * window, revalidation round-trips included. See `src/pwa/sw-policy.ts`
 * for the exact classification rules.
 *
 * Enabled by default. Administrators can opt out site-wide through
 * OpenStation Preferences → Features → Extended options → Shared asset
 * cache. The filter below can force or veto the site-wide setting.
 *
 * The shell posts the resolved flag to the running worker at boot.
 * Changes apply after reloading OpenStation; the served worker bytes
 * remain identical for logged-in and anonymous requests.
 *
 * @return bool
 */
function openstation_pwa_admin_asset_cache_enabled() {
	$settings = openstation_get_os_settings( get_current_user_id() );
	$enabled  = ! empty( $settings['adminAssetCacheEnabled'] );

	/**
	 * Filters whether the SW's shared admin-asset cache is enabled.
	 *
	 * Return `true` to let the service worker cache versioned admin
	 * static assets in a shared, origin-wide bucket, or `false` to
	 * veto it regardless of the Extended option. The value
	 * reaches the worker as an `os-sw-config` message on the next shell
	 * boot, so a change takes effect without altering the served script
	 * — no SW update, no URL change, no re-registration.
	 *
	 * @param bool $enabled The site-wide `admin_asset_cache` Extended
	 *                      option, enabled by default.
	 */
	return (bool) apply_filters( 'openstation_pwa_admin_asset_cache', $enabled );
}

/**
 * Builds the `self.__OS_SW_CONFIG` preamble line injected ahead of the
 * service-worker bundle bytes by {@see openstation_pwa_serve_service_worker()}.
 *
 * The preamble is how per-site PHP state reaches the SW: the script is
 * a static build artifact, but the *served response* is assembled per
 * request, and the browser's byte-equality update check treats any
 * change in these values as a new SW version (`updateViaCache: 'none'`
 * at registration makes that check unconditional). The SW URL never
 * changes, so the foreign-SW `scriptURL` comparison in
 * `src/pwa/sw-register.ts` is unaffected.
 *
 * `pluginUrl` also lets the SW resolve its own asset paths on hosts
 * with a non-default `wp-content` layout (Bedrock, moved
 * `WP_CONTENT_DIR`) instead of hardcoding the conventional path.
 *
 * @return string One line of JavaScript, newline-terminated.
 */
function openstation_pwa_sw_config_preamble() {
	/*
	 * Site-level values ONLY. Nothing here may depend on who is asking.
	 *
	 * `adminAssetCache` and `windowPrewarm` are per-user preferences,
	 * and a service worker is origin-wide. Putting them in the served
	 * bytes made the body differ between an anonymous and a logged-in
	 * request, so any in-scope logged-out navigation — the interim-login
	 * iframe, logging out — served a different script. The browser
	 * treats different bytes as an update, installs it, activates it,
	 * and the shell's `controllerchange` handler hard-reloads the
	 * desktop out from under the user.
	 *
	 * The shell pushes both flags to the running worker at boot instead
	 * (`os-sw-config`), and the toggle pushes changes as they happen.
	 * The worker starts with both off, so until that message lands it
	 * simply does less — never more.
	 *
	 * `version` is the plugin's, and it is here so that a release is a
	 * byte change in the served script. The bundle itself is stamped
	 * with a content hash (see the serving function), so a release that
	 * touched nothing under `src/pwa/` would otherwise serve the very
	 * same bytes, and the browser — which only ever installs a worker
	 * whose bytes differ — would have nothing to install. An installed
	 * app on a phone rarely navigates; the shell re-checks the script on
	 * every return to the foreground (`src/pwa/sw-register.ts`), and the
	 * version in the preamble is what makes that check find a release.
	 *
	 * `shellBuild` is the content hash of the shell's own built files
	 * ({@see openstation_shell_build_stamp()}). It makes a deploy that
	 * changed the shell a new worker too, and — more importantly — it
	 * tells the shell, when that worker takes over mid-session, whether
	 * the shell it is running is the one the server now serves. A new
	 * worker is never a reason to reload on its own: a release that
	 * changed nothing under `assets/` produces a worker whose
	 * `shellBuild` equals the running shell's, and the shell stays put.
	 */
	$config = array(
		'pluginUrl'  => OPENSTATION_URL,
		'version'    => OPENSTATION_VERSION,
		'shellBuild' => openstation_shell_build_stamp(),
	);
	return sprintf( "self.__OS_SW_CONFIG = %s;\n", wp_json_encode( $config ) );
}

/**
 * Content hash of the shell's built front-end: every stylesheet under
 * `assets/css/` and every bundle under `assets/js/`.
 *
 * "Did the shell change?" answered from bytes, not clocks. A deploy
 * rewrites every file's mtime whether or not its contents moved, and
 * the plugin version moves on releases that never touched the shell;
 * neither is a reason to disturb a desktop someone is working in. The
 * stamp changes exactly when a shell file's bytes do.
 *
 * Two readers: `openStationConfig.pwa.shellBuild`, which the shell
 * boots with, and the served service worker's preamble, so the worker
 * knows which shell it was served alongside. When a worker takes over
 * a running shell the two are compared, and only a difference — a real
 * change in the shell files — earns the user an offer to reload. See
 * `src/pwa/sw-register.ts`.
 *
 * Hashing a few megabytes of bundles on every shell request would be
 * wasteful, so the stamp is memoised in one transient behind the cheap
 * signature of the same files (path, size, mtime). A deploy changes
 * the signature and the hash is recomputed once; identical bytes come
 * out as the identical stamp, and a touched-but-unchanged file costs a
 * single rehash.
 *
 * @param string|null $dir Plugin directory to read. `OPENSTATION_DIR` by
 *                         default; tests hand in a fixture.
 * @return string Sixteen hex characters, or '' when nothing is built.
 */
function openstation_shell_build_stamp( $dir = null ) {
	static $memo = array();

	$dir = null === $dir ? OPENSTATION_DIR : trailingslashit( $dir );

	$files = array();
	foreach ( array( 'assets/css/*.css', 'assets/js/*.js' ) as $pattern ) {
		$matches = glob( $dir . $pattern );
		if ( is_array( $matches ) ) {
			$files = array_merge( $files, $matches );
		}
	}
	sort( $files );
	if ( empty( $files ) ) {
		return '';
	}

	$signature = array( $dir );
	foreach ( $files as $file ) {
		$signature[] = substr( $file, strlen( $dir ) ) . ':' . filesize( $file ) . ':' . filemtime( $file );
	}
	$signature = md5( implode( "\n", $signature ) );

	if ( isset( $memo[ $signature ] ) ) {
		return $memo[ $signature ];
	}

	$cached = get_transient( 'openstation_shell_build' );
	if ( is_array( $cached ) && isset( $cached['signature'], $cached['stamp'] ) && $cached['signature'] === $signature && is_string( $cached['stamp'] ) ) {
		$memo[ $signature ] = $cached['stamp'];
		return $cached['stamp'];
	}

	$hashes = array();
	foreach ( $files as $file ) {
		$hashes[] = substr( $file, strlen( $dir ) ) . ':' . md5_file( $file );
	}
	$stamp = substr( md5( implode( "\n", $hashes ) ), 0, 16 );

	$memo[ $signature ] = $stamp;
	set_transient(
		'openstation_shell_build',
		array(
			'signature' => $signature,
			'stamp'     => $stamp,
		),
		DAY_IN_SECONDS
	);
	return $stamp;
}

/**
 * Detects which PWA endpoint the current request is targeting, if any.
 *
 * Mirrors `openstation_is_portal_request()`'s strategy: read the
 * unparsed REQUEST_URI rather than relying on rewrite-rule resolution.
 *
 * @return string Empty string when not a PWA endpoint, otherwise one
 *                of `'manifest'` | `'sw'`.
 */
function openstation_pwa_endpoint_kind() {
	// `esc_url_raw` rather than `sanitize_text_field`: the value is a URL
	// and the latter strips percent-encoded octets, which would corrupt
	// the path before it can be compared against the endpoint constants.
	$uri = isset( $_SERVER['REQUEST_URI'] ) ? esc_url_raw( wp_unslash( $_SERVER['REQUEST_URI'] ) ) : '';
	if ( ! is_string( $uri ) || '' === $uri ) {
		return '';
	}
	$path = (string) wp_parse_url( $uri, PHP_URL_PATH );
	if ( '' === $path ) {
		return '';
	}
	$home_path = wp_parse_url( home_url( '/' ), PHP_URL_PATH );
	$home_path = is_string( $home_path ) ? rtrim( $home_path, '/' ) : '';
	$portal    = $home_path . '/' . trim( OPENSTATION_PORTAL_PATH, '/' ) . '/';
	if ( $path === $portal . OPENSTATION_PWA_MANIFEST_FRAGMENT ) {
		return 'manifest';
	}
	if ( $path === $portal . OPENSTATION_PWA_SW_FRAGMENT ) {
		return 'sw';
	}
	// Extensionless fallback (`/?openstation_sw=1`) for hosts whose web
	// server 404s virtual `.js` paths before WordPress runs.
	//
	// Pinned to the site root — the one URL
	// {@see openstation_pwa_sw_fallback_url()} builds and the only one
	// the registration ever requests. Matching the query alone would
	// have turned *any* path into a service-worker endpoint, which is
	// harmless in practice (the handler streams a static file from
	// disk and reflects nothing from the request) but wider than the
	// contract this function documents, and a service worker's scope
	// is decided by the path it is served from — so the path is not an
	// incidental detail here.
	// phpcs:ignore WordPress.Security.NonceVerification.Recommended -- public read-only endpoint selector, same trust level as the path match above.
	if ( isset( $_GET[ OPENSTATION_PWA_SW_QUERY ] ) && '1' === $_GET[ OPENSTATION_PWA_SW_QUERY ] ) {
		$home_root = '' === $home_path ? '/' : $home_path . '/';
		if ( $path === $home_root || $path === $home_path ) {
			return 'sw';
		}
	}
	return '';
}

/**
 * Intercepts the manifest and SW endpoints, emitting the response body.
 *
 * Hooks at the same `parse_request` priority as the portal handler so
 * we beat 404 logic but the request environment (auth state, options
 * cache, etc.) is fully bootstrapped.
 *
 * Both endpoints are intentionally **public** (no `is_user_logged_in`
 * guard). The manifest is loaded by the browser BEFORE login when a
 * user revisits the install URL; the SW is fetched by the browser
 * with no cookies on update checks. Both reveal only data already
 * surfaced by the front-end (site name, blog icon, plugin version).
 *
 * @param WP $wp Current WordPress environment instance (unused).
 */
function openstation_pwa_handle_request( $wp ) {
	unset( $wp );

	$kind = openstation_pwa_endpoint_kind();
	if ( '' === $kind ) {
		return;
	}

	if ( 'manifest' === $kind ) {
		openstation_pwa_serve_manifest();
		exit;
	}

	if ( 'sw' === $kind ) {
		openstation_pwa_serve_service_worker();
		exit;
	}
}
add_action( 'parse_request', 'openstation_pwa_handle_request' );

/**
 * Builds the manifest array, applies the `openstation_pwa_manifest`
 * filter, encodes as JSON and prints it.
 */
function openstation_pwa_serve_manifest() {
	$manifest = openstation_pwa_build_manifest();

	/**
	 * Filters the web-app manifest payload before encoding.
	 *
	 * Common edits: replace the icon list with site-specific artwork,
	 * add `shortcuts` so the OS-level app menu offers
	 * deep-link entries, change `display` to `'fullscreen'`. Returning
	 * a non-array silently disables the manifest — no PHP warning, but
	 * the browser will fail the install criterion.
	 *
	 * @param array $manifest Manifest associative array.
	 */
	$manifest = apply_filters( 'openstation_pwa_manifest', $manifest );

	if ( ! is_array( $manifest ) ) {
		status_header( 500 );
		return;
	}

	header( 'Content-Type: application/manifest+json; charset=utf-8' );
	// 5-minute browser cache so a site-icon swap propagates quickly,
	// but the network isn't hit on every shell load.
	header( 'Cache-Control: public, max-age=300' );
	echo wp_json_encode( $manifest, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );
}

/**
 * Assembles the default manifest fields.
 *
 * @return array
 */
function openstation_pwa_build_manifest() {
	$site_name = get_bloginfo( 'name' );
	if ( '' === $site_name ) {
		$site_name = 'WordPress';
	}
	$short_name = wp_html_excerpt( $site_name, 12, '' );
	if ( '' === $short_name ) {
		$short_name = $site_name;
	}

	// `start_url` is the actual landing URL after the `/openstation/`
	// portal redirect — pointing the PWA directly at it lets us narrow
	// `scope` to `/wp-admin/` without breaking the launch path. The
	// portal redirect still exists for typed / bookmarked
	// `/openstation/` visits in regular browser tabs.
	//
	// `scope` is `/wp-admin/`, not `/`. The wider `/` scope had two
	// failure modes that this fixes:
	//
	// - Front-end URLs (e.g. `/2026/05/post-123/`) were considered
	// in-scope, so Chrome's "Open in app" link-capturing redirected
	// external-link clicks (Comments "In response to" column, etc.)
	// into the installed PWA window instead of opening a real
	// browser tab. Excluding the front-end from scope makes those
	// clicks open in a browser tab as users expect.
	// - Every same-origin `<a target="_blank">` from inside the PWA
	// opened a NEW standalone PWA window for the same reason. With
	// scope narrowed, only `/wp-admin/*` links capture into the
	// PWA; everything else escapes to the system browser.
	//
	// `id` is held at the previous `/openstation/` value so existing
	// installs aren't treated as a different app and reset by Chrome
	// after this change ships.
	// The shell screen, bare: it resolves the entry itself from the
	// saved session. Installs made when this was
	// `index.php?desktop_mode_portal=1` still work — that URL is an
	// alias the admin_init redirect sends here (`includes/portal.php`).
	$start_url = openstation_shell_url();
	$scope     = admin_url( '/', 'relative' );
	if ( '' === $scope ) {
		$scope = '/wp-admin/';
	}

	$manifest_url = openstation_pwa_manifest_url();

	return array(
		'name'                        => $site_name,
		'short_name'                  => $short_name,
		'description'                 => sprintf(
			/* translators: %s: site name */
			__( '%s — installed as a desktop app.', 'desktop-mode' ),
			$site_name
		),
		'start_url'                   => $start_url,
		'scope'                       => $scope,
		'id'                          => openstation_portal_url(),
		'display'                     => 'standalone',
		'display_override'            => array( 'standalone', 'minimal-ui' ),
		'orientation'                 => 'any',
		// The shell's backstop (`--os-backstop`): the floor under the
		// wallpaper, and what the splash and the status bar are painted
		// with. Filter to override per-site without redefining the
		// whole manifest.
		'theme_color'                 => OPENSTATION_PWA_THEME_COLOR,
		'background_color'            => OPENSTATION_PWA_THEME_COLOR,
		'lang'                        => get_bloginfo( 'language' ),
		'dir'                         => is_rtl() ? 'rtl' : 'ltr',
		'icons'                       => openstation_pwa_default_icons(),
		// Self-reference under `related_applications` so
		// `navigator.getInstalledRelatedApps()` (Chrome / Edge) returns
		// a hit when this PWA is installed in the current profile.
		// `prefer_related_applications: false` keeps the install prompt
		// pointed at this site itself (not redirected to a related
		// native app). Without these two fields, a regular browser tab
		// has no way to detect "already installed in this profile" —
		// `display-mode: standalone` is only true inside the PWA
		// window. The detection is what powers the dock-tile click
		// handler's "X is already installed" toast.
		'related_applications'        => array(
			array(
				'platform' => 'webapp',
				'url'      => $manifest_url,
				'id'       => openstation_portal_url(),
			),
		),
		'prefer_related_applications' => false,
	);
}

/**
 * Resolves the default icon set.
 *
 * Priority:
 *   1. WordPress Site Icon (`Settings → General → Site Icon`) — yields
 *      multiple PNG sizes via `get_site_icon_url()`. Authoritative
 *      when the operator has uploaded a brand mark for their site.
 *   2. Plugin-bundled icons under `assets/pwa/` — the official
 *      openstation brand mark (the same artwork shown on the
 *      WordPress.org plugin directory listing).
 *
 * **The bundled artwork is full-bleed, opaque and square.** Every
 * platform masks a home-screen tile itself, and it fills any
 * transparency first: iOS fills with white, then rounds. Artwork that
 * rounds its own corners therefore installs as a mark floating on a
 * white square, which is exactly how the pre-full-bleed set installed
 * on iOS. Do not re-round these files, and do not reintroduce alpha.
 *
 * Three purposes go out for the bundled set, because the platforms
 * genuinely want three different pictures:
 *
 *   - `any`        the tile as drawn.
 *   - `maskable`   the same tile at 80%, so Android's adaptive masks
 *                  (circle, squircle, teardrop, depending on the
 *                  launcher) crop into margin rather than into the
 *                  mark.
 *   - `monochrome` the silhouette alone, for Android 13+ themed
 *                  icons, which recolour it to the wallpaper palette.
 *
 * A Site Icon gets `any` only. The other two purposes describe how a
 * specific piece of artwork is composed, and we know that about ours
 * and not about theirs — declaring someone's logo maskable when it is
 * not is how you get a cropped logo, and pairing their `any` with our
 * `monochrome` would put the OpenStation mark on their app.
 *
 * @return array<int, array<string, string>>
 */
function openstation_pwa_default_icons() {
	$icons = array();

	$site_icon_id = (int) get_option( 'site_icon' );
	if ( $site_icon_id > 0 ) {
		// `get_site_icon_url()` resolves to a registered intermediate
		// size. List the canonical PWA sizes (192/512) explicitly so
		// Chrome's installability heuristic finds an entry whose
		// `sizes` field matches the returned image.
		foreach ( array( 192, 512 ) as $size ) {
			$url = get_site_icon_url( $size );
			if ( is_string( $url ) && '' !== $url ) {
				$icons[] = array(
					'src'     => $url,
					'sizes'   => $size . 'x' . $size,
					'type'    => 'image/png',
					'purpose' => 'any',
				);
			}
		}
	}

	if ( ! empty( $icons ) ) {
		return $icons;
	}

	$bundled = array(
		'any'        => array( 128, 180, 192, 256, 512 ),
		'maskable'   => array( 192, 512 ),
		'monochrome' => array( 192, 512 ),
	);

	foreach ( $bundled as $purpose => $sizes ) {
		foreach ( $sizes as $size ) {
			$icons[] = array(
				'src'     => openstation_pwa_bundled_icon_url( $size, $purpose ),
				'sizes'   => "{$size}x{$size}",
				'type'    => 'image/png',
				'purpose' => $purpose,
			);
		}
	}

	return $icons;
}

/**
 * Builds the URL of one bundled icon file.
 *
 * The three purposes are three different files, and the filenames say
 * which: `icon-192.png`, `icon-maskable-192.png`, `icon-mono-192.png`.
 * Kept in one place so the head tags and the manifest cannot drift
 * apart on a rename.
 *
 * @param int    $size    Square pixel size.
 * @param string $purpose One of `any` | `maskable` | `monochrome`.
 * @return string Absolute URL.
 */
function openstation_pwa_bundled_icon_url( $size, $purpose = 'any' ) {
	$infix = '';
	if ( 'maskable' === $purpose ) {
		$infix = 'maskable-';
	} elseif ( 'monochrome' === $purpose ) {
		$infix = 'mono-';
	}

	return OPENSTATION_URL . "assets/pwa/icon-{$infix}{$size}.png";
}

/**
 * Serves the service-worker bundle.
 *
 * Reads the built `assets/js/sw[.min].js` from disk and streams it back
 * with the headers a SW needs to be valid:
 *
 *   - `Content-Type: application/javascript`
 *   - `Service-Worker-Allowed: <home path>` — required for a
 *     home-path-scoped registration when the script itself is served
 *     from `<home>/openstation/`. Without this header the browser
 *     rejects the `register()` call with `SecurityError: The path of
 *     the provided scope is not under the max scope allowed`.
 *   - `Cache-Control: no-cache, must-revalidate` — the browser already
 *     re-checks SW scripts on a 24h cycle, but caching the response
 *     defeats the immediate-update guarantee.
 *
 * Falls back to a 503 + log entry when the file is missing (a deploy
 * that didn't run `npm run build`). Logging gives the operator a
 * concrete pointer; 503 (vs. 404) tells the browser the SW genuinely
 * isn't available right now and it should retry later.
 */
function openstation_pwa_serve_service_worker() {
	$suffix = openstation_asset_suffix();
	$path   = OPENSTATION_DIR . 'assets/js/sw' . $suffix . '.js';

	if ( ! file_exists( $path ) ) {
		// Guard against hosts that disable error_log() via the
		// `disable_functions` ini directive.
		if ( function_exists( 'error_log' ) ) {
			error_log( '[openstation] service worker bundle missing at ' . $path . ' — run `npm run build` to generate it.' ); // phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_error_log
		}
		status_header( 503 );
		header( 'Cache-Control: no-cache, must-revalidate' );
		return;
	}

	$body = file_get_contents( $path ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents
	if ( false === $body ) {
		status_header( 503 );
		return;
	}

	header( 'Content-Type: application/javascript; charset=utf-8' );
	// The site's own home path — root everywhere except a subdirectory
	// network's subsites, whose workers are scoped to the site path so
	// every site of the network can register its own.
	header( 'Service-Worker-Allowed: ' . openstation_pwa_sw_scope() );
	header( 'Cache-Control: no-cache, must-revalidate' );
	header( 'X-Content-Type-Options: nosniff' );

	// Stamp the SW with a CONTENT HASH so the browser's byte-equality
	// check on update notices a *real* change.
	//
	// Earlier versions stamped with the file's `filemtime()`. Problem:
	// `npm run build` rewrites `sw.min.js` on every run, bumping its
	// mtime even when the SW source is byte-identical. Each rebuild
	// produced a different stamp → different SW response → browser
	// installed a "new" SW → `controllerchange` fired → the shell of
	// the day auto-reloaded the page. The user observed a "phantom
	// reload" 2–3s after every `npm run build`, even when only an
	// unrelated bundle (e.g. `desktop.min.js`) had changed.
	//
	// A content hash collapses identical bodies onto identical stamps
	// — only a *real* change in `src/pwa/sw.ts` installs a new worker.
	// (The shell no longer reloads on a new worker at all; see
	// `src/pwa/sw-register.ts`.) `md5` is plenty for an integrity
	// stamp here (no security implications) and short enough that the
	// inline comment stays under one line.
	$stamp = substr( md5( $body ), 0, 16 );
	printf( "/* openstation SW build: %s */\n", esc_html( $stamp ) );
	// Per-request config, injected ahead of the bundle. Deliberately
	// NOT part of the stamp hash above: the stamp identifies the
	// *bundle*, while a config change carries itself to the browser's
	// update check through its own bytes. Don't "fix" the hash to
	// cover the full response — identical bundles must keep identical
	// stamps (see the phantom-reload note above).
	// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- JS assembled via wp_json_encode; HTML escaping would corrupt the script.
	echo openstation_pwa_sw_config_preamble();
	// `$body` is the SW JavaScript bundle read off disk — escaping
	// would corrupt the script. Suppress the sniff with the standard
	// `--` separator (an em-dash silently fails to satisfy phpcs).
	// phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- JS bytes from disk.
	echo $body;
}

/**
 * The colour the app is painted with outside the page: the manifest's
 * `theme_color` and `background_color`, and the `theme-color` meta.
 * The shell's backstop, `--os-backstop` in `variables.css`.
 */
const OPENSTATION_PWA_THEME_COLOR = '#0c0b0f';

/**
 * The iOS status-bar styles a home-screen web app may ask for.
 *
 * `black`: an opaque bar above the page, white glyphs; the page
 * starts below it and `env( safe-area-inset-top )` is 0.
 * `black-translucent`: the page runs under the bar and reads
 * `env( safe-area-inset-top )` to keep out of it; on current iOS the
 * bar is drawn as a translucent band over the page's top edge.
 * `default`: the system's own bar for the appearance in force.
 */
const OPENSTATION_PWA_STATUS_BAR_STYLES = array( 'black', 'black-translucent', 'default' );

/**
 * The iOS status-bar style for the installed app.
 *
 * Defaults to `black`: the shell is near-black to its edges, so an
 * opaque black bar above it is one continuous surface and the page
 * is laid out below it, unambiguously. Under `black-translucent` the
 * page extends under the bar and iOS paints the bar as a translucent
 * band over the shell's top edge — a strip that reads as misplaced
 * chrome rather than as immersion, on a surface that is already the
 * bar's colour.
 *
 * @return string One of `black`, `black-translucent`, `default`.
 */
function openstation_pwa_status_bar_style() {
	/**
	 * Filters the iOS status-bar style for the installed app.
	 *
	 * @param string $style One of `black`, `black-translucent`, `default`.
	 */
	$style = apply_filters( 'openstation_pwa_status_bar_style', 'black' );
	return in_array( $style, OPENSTATION_PWA_STATUS_BAR_STYLES, true ) ? $style : 'black';
}

/**
 * Emits the `<link rel="manifest">` tag and the matching theme-color
 * meta into the admin `<head>` — only when openstation is the active
 * surface for this request (no chromeless iframes, no classic admin).
 *
 * Without these tags the browser never discovers the manifest and the
 * "install" criterion silently fails. Putting them in `<head>` (rather
 * than via `wp_localize_script`'s inline script tag) is what the
 * spec requires.
 */
function openstation_pwa_render_head_tags() {
	if ( ! is_admin() || ! is_user_logged_in() ) {
		return;
	}
	if ( ! openstation_is_shell_request() ) {
		return;
	}

	printf(
		'<link rel="manifest" href="%s">' . "\n",
		esc_url( openstation_pwa_manifest_url() )
	);
	printf(
		'<meta name="theme-color" content="%s">' . "\n",
		esc_attr( OPENSTATION_PWA_THEME_COLOR )
	);
	// `mobile-web-app-capable` is the cross-browser standard;
	// `apple-mobile-web-app-capable` is the legacy iOS-only spelling
	// (still required by older Safari versions). Chromium logs a
	// deprecation warning if only the apple-prefixed form is present.
	// We emit both so iOS keeps treating the home-screen shortcut as
	// a standalone app while Chromium stops the warning.
	echo '<meta name="mobile-web-app-capable" content="yes">' . "\n";
	echo '<meta name="apple-mobile-web-app-capable" content="yes">' . "\n";
	printf(
		'<meta name="apple-mobile-web-app-status-bar-style" content="%s">' . "\n",
		esc_attr( openstation_pwa_status_bar_style() )
	);
	printf(
		'<meta name="apple-mobile-web-app-title" content="%s">' . "\n",
		esc_attr( get_bloginfo( 'name' ) )
	);
	printf(
		'<link rel="apple-touch-icon" sizes="180x180" href="%s">' . "\n",
		esc_url( openstation_pwa_apple_touch_icon_url() )
	);
}
add_action( 'admin_head', 'openstation_pwa_render_head_tags', 1 );

/**
 * Resolves the 180×180 tile iOS uses for a home-screen install.
 *
 * Core does emit an `apple-touch-icon` from the Site Icon, but only on
 * `wp_head` and `login_head` — `wp_site_icon()` is not hooked to
 * `admin_head` at all. So inside wp-admin, which is the only place
 * anyone installs this app from, there is no tile unless we emit one.
 * That is why four bundled PNGs could sit in `assets/pwa/` and still
 * never reach an iPhone.
 *
 * 180 is iPhone @3x and the size iOS downscales from for everything
 * smaller, so one link covers the family.
 *
 * @return string Absolute URL.
 */
function openstation_pwa_apple_touch_icon_url() {
	$site_icon_id = (int) get_option( 'site_icon' );
	if ( $site_icon_id > 0 ) {
		$url = get_site_icon_url( 180 );
		if ( is_string( $url ) && '' !== $url ) {
			return $url;
		}
	}

	return openstation_pwa_bundled_icon_url( 180 );
}

/**
 * Reads the per-user PWA UI state.
 *
 * @param int $user_id Defaults to current user.
 * @return array{installHintDismissed: bool, notificationsEnabled: bool}
 */
function openstation_pwa_get_user_state( $user_id = 0 ) {
	if ( 0 === $user_id ) {
		$user_id = get_current_user_id();
	}
	$raw = get_user_meta( $user_id, OPENSTATION_PWA_USER_META, true );
	if ( ! is_array( $raw ) ) {
		$raw = array();
	}
	return array(
		'installHintDismissed' => ! empty( $raw['installHintDismissed'] ),
		'notificationsEnabled' => ! empty( $raw['notificationsEnabled'] ),
	);
}

/**
 * Writes the per-user PWA UI state, merging with the existing blob so
 * partial updates from the JS side don't wipe other keys.
 *
 * @param array $patch   Partial state to merge.
 * @param int   $user_id Defaults to current user.
 */
function openstation_pwa_update_user_state( array $patch, $user_id = 0 ) {
	if ( 0 === $user_id ) {
		$user_id = get_current_user_id();
	}
	$current = openstation_pwa_get_user_state( $user_id );
	$next    = array_merge( $current, $patch );
	update_user_meta( $user_id, OPENSTATION_PWA_USER_META, $next );
}

/**
 * Registers the `/desktop-mode/v1/pwa-state` REST routes.
 */
function openstation_pwa_register_rest_routes() {
	register_rest_route(
		'desktop-mode/v1',
		'/pwa-state',
		array(
			array(
				'methods'             => WP_REST_Server::READABLE,
				'callback'            => 'openstation_pwa_rest_get_state',
				'permission_callback' => 'openstation_pwa_rest_permission',
			),
			array(
				'methods'             => WP_REST_Server::CREATABLE,
				'callback'            => 'openstation_pwa_rest_post_state',
				'permission_callback' => 'openstation_pwa_rest_permission',
				'args'                => array(
					'installHintDismissed' => array(
						'type'     => 'boolean',
						'required' => false,
					),
					'notificationsEnabled' => array(
						'type'     => 'boolean',
						'required' => false,
					),
				),
			),
		)
	);

	// Future: register POST /pwa-push-subscription here when phase 4
	// lands. The state route is intentionally orthogonal so the v1
	// surface stays stable when push arrives.
}
add_action( 'rest_api_init', 'openstation_pwa_register_rest_routes' );

/**
 * REST permission gate — same shape as the session routes: logged in
 * with OpenStation enabled. See
 * {@see openstation_rest_require_enabled()}.
 *
 * @return true|WP_Error
 */
function openstation_pwa_rest_permission() {
	return openstation_rest_require_enabled();
}

/**
 * GET handler — returns the current user's PWA state.
 */
function openstation_pwa_rest_get_state() {
	return rest_ensure_response( openstation_pwa_get_user_state() );
}

/**
 * POST handler — merges the supplied keys into the user's state.
 *
 * @param WP_REST_Request $request REST request.
 */
function openstation_pwa_rest_post_state( $request ) {
	$patch = array();
	if ( null !== $request->get_param( 'installHintDismissed' ) ) {
		$patch['installHintDismissed'] = (bool) $request->get_param( 'installHintDismissed' );
	}
	if ( null !== $request->get_param( 'notificationsEnabled' ) ) {
		$patch['notificationsEnabled'] = (bool) $request->get_param( 'notificationsEnabled' );
	}
	if ( ! empty( $patch ) ) {
		openstation_pwa_update_user_state( $patch );
	}
	return rest_ensure_response( openstation_pwa_get_user_state() );
}