499 lines
18 KiB
Dart
499 lines
18 KiB
Dart
import 'package:actors/actors.dart';
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import 'package:drift/drift.dart' show Value;
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import 'dart:typed_data';
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import 'package:signals/signals.dart';
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import '../../database/database.dart';
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import '../../mews/document.dart';
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import '../../protocols/tofu.dart' show TofuPin;
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import '../actors/fetch_actor.dart';
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import '../internal_actions.dart';
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import '../internal_pages.dart';
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import '../key_store.dart';
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import '../pages/mews_urls.dart';
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/// What went wrong while browsing. The presentation layer maps these to
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/// user-facing messages; no raw codes cross into the UI.
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sealed class BrowseError {
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const BrowseError();
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}
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class LoadFailed extends BrowseError {
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const LoadFailed();
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}
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class BrokenPage extends BrowseError {
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const BrokenPage(this.source);
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/// The markup that failed to parse; "show page text" recovers its content.
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final String source;
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}
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/// A protocol status with the site's own message for the reader: a temporary
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/// or permanent failure, a client or server error.
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class ProtocolFailure extends BrowseError {
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const ProtocolFailure(this.message);
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final String message;
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}
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/// Redirects went around more times than the transports follow.
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class RedirectLoop extends BrowseError {
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const RedirectLoop();
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}
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/// A body of a type the reader cannot show.
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class UnsupportedPage extends BrowseError {
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const UnsupportedPage(this.mime);
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final String mime;
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}
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/// The site asked for a client certificate (Gemini 6x). Choosing an identity
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/// is the reader's decision, made on a page of its own.
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class ClientCertificateRequired extends BrowseError {
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const ClientCertificateRequired({
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required this.host,
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required this.port,
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required this.status,
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required this.meta,
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});
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final String host;
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final int port;
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final int status;
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final String meta;
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}
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/// The site's certificate is not the one pinned for it, and the pin has not
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/// expired. The reader can still choose to trust what was presented.
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class CertificateChanged extends BrowseError {
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const CertificateChanged({required this.host, required this.port, required this.presented});
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final String host;
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final int port;
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final TofuPin presented;
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}
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/// Coordinates navigation: owns the signals the reader UI observes and
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/// dispatches fetch commands to the fetch actor. Local-first: a cached page is
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/// revalidated with the server but survives any network failure.
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class BrowserController {
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BrowserController({
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required MewsDatabase db,
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required Actor<FetchCommand, FetchResult> fetch,
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required KeyStore keys,
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InternalPages? internalPages,
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InternalActions? internalActions,
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}) : _db = db,
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_fetch = fetch,
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_keys = keys,
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_internalPages = internalPages,
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_internalActions = internalActions;
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final MewsDatabase _db;
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final Actor<FetchCommand, FetchResult> _fetch;
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final KeyStore _keys;
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final InternalPages? _internalPages;
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final InternalActions? _internalActions;
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/// The stack of visited pages; the reader is at [_stackIndex].
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final List<String> _stack = [];
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int _stackIndex = -1;
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final currentPage = signal<MewsPage?>(null);
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final loading = signal(false);
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final error = signal<BrowseError?>(null);
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/// Pages opened this session, so links can show the visited color.
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final visitedUrls = signal(<String>{});
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/// The parsed pages next to the current one in the stack, ready to show
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/// while swiping between them.
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final backPage = signal<MewsPage?>(null);
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final forwardPage = signal<MewsPage?>(null);
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/// The address the reader is standing on, which an error page speaks about.
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/// Empty when there is nowhere to be yet.
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String get currentAddress => _stackIndex >= 0 ? _stack[_stackIndex] : '';
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bool get canGoBack => _stackIndex > 0;
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bool get canGoForward => _stackIndex >= 0 && _stack.length - 1 > _stackIndex;
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/// Normalizes what the reader typed into an address: bare domains become
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/// https URLs; anything already carrying a scheme (mews:, https:, ...) is
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/// left alone.
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static String normalizeAddress(String input) {
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final trimmed = input.trim();
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if (trimmed.isEmpty) return '';
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if (_schemePattern.hasMatch(trimmed)) return trimmed;
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return 'https://$trimmed';
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}
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static final _schemePattern = RegExp(r'^[a-zA-Z][a-zA-Z0-9+.-]*:');
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/// The wap. subdomain equivalent of [url], or null when the host already
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/// starts with it or the address is not a plain web URL.
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static String? wapUrlOf(String url) {
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final uri = Uri.tryParse(url);
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if (uri == null || !uri.hasScheme || uri.host.isEmpty) return null;
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if (uri.scheme != 'http' && uri.scheme != 'https') return null;
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if (uri.host.startsWith('wap.')) return null;
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return uri.replace(host: 'wap.${uri.host}').toString();
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}
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Future<void> open(String input) async {
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final url = MewsUrls.canonical(normalizeAddress(input));
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if (url.isEmpty) return;
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// Action links change something and stay on the current page instead of
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// joining the walk history.
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if (MewsUrls.isAction(url)) {
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// Only the client's own pages may change the reader's data. A fetched
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// page linking to mews:do/... must not act on their behalf (spec 8.1).
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if (!_onInternalPage) return;
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if (await (_internalActions?.apply(url) ?? Future.value(false))) {
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await _loadCurrent();
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}
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return;
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}
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_stack.removeRange(_stackIndex + 1, _stack.length);
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_stack.add(url);
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_stackIndex++;
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_updateNeighbors();
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await _loadCurrent();
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// The address as typed is only the reader's first guess at where a site
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// lives. A Mews site commonly lives on a wap. subdomain, and a hostname
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// that answers on neither the web nor its wap. subdomain may still be a
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// capsule: gemini is tried next and spartan last. Only an address typed
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// without a scheme is offered the capsule guesses, because an explicit
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// scheme is the reader naming the place to go.
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var candidate = url;
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if (error.value != null && _stack[_stackIndex] == candidate) {
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final wap = wapUrlOf(candidate);
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if (wap != null) {
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final firstError = error.value;
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candidate = wap;
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_stack[_stackIndex] = candidate;
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_updateNeighbors();
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await _loadCurrent();
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// The address as followed is the closer match: when the wap.
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// attempt does not work either, its error is the one to show and the
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// stack goes back to the address the reader followed, so the
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// address bar and anything acting on the failure (like opening the
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// page in a web browser) speak of the real address, not the guess.
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if (error.value != null && firstError != null) {
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error.value = firstError;
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candidate = url;
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_stack[_stackIndex] = url;
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_updateNeighbors();
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}
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}
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}
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if (error.value != null && _stack[_stackIndex] == candidate) {
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final typed = input.trim();
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final web = Uri.tryParse(url);
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if (web != null && web.host.isNotEmpty && !_schemePattern.hasMatch(typed)) {
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final firstError = error.value;
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for (final scheme in ['gemini', 'spartan']) {
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candidate = Uri(scheme: scheme, host: web.host, path: web.path).toString();
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_stack[_stackIndex] = candidate;
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_updateNeighbors();
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await _loadCurrent();
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if (error.value == null) return;
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}
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// Nothing answered; the web address is the closest guess the reader
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// typed, so it is what the address bar shows with the first error.
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_stack[_stackIndex] = url;
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_updateNeighbors();
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if (firstError != null) error.value = firstError;
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}
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}
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}
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Future<void> back() async {
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if (!canGoBack) return;
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_stackIndex--;
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// The neighbor was parsed for the swipe already; show it right away so
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// the transition lands on content instead of a blank page while
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// _loadCurrent revalidates it against the server.
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_showParsedNeighbor(backPage.value);
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_updateNeighbors();
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await _loadCurrent();
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}
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Future<void> forward() async {
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if (!canGoForward) return;
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_stackIndex++;
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_showParsedNeighbor(forwardPage.value);
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_updateNeighbors();
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await _loadCurrent();
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}
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void _showParsedNeighbor(MewsPage? page) {
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if (page == null) return;
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currentPage.value = page;
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error.value = null;
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visitedUrls.value = {...visitedUrls.value, page.url};
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}
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Future<void> reload() => _loadCurrent();
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/// Whether the reader is standing on one of the client's own pages.
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bool get _onInternalPage =>
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_stackIndex >= 0 && MewsUrls.isInternal(_stack[_stackIndex]);
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/// Rebuilds the open page when it is one of ours, so a change made elsewhere
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/// shows up without the reader navigating.
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Future<void> refreshInternalPage() async {
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if (!_onInternalPage) return;
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await _loadCurrent();
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}
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Future<void> submitForm(String action, String method, Map<String, String> fields) async {
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// A form on one of our own pages is a navigation or an action, never a
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// network request; the fetch client cannot speak the mews scheme.
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if (MewsUrls.isInternal(action)) {
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final base = Uri.parse(action);
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final verb = MewsUrls.verbOf(action);
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return open(verb == null
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? MewsUrls.page(base, fields)
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: MewsUrls.action(verb, {...base.queryParameters, ...fields}));
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}
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loading.value = true;
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error.value = null;
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final FetchResult result;
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try {
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result = await _fetch.send(SubmitForm(url: action, method: method, fields: fields));
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} catch (_) {
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// A submit that throws out of the actor is still just a failed load.
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loading.value = false;
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error.value = const LoadFailed();
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return;
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}
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loading.value = false;
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switch (result) {
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case FetchFormOk(:final page):
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_stack.removeRange(_stackIndex + 1, _stack.length);
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_stack.add(page.url);
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_stackIndex++;
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_updateNeighbors();
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_show(page);
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// A form on a protocol page, like an input request, answers with a
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// page of the protocol's own, which joins the walk like any fetched
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// page so going back returns to the question.
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case FetchPageOk(:final page, :final source, :final etag, :final lastModified, :final notModified, :final pinUpdates):
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for (final update in pinUpdates) {
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await _db.savePin(update.host, update.port, update.pin);
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}
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_stack.removeRange(_stackIndex + 1, _stack.length);
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_stack.add(page.url);
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_stackIndex++;
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_updateNeighbors();
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_show(page);
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if (!notModified && source.isNotEmpty) {
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await _db.saveCachedPage(CachedPagesCompanion.insert(
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url: page.url,
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source: source,
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title: Value(page.title),
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etag: Value(etag),
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lastModified: Value(lastModified),
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));
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}
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case FetchProtocolError(:final message):
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error.value = ProtocolFailure(message);
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case FetchCertificateChanged(:final host, :final port, :final presented):
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error.value = CertificateChanged(host: host, port: port, presented: presented);
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case _:
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error.value = const LoadFailed();
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}
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}
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/// Reopens the most recent page from the previous session, or the hub when
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/// there is nothing to return to.
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Future<void> restoreLastSession() async {
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final url = await _db.lastVisitedUrl() ?? MewsUrls.hub;
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_stack.add(url);
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_stackIndex = 0;
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_updateNeighbors();
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await _loadCurrent();
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}
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/// Parses the stack's neighboring pages in the fetch actor so swipes can
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/// show the real content. Results arriving after another navigation are
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/// dropped, so rapid navigation never shows a stale neighbor.
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void _updateNeighbors() {
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_loadNeighbor(_stackIndex - 1, backPage);
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_loadNeighbor(_stackIndex + 1, forwardPage);
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}
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Future<void> _loadNeighbor(int index, Signal<MewsPage?> target) async {
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final expectedIndex = _stackIndex;
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if (index < 0 || index >= _stack.length) {
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target.value = null;
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return;
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}
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final url = _stack[index];
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if (_internalPages?.handles(url) ?? false) {
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target.value = await _internalPages!.pageFor(url);
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return;
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}
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final cached = await _db.cachedPage(url);
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if (_stackIndex != expectedIndex) return;
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if (cached == null) {
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target.value = null;
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return;
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}
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final result = await _fetch.send(ParseSource(url: url, source: cached.source));
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if (_stackIndex != expectedIndex) return;
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target.value = result is FetchPageOk ? result.page : null;
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}
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Future<void> _loadCurrent() async {
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if (_stackIndex < 0) return;
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final url = _stack[_stackIndex];
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loading.value = true;
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error.value = null;
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// Internal pages are built from the local database, never fetched or
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// cached; they join the stack like any other page.
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if (_internalPages?.handles(url) ?? false) {
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final page = await _internalPages!.pageFor(url);
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loading.value = false;
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if (page != null) {
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currentPage.value = page;
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error.value = null;
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// Our own addresses stay out of visitedUrls: a sort or filter link
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// would otherwise take the visited color after one use.
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} else {
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currentPage.value = null;
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error.value = const LoadFailed();
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}
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return;
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}
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final cached = await _db.cachedPage(url);
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final uri = Uri.tryParse(url);
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final credentials = await _geminiCredentials(uri);
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final result = await _fetch.send(FetchPage(
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url: url,
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etag: cached?.etag,
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lastModified: cached?.lastModified,
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cachedSource: cached?.source,
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pins: credentials.pins,
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clientCert: credentials.clientCert,
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clientKey: credentials.clientKey,
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));
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loading.value = false;
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switch (result) {
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case FetchPageOk(:final page, :final source, :final etag, :final lastModified, :final notModified, :final pinUpdates):
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currentPage.value = page;
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error.value = null;
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visitedUrls.value = {...visitedUrls.value, url};
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// Opening a post is reading it. Nothing happens when the address is
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// not one, so this needs no knowledge of the reader's subscriptions.
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await _db.markEntryRead(url);
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for (final update in pinUpdates) {
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await _db.savePin(update.host, update.port, update.pin);
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}
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// An empty source is a body with no text worth keeping, like an
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// image; there is nothing to cache.
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if (!notModified && source.isNotEmpty) {
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await _db.saveCachedPage(CachedPagesCompanion.insert(
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url: url,
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source: source,
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title: Value(page.title),
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etag: Value(etag),
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lastModified: Value(lastModified),
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));
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await _db.recordVisit(url, page.title);
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}
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case FetchParseError(:final source):
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currentPage.value = null;
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error.value = BrokenPage(source);
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case FetchProtocolError(:final message):
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currentPage.value = null;
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error.value = ProtocolFailure(message);
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case FetchRedirectLoop():
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currentPage.value = null;
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error.value = const RedirectLoop();
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case FetchUnsupportedType(:final mime):
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currentPage.value = null;
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error.value = UnsupportedPage(mime);
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case FetchCertificateChanged(:final host, :final port, :final presented):
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currentPage.value = null;
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error.value = CertificateChanged(host: host, port: port, presented: presented);
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case FetchClientCertificateRequired(:final status, :final meta):
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currentPage.value = null;
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error.value = ClientCertificateRequired(
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host: uri?.host ?? '', port: uri != null && uri.hasPort ? uri.port : 1965,
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status: status, meta: meta);
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case _:
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currentPage.value = null;
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error.value = const LoadFailed();
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}
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}
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/// Records the certificate the error page is showing as the new pin and
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/// reloads. Only the reader can make this choice, from the error page.
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Future<void> trustPresentedCertificate() async {
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final shown = error.value;
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if (shown is! CertificateChanged) return;
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await _db.savePin(shown.host, shown.port, shown.presented);
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await _loadCurrent();
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}
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/// Binds the certificate the reader picked to the site asking for one and
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/// reloads, so the site sees the identity on the connection that follows.
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Future<void> chooseCertificate(int certificateId) async {
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final shown = error.value;
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if (shown is! ClientCertificateRequired) return;
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await _db.bindCertificate(shown.host, shown.port, certificateId);
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await _loadCurrent();
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}
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/// The raw bytes of a body on a protocol page, for the renderer to show an
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/// image. There is no address the platform could load it from, so it comes
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/// through the fetch actor wearing the same trust and identity as the page.
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Future<Uint8List?> fetchImageBytes(String url) async {
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final credentials = await _geminiCredentials(Uri.tryParse(url));
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final result = await _fetch.send(FetchBytes(
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url: url,
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pins: credentials.pins,
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clientCert: credentials.clientCert,
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clientKey: credentials.clientKey,
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));
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return result is FetchBytesOk ? result.data : null;
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}
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/// What a fetch of [uri] over gemini needs: the reader's pinned hosts,
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/// which live on this isolate's database and not in the actor's, and the
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/// identity bound to this host, worn only there.
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Future<({Map<String, TofuPin> pins, String? clientCert, String? clientKey})>
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_geminiCredentials(Uri? uri) async {
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if (uri == null || uri.scheme != 'gemini') {
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return (pins: const <String, TofuPin>{}, clientCert: null, clientKey: null);
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}
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final pins = await _db.allPins();
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final port = uri.hasPort ? uri.port : 1965;
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final bound = await _db.bindingFor(uri.host, port);
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if (bound == null) return (pins: pins, clientCert: null, clientKey: null);
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final held = await _db.clientCertificate(bound);
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return (
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pins: pins,
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clientCert: held?.certPem,
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clientKey: await _keys.read(bound),
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);
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}
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void _show(MewsPage page) {
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currentPage.value = page;
|
|
_db.recordVisit(page.url, page.title);
|
|
}
|
|
}
|