import 'dart:io';

import 'package:file_picker/file_picker.dart';
import 'package:path/path.dart' as p;
import 'package:share_plus/share_plus.dart' show ShareParams, SharePlus;

import '../database/database.dart';
import '../l10n/strings.dart';
import 'controllers/bookmarks_controller.dart';
import 'controllers/reader_settings_controller.dart'
    show ReaderSettingsController;
import 'controllers/subscriptions_controller.dart';
import 'key_store.dart';
import 'pages/mews_urls.dart';
import 'pages/quotations_page.dart' show citationFor;
import 'pem.dart';

/// Applies the change an action address encodes, e.g. mews:do/set-theme.
/// Returns whether anything changed, so the navigator can skip a rerender that
/// would show the same page.
///
/// An unknown verb or a missing argument does nothing and reports nothing: the
/// only links carrying these addresses are the ones the client builds, so a
/// miss is a bug rather than something to explain to the reader.
/// A PEM file the reader picked, or null when the pick was cancelled. [name]
/// names the identity after its file, which is what the reader chose.
typedef PickedPem = ({String name, String content});

class InternalActions {
  InternalActions({
    required MewsDatabase db,
    required Future<void> Function() applyLanguage,
    required ReaderSettingsController settings,
    required BookmarksController bookmarks,
    required SubscriptionsController subscriptions,
    required KeyStore keys,
    required Strings strings,
    Future<PickedPem?> Function(String title)? pickPemFile,
    Future<void> Function(String text)? share,
  })  : _db = db,
        _applyLanguage = applyLanguage,
        _settings = settings,
        _bookmarks = bookmarks,
        _subscriptions = subscriptions,
        _keys = keys,
        _strings = strings,
        _pickPemFile = pickPemFile ?? _pickPemFromFileSystem,
        _share = share ?? _shareThroughSystem;

  final MewsDatabase _db;
  final Future<void> Function() _applyLanguage;
  final ReaderSettingsController _settings;
  final BookmarksController _bookmarks;
  final SubscriptionsController _subscriptions;
  final KeyStore _keys;
  final Strings _strings;
  final Future<PickedPem?> Function(String title) _pickPemFile;
  final Future<void> Function(String text) _share;

  /// Hands [text] to the system share sheet.
  static Future<void> _shareThroughSystem(String text) =>
      SharePlus.instance.share(ShareParams(text: text));

  /// Opens the platform file picker for one PEM file, titled with what the
  /// step asks for. A single file may hold both the certificate and its key,
  /// or either one alone. A cancelled pick comes back as nothing.
  static Future<PickedPem?> _pickPemFromFileSystem(String title) async {
    final files = await FilePicker.pickFiles(
        dialogTitle: title,
        type: FileType.custom,
        allowedExtensions: const ['pem', 'crt', 'cer', 'key']);
    final path = files.singleOrNull?.path;
    if (path == null) return null;
    return (
      name: p.basenameWithoutExtension(path),
      content: await File(path).readAsString(),
    );
  }

  Future<bool> apply(String url) async {
    final verb = MewsUrls.verbOf(url);
    if (verb == null) return false;
    final args = Uri.parse(url).queryParameters;
    return switch (verb) {
      'set-font' => _settings.setFont(args['value'] ?? ''),
      'set-size' => _setSize(args['step']),
      'set-theme' => _settings.setThemeMode(args['value'] ?? ''),
      'set-colors' => _settings.setVariant(args['value'] ?? ''),
      'set-language' => _setLanguage(args['value']),
      'mark-read' => _markRead(args, read: true),
      'mark-unread' => _markRead(args, read: false),
      'refresh-subscriptions' => _refreshAll(),
      'refresh-subscription' => _refreshOne(args['url']),
      'remove-bookmark' => _withUrl(args, _bookmarks.remove),
      'unsubscribe' => _withUrl(args, _subscriptions.remove),
      'forget-page' => _withUrl(args, _db.forgetPage),
      'clear-history' => _clearHistory(),
      'add-tag' => _changeTag(args, add: true),
      'remove-tag' => _changeTag(args, add: false),
      'delete-tag' => _deleteTag(args['tag']),
      'import-certificate' => _importCertificate(),
      'rename-certificate' => _renameCertificate(args),
      'delete-certificate' => _deleteCertificate(args),
      'share-quotation' => _shareQuotation(args['id']),
      'remove-quotation' => _removeQuotation(args['id']),
      _ => false,
    };
  }

  /// Reads a certificate and its key from picked PEM files. The first pick
  /// may hold both; when it holds only one, the other is asked for again, by
  /// name, so a key picked on its own is not silently dropped. A cancelled
  /// pick imports nothing.
  Future<bool> _importCertificate() async {
    final first = await _pickPemFile(_strings.t('certificates-pick-title'));
    if (first == null) return false;
    String? cert = certificateOf(first.content);
    String? key = privateKeyOf(first.content);
    if (cert == null || key == null) {
      final asking = cert == null
          ? _strings.t('certificates-pick-cert-title')
          : _strings.t('certificates-pick-key-title');
      final second = await _pickPemFile(asking);
      if (second == null) return false;
      cert ??= certificateOf(second.content);
      key ??= privateKeyOf(second.content);
    }
    if (cert == null || key == null) return false;
    final name = first.name.trim();
    final id = await _db.addClientCertificate(
        name.isEmpty ? _strings.t('certificates-default-name') : name, cert);
    await _keys.save(id, key);
    return true;
  }

  Future<bool> _renameCertificate(Map<String, String> args) async {
    final id = int.tryParse(args['id'] ?? '');
    final name = args['name']?.trim();
    if (id == null || name == null || name.isEmpty) return false;
    await _db.renameClientCertificate(id, name);
    return true;
  }

  Future<bool> _deleteCertificate(Map<String, String> args) async {
    final id = int.tryParse(args['id'] ?? '');
    if (id == null) return false;
    await _keys.delete(id);
    await _db.deleteClientCertificate(id);
    return true;
  }

  /// Changing the language has to load its messages before the page is built
  /// again, or the rerender would still read the old ones.
  Future<bool> _setLanguage(String? tag) async {
    if (tag == null || tag.isEmpty) return false;
    if (!await _settings.setLanguage(tag)) return false;
    await _applyLanguage();
    return true;
  }

  Future<bool> _setSize(String? step) => switch (step) {
    'up' => _settings.increaseSize(),
    'down' => _settings.decreaseSize(),
    _ => Future.value(false),
  };

  /// Runs [change] on the address the action names, if it names one.
  Future<bool> _withUrl(
      Map<String, String> args, Future<void> Function(String) change) async {
    final url = args['url'];
    if (url == null || url.isEmpty) return false;
    await change(url);
    return true;
  }

  /// Adds or removes one tag. An empty name is refused, so submitting an
  /// empty box does nothing.
  Future<bool> _changeTag(Map<String, String> args, {required bool add}) async {
    final kind = switch (args['kind']) {
      'bookmark' => TagKind.bookmark,
      'subscription' => TagKind.subscription,
      _ => null,
    };
    final url = args['url'];
    final tag = args['tag']?.trim();
    if (kind == null || url == null || url.isEmpty) return false;
    if (tag == null || tag.isEmpty) return false;
    if (add) {
      await _db.addTag(kind, url, tag);
    } else {
      await _db.removeTag(kind, url, tag);
    }
    return true;
  }

  Future<bool> _deleteTag(String? tag) async {
    if (tag == null || tag.isEmpty) return false;
    await _db.deleteTag(tag);
    return true;
  }

  Future<bool> _clearHistory() async {
    await _db.clearHistory();
    return true;
  }

  Future<bool> _markRead(Map<String, String> args, {required bool read}) async {
    final url = args['url'];
    if (url == null || url.isEmpty) return false;
    final site = args['site'];
    if (read) {
      await _subscriptions.markRead(url, siteUrl: site);
    } else {
      await _subscriptions.markUnread(url, siteUrl: site);
    }
    return true;
  }

  /// The check redraws the page itself as it runs, so the caller need not.
  Future<bool> _refreshAll() async {
    await _subscriptions.refreshAll();
    return false;
  }

  Future<bool> _refreshOne(String? siteUrl) async {
    if (siteUrl == null || siteUrl.isEmpty) return false;
    await _subscriptions.refreshOne(siteUrl);
    return false;
  }

  /// Shares the quotation with its citation. Nothing on the page changes, so
  /// the reader stays exactly where they were.
  Future<bool> _shareQuotation(String? id) async {
    final quotation = await _quotation(id);
    if (quotation == null) return false;
    await _share('${quotation.quote}\n\n'
        '${citationFor(quotation, _strings)}');
    return false;
  }

  Future<bool> _removeQuotation(String? id) async {
    final quotation = await _quotation(id);
    if (quotation == null) return false;
    await _db.removeQuotation(quotation.id);
    return true;
  }

  Future<Quotation?> _quotation(String? id) async {
    final parsed = int.tryParse(id ?? '');
    if (parsed == null) return null;
    return _db.quotationById(parsed);
  }
}