using System.Diagnostics;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Navigation;
using DorkNet.Launcher.Backend;

namespace DorkNet.Launcher;

/// <summary>The launcher's only Window. Code-behind directly drives the
/// XAML controls — no MVVM framework. The <c>Backend/*</c> classes do
/// the work; the code-behind is glue + UI updates marshalled back to
/// the dispatcher thread.</summary>
public partial class MainWindow : Window
{
    private readonly AppState _state;
    private readonly ReleaseDownloader _releases = new();
    private readonly ClientPatcher _patcher = new();
    private readonly ServerProcess _server = new();
    private Tunnel? _tunnel;
    private VersionsManifest? _manifest;
    private string? _hostApex;

    public MainWindow()
    {
        InitializeComponent();
        _state = AppState.Load();
        Loaded += OnWindowLoaded;
        Closed += async (_, _) => await ShutdownServerAsync();
    }

    private async void OnWindowLoaded(object sender, RoutedEventArgs e)
    {
        // Hydrate UI from persisted state, then fetch the manifest in the
        // background so the user can start clicking immediately even if the
        // version list is slow.
        ReflectStateInUi();
        await RefreshManifestAsync();
    }

    // ── View routing ────────────────────────────────────────────────────
    private void ShowView(string name)
    {
        FirstRunView.Visibility = name == "first-run" ? Visibility.Visible : Visibility.Collapsed;
        HostView.Visibility = name == "host" ? Visibility.Visible : Visibility.Collapsed;
        JoinView.Visibility = name == "join" ? Visibility.Visible : Visibility.Collapsed;
        SettingsView.Visibility = name == "settings" ? Visibility.Visible : Visibility.Collapsed;
    }

    private string CurrentViewName()
    {
        if (SettingsView.Visibility == Visibility.Visible) return "settings";
        if (HostView.Visibility == Visibility.Visible) return "host";
        if (JoinView.Visibility == Visibility.Visible) return "join";
        return "first-run";
    }

    private string? _previousView;

    private void ReflectStateInUi()
    {
        // Mirror persisted values into the host/join input fields so the
        // user doesn't re-type them every launch.
        var path = _state.RecRoomPath ?? "(not picked)";
        HostRecRoomPath.Text = path;
        JoinRecRoomPath.Text = path;

        PhotonAppIdInput.Text = _state.PhotonAppId;
        PhotonVoiceAppIdInput.Text = _state.PhotonVoiceAppId;
        SelectComboBoxByTag(PhotonRegionSelect, _state.PhotonRegion);
        ServerNameInput.Text = _state.ServerName;

        CachePathsText.Text =
            $"State:   {AppPaths.StateFile}\n" +
            $"Servers: {AppPaths.ServersRoot}\n" +
            $"Patchers: {AppPaths.PatchersRoot}\n" +
            $"Logs:    {AppPaths.LogsRoot}";

        RefreshJoinReadiness();

        ShowView(_state.Mode switch
        {
            AppMode.Host => "host",
            AppMode.Join => "join",
            _ => "first-run",
        });
    }

    private async Task RefreshManifestAsync()
    {
        _manifest = await new VersionsManifest().FetchAsync();
        if (_manifest is null)
        {
            HostStatusText.Text = "Couldn't load versions.json from GitHub. " +
                "Check internet, then reopen.";
            return;
        }
        VersionSelect.Items.Clear();
        foreach (var v in _manifest.Branches.Where(b => b.Supported))
        {
            var item = new ComboBoxItem
            {
                Content = $"Rec Room {v.ClientBuild} ({v.Branch})",
                Tag = v.VersionKey,
            };
            VersionSelect.Items.Add(item);
            if (v.VersionKey == _state.SelectedVersion) item.IsSelected = true;
        }
        if (VersionSelect.SelectedItem is null && VersionSelect.Items.Count > 0)
            VersionSelect.SelectedIndex = 0;
    }

    private static void SelectComboBoxByTag(ComboBox cb, string tag)
    {
        foreach (var item in cb.Items.OfType<ComboBoxItem>())
        {
            if (string.Equals(item.Tag?.ToString(), tag, StringComparison.OrdinalIgnoreCase))
            {
                item.IsSelected = true;
                return;
            }
        }
    }

    // ── First-run wizard / mode picks ───────────────────────────────────
    private void OnPickHost(object sender, RoutedEventArgs e)
    {
        _state.Mode = AppMode.Host;
        _state.Save();
        ReflectStateInUi();
    }

    private void OnPickJoin(object sender, RoutedEventArgs e)
    {
        _state.Mode = AppMode.Join;
        _state.Save();
        ReflectStateInUi();
    }

    private void OnOpenSettings(object sender, RoutedEventArgs e)
    {
        _previousView = CurrentViewName();
        ShowView("settings");
    }

    private void OnBackFromSettings(object sender, RoutedEventArgs e)
    {
        ShowView(_previousView ?? (_state.Mode == AppMode.Join ? "join" : "host"));
    }

    private void OnNavigate(object sender, RequestNavigateEventArgs e)
    {
        Process.Start(new ProcessStartInfo(e.Uri.AbsoluteUri) { UseShellExecute = true });
        e.Handled = true;
    }

    // ── Shared field handlers ───────────────────────────────────────────
    private void OnPickRecRoom(object sender, RoutedEventArgs e)
    {
        var picked = RecRoomPicker.Pick(_state.RecRoomPath);
        if (picked is null) return;
        var (ok, reason) = RecRoomPicker.Validate(picked);
        if (!ok) { ShowError(reason); return; }
        _state.RecRoomPath = picked;
        _state.Save();
        ReflectStateInUi();
    }

    private void OnServerNameChanged(object sender, RoutedEventArgs e)
    {
        _state.ServerName = ServerNameInput.Text.Trim();
        _state.Save();
    }

    private void OnPhotonChanged(object sender, RoutedEventArgs e)
    {
        _state.PhotonAppId = PhotonAppIdInput.Text.Trim();
        _state.PhotonVoiceAppId = PhotonVoiceAppIdInput.Text.Trim();
        if (PhotonRegionSelect.SelectedItem is ComboBoxItem item)
            _state.PhotonRegion = item.Tag?.ToString() ?? "us";
        _state.Save();
    }

    // ── Host flow ───────────────────────────────────────────────────────
    private async void OnHostStart(object sender, RoutedEventArgs e)
    {
        if (string.IsNullOrEmpty(_state.RecRoomPath))
        { ShowError("Pick your Rec Room install first."); return; }
        if (string.IsNullOrEmpty(_state.PhotonAppId))
        { ShowError("Photon AppId required (free at dashboard.photonengine.com)."); return; }

        if (_manifest is null) await RefreshManifestAsync();
        if (VersionSelect.SelectedItem is not ComboBoxItem item || item.Tag is null)
        { ShowError("Pick a version to host."); return; }
        var versionKey = item.Tag.ToString();
        var version = _manifest?.Branches.FirstOrDefault(b => b.VersionKey == versionKey);
        if (version is null)
        { ShowError($"Unknown version: {versionKey}"); return; }

        HostStartBtn.IsEnabled = false;
        HostStopBtn.Visibility = Visibility.Visible;
        JoinCodePanel.Visibility = Visibility.Collapsed;

        try
        {
            var progress = new Progress<DownloadProgress>(p =>
                HostStatusText.Text = FormatProgress("Downloading server", p));

            HostStatusText.Text = "Downloading server binary…";
            var serverDir = await _releases.EnsureServerAsync(version, progress);

            HostStatusText.Text = "Opening Cloudflare tunnel…";
            _tunnel = new Tunnel();
            var publicUrl = await _tunnel.StartAsync(localPort: 5005);
            _hostApex = new Uri(publicUrl).Host;

            HostStatusText.Text = "Starting the server…";
            await _server.StartAsync(serverDir, _state, _hostApex);
            _state.SelectedVersion = version.VersionKey;
            _state.Save();

            HostStatusText.Text = "Downloading client patcher…";
            var patcherDir = await _releases.EnsurePatcherAsync(version, progress);

            HostStatusText.Text = "Patching your Rec Room client…";
            var patch = await _patcher.ApplyAsync(
                patcherDir, _state.RecRoomPath!,
                _state.PhotonAppId, _state.PhotonVoiceAppId, _hostApex);
            if (!patch.Ok) { ShowError("Patcher failed: " + Truncate(patch.Log, 500)); return; }

            var code = JoinCode.Encode(new JoinPayload
            {
                Host = _hostApex,
                VersionKey = version.VersionKey,
                PhotonAppId = _state.PhotonAppId,
                PhotonVoiceAppId = _state.PhotonVoiceAppId,
                PhotonRegion = _state.PhotonRegion,
                Name = _state.ServerName,
            });
            JoinCodeText.Text = code;
            JoinCodePanel.Visibility = Visibility.Visible;
            HostStatusText.Text = $"Hosting at {publicUrl}";
        }
        catch (Exception ex)
        {
            ShowError(ex.Message);
            HostStartBtn.IsEnabled = true;
            HostStopBtn.Visibility = Visibility.Collapsed;
        }
    }

    private async void OnHostStop(object sender, RoutedEventArgs e)
    {
        await ShutdownServerAsync();
        HostStartBtn.IsEnabled = true;
        HostStopBtn.Visibility = Visibility.Collapsed;
        JoinCodePanel.Visibility = Visibility.Collapsed;
        HostStatusText.Text = "Stopped.";
    }

    private async Task ShutdownServerAsync()
    {
        try { await _server.StopAsync(); } catch { }
        if (_tunnel is not null) { try { await _tunnel.DisposeAsync(); } catch { } _tunnel = null; }
    }

    private void OnCopyJoinCode(object sender, RoutedEventArgs e)
    {
        try { Clipboard.SetText(JoinCodeText.Text); }
        catch (Exception ex) { ShowError("Copy failed: " + ex.Message); }
    }

    // ── Join flow ───────────────────────────────────────────────────────
    private void OnJoinCodeInputChanged(object sender, TextChangedEventArgs e)
        => RefreshJoinReadiness();

    private void RefreshJoinReadiness()
    {
        if (JoinApplyBtn is null) return;
        var hasCode = JoinCodeInput?.Text?.Trim().Length > 10;
        var hasPath = !string.IsNullOrEmpty(_state.RecRoomPath);
        JoinApplyBtn.IsEnabled = hasCode && hasPath;
    }

    private void OnDecodeJoinCode(object sender, RoutedEventArgs e)
    {
        var code = JoinCodeInput.Text.Trim();
        var payload = JoinCode.Decode(code);
        if (payload is null)
        {
            JoinPreviewBorder.Visibility = Visibility.Visible;
            JoinPreviewText.Text = "Invalid join code.";
            return;
        }
        JoinPreviewBorder.Visibility = Visibility.Visible;
        JoinPreviewText.Text =
            $"Connecting to {(string.IsNullOrEmpty(payload.Name) ? "(unnamed server)" : payload.Name)}\n" +
            $"Host: {payload.Host}\n" +
            $"Version: {payload.VersionKey}";
    }

    private async void OnJoinApply(object sender, RoutedEventArgs e)
    {
        if (string.IsNullOrEmpty(_state.RecRoomPath))
        { ShowError("Pick your Rec Room install first."); return; }
        var payload = JoinCode.Decode(JoinCodeInput.Text.Trim());
        if (payload is null)
        { ShowError("Invalid join code."); return; }
        if (_manifest is null) await RefreshManifestAsync();
        var version = _manifest?.Branches.FirstOrDefault(b => b.VersionKey == payload.VersionKey);
        if (version is null)
        { ShowError($"Host is on a version this launcher doesn't know about: {payload.VersionKey}"); return; }

        JoinApplyBtn.IsEnabled = false;
        try
        {
            var progress = new Progress<DownloadProgress>(p =>
                JoinStatusText.Text = FormatProgress("Downloading patcher", p));

            JoinStatusText.Text = "Downloading client patcher…";
            var patcherDir = await _releases.EnsurePatcherAsync(version, progress);

            JoinStatusText.Text = "Patching your Rec Room client…";
            var patch = await _patcher.ApplyAsync(
                patcherDir, _state.RecRoomPath!,
                payload.PhotonAppId, payload.PhotonVoiceAppId, payload.Host);
            if (!patch.Ok) { ShowError("Patcher failed: " + Truncate(patch.Log, 500)); return; }

            JoinStatusText.Text = "Patched. Launch Rec Room from Steam to connect.";
        }
        catch (Exception ex) { ShowError(ex.Message); }
        finally { RefreshJoinReadiness(); }
    }

    // ── Helpers ─────────────────────────────────────────────────────────
    private static string FormatProgress(string label, DownloadProgress p)
    {
        if (p.TotalBytes <= 0) return $"{label}…";
        var mb = p.BytesRead / (1024.0 * 1024.0);
        var totalMb = p.TotalBytes / (1024.0 * 1024.0);
        return $"{label}: {mb:F1} / {totalMb:F1} MB ({(int)(p.Fraction * 100)}%)";
    }

    private static string Truncate(string s, int max)
        => s.Length <= max ? s : s[..max] + "...";

    private void ShowError(string message)
        => System.Windows.MessageBox.Show(this, message, "DorkNet",
            MessageBoxButton.OK, MessageBoxImage.Warning);
}