using System.Drawing.Drawing2D;
using System.Runtime.InteropServices;

namespace BSO.Launcher;

/// <summary>
/// Setup-Assistent der heruntergeladenen BSO-Launcher-Setup.exe: Willkommen (mit Sprachwahl) -> Ordner und Verknuepfungen
/// -> Installieren -> Fertig. Ist dieselbe oder eine neuere Version schon installiert, bietet er Starten an (gleiche Version:
/// auch Neu installieren). Eigenes dunkles Fenster im Stil des Launchers.
/// </summary>
public sealed class SetupForm : Form
{
    static readonly Color Back = Color.FromArgb(0x10, 0x13, 0x1a), Field = Color.FromArgb(0x1a, 0x1f, 0x29), Line = Color.FromArgb(0x26, 0x2c, 0x38),
        Bright = Color.FromArgb(0xe8, 0xec, 0xf2), Muted = Color.FromArgb(0x8b, 0x95, 0xa5), Accent = Color.FromArgb(0x1f, 0x6f, 0xe5),
        Bad = Color.FromArgb(0xff, 0x8a, 0x8d);
    const int Header = 96;

    readonly string version = SelfUpdate.CurrentVersion;
    readonly string? installed = Installer.InstalledVersion();
    readonly FlowLayoutPanel content = new(), buttons = new(), langs = new();
    readonly Label close = new();
    readonly Image? logo = Installer.Logo();
    Action page;
    bool installing;

    // Auswahl - bleibt beim Sprachwechsel und Zurueck erhalten
    string folder = Installer.RegisteredDir ?? Installer.DefaultDir;
    bool desktop, startMenu;
    string? installedTo;

    static string L(string de, string en) => Lang.Current == "en" ? en : de;

    public SetupForm()
    {
        bool fresh = installed == null;
        desktop = fresh || Installer.HasDesktopShortcut;
        startMenu = fresh || Installer.HasStartMenuShortcut;

        Text = "BSO Launcher Setup";
        FormBorderStyle = FormBorderStyle.None;
        StartPosition = FormStartPosition.CenterScreen;
        AutoScaleMode = AutoScaleMode.Dpi;
        ClientSize = new Size(600, 430);
        BackColor = Back;
        ForeColor = Bright;
        Font = new Font("Segoe UI", 10f);
        DoubleBuffered = true;
        try { Icon = Icon.ExtractAssociatedIcon(Environment.ProcessPath ?? Application.ExecutablePath); } catch { }

        content.SetBounds(32, Header + 18, 536, 250);
        content.FlowDirection = FlowDirection.TopDown;
        content.WrapContents = false;
        buttons.SetBounds(32, 368, 536, 44);
        buttons.FlowDirection = FlowDirection.RightToLeft;
        buttons.WrapContents = false;

        langs.SetBounds(460, 34, 96, 30);
        langs.FlowDirection = FlowDirection.LeftToRight;
        langs.WrapContents = false;
        close.SetBounds(560, 8, 32, 28);
        close.Text = "✕";
        close.ForeColor = Muted;
        close.TextAlign = ContentAlignment.MiddleCenter;
        close.Cursor = Cursors.Hand;
        close.Click += (_, _) => { if (!installing) Close(); };
        close.MouseEnter += (_, _) => close.ForeColor = Bright;
        close.MouseLeave += (_, _) => close.ForeColor = Muted;
        Controls.AddRange(new Control[] { content, buttons, langs, close });

        MouseDown += (_, e) => { if (e.Button == MouseButtons.Left && e.Y < Header) DragWindow(); };
        page = Welcome;
        Go(Welcome);
    }

    // ---------------------------------------------------------------- Seiten

    void Welcome()
    {
        if (installed != null && !SelfUpdate.IsNewer(version, installed))
        {
            bool same = installed == version;
            Title(L("BSO Launcher ist schon installiert", "BSO Launcher is already installed"));
            Paragraph(same
                ? L($"Version {installed} ist auf diesem PC schon installiert. Du kannst ihn starten oder neu installieren.",
                    $"Version {installed} is already installed on this PC. You can start it or install it again.")
                : L($"Auf diesem PC ist schon die neuere Version {installed} installiert (dieses Setup: {version}).",
                    $"The newer version {installed} is already installed on this PC (this setup: {version})."));
            Paragraph(Installer.InstallDir, Muted, 9f);
            Button(L("Launcher starten", "Start launcher"), true, () => { Installer.StartInstalled(); Close(); });
            if (same) Button(L("Neu installieren", "Reinstall"), false, () => Go(Options));
            return;
        }
        if (installed != null)
        {
            Title(L($"Update auf Version {version}", $"Update to version {version}"));
            Paragraph(L($"Installiert ist Version {installed}. Das Setup aktualisiert den BSO Launcher – deine Anmeldung und Einstellungen bleiben erhalten.",
                $"Version {installed} is installed. This setup updates the BSO Launcher – your sign-in and settings are kept."));
        }
        else
        {
            Title(L("Willkommen", "Welcome"));
            Paragraph(L($"Dieses Setup installiert den BSO Launcher {version} – Multiplayer für Bus-Simulator 2012.",
                $"This setup installs the BSO Launcher {version} – multiplayer for Bus-Simulator 2012."));
            Paragraph(L("Der Launcher installiert danach die BSO-Mod für dich und hält sich und die Mod selbst aktuell. Admin-Rechte brauchst du nicht.",
                "The launcher then installs the BSO mod for you and keeps itself and the mod up to date. No admin rights needed."));
        }
        Paragraph(L("Sprache wählst du oben rechts.", "Choose your language in the top right."), Muted, 9f);
        Button(L("Weiter", "Next"), true, () => Go(Options));
        Button(L("Abbrechen", "Cancel"), false, Close);
    }

    void Options()
    {
        Title(L("Ordner und Verknüpfungen", "Folder and shortcuts"));
        Paragraph(L("Installieren in:", "Install to:"), Muted, 9f, 0);

        var row = new FlowLayoutPanel { AutoSize = true, WrapContents = false, Margin = new Padding(0, 4, 0, 4) };
        var path = new TextBox { Text = folder, Width = 404, BackColor = Field, ForeColor = Bright, BorderStyle = BorderStyle.FixedSingle, Margin = new Padding(0, 2, 8, 0) };
        path.TextChanged += (_, _) => folder = path.Text;
        var browse = MakeButton(L("Ändern …", "Change …"), false, () =>
        {
            using var dialog = new FolderBrowserDialog { Description = L("Ordner für den BSO Launcher wählen", "Choose a folder for the BSO Launcher"), UseDescriptionForTitle = true };
            try { dialog.InitialDirectory = Directory.Exists(folder) ? folder : Path.GetDirectoryName(folder) ?? ""; } catch { }
            if (dialog.ShowDialog(this) == DialogResult.OK) path.Text = Installer.NormalizeDir(dialog.SelectedPath);
        });
        browse.MinimumSize = new Size(110, 30);
        row.Controls.AddRange(new Control[] { path, browse });
        content.Controls.Add(row);
        Paragraph(L($"Braucht etwa {Installer.SelfSize / 1024 / 1024} MB · nur für deinen Windows-Benutzer",
            $"Needs about {Installer.SelfSize / 1024 / 1024} MB · only for your Windows user"), Muted, 9f);

        Check(L("Verknüpfung auf dem Desktop", "Desktop shortcut"), desktop, v => desktop = v);
        Check(L("Eintrag im Startmenü", "Start menu entry"), startMenu, v => startMenu = v);
        var error = Paragraph("", Bad, 9.5f);

        Button(L("Installieren", "Install"), true, () =>
        {
            string dir;
            try { dir = Installer.NormalizeDir(folder); }
            catch { error.Text = L("Ungültiger Ordner", "Invalid folder"); return; }
            if (Installer.CheckWritable(dir) is { } problem) { error.Text = Lang.T(problem); return; }
            Go(() => Install(dir));
        });
        Button(L("Zurück", "Back"), false, () => Go(Welcome));
    }

    void Install(string dir)
    {
        Title(L("Wird installiert …", "Installing …"));
        var status = Paragraph(Lang.T("Vorbereiten …"), Muted, 9.5f);
        var bar = new Bar { Width = 536, Height = 8, Margin = new Padding(0, 8, 0, 0) };
        content.Controls.Add(bar);
        installing = true;
        langs.Enabled = false;
        _ = Task.Run(() =>
        {
            try
            {
                Installer.Install(dir, desktop, startMenu, (p, text) => BeginInvoke(() => { bar.Value = p; status.Text = text; }));
                installedTo = dir;
                BeginInvoke(() => { installing = false; langs.Enabled = true; Go(Finish); });
            }
            catch (Exception e)
            {
                BeginInvoke(() => { installing = false; langs.Enabled = true; Go(() => Failed(e.Message)); });
            }
        });
    }

    void Failed(string message)
    {
        Title(L("Installation fehlgeschlagen", "Installation failed"));
        Paragraph(message, Bad);
        Paragraph(L("Läuft der Launcher noch? Dann schliessen und nochmal versuchen.", "Is the launcher still running? Close it and try again."), Muted, 9f);
        Button(L("Schliessen", "Close"), false, Close);
        Button(L("Zurück", "Back"), true, () => Go(Options));
    }

    void Finish()
    {
        Title(L("Fertig!", "Done!"));
        Paragraph(L($"Der BSO Launcher {version} ist installiert.", $"The BSO Launcher {version} is installed."));
        Paragraph(installedTo ?? Installer.InstallDir, Muted, 9f);
        Paragraph(L("Deinstallieren kannst du ihn jederzeit in den Launcher-Einstellungen oder unter Windows-Einstellungen → Apps.",
            "You can uninstall it any time in the launcher settings or under Windows Settings → Apps."), Muted, 9f);
        bool start = true;
        Check(L("BSO Launcher jetzt starten", "Start BSO Launcher now"), true, v => start = v);
        Button(L("Fertig", "Finish"), true, () => { if (start) Installer.StartInstalled(); Close(); });
    }

    // ---------------------------------------------------------------- Bausteine

    void Go(Action next)
    {
        page = next;
        Invalidate(); // Kopf (Sprache)
        SuspendLayout();
        content.Controls.Clear();
        buttons.Controls.Clear();
        DrawLangs();
        next();
        ResumeLayout();
    }

    void DrawLangs()
    {
        langs.Controls.Clear();
        foreach (string l in new[] { "de", "en" })
        {
            var b = MakeButton(l.ToUpperInvariant(), Lang.Current == l, () =>
            {
                Lang.Set(l);
                try { var s = Settings.Load(); s.Language = l; s.Save(); } catch { } // gleich auch fuer den Launcher
                Go(page);
            });
            b.AutoSize = false;
            b.MinimumSize = Size.Empty;
            b.Size = new Size(44, 28);
            b.Padding = Padding.Empty;
            b.Margin = new Padding(0, 0, 4, 0);
            b.Font = new Font("Segoe UI", 8.5f, FontStyle.Bold);
            langs.Controls.Add(b);
        }
    }

    void Title(string text) => Paragraph(text, Bright, 15f, 6, FontStyle.Bold);

    Label Paragraph(string text, Color? color = null, float size = 10f, int below = 8, FontStyle style = FontStyle.Regular)
    {
        var label = new Label
        {
            Text = text, AutoSize = true, MaximumSize = new Size(536, 0), ForeColor = color ?? Bright,
            Font = new Font("Segoe UI", size, style), Margin = new Padding(0, 0, 0, below), UseMnemonic = false
        };
        content.Controls.Add(label);
        return label;
    }

    void Check(string text, bool value, Action<bool> changed)
    {
        var box = new CheckBox { Text = text, Checked = value, AutoSize = true, ForeColor = Bright, Margin = new Padding(0, 4, 0, 2), Cursor = Cursors.Hand };
        box.CheckedChanged += (_, _) => changed(box.Checked);
        content.Controls.Add(box);
    }

    void Button(string text, bool primary, Action click) => buttons.Controls.Add(MakeButton(text, primary, click));

    static Button MakeButton(string text, bool primary, Action click)
    {
        var b = new Button
        {
            Text = text, AutoSize = true, MinimumSize = new Size(120, 36), FlatStyle = FlatStyle.Flat, Cursor = Cursors.Hand,
            BackColor = primary ? Accent : Field, ForeColor = Color.White, Font = new Font("Segoe UI", 9.5f, FontStyle.Bold),
            Margin = new Padding(10, 0, 0, 0), Padding = new Padding(12, 0, 12, 0), UseMnemonic = false
        };
        b.FlatAppearance.BorderSize = primary ? 0 : 1;
        b.FlatAppearance.BorderColor = Line;
        b.Click += (_, _) => click();
        return b;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        var g = e.Graphics;
        g.SmoothingMode = SmoothingMode.AntiAlias;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        using (var border = new Pen(Line)) { g.DrawRectangle(border, 0, 0, ClientSize.Width - 1, ClientSize.Height - 1); g.DrawLine(border, 0, Header, ClientSize.Width, Header); }
        if (logo != null) g.DrawImage(logo, 28, 22, 52, 52);
        using var title = new Font("Segoe UI", 15f, FontStyle.Bold);
        TextRenderer.DrawText(g, "BSO Launcher", title, new Point(92, 20), Bright);
        using var sub = new Font("Segoe UI", 9f);
        TextRenderer.DrawText(g, L($"Setup · Version {version}", $"Setup · version {version}"), sub, new Point(94, 52), Muted);
    }

    protected override void OnFormClosing(FormClosingEventArgs e)
    {
        if (installing && e.CloseReason == CloseReason.UserClosing) e.Cancel = true; // nicht mitten im Kopieren abbrechen
        base.OnFormClosing(e);
    }

    [DllImport("user32.dll")] static extern bool ReleaseCapture();
    [DllImport("user32.dll")] static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wParam, IntPtr lParam);

    void DragWindow()
    {
        ReleaseCapture();
        SendMessage(Handle, 0x00A1, 2, IntPtr.Zero); // WM_NCLBUTTONDOWN, HTCAPTION
    }

    /// <summary>Fortschrittsbalken im Launcher-Stil (Verlauf blau -> tuerkis).</summary>
    sealed class Bar : Control
    {
        double value;
        [System.ComponentModel.DesignerSerializationVisibility(System.ComponentModel.DesignerSerializationVisibility.Hidden)]
        public double Value { get => value; set { this.value = Math.Clamp(value, 0, 1); Invalidate(); } }
        public Bar() { DoubleBuffered = true; }

        protected override void OnPaint(PaintEventArgs e)
        {
            var all = new Rectangle(0, 0, Width, Height);
            using (var back = new SolidBrush(Color.FromArgb(0x23, 0x2a, 0x36))) e.Graphics.FillRectangle(back, all);
            if (value <= 0) return;
            using var fill = new LinearGradientBrush(all, Color.FromArgb(0x1f, 0x6f, 0xe5), Color.FromArgb(0x5e, 0xe4, 0xff), 0f);
            e.Graphics.FillRectangle(fill, new Rectangle(0, 0, (int)(Width * value), Height));
        }
    }
}