using LicenseLabrador.Client;

namespace Predictalytics.WinFormsHost.Services;

/// <summary>
/// Modal dialog shown at startup when no usable license is present.
/// Lets the user enter/activate a license key; closes with OK only after a
/// successful, checksum-verified validation.
/// </summary>
public sealed class LicenseDialog : Form
{
    private readonly LicenseClient _client;
    private readonly Label _lblStatus;
    private readonly TextBox _txtKey;
    private readonly Button _btnActivate;
    private readonly Button _btnExit;

    public LicenseResult? Result { get; private set; }

    public LicenseDialog(LicenseClient client, LicenseResult? lastResult)
    {
        _client = client;

        Text = "Predictalytics — Lizenzaktivierung";
        FormBorderStyle = FormBorderStyle.FixedDialog;
        MaximizeBox = false;
        MinimizeBox = false;
        StartPosition = FormStartPosition.CenterScreen;
        ClientSize = new Size(460, 190);

        var lblInfo = new Label
        {
            Text = "Diese Installation benötigt eine gültige Lizenz.\nBitte Lizenzschlüssel eingeben (Format: XXXXX-XXXXX-XXXXX-XXXXX-XXXXX):",
            Location = new Point(12, 12),
            Size = new Size(436, 34)
        };

        _txtKey = new TextBox
        {
            Location = new Point(12, 52),
            Size = new Size(436, 26),
            Font = new Font("Consolas", 11f),
            CharacterCasing = CharacterCasing.Upper
        };

        _lblStatus = new Label
        {
            Location = new Point(12, 84),
            Size = new Size(436, 50),
            ForeColor = Color.Firebrick,
            Text = FormatInitialStatus(lastResult)
        };

        _btnActivate = new Button
        {
            Text = "Aktivieren",
            Location = new Point(252, 146),
            Size = new Size(96, 30)
        };
        _btnActivate.Click += async (_, _) => await ActivateAsync();

        _btnExit = new Button
        {
            Text = "Beenden",
            Location = new Point(354, 146),
            Size = new Size(94, 30),
            DialogResult = DialogResult.Cancel
        };

        AcceptButton = _btnActivate;
        CancelButton = _btnExit;
        Controls.AddRange(new Control[] { lblInfo, _txtKey, _lblStatus, _btnActivate, _btnExit });
    }

    private static string FormatInitialStatus(LicenseResult? lastResult)
    {
        if (lastResult == null || lastResult.State == LicenseState.NoLicense) return "";
        return $"Letzte Prüfung: {lastResult.State} — {lastResult.Message}";
    }

    private async Task ActivateAsync()
    {
        var key = _txtKey.Text.Trim();
        if (string.IsNullOrWhiteSpace(key))
        {
            _lblStatus.Text = "Bitte einen Lizenzschlüssel eingeben.";
            return;
        }

        _btnActivate.Enabled = false;
        _lblStatus.ForeColor = Color.DimGray;
        _lblStatus.Text = "Prüfe Lizenz am Server...";

        try
        {
            var result = await _client.ValidateAsync(key);
            if (result.IsUsable && _client.VerifyChecksum(result))
            {
                Result = result;
                DialogResult = DialogResult.OK;
                Close();
                return;
            }

            _lblStatus.ForeColor = Color.Firebrick;
            _lblStatus.Text = $"Lizenz nicht nutzbar ({result.State}):\n{result.Message}";
        }
        catch (Exception ex)
        {
            _lblStatus.ForeColor = Color.Firebrick;
            _lblStatus.Text = $"Fehler bei der Prüfung: {ex.Message}";
        }
        finally
        {
            _btnActivate.Enabled = true;
        }
    }
}