@implements IAsyncDisposable
@inject IJSRuntime JS

@if (IsOpen)
{
    <div class="qr-overlay" @onclick="Cancel">
        <div class="qr-dialog" role="dialog" aria-modal="true" aria-labelledby="qr-title" @onclick:stopPropagation="true">
            <div class="qr-header">
                <div>
                    <h3 id="qr-title">@Title</h3>
                    @if (!string.IsNullOrEmpty(Subtitle))
                    {
                        <p class="qr-subtitle">@Subtitle</p>
                    }
                </div>
                <button type="button" class="qr-close" @onclick="Cancel" aria-label="Schließen">✕</button>
            </div>

            <div class="qr-body">
                <div id="@_elementId" class="qr-viewport"></div>

                @if (isStarting)
                {
                    <div class="qr-status"><span class="spinner"></span> Kamera wird gestartet…</div>
                }
                else if (!string.IsNullOrEmpty(cameraError))
                {
                    <div class="qr-status error">📷 @cameraError</div>
                }
                else
                {
                    <div class="qr-status">QR-Code des Reports vor die Kamera halten</div>
                }

                <div class="qr-manual">
                    <label for="qr-manual-input">Oder Link / Nummer einfügen</label>
                    <div class="qr-manual-row">
                        <input id="qr-manual-input" type="text" class="form-control" placeholder="https://files.cnlaunch.com/…?dataRecordSn=…"
                               @bind="manualText" @bind:event="oninput" @onkeydown="OnManualKeyDown" />
                        <button type="button" class="btn btn-primary" @onclick="SubmitManual" disabled="@string.IsNullOrWhiteSpace(manualText)">Übernehmen</button>
                    </div>
                </div>
            </div>
        </div>
    </div>
}

@code {
    [Parameter] public bool IsOpen { get; set; }
    [Parameter] public EventCallback<bool> IsOpenChanged { get; set; }
    [Parameter] public string Title { get; set; } = "QR-Code scannen";
    [Parameter] public string? Subtitle { get; set; }
    [Parameter] public EventCallback<string> OnScanned { get; set; }

    private readonly string _elementId = $"qr-reader-{Guid.NewGuid():N}";
    private DotNetObjectReference<QrScannerModal>? _selfRef;
    private bool _scannerActive;
    private bool _wasOpen;
    private bool isStarting;
    private string? cameraError;
    private string manualText = "";

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (IsOpen && !_wasOpen)
        {
            _wasOpen = true;
            await StartScanner();
        }
        else if (!IsOpen && _wasOpen)
        {
            _wasOpen = false;
            await StopScanner();
        }
    }

    private async Task StartScanner()
    {
        cameraError = null;
        isStarting = true;
        manualText = "";
        StateHasChanged();

        try
        {
            _selfRef ??= DotNetObjectReference.Create(this);
            await JS.InvokeVoidAsync("qrScanner.start", _elementId, _selfRef);
            _scannerActive = true;
        }
        catch (JSException ex)
        {
            cameraError = ExtractMessage(ex.Message);
        }
        catch (Exception ex)
        {
            cameraError = ex.Message;
        }
        finally
        {
            isStarting = false;
            StateHasChanged();
        }
    }

    private static string ExtractMessage(string raw)
    {
        if (raw.Contains("NotAllowedError", StringComparison.OrdinalIgnoreCase) || raw.Contains("Permission", StringComparison.OrdinalIgnoreCase))
            return "Kamerazugriff wurde verweigert. Bitte Berechtigung im Browser erlauben.";
        if (raw.Contains("NotFoundError", StringComparison.OrdinalIgnoreCase) || raw.Contains("Keine Kamera", StringComparison.OrdinalIgnoreCase))
            return "Keine Kamera gefunden.";
        var idx = raw.IndexOf('\n');
        return idx > 0 ? raw[..idx] : raw;
    }

    private async Task StopScanner()
    {
        if (!_scannerActive) return;
        _scannerActive = false;
        try { await JS.InvokeVoidAsync("qrScanner.stop"); } catch { }
    }

    [JSInvokable]
    public async Task OnQrScanned(string text)
    {
        if (string.IsNullOrWhiteSpace(text)) return;
        await Close();
        await OnScanned.InvokeAsync(text.Trim());
    }

    private async Task SubmitManual()
    {
        if (string.IsNullOrWhiteSpace(manualText)) return;
        var text = manualText.Trim();
        await Close();
        await OnScanned.InvokeAsync(text);
    }

    private async Task OnManualKeyDown(KeyboardEventArgs e)
    {
        if (e.Key == "Enter") await SubmitManual();
    }

    private async Task Cancel() => await Close();

    private async Task Close()
    {
        await StopScanner();
        _wasOpen = false;
        if (IsOpen)
        {
            IsOpen = false;
            await IsOpenChanged.InvokeAsync(false);
        }
    }

    public async ValueTask DisposeAsync()
    {
        await StopScanner();
        _selfRef?.Dispose();
    }
}