EnvelopeGenerator/EnvelopeGenerator.ReceiverUI/Pages/ReportViewer.razor

@page "/receiver"
@using System.Drawing
@using DevExpress.Drawing
@using DevExpress.Utils
@using DevExpress.XtraPrinting
@using DevExpress.XtraPrinting.Drawing
@using XtraReport = DevExpress.XtraReports.UI.XtraReport
@using BottomMarginBand = DevExpress.XtraReports.UI.BottomMarginBand
@using XRLabel = DevExpress.XtraReports.UI.XRLabel
@using XRPictureBox = DevExpress.XtraReports.UI.XRPictureBox
@using XRControl = DevExpress.XtraReports.UI.XRControl
@using ImageSizeMode = DevExpress.XtraPrinting.ImageSizeMode
@using EnvelopeGenerator.ReceiverUI.Services;
@inject IJSRuntime JSRuntime
@inject InMemoryReportStorageWebExtension ReportStorage

<link href="_content/DevExpress.Blazor.Themes/blazing-berry.bs5.min.css" rel="stylesheet" />
<link href="_content/DevExpress.Blazor.Reporting.Viewer/css/dx-blazor-reporting-components.bs5.css" rel="stylesheet" />

<div class="card m-3">
    <div class="card-body">
        <h5 class="card-title">Unterschrift</h5>
        <p class="card-text text-muted mb-2">
            @if(SignatureApplied) {
                <span>Die Unterschrift wurde dem Bericht hinzugefuegt. Sie koennen die Unterschrift erneuern oder das signierte PDF exportieren.</span>
            } else {
                <span>Bitte fuegen Sie vor dem PDF-Export Ihre Unterschrift hinzu.</span>
            }
        </p>
        @if(!string.IsNullOrWhiteSpace(SignatureValidationMessage)) {
            <div class="text-danger mb-2">@SignatureValidationMessage</div>
        }
        <div class="d-flex gap-2 flex-wrap">
            <button class="btn btn-primary" @onclick="OpenSignaturePopupAsync">
                @(SignatureApplied ? "Unterschrift erneuern" : "Unterschrift hinzufuegen")
            </button>
            <button class="btn btn-success" disabled="@(!SignatureApplied)" @onclick="ExportSignedPdfAsync">Signiertes PDF exportieren</button>
        </div>
    </div>
</div>

<DxPopup @bind-Visible="SignaturePopupVisible"
         HeaderText="Unterschrift erfassen"
         Width="620px"
         ShowFooter="true"
         CloseOnEscape="true"
         CloseOnOutsideClick="false">
    <BodyContentTemplate>
        <ul class="nav nav-tabs mb-3">
            <li class="nav-item">
                <button type="button" class="nav-link @(ActiveSignatureTab == SignatureTabDraw ? "active" : null)" @onclick="() => SetSignatureTabAsync(SignatureTabDraw)">Zeichnen</button>
            </li>
            <li class="nav-item">
                <button type="button" class="nav-link @(ActiveSignatureTab == SignatureTabText ? "active" : null)" @onclick="() => SetSignatureTabAsync(SignatureTabText)">Text</button>
            </li>
            <li class="nav-item">
                <button type="button" class="nav-link @(ActiveSignatureTab == SignatureTabImage ? "active" : null)" @onclick="() => SetSignatureTabAsync(SignatureTabImage)">Bild</button>
            </li>
        </ul>

        @if(ActiveSignatureTab == SignatureTabDraw) {
            <p class="text-muted mb-2">Bitte unterschreiben Sie im folgenden Feld.</p>
            <canvas id="receiver-signature-pad" width="520" height="160" class="border rounded bg-white w-100" style="max-width: 520px; touch-action: none;"></canvas>
        } else if(ActiveSignatureTab == SignatureTabText) {
            <p class="text-muted mb-2">Geben Sie Ihre Unterschrift als Text ein und waehlen Sie eine Schriftart.</p>
            <div class="row g-2 mb-2">
                <div class="col-12 col-md-7">
                    <input class="form-control" placeholder="Ihre Unterschrift" value="@TypedSignatureText" @oninput="OnTypedSignatureChanged" />
                </div>
                <div class="col-12 col-md-5">
                    <select class="form-select" value="@TypedSignatureFont" @onchange="OnTypedSignatureFontChanged">
                        @foreach(var font in TypedSignatureFonts) {
                            <option value="@font.Value" style="font-family: @font.Value">@font.Text</option>
                        }
                    </select>
                </div>
            </div>
            <canvas id="receiver-typed-signature-pad" width="520" height="160" class="border rounded bg-white w-100" style="max-width: 520px;"></canvas>
        } else {
            <p class="text-muted mb-2">Laden Sie ein Bild Ihrer Unterschrift hoch.</p>
            <input id="receiver-signature-image-input" class="form-control mb-2" type="file" accept="image/png,image/jpeg,image/webp" />
            <canvas id="receiver-image-signature-pad" width="520" height="160" class="border rounded bg-white w-100" style="max-width: 520px;"></canvas>
        }


        <div class="border-top mt-3 pt-3">
            <p class="text-muted mb-2">Bitte geben Sie die folgenden Angaben ein. Das Datum wird automatisch hinzugefuegt.</p>
            <div class="row g-2">
                <div class="col-12 col-md-6">
                    <label class="form-label" for="receiver-signer-name">Vor- und Nachname *</label>
                    <input id="receiver-signer-name" class="form-control" value="@SignerFullName" @oninput="args => SignerFullName = args.Value?.ToString() ?? string.Empty" />
                </div>
                <div class="col-12 col-md-6">
                    <label class="form-label" for="receiver-signer-position">Position</label>
                    <input id="receiver-signer-position" class="form-control" value="@SignerPosition" @oninput="args => SignerPosition = args.Value?.ToString() ?? string.Empty" />
                </div>
                <div class="col-12 col-md-6">
                    <label class="form-label" for="receiver-signature-place">Ort *</label>
                    <input id="receiver-signature-place" class="form-control" value="@SignaturePlace" @oninput="args => SignaturePlace = args.Value?.ToString() ?? string.Empty" />
                </div>
            </div>
        </div>

        @if(!string.IsNullOrWhiteSpace(PopupValidationMessage)) {
            <div class="text-danger mt-2">@PopupValidationMessage</div>
        }
    </BodyContentTemplate>
    <FooterContentTemplate>
        <div class="d-flex gap-2 flex-wrap justify-content-end w-100">
            <button class="btn btn-outline-secondary" @onclick="RenewSignatureAsync">Unterschrift erneuern</button>
            <button class="btn btn-primary" @onclick="ApplySignatureAsync">Zum Bericht hinzufuegen</button>
            <button class="btn btn-secondary" @onclick="CloseSignaturePopup">Schliessen</button>
        </div>
    </FooterContentTemplate>
</DxPopup>

@if(Report is not null) {
    <DxReportViewer @key="ViewerKey" @ref="reportViewer" Report="Report" RootCssClasses="w-100 h-100" />
}

@code {
    const string SignatureTabDraw = "draw";
    const string SignatureTabText = "text";
    const string SignatureTabImage = "image";
    const string DrawCanvasId = "receiver-signature-pad";
    const string TypedCanvasId = "receiver-typed-signature-pad";
    const string ImageInputId = "receiver-signature-image-input";
    const string ImageCanvasId = "receiver-image-signature-pad";

    readonly (string Text, string Value)[] TypedSignatureFonts = {
        ("Brush Script", "'Brush Script MT', cursive"),
        ("Segoe Script", "'Segoe Script', cursive"),
        ("Lucida Handwriting", "'Lucida Handwriting', cursive"),
        ("Comic Sans", "'Comic Sans MS', cursive"),
        ("Cursive", "cursive")
    };

    DxReportViewer reportViewer;
    XtraReport? Report;
    bool SignatureApplied;
    bool SignaturePopupVisible;
    string? SignatureValidationMessage;
    string? PopupValidationMessage;
    string ActiveSignatureTab = SignatureTabDraw;
    string TypedSignatureText = string.Empty;
    string TypedSignatureFont = "'Brush Script MT', cursive";
    string SignerFullName = string.Empty;
    string SignerPosition = string.Empty;
    string SignaturePlace = string.Empty;
    int ViewerKey;

    protected override async Task OnInitializedAsync() {
        Report = CreateReportInstance();

        await Task.CompletedTask;
    }

    async Task OpenSignaturePopupAsync() {
        ActiveSignatureTab = SignatureTabDraw;
        SignaturePopupVisible = true;
        SignatureValidationMessage = null;
        PopupValidationMessage = null;
        await InvokeAsync(StateHasChanged);
        await Task.Delay(50);
        await InitializeActiveSignatureTabAsync();
    }

    async Task SetSignatureTabAsync(string tab) {
        ActiveSignatureTab = tab;
        PopupValidationMessage = null;
        await InvokeAsync(StateHasChanged);
        await Task.Delay(50);
        await InitializeActiveSignatureTabAsync();
    }

    async Task InitializeActiveSignatureTabAsync() {
        if(ActiveSignatureTab == SignatureTabDraw) {
            await JSRuntime.InvokeVoidAsync("receiverSignature.initialize", DrawCanvasId);
        } else if(ActiveSignatureTab == SignatureTabText) {
            await JSRuntime.InvokeVoidAsync("receiverSignature.initializeTyped", TypedCanvasId);
            await RenderTypedSignatureAsync();
        } else {
            await JSRuntime.InvokeVoidAsync("receiverSignature.initializeImage", ImageInputId, ImageCanvasId);
        }
    }

    async Task RenewSignatureAsync() {
        PopupValidationMessage = null;

        if(ActiveSignatureTab == SignatureTabDraw) {
            await JSRuntime.InvokeVoidAsync("receiverSignature.clear", DrawCanvasId);
        } else if(ActiveSignatureTab == SignatureTabText) {
            TypedSignatureText = string.Empty;
            await JSRuntime.InvokeVoidAsync("receiverSignature.clearTyped", TypedCanvasId);
        } else {
            await JSRuntime.InvokeVoidAsync("receiverSignature.clearImage", ImageInputId, ImageCanvasId);
        }
    }

    void CloseSignaturePopup() {
        PopupValidationMessage = null;
        SignaturePopupVisible = false;
    }

    async Task OnTypedSignatureChanged(Microsoft.AspNetCore.Components.ChangeEventArgs args) {
        TypedSignatureText = args.Value?.ToString() ?? string.Empty;
        await RenderTypedSignatureAsync();
    }

    async Task OnTypedSignatureFontChanged(Microsoft.AspNetCore.Components.ChangeEventArgs args) {
        TypedSignatureFont = args.Value?.ToString() ?? TypedSignatureFont;
        await RenderTypedSignatureAsync();
    }

    async Task RenderTypedSignatureAsync() {
        await JSRuntime.InvokeVoidAsync("receiverSignature.renderTypedSignature", TypedCanvasId, TypedSignatureText, TypedSignatureFont);
    }

    async Task ApplySignatureAsync() {
        if(string.IsNullOrWhiteSpace(SignerFullName)) {
            PopupValidationMessage = "Bitte geben Sie Vor- und Nachname ein.";
            return;
        }

        if(string.IsNullOrWhiteSpace(SignaturePlace)) {
            PopupValidationMessage = "Bitte geben Sie den Ort ein.";
            return;
        }

        var signatureDataUrl = await GetActiveSignatureDataUrlAsync();

        if(string.IsNullOrWhiteSpace(signatureDataUrl)) {
            PopupValidationMessage = "Die Unterschrift ist fuer den PDF-Export erforderlich.";
            return;
        }

        PopupValidationMessage = null;
        SignatureValidationMessage = null;
        Report = CreateSignedReportInstance(signatureDataUrl, SignerFullName.Trim(), SignerPosition.Trim(), SignaturePlace.Trim());
        SignatureApplied = true;
        SignaturePopupVisible = false;
        ViewerKey++;
    }

    async Task<string?> GetActiveSignatureDataUrlAsync() {
        if(ActiveSignatureTab == SignatureTabDraw)
            return await JSRuntime.InvokeAsync<string?>("receiverSignature.getDataUrl", DrawCanvasId);

        if(ActiveSignatureTab == SignatureTabText) {
            await RenderTypedSignatureAsync();
            return await JSRuntime.InvokeAsync<string?>("receiverSignature.getTypedDataUrl", TypedCanvasId);
        }

        return await JSRuntime.InvokeAsync<string?>("receiverSignature.getImageDataUrl", ImageCanvasId);
    }

    async Task ExportSignedPdfAsync() {
        if(!SignatureApplied || Report is null) {
            SignatureValidationMessage = "Bitte fuegen Sie die Unterschrift zuerst zum Bericht hinzu.";
            return;
        }

        try {
            SignatureValidationMessage = null;
            await reportViewer.ExportToAsync(ExportFormat.Pdf);
        } catch(Exception) {
            SignatureValidationMessage = "Das signierte PDF konnte nicht exportiert werden. Bitte laden Sie die Seite neu und versuchen Sie es erneut.";
        }
    }

    XtraReport CreateReportInstance() {
        return ReportStorage.TryGetReport("LargeDatasetReport", out var savedReport)
            ? savedReport
            : PredefinedReports.ReportsFactory.GetReport("LargeDatasetReport");
    }

    XtraReport CreateSignedReportInstance(string signatureDataUrl, string signerFullName, string signerPosition, string signaturePlace) {
        var report = CreateReportInstance();
        AddSignature(report, signatureDataUrl, signerFullName, signerPosition, signaturePlace);
        return report;
    }

    static void AddSignature(XtraReport report, string signatureDataUrl, string signerFullName, string signerPosition, string signaturePlace) {
        var imageBytes = Convert.FromBase64String(signatureDataUrl[(signatureDataUrl.IndexOf(',') + 1)..]);
        using var imageStream = new MemoryStream(imageBytes);
        var imageSource = new ImageSource(DXImage.FromStream(imageStream));
        var bottomMargin = report.Bands.OfType<BottomMarginBand>().FirstOrDefault();

        if(bottomMargin is null) {
            bottomMargin = new BottomMarginBand();
            report.Bands.Add(bottomMargin);
        }

        RemoveExistingSignature(bottomMargin);

        // Layout constants
        const float sigX         = 390F;
        const float sigWidth     = 230F;
        const float sigImgHeight = 70F;
        const float infoHeight   = 65F;  // up to 4 lines at 8pt
        const float innerGap     = 5F;
        const float bottomPad    = 6F;
        const float defaultTopPad = 8F;
        const float maxBandHeight = 210F;

        float requiredHeight = defaultTopPad + sigImgHeight + innerGap + infoHeight + bottomPad;

        // Grow band if needed, but cap at maxBandHeight to avoid overlapping page content
        bottomMargin.HeightF = Math.Min(maxBandHeight, Math.Max(bottomMargin.HeightF, requiredHeight));

        // If band is tighter than required, compress top padding so content still fits
        float topPad = Math.Max(0F, bottomMargin.HeightF - bottomPad - infoHeight - innerGap - sigImgHeight);

        float imageY = topPad;
        float labelY = imageY + sigImgHeight + innerGap;

        var signatureInformation = string.IsNullOrWhiteSpace(signerPosition)
            ? $"Empfaengerunterschrift\n{signerFullName}\n{signaturePlace}, {DateTime.Now:d}"
            : $"Empfaengerunterschrift\n{signerFullName}\n{signerPosition}\n{signaturePlace}, {DateTime.Now:d}";

        var signature = new XRPictureBox {
            Name = "receiverSignatureImage",
            ImageSource = imageSource,
            BoundsF = new RectangleF(sigX, imageY, sigWidth, sigImgHeight),
            Sizing = ImageSizeMode.ZoomImage,
            Borders = BorderSide.Bottom,
            BorderColor = System.Drawing.Color.FromArgb(73, 80, 87)
        };

        var signatureLabel = new XRLabel {
            Name = "receiverSignatureLabel",
            Text = signatureInformation,
            Multiline = true,
            BoundsF = new RectangleF(sigX, labelY, sigWidth, infoHeight),
            Font = new DXFont("Open Sans", 8F, DXFontStyle.Regular),
            ForeColor = System.Drawing.Color.FromArgb(73, 80, 87),
            TextAlignment = TextAlignment.TopLeft
        };

        bottomMargin.Controls.AddRange(new XRControl[] { signature, signatureLabel });
    }

    static void RemoveExistingSignature(BottomMarginBand bottomMargin) {
        var controls = bottomMargin.Controls
            .Cast<XRControl>()
            .Where(control => control.Name is "receiverSignatureLabel" or "receiverSignatureImage")
            .ToArray();

        foreach(var control in controls)
            bottomMargin.Controls.Remove(control);
    }
}