# EnvelopeGenerator — Copilot Context Notes (English)

## Purpose
A digital document signing system. Senders upload PDFs and place signature annotation fields via PSPDFKit (EnvelopeGenerator.Web). Receivers open the document in a Blazor WASM viewer, confirm each signature field via a checkbox overlay, draw/type/upload their signature, and export the stamped PDF.

---

## Solution Structure

| Project | Target | Description |
|---|---|---|
| `EnvelopeGenerator.API` | net8.0 | ASP.NET Core Web API. Receiver auth (cookie), annotation reading, PDF serving. |
| `EnvelopeGenerator.ReceiverUI` | net8.0 WASM | Blazor WebAssembly. Receiver UI. YARP proxies API calls. |
| `EnvelopeGenerator.Web` | net7/8/9 | Razor Pages. Sender UI + PSPDFKit annotation placement. |
| `EnvelopeGenerator.Application` | multi | MediatR CQRS handlers. |
| `EnvelopeGenerator.Domain` | multi | Domain models, constants, interfaces. |
| `EnvelopeGenerator.Infrastructure` | multi | EF Core repos, DB context. |
| `EnvelopeGenerator.PdfEditor` | multi | iText7 utilities. NOT used in ReceiverUI flow. |
| `EnvelopeGenerator.DependencyInjection` | multi | DI registration helpers. |
| VB.NET projects (Service/Form/BBTests) | net462 | Legacy. Do NOT touch. |

---

## Key Files

| File | Purpose |
|---|---|
| `ReceiverUI/Pages/ReportViewer.razor` | Main receiver page. All signing logic. |
| `ReceiverUI/wwwroot/js/receiver-signature.js` | JS: checkbox overlay, signature pad (draw/type/image). |
| `ReceiverUI/wwwroot/fake-data/annotations.json` | Dev-mode fake annotations (YARP proxy target). |
| `ReceiverUI/Models/AnnotationDto.cs` | Annotation position model. All properties non-nullable. |
| `ReceiverUI/Services/AnnotationService.cs` | Fetches `List<AnnotationDto>` from API or fake-data. |
| `ReceiverUI/Services/DocumentService.cs` | Fetches PDF bytes from API. |
| `ReceiverUI/Services/AuthService.cs` | Manages receiver session cookie. |
| `API/Controllers/AnnotationController.cs` | GET `api/Annotation/{key}` ? annotation list. |
| `API/Controllers/DocumentController.cs` | GET `api/Document/{key}` ? PDF bytes. |

---

## AnnotationDto — Coordinate System

```
Unit   : 1/100 inch (DX units) — DevExpress XtraReports native
Origin : Top-left corner of page
X      : increases rightward
Y      : increases downward

A4 in DX units: Width = 827, Height = 1169

Conversions:
  PSPDFKit (pt, top-left):      xDX = xPsPdf * (100/72)
  GDPicture (pt, bottom-left):  yDX = (pageHeightPt - yGD - elemHeightPt) * (100/72)
  DX ? PDF points:              pt  = dx * (72/100)
```

---

## ReceiverUI Signing Flow (ReportViewer.razor)

### On Load (`OnInitializedAsync`)
1. `AuthService.CheckEnvelopeAccessAsync` ? redirect to login if unauthorized
2. `AnnotationService.GetAnnotationsAsync` ? fills `_annotations`
3. `DocumentService.GetDocumentAsync` ? fills `_basePdfBytes` (real mode)
4. `BuildFreshBaseReport()` ? `XtraReport` for `DxReportViewer`

### Signature Popup
- Tabs: Draw / Text / Image
- Fields: full name (required), position (optional), place (required)
- Saved to `_capturedSignature` record
- If annotations exist ? popup closes ? JS checkbox overlays installed

### JS Checkbox Overlay (`receiver-signature.js`)
- `receiverSignature.installAnnotationCheckboxes(annotations, checkedIds, dotNetRef)`
- One `.annot-sig-cb-wrapper` div per annotation, absolutely positioned over viewer scroll container
- Position: `left = pageRect.left + ann.x * scaleX`, `top = pageRect.top + ann.y * scaleY`
  - `scaleX = pagePixelWidth / 827`, `scaleY = pagePixelHeight / 1169`
- Click ? `dotNetRef.invokeMethodAsync('OnAnnotationToggled', id, checked)`

### Apply Signatures ("Unterschriften anwenden" — `SubmitSignaturesAsync`)

**Real PDF mode (`_basePdfBytes` is set):**
- Calls `StampSignaturesOnPdf` using **iText7** directly on PDF bytes
- Coordinate conversion: `xPt = ann.X * (72/100)`, `yPt = pageHeight - ann.Y * (72/100) - sigHeight` (Y flip: DX top-down ? PDF bottom-up)
- Returns stamped bytes ? loaded into new `XtraReport` with `XRPdfContent`
- Viewer refreshed with `ViewerKey++`

**Dev/fake mode (`_basePdfBytes` is null):**
- Falls back to `AddSignatureAtAnnotation` (XtraReports DetailBand + BeforePrint counter)
- This is intentionally left as a dev fallback only

### Export
- `reportViewer.ExportToAsync(ExportFormat.Pdf)`

---

## StampSignaturesOnPdf — iText7 Implementation

```csharp
// Located in ReportViewer.razor @code section
// Called by SubmitSignaturesAsync when _basePdfBytes is available

static byte[] StampSignaturesOnPdf(
    byte[] sourcePdfBytes, byte[] signatureImageBytes,
    string signerFullName, string signerPosition, string signaturePlace,
    IReadOnlyList<AnnotationDto> annotations)
{
    // Opens PDF with PdfReader/PdfWriter
    // For each annotation:
    //   pageNum = ann.Page (clamped to totalPages)
    //   xPt = ann.X * (72f/100f)
    //   imgBottomY = pageHeight - ann.Y * (72f/100f) - sigHeightPt  ? Y-axis flip
    //   PdfCanvas.AddImageFittedIntoRectangle(imageData, rect, false)
    //   Separator line at bottom of image
    //   Canvas text block below separator (font: Helvetica 7pt, color: RGB(73,80,87))
    // Returns stamped byte[]
}
```

---

## BuildFreshBaseReport()

```csharp
// Real PDF mode:
var report = new XtraReport();
var detail = new DetailBand();
report.Bands.Add(detail);
detail.Controls.Add(new XRPdfContent { Source = _basePdfBytes, GenerateOwnPages = true });
return report;

// Dev/fake mode: returns pre-built report from ReportStorage
```

---

## NuGet Packages in ReceiverUI

| Package | Version | Purpose |
|---|---|---|
| `DevExpress.Blazor.Reporting.Viewer` | 25.2.3 | DxReportViewer component |
| `DevExpress.Blazor.PdfViewer` | 25.2.3 | PDF viewer |
| `DevExpress.Drawing.Skia` | 25.2.3 | Drawing backend |
| `itext` | 8.0.5 | PDF stamping (iText7) |
| `SkiaSharp.*` | 3.119.1 | WASM native rendering |

---

## Mistakes History — Do NOT Repeat

| Mistake | Why Wrong |
|---|---|
| `BottomMarginBand` for per-page signatures | Repeats on every page; Y offset wrong |
| `imageY = (page-1) * 1169 + ann.Y` | Inflates DetailBand; 35 pages ? 140 pages |
| `e.Graph?.PrintingSystem` in BeforePrint | `Graph` not on `CancelEventArgs` |
| `ctrl.Report?.PrintingSystem` | `PrintingSystem` not on `XtraReportBase` in WASM |
| Adding stamp endpoint to `DocumentController` | Not needed; stamping is done client-side in ReceiverUI |
| iText7 via API (server-side) | Unnecessary; iText7 runs fine in WASM directly |

---

## DevExpress Article (2023-08-28) — Why It Does NOT Apply

The article describes **X.509 cryptographic digital signatures** via `PdfDocumentSigner` + `Pkcs7Signer`.  
Our use case is **visual/image stamping** at specific page coordinates — different problem, different API.  
`XRPdfSignature` in the article requires pre-placed fields in the report designer, not runtime coordinates.

---

## Change Log

| Session | Date | Change |
|---|---|---|
| 1–3 | — | Core infrastructure: services, YARP proxy, JS overlay, signature pad |
| 4 | — | `AddSignatureAtAnnotation` with BottomMarginBand — ? repeated on all pages |
| 5 | — | `BeforePrint` + `e.Graph?.PrintingSystem` — ? compile error |
| 6 | — | BeforePrint counter — ? correct pattern, wrong band |
| 7 | — | Switched to DetailBand — ? correct band |
| 8 | — | `(page-1)*1169+Y` offset — ? 35?140 page inflation |
| 9 | — | Fixed: `BoundsF.Y = ann.Y` + counter; created COPILOT_CONTEXT.md |
| 10 | — | Investigated DevExpress article — not applicable to our case |
| 10 | — | Added iText7 to ReceiverUI; implemented `StampSignaturesOnPdf` — ? deterministic coordinates, no page count side effects |
| 10 | — | Split COPILOT_CONTEXT.md into COPILOT_CONTEXT_EN.md and COPILOT_CONTEXT_TR.md |