# C4 Architecture Document - Level 3: Component Diagram (Landing Page)

Detailed breakdown of the logical components within the **Sales Landing App** and **BFF Service**.

## 1. Frontend Components (Sales Landing App)

### 1.1. Modules
- **Auth Module**: Login form, Token handling.
- **Customer Module**: Input form, Camera/Upload Component for OCR.
- **Product Module**: Product selection interface (Card selection for UVL-IC/UVL-EL).
- **Illustration Module**: PDF display (PDF Viewer) and download/Submit buttons.

### 1.2. Shared
- **UI Kit**: Button, Input, Modal (matching the Design System).
- **API Client**: Axios wrapper for calling the BFF.

## 2. Backend Components (BFF Service)

### 2.1. Controllers
- **AuthController**: Authentication via Auth API.
- **OCRController**: Proxies images to the OCR Service.
- **IllustrationController**: Aggregates data -> Calls PDF Engine -> Returns URL/File.
- **SubmissionController**: Submits final data to the Core system.

### 2.2. Services
- **ClientService**: Saves/Retrieves customer information from the Database.

## 3. Component Diagram

```mermaid
C4Component
    title Component Diagram - Landing Page System

    Container_Boundary(frontend, "Sales Landing App") {
        Component(c_auth, "Auth Module", "React", "Login Screen")
        Component(c_cust, "Customer Module", "React", "Form & OCR Upload")
        Component(c_pdf, "Illustration Module", "React", "PDF View & Submit")
    }

    Container_Boundary(backend, "BFF Service") {
        Component(ctl_ocr, "OCR Controller", "Node.js", "Handle Upload & Proxy")
        Component(ctl_ill, "Illustration Controller", "Node.js", "Coordinate PDF Gen")
        Component(svc_client, "Client Service", "Node.js", "Manage Client Data DB")
    }

    ContainerDb(db, "PostgreSQL", "Database", "Store Drafts")
    System_Ext(ocr_ext, "External OCR", "Service")
    System_Ext(pdf_ext, "External PDF Gen", "Service")

    Rel(c_auth, ctl_ocr, "Authenticated Req")
    Rel(c_cust, ctl_ocr, "Upload Image")
    Rel(c_cust, ctl_ill, "Request PDF")
    
    Rel(ctl_ocr, ocr_ext, "Proxy")
    Rel(ctl_ill, pdf_ext, "Proxy")
    Rel(ctl_ill, svc_client, "Save Info")
    Rel(svc_client, db, "Persist")
```

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*Authored by: Agent mbl-landing-page-architecture*