# System Architecture

## System Overview

SlpModularCms is a modular, ASP.NET Core-based CMS platform. The backend is structured as a monolith-with-modules: a single API host (`SlpModularCms.Api`) that dynamically loads feature modules at startup. Each module is self-contained and registers its own services and HTTP middleware. Persistence is handled via Entity Framework Core with SQL Server. Authentication uses JWT Bearer tokens with refresh token rotation.

The frontend is a React SPA (to be built) that communicates with the API via REST/JSON. The example app (from ZIP) provides the design foundation: Vite + React Router v7 + shadcn/ui + Tailwind CSS v4 with primary color `#ac0000`.

## Architecture Diagram

```mermaid
graph TD
    subgraph ClientLayer["Client Layer"]
        Frontend["React SPA\nVite + TanStack Router + shadcn/ui\nTailwind CSS v4 #ac0000"]
    end

    subgraph ApiLayer["API Layer"]
        Api["SlpModularCms.Api\nASP.NET Core\nJWT Bearer, CORS, Swagger"]
        Identity["Identity Module\nAuthController\nSetupController\nUsersController"]
        Avail["Availability Module\nAvailabilityController\nPersistentService + CircuitBreaker"]
    end

    subgraph CoreLayer["Core Layer"]
        Core["SlpModularCms.Core\nApplicationDbContext\nDomain Entities\nIdentity Services\nIModule interface"]
    end

    subgraph DataLayer["Data Layer"]
        DB[("SQL Server\nIdentity tables\nRefreshTokens\nInvitations\nGlobalAvailabilityState")]
    end

    Frontend -->|HTTP REST / JSON| Api
    Api --> Identity
    Api --> Avail
    Identity --> Core
    Avail --> Core
    Core --> DB

    style Frontend fill:#2196F3,stroke:#0D47A1,color:#fff
    style Api fill:#4CAF50,stroke:#2E7D32,color:#fff
    style Identity fill:#4CAF50,stroke:#2E7D32,color:#fff
    style Avail fill:#4CAF50,stroke:#2E7D32,color:#fff
    style Core fill:#FFC107,stroke:#F57F17,color:#000
    style DB fill:#FF5722,stroke:#BF360C,color:#fff
```

## Component Descriptions

### SlpModularCms.Api
- **Purpose**: Web API host and application entry point
- **Responsibilities**: Bootstrap, module loading, middleware pipeline, CORS, Swagger
- **Dependencies**: SlpModularCms.Core, SlpModularCms.Modules.Identity, SlpModularCms.Modules.Availability
- **Type**: Application

### SlpModularCms.Core
- **Purpose**: Shared domain layer
- **Responsibilities**: Domain entities, EF Core DbContext, authentication services, module interface
- **Dependencies**: EF Core, ASP.NET Identity, SQL Server provider
- **Type**: Shared Library

### SlpModularCms.Modules.Identity
- **Purpose**: Identity and user management module
- **Responsibilities**: HTTP endpoints for auth, setup, and user invitation flows
- **Dependencies**: SlpModularCms.Core
- **Type**: Application Module

### SlpModularCms.Modules.Availability
- **Purpose**: System availability tracking module
- **Responsibilities**: Exposes system status, allows owners to update it, caches with circuit breaker
- **Dependencies**: SlpModularCms.Core
- **Type**: Application Module

### SlpModularCms.Frontend (To Be Built)
- **Purpose**: Admin SPA for CMS management
- **Responsibilities**: Login, dashboard, user management, CMS content management, availability status display
- **Dependencies**: SlpModularCms.Api (REST)
- **Type**: Frontend Application

## Data Flow

```mermaid
sequenceDiagram
    participant Browser
    participant AuthController
    participant AuthService
    participant DB

    Note over Browser,DB: Login Flow
    Browser->>AuthController: POST /auth/login
    AuthController->>AuthService: AuthenticateAsync()
    AuthService->>DB: Validate credentials
    DB-->>AuthService: User found
    AuthService-->>AuthController: access + refresh tokens
    AuthController-->>Browser: 200 OK with tokens

    Note over Browser,DB: Invite Flow
    Browser->>AuthController: POST /users/invite
    AuthController->>AuthService: CreateInvitationAsync()
    AuthService->>DB: Store Invitation entity
    DB-->>AuthService: Stored
    AuthService-->>AuthController: invite token
    AuthController-->>Browser: 200 OK with invite link

    Note over Browser,DB: New User Setup
    Browser->>AuthController: POST /users/complete-setup
    AuthController->>AuthService: CompleteInvitationAsync()
    AuthService->>DB: Set password, activate account
    DB-->>AuthService: Updated
    AuthService-->>AuthController: success
    AuthController-->>Browser: 200 OK
```

## Integration Points
- **External APIs**: None currently
- **Databases**: SQL Server (via EF Core)
- **Third-party Services**: None currently

## Infrastructure Components
- **Deployment Model**: Single API process + React SPA (separate deploy or static files)
- **Authentication**: JWT Bearer tokens (HS256 or RS256 based on JwtSettings config)
- **Database Migrations**: EF Core Code-First migrations in SlpModularCms.Core/Migrations/