# 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

```
+--------------------------------------------------+
|              Client Layer                        |
|  +--------------------------------------------+ |
|  |   React SPA (SlpModularCms.Frontend)       | |
|  |   Vite + React Router v7 + shadcn/ui       | |
|  |   Tailwind CSS v4 (#ac0000 theme)          | |
|  +--------------------------------------------+ |
+---------------------------+----------------------+
                            | HTTP REST / JSON
+---------------------------v----------------------+
|              API Layer                           |
|  +--------------------------------------------+ |
|  |       SlpModularCms.Api (ASP.NET Core)     | |
|  |   - JWT Bearer Auth Middleware             | |
|  |   - CORS, Swagger/OpenAPI                  | |
|  |   - Module registration pipeline          | |
|  +--------------------------------------------+ |
|                                                  |
|  +------------------+  +---------------------+  |
|  |  Identity Module |  | Availability Module |  |
|  |  - AuthController|  | - AvailabilityCtrl  |  |
|  |  - SetupCtrl     |  | - PersistentService |  |
|  |  - UsersCtrl     |  | - CircuitBreaker    |  |
|  +------------------+  +---------------------+  |
+---------------------------+----------------------+
                            |
+---------------------------v----------------------+
|              Core Layer                          |
|  +--------------------------------------------+ |
|  |          SlpModularCms.Core                | |
|  |  - ApplicationDbContext (EF Core)          | |
|  |  - Domain Entities                         | |
|  |  - Identity Services (Auth, Setup, Invite) | |
|  |  - IModule interface + ModuleInfo          | |
|  +--------------------------------------------+ |
+---------------------------+----------------------+
                            |
+---------------------------v----------------------+
|              Data Layer                          |
|  +--------------------------------------------+ |
|  |         SQL Server Database                | |
|  |  - ASP.NET Identity tables                 | |
|  |  - RefreshTokens                           | |
|  |  - Invitations                             | |
|  |  - GlobalAvailabilityState                 | |
|  +--------------------------------------------+ |
+--------------------------------------------------+
```

## 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

```
Login Flow:
  Browser -> POST /auth/login -> AuthController
          -> AuthService.AuthenticateAsync()
          -> PasswordHasher validates credentials
          -> JwtService generates access + refresh tokens
          -> Returns {accessToken, refreshToken}

Invite Flow:
  Admin -> POST /users/invite -> UsersController
        -> InvitationService.CreateInvitationAsync()
        -> Stores Invitation entity with token
        -> Returns invite link

New User Setup:
  User -> POST /users/complete-setup -> UsersController
       -> InvitationService.CompleteInvitationAsync()
       -> Sets password, activates account
```

## 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/