# DreamChat API Specification

## Overview

This document defines the REST API and WebSocket specifications for DreamChat.

- **REST API**: For CRUD operations, file uploads, and synchronous requests
- **WebSocket**: For real-time chat streaming
- **OpenAPI**: Auto-generated from NestJS decorators for frontend client generation

## Base URL

```
Development: http://localhost:3000/api
Production: https://api.dreamchat.example/api
```

## Authentication

### JWT Token Flow

```http
POST /api/auth/login
Content-Type: application/json

{
  "username": "user@example.com",
  "password": "securepassword"
}

Response:
{
  "accessToken": "eyJhbGciOiJIUzI1NiIs...",
  "refreshToken": "eyJhbGciOiJIUzI1NiIs...",
  "expiresIn": 3600
}
```

### Keycloak Integration

```http
GET /api/auth/keycloak
Redirect to Keycloak login

Callback:
GET /api/auth/keycloak/callback?code=...
Response: { accessToken, refreshToken, expiresIn }
```

### WebSocket Auth

WebSocket connections authenticate via query parameter:
```
ws://localhost:3000/chat?token=eyJhbGciOiJIUzI1NiIs...
```

## REST API Endpoints

### Authentication Module

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| POST | `/auth/login` | Local login | Public |
| POST | `/auth/refresh` | Refresh token | Public |
| POST | `/auth/logout` | Logout | Bearer |
| GET | `/auth/me` | Get current user | Bearer |
| GET | `/auth/keycloak` | Keycloak login URL | Public |
| GET | `/auth/keycloak/callback` | Keycloak callback | Public |

### Users Module

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| POST | `/users` | Register new user | Public |
| GET | `/users/:id` | Get user profile | Bearer |
| PATCH | `/users/:id` | Update user | Bearer (own only) |
| DELETE | `/users/:id` | Delete user | Bearer (own/admin) |

### Characters Module

```typescript
// DTOs
class CreateCharacterDto {
  name: string;
  personalityPrompt: string;
  backstory?: string;
  attributes?: Record<string, any>;
  avatarUrl?: string;
  config?: Record<string, any>;
}

class CharacterResponseDto {
  id: string;
  name: string;
  avatarUrl: string;
  personalityPrompt: string;
  backstory: string;
  attributes: Record<string, any>;
  createdAt: Date;
}
```

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| GET | `/characters` | List user's characters | Bearer |
| POST | `/characters` | Create character | Bearer |
| GET | `/characters/:id` | Get character details | Bearer |
| PATCH | `/characters/:id` | Update character | Bearer (owner) |
| DELETE | `/characters/:id` | Delete character | Bearer (owner) |

**Example Requests:**

```http
POST /api/characters
Authorization: Bearer {token}
Content-Type: application/json

{
  "name": "Alice",
  "personalityPrompt": "You are Alice, a curious and adventurous explorer...",
  "backstory": "Alice grew up in a small village...",
  "attributes": {
    "traits": ["curious", "brave", "witty"],
    "age": 25,
    "species": "human",
    "skills": ["navigation", "survival"]
  }
}

Response: 201 Created
{
  "id": "uuid",
  "name": "Alice",
  "personalityPrompt": "...",
  "attributes": { ... },
  "createdAt": "2026-02-23T10:00:00Z"
}
```

### Conversations Module

```typescript
class CreateConversationDto {
  characterId: string;
  title?: string;
}

class ConversationResponseDto {
  id: string;
  title: string;
  character: CharacterSummaryDto;
  messageCount: number;
  createdAt: Date;
}
```

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| GET | `/conversations` | List conversations | Bearer |
| POST | `/conversations` | Create conversation | Bearer |
| GET | `/conversations/:id` | Get conversation | Bearer |
| PATCH | `/conversations/:id` | Update conversation | Bearer |
| DELETE | `/conversations/:id` | Delete conversation | Bearer |

### Messages Module

```typescript
class CreateMessageDto {
  content: string;
}

class MessageResponseDto {
  id: string;
  role: 'user' | 'assistant';
  content: string;
  tokensUsed?: number;
  model?: string;
  createdAt: Date;
}
```

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| GET | `/conversations/:id/messages` | Get messages (paginated) | Bearer |
| POST | `/conversations/:id/messages` | Send message (non-streaming) | Bearer |
| DELETE | `/messages/:id` | Delete message | Bearer |

### Import Module

```typescript
class FileImportDto {
  // Multipart form data
  file: File;
}

class UrlImportDto {
  url: string;
}

class ImportResponseDto {
  id: string;
  status: 'pending' | 'processing' | 'completed' | 'failed';
  sourceName: string;
  fileSize?: number;
  content?: string;
  errorMessage?: string;
  createdAt: Date;
}
```

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| POST | `/import/file` | Import file (txt, pdf, md) | Bearer |
| POST | `/import/url` | Import from URL | Bearer |
| GET | `/import/:id` | Get import status | Bearer |
| GET | `/import` | List imports | Bearer |
| DELETE | `/import/:id` | Delete import | Bearer |

**File Upload Request:**

```http
POST /api/import/file
Authorization: Bearer {token}
Content-Type: multipart/form-data

------Boundary
Content-Disposition: form-data; name="file"; filename="story.txt"
Content-Type: text/plain

(file content here)
------Boundary--

Response: 202 Accepted
{
  "id": "import-uuid",
  "status": "processing",
  "sourceName": "story.txt",
  "createdAt": "2026-02-23T10:00:00Z"
}
```

**URL Import Request:**

```http
POST /api/import/url
Authorization: Bearer {token}
Content-Type: application/json

{
  "url": "https://archiveofourown.org/works/12345678"
}

Response: 202 Accepted
{
  "id": "import-uuid",
  "status": "processing",
  "sourceName": "https://archiveofourown.org/works/12345678"
}

// If no scraper available:
Response: 400 Bad Request
{
  "error": "UNSUPPORTED_URL",
  "message": "No scraper available for this URL"
}
```

### Story Module (Phase 2)

```typescript
class CreateStoryBranchDto {
  parentId?: string;  // null for root
  userDirection: string;
}

class StoryBranchResponseDto {
  id: string;
  conversationId: string;
  parentId?: string;
  title: string;
  content: string;
  userDirection: string;
  depth: number;
  children: StoryBranchResponseDto[];
  createdAt: Date;
}
```

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| GET | `/conversations/:id/story` | Get story tree | Bearer |
| POST | `/conversations/:id/story/branches` | Create new branch | Bearer |
| GET | `/story-branches/:id` | Get branch details | Bearer |
| PATCH | `/story-branches/:id` | Update branch | Bearer |
| DELETE | `/story-branches/:id` | Delete branch | Bearer |

**Get Story Tree:**

```http
GET /api/conversations/conv-id/story
Authorization: Bearer {token}

Response:
{
  "root": {
    "id": "root-uuid",
    "title": "The Beginning",
    "content": "Once upon a time...",
    "depth": 0,
    "children": [
      {
        "id": "branch-1",
        "title": "The Left Path",
        "content": "You chose the left path...",
        "userDirection": "Go left into the dark forest",
        "depth": 1,
        "children": []
      },
      {
        "id": "branch-2",
        "title": "The Right Path", 
        "content": "You chose the right path...",
        "userDirection": "Go right towards the castle",
        "depth": 1,
        "children": []
      }
    ]
  }
}
```

### Multi-Character Module (Phase 3)

```typescript
class AddParticipantDto {
  characterId: string;
  autoRespond: boolean;
}

class ParticipantResponseDto {
  id: string;
  character: CharacterSummaryDto;
  isActive: boolean;
  autoRespond: boolean;
}
```

| Method | Endpoint | Description | Auth |
|--------|----------|-------------|------|
| GET | `/conversations/:id/participants` | List participants | Bearer |
| POST | `/conversations/:id/participants` | Add participant | Bearer |
| DELETE | `/conversations/:id/participants/:charId` | Remove participant | Bearer |

## WebSocket Specification

### Connection

```javascript
const ws = new WebSocket('ws://localhost:3000/chat?token=JWT_TOKEN');

ws.onopen = () => {
  console.log('Connected');
};

ws.onmessage = (event) => {
  const message = JSON.parse(event.data);
  handleMessage(message);
};
```

### Message Protocol

All WebSocket messages use JSON format:

```typescript
interface WebSocketMessage {
  type: string;
  payload: any;
  timestamp: string;
  requestId?: string;  // For correlating responses
}
```

### Client → Server Events

#### 1. Join Conversation

```typescript
// Join a conversation room
{
  "type": "JOIN_CONVERSATION",
  "payload": {
    "conversationId": "conv-uuid"
  },
  "requestId": "req-123"
}

// Response
{
  "type": "CONVERSATION_JOINED",
  "payload": {
    "conversationId": "conv-uuid",
    "history": [ /* last N messages */ ]
  },
  "requestId": "req-123"
}
```

#### 2. Send Message (Streaming)

```typescript
{
  "type": "SEND_MESSAGE",
  "payload": {
    "conversationId": "conv-uuid",
    "content": "Hello, how are you?",
    "streaming": true  // Enable streaming response
  },
  "requestId": "msg-456"
}
```

#### 3. Stop Generation

```typescript
{
  "type": "STOP_GENERATION",
  "payload": {
    "conversationId": "conv-uuid"
  }
}
```

#### 4. Leave Conversation

```typescript
{
  "type": "LEAVE_CONVERSATION",
  "payload": {
    "conversationId": "conv-uuid"
  }
}
```

### Server → Client Events

#### 1. Message Acknowledged

```typescript
{
  "type": "MESSAGE_ACK",
  "payload": {
    "messageId": "msg-uuid",
    "status": "received"
  },
  "requestId": "msg-456"
}
```

#### 2. Stream Chunk

```typescript
{
  "type": "STREAM_CHUNK",
  "payload": {
    "conversationId": "conv-uuid",
    "chunk": " part of response",
    "isComplete": false
  },
  "requestId": "msg-456"
}
```

#### 3. Stream Complete

```typescript
{
  "type": "STREAM_COMPLETE",
  "payload": {
    "conversationId": "conv-uuid",
    "messageId": "assistant-msg-uuid",
    "content": "Full response text",
    "tokensUsed": 150,
    "model": "openai/gpt-4o"
  },
  "requestId": "msg-456"
}
```

#### 4. Error

```typescript
{
  "type": "ERROR",
  "payload": {
    "code": "LLM_ERROR",
    "message": "Failed to generate response",
    "details": { ... }
  },
  "requestId": "msg-456"
}
```

### Error Codes

| Code | Description | HTTP Status |
|------|-------------|-------------|
| `UNAUTHORIZED` | Invalid or expired token | 401 |
| `FORBIDDEN` | Insufficient permissions | 403 |
| `NOT_FOUND` | Resource not found | 404 |
| `VALIDATION_ERROR` | Invalid input data | 400 |
| `LLM_ERROR` | LLM provider error | 502 |
| `RATE_LIMITED` | Too many requests | 429 |
| `FILE_TOO_LARGE` | File exceeds 50MB | 413 |
| `UNSUPPORTED_URL` | No scraper for URL | 400 |

## OpenAPI Configuration

### NestJS Setup

```typescript
// main.ts
const config = new DocumentBuilder()
  .setTitle('DreamChat API')
  .setDescription('Character simulation and chat API')
  .setVersion('1.0')
  .addBearerAuth()
  .addTag('auth', 'Authentication endpoints')
  .addTag('users', 'User management')
  .addTag('characters', 'Character CRUD')
  .addTag('conversations', 'Chat sessions')
  .addTag('messages', 'Chat messages')
  .addTag('import', 'Data import')
  .build();

const document = SwaggerModule.createDocument(app, config);
SwaggerModule.setup('api/docs', app, document);

// Also serve raw JSON for client generation
writeFileSync('./openapi-spec.json', JSON.stringify(document, null, 2));
```

### Frontend Client Generation

```bash
# Generate TypeScript client
npx openapi-generator-cli generate \
  -i ./openapi-spec.json \
  -g typescript-fetch \
  -o ./apps/frontend/src/api/generated \
  --additional-properties=supportsES6=true,npmName=dreamchat-api

# Or use Orval for React Query hooks
npx orval --config ./orval.config.js
```

## Rate Limiting

| Endpoint | Limit |
|----------|-------|
| Auth endpoints | 10 req/min |
| General API | 100 req/min |
| File upload | 5 req/min |
| WebSocket messages | 60 msg/min |
| LLM streaming | 20 requests/min |

```typescript
// Rate limit headers
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 95
X-RateLimit-Reset: 1645603200
```