# Chat History Implementation

This document describes the implementation of the chat history functionality based on the old web API code from the `plan/old` folder.

## Overview

The implementation includes:
1. **New Chat History Module**: A complete module for managing chat sessions and messages
2. **Updated AI Chat Module**: Enhanced with proper routing
3. **Database Entities**: New entities for chat sessions and messages
4. **API Endpoints**: RESTful endpoints for all chat history operations

## New Files Created

### Database Entities
- `app/database/entity/chat_sessions.entity.go` - Chat sessions entity
- `app/database/entity/chat_messages_new.entity.go` - Chat messages entity (renamed to avoid conflicts)

### Chat History Module
- `app/module/chat_history/chat_history.module.go` - Module definition
- `app/module/chat_history/chat_history.router.go` - Router configuration
- `app/module/chat_history/request/chat_history.request.go` - Request DTOs
- `app/module/chat_history/response/chat_history.response.go` - Response DTOs
- `app/module/chat_history/mapper/chat_history.mapper.go` - Entity to response mappers
- `app/module/chat_history/repository/chat_history.repository.go` - Data access layer
- `app/module/chat_history/service/chat_history.service.go` - Business logic layer
- `app/module/chat_history/controller/chat_history.controller.go` - API controller

### AI Chat Module Updates
- `app/module/ai_chat/ai_chat.router.go` - Router configuration for AI chat

### Database Migration
- `migrations/001_create_chat_history_tables.sql` - SQL migration script
- `migrations/001_create_chat_history_tables.go` - Go migration script
- `scripts/migrate.go` - Migration runner script

## API Endpoints

### Chat History Endpoints

#### Sessions
- `GET /chat-history/sessions` - Get user's chat sessions
- `GET /chat-history/sessions/{sessionId}` - Get specific session with messages
- `POST /chat-history/sessions` - Create new session
- `PUT /chat-history/sessions/{sessionId}` - Update session
- `DELETE /chat-history/sessions/{sessionId}` - Delete session

#### Messages
- `GET /chat-history/sessions/{sessionId}/messages` - Get session messages
- `POST /chat-history/sessions/{sessionId}/messages` - Create message
- `PUT /chat-history/messages/{messageId}` - Update message
- `DELETE /chat-history/messages/{messageId}` - Delete message

#### Combined Operations
- `POST /chat-history/save` - Save complete chat history (sessions + messages)

### AI Chat Endpoints (Updated)
- `GET /ai-chat/sessions` - Get user's AI chat sessions
- `GET /ai-chat/sessions/{id}` - Get specific AI chat session
- `POST /ai-chat/sessions` - Create AI chat session
- `PUT /ai-chat/sessions/{id}` - Update AI chat session
- `DELETE /ai-chat/sessions/{id}` - Delete AI chat session
- `GET /ai-chat/sessions/{sessionId}/messages` - Get AI chat messages
- `POST /ai-chat/sessions/{sessionId}/messages` - Send AI chat message
- `PUT /ai-chat/sessions/{sessionId}/messages/{messageId}` - Update AI chat message
- `DELETE /ai-chat/sessions/{sessionId}/messages/{messageId}` - Delete AI chat message
- `GET /ai-chat/logs` - Get user's AI chat logs
- `GET /ai-chat/logs/{id}` - Get specific AI chat log

## Database Schema

### chat_sessions Table
```sql
CREATE TABLE chat_sessions (
    id SERIAL PRIMARY KEY,
    session_id VARCHAR(255) NOT NULL UNIQUE,
    user_id INTEGER NOT NULL,
    agent_id VARCHAR(255) NOT NULL,
    title VARCHAR(255) NOT NULL DEFAULT 'Chat Session',
    message_count INTEGER DEFAULT 0,
    status VARCHAR(50) DEFAULT 'active',
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
```

### chat_messages_new Table
```sql
CREATE TABLE chat_messages_new (
    id SERIAL PRIMARY KEY,
    session_id VARCHAR(255) NOT NULL,
    message_type VARCHAR(50) NOT NULL CHECK (message_type IN ('user', 'assistant')),
    content TEXT NOT NULL,
    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);
```

## Key Features Implemented

### 1. Session Management
- Create, read, update, delete chat sessions
- Session-based architecture with unique session IDs
- User ownership validation
- Message count tracking

### 2. Message Management
- Create, read, update, delete messages within sessions
- Support for user and assistant message types
- Automatic message count updates
- Cascade deletion when sessions are deleted

### 3. Combined Operations
- Save complete chat history in one operation
- Update existing sessions or create new ones
- Bulk message operations

### 4. Security
- User authentication required for all operations
- User ownership validation for all resources
- Proper error handling and validation

## Migration Instructions

### 1. Run Database Migration
```bash
# Option 1: Run the Go migration script
go run scripts/migrate.go

# Option 2: Run SQL migration manually
psql -d your_database -f migrations/001_create_chat_history_tables.sql
```

### 2. Update Application
The application has been updated to include:
- New modules in `main.go`
- Updated router configuration
- New API endpoints

### 3. Test the Implementation
```bash
# Start the application
go run main.go

# Test endpoints
curl -X GET "http://localhost:8080/chat-history/sessions" \
  -H "Authorization: Bearer YOUR_TOKEN"

curl -X POST "http://localhost:8080/chat-history/save" \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "user_id": 1,
    "agent_id": "agent-123",
    "session_id": "session-456",
    "title": "Test Chat",
    "messages": [
      {"type": "user", "content": "Hello"},
      {"type": "assistant", "content": "Hi there!"}
    ]
  }'
```

## Differences from Old Code

### Architecture Changes
- **Language**: Converted from TypeScript/JavaScript to Go
- **Framework**: Converted from Next.js API routes to Fiber (Go web framework)
- **Database**: Converted from SQLite to PostgreSQL (via GORM)
- **Structure**: Implemented clean architecture with repository, service, and controller layers

### API Changes
- **Authentication**: Added Bearer token authentication
- **Validation**: Added comprehensive request validation
- **Error Handling**: Standardized error responses
- **Pagination**: Added pagination support for list endpoints

### Database Changes
- **Schema**: Adapted SQLite schema to PostgreSQL
- **Relationships**: Added proper foreign key relationships
- **Indexes**: Added performance indexes
- **Constraints**: Added data validation constraints

## Future Enhancements

1. **Real-time Features**: Add WebSocket support for real-time chat
2. **File Attachments**: Support for file uploads in messages
3. **Message Search**: Full-text search across messages
4. **Analytics**: Chat analytics and reporting
5. **Export**: Export chat history to various formats
6. **Archiving**: Automatic archiving of old sessions

## Troubleshooting

### Common Issues

1. **Migration Errors**: Ensure database connection is properly configured
2. **Authentication Errors**: Verify Bearer token is valid and user exists
3. **Validation Errors**: Check request payload matches expected schema
4. **Permission Errors**: Ensure user owns the resource being accessed

### Debug Mode
Enable debug logging by setting the log level to debug in your configuration.

## Support

For issues or questions regarding this implementation, please refer to the application logs or contact the development team.