AI Model Gateway

A Rust web service that provides a REST API for AI model interactions using the OpenRouter API.

Features

• Multiple endpoints for AI model interactions:
  • /api/chat for basic chat completions
  • /api/prompt for enhanced message formatting
• Support for OpenAI and Anthropic models
• Environment-based configuration
• Health check endpoint
• Proper error handling and validation
• Comprehensive logging

Prerequisites

• Rust (latest stable version)
• OpenRouter API key (get one at OpenRouter)

Installation

1. Clone the repository:

git clone <repository-url>
cd ai-model-switcher

2. Create a .env file in the project root:

OPENROUTER_API_KEY=your-api-key-here
SERVER_HOST=0.0.0.0
SERVER_PORT=80
OPENROUTER_API_URL=https://openrouter.ai/api/v1/chat/completions

3. Build the project:

cargo build

Usage

Starting the Server

Run the server:

cargo run

The server will start at http://0.0.0.0:80 by default.

API Reference

Health Check

GET /

Returns "AI API Server is running" if the server is operational.

Chat Completion Endpoint

The /api/chat endpoint provides basic chat completion functionality.

Request Format

POST /api/chat
Content-Type: application/json

{
    "model": "openai/gpt-3.5-turbo",
    "messages": [
        {
            "role": "user",
            "content": "What is the meaning of life?"
        }
    ]
}

Prompt Endpoint

The /api/prompt endpoint provides enhanced message formatting capabilities while maintaining compatibility with all supported models.

Request Format

POST /api/prompt
Content-Type: application/json

{
    "model": "anthropic/claude-3-5-sonnet",
    "messages": [
        {
            "role": "system",
            "content": [
                {
                    "type": "text",
                    "text": "You are a helpful assistant."
                }
            ]
        },
        {
            "role": "user",
            "content": [
                {
                    "type": "text",
                    "text": "What is the meaning of life?"
                }
            ]
        }
    ]
}

The endpoint supports two content formats:

1. Simple string content (same as /api/chat):

"content": "Your message here"

2. Structured content with parts:

"content": [
    {
        "type": "text",
        "text": "Your message here"
    }
]

Supported Message Roles

• user: For user messages
• assistant: For AI responses
• system: For system instructions
• tool: For tool responses (requires tool_call_id)

Optional Fields

• name: Optional identifier for the message sender
• tool_call_id: Required for tool role messages

Supported Models

• openai/gpt-3.5-turbo
• openai/gpt-4
• anthropic/claude-3-5-sonnet
• meta-llama/llama-3.2-3b-instruct:free
• meta-llama/llama-3.2-1b-instruct:free

Response Format

{
    "message": {
        "role": "assistant",
        "content": "The model's response..."
    }
}

Error Responses

• 400 Bad Request: When messages array is empty or model is not specified
• 400 Bad Request: When an unsupported model is specified
• 500 Internal Server Error: For server-side errors

Environment Variables

• OPENROUTER_API_KEY: Your OpenRouter API key (required)
• SERVER_HOST: Host to bind the server to (default: "0.0.0.0")
• SERVER_PORT: Port to bind the server to (default: 80)
• OPENROUTER_API_URL: OpenRouter API URL (default: "https://openrouter.ai/api/v1/chat/completions")

Development

Running in Development Mode

For development, you might want to use different environment variables:

SERVER_HOST=127.0.0.1
SERVER_PORT=3000

Error Handling Best Practices

1. Always check the response status code
2. Implement proper timeout handling
3. Handle rate limiting appropriately
4. Validate input before sending to the API

License

MIT License

Contributing

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Support

For support, please open an issue in this repository.