main.py

import os  # Import the os module for working with the operating system
from fastapi import FastAPI, HTTPException  # Import necessary modules from FastAPI
from pydantic import BaseModel  # Import BaseModel from pydantic for data validation
from huggingface_hub import InferenceClient  # Import InferenceClient from huggingface_hub
import uvicorn  # Import uvicorn for running the FastAPI application

app = FastAPI()  # Create a FastAPI instance

# Define the primary and fallback models
primary = "mistralai/Mixtral-8x7B-Instruct-v0.1"
fallbacks = ["mistralai/Mistral-7B-Instruct-v0.2", "mistralai/Mistral-7B-Instruct-v0.1"]

# Define the data model for the request body
class Item(BaseModel):
    input: str = None
    system_prompt: str = None
    system_output: str = None
    history: list = None
    templates: list = None
    temperature: float = 0.0
    max_new_tokens: int = 1048
    top_p: float = 0.15
    repetition_penalty: float = 1.0
    key: str = None

# Function to generate the response JSON
def generate_response_json(item, output, tokens, model_name):
    return {
        "settings": {
            "input": item.input if item.input is not None else "",
            "system prompt": item.system_prompt if item.system_prompt is not None else "",
            "system output": item.system_output if item.system_output is not None else "",
            "temperature": f"{item.temperature}" if item.temperature is not None else "",
            "max new tokens": f"{item.max_new_tokens}" if item.max_new_tokens is not None else "",
            "top p": f"{item.top_p}" if item.top_p is not None else "",
            "repetition penalty": f"{item.repetition_penalty}" if item.repetition_penalty is not None else "",
            "do sample": "True",
            "seed": "42"
        },
        "response": {
            "output": output.strip().lstrip('\n').rstrip('\n').lstrip('<s>').rstrip('</s>').strip(),
            "unstripped": output,
            "tokens": tokens,
            "model": "primary" if model_name == primary else "fallback",
            "name": model_name
        }
    }

# Endpoint for generating text
@app.post("/")
async def generate_text(item: Item = None):
    try:
        if item is None:
            raise HTTPException(status_code=400, detail="JSON body is required.")

        if item.input is None and item.system_prompt is None or item.input == "" and item.system_prompt == "":
            raise HTTPException(status_code=400, detail="Parameter `input` or `system prompt` is required.")
        
        input_ = ""
        if item.system_prompt != None and item.system_output != None:
            input_ = f"<s>[INST] {item.system_prompt} [/INST] {item.system_output}</s>"
        elif item.system_prompt != None:
            input_ = f"<s>[INST] {item.system_prompt} [/INST]</s>"
        elif item.system_output != None:
            input_ = f"<s>{item.system_output}</s>"

        if item.templates != None:
            for num, template in enumerate(item.templates, start=1):
                input_ += f"\n<s>[INST] Beginning of archived conversation {num} [/INST]</s>"
                for i in range(0, len(template), 2):
                    input_ += f"\n<s>[INST] {template[i]} [/INST]"
                    input_ += f"\n{template[i + 1]}</s>"
                input_ += f"\n<s>[INST] End of archived conversation {num} [/INST]</s>"

        input_ += f"\n<s>[INST] Beginning of active conversation [/INST]</s>"
        if item.history != None:
            for input_, output_ in item.history:
                input_ += f"\n<s>[INST] {input_} [/INST]"
                input_ += f"\n{output_}"
        input_ += f"\n<s>[INST] {item.input} [/INST]"

        temperature = float(item.temperature)
        if temperature < 1e-2:
            temperature = 1e-2
        top_p = float(item.top_p)

        generate_kwargs = dict(
            temperature=temperature,
            max_new_tokens=item.max_new_tokens,
            top_p=top_p,
            repetition_penalty=item.repetition_penalty,
            do_sample=True,
            seed=42,
        )

        tokens = 0
        client = InferenceClient(primary)
        stream = client.text_generation(input_, **generate_kwargs, stream=True, details=True, return_full_text=True)
        output = ""
        for response in stream:
            tokens += 1
            output += response.token.text
        return generate_response_json(item, output, tokens, primary)

    except HTTPException as http_error:
        raise http_error

    except Exception as e:
        tokens = 0
        error = ""
        
        for model in fallbacks:
            try:
                client = InferenceClient(model)
                stream = client.text_generation(input_, **generate_kwargs, stream=True, details=True, return_full_text=True)
                output = ""
                for response in stream:
                    tokens += 1
                    output += response.token.text
                return generate_response_json(item, output, tokens, model)

            except Exception as e:
                error = f"All models failed. {e}" if e else "All models failed."
                continue

        raise HTTPException(status_code=500, detail=error)

    if "KEY" in os.environ:
        if item.key != os.environ["KEY"]:
            raise HTTPException(status_code=401, detail="Valid key is required.")

if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)