from fastapi import FastAPI, HTTPException
from fastapi.responses import StreamingResponse, JSONResponse
from pydantic import BaseModel
import pandas as pd
import os
import requests
from transformers import GPT2LMHeadModel, GPT2Tokenizer, AutoTokenizer, pipeline
from io import StringIO
from fastapi.middleware.cors import CORSMiddleware
from huggingface_hub import HfFolder
from tqdm import tqdm

app = FastAPI()

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # You can specify domains here
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# Access the Hugging Face API token from environment variables
hf_token = os.getenv('HF_API_TOKEN')

if not hf_token:
    raise ValueError("Hugging Face API token is not set. Please set the HF_API_TOKEN environment variable.")

# Load GPT-2 model and tokenizer
tokenizer_gpt2 = GPT2LMHeadModel.from_pretrained('gpt2')
model_gpt2 = GPT2LMHeadModel.from_pretrained('gpt2')


# Create a pipeline for text generation using GPT-2
text_generator = pipeline("text-generation", model=model_gpt2, tokenizer=tokenizer_gpt2)

# Define prompt template
prompt_template = """\
You are an expert in generating synthetic data for machine learning models.

Your task is to generate a synthetic tabular dataset based on the description provided below.

Description: {description}

The dataset should include the following columns: {columns}

Please provide the data in CSV format.

Example Description:
Generate a dataset for predicting house prices with columns: 'Size', 'Location', 'Number of Bedrooms', 'Price'

Example Output:
Size,Location,Number of Bedrooms,Price
1200,Suburban,3,250000
900,Urban,2,200000
1500,Rural,4,300000
...

Description:
{description}
Columns:
{columns}
Output: """

# Set up the Mixtral model and tokenizer
token = os.getenv("HF_TOKEN")
HfFolder.save_token(token)

tokenizer_mixtral = AutoTokenizer.from_pretrained("mistralai/Mixtral-8x7B-Instruct-v0.1", token=token)

API_URL = "https://api-inference.huggingface.co/models/mistralai/Mixtral-8x7B-Instruct-v0.1"

generation_params = {
    "top_p": 0.90,
    "temperature": 0.8,
    "max_new_tokens": 512,
    "return_full_text": False,
    "use_cache": False
}

def preprocess_user_prompt(user_prompt):
    generated_text = text_generator(user_prompt, max_length=50, num_return_sequences=1)[0]["generated_text"]
    return generated_text

def format_prompt(description, columns):
    processed_description = preprocess_user_prompt(description)
    prompt = prompt_template.format(description=processed_description, columns=",".join(columns))
    return prompt

def generate_synthetic_data(description, columns):
    formatted_prompt = format_prompt(description, columns)
    payload = {"inputs": formatted_prompt, "parameters": generation_params}
    response = requests.post(API_URL, headers={"Authorization": f"Bearer {token}"}, json=payload)
    return response.json()[0]["generated_text"]

def process_generated_data(csv_data, expected_columns):
    try:
        cleaned_data = csv_data.replace('\r\n', '\n').replace('\r', '\n')
        data = StringIO(cleaned_data)
        df = pd.read_csv(data, delimiter=',')
        if set(df.columns) != set(expected_columns):
            print(f"Unexpected columns in the generated data: {df.columns}")
            return None
        return df
    except pd.errors.ParserError as e:
        print(f"Failed to parse CSV data: {e}")
        return None

def generate_large_synthetic_data(description, columns, num_rows=1000, rows_per_generation=100):
    data_frames = []
    for _ in tqdm(range(num_rows // rows_per_generation), desc="Generating Data"):
        generated_data = generate_synthetic_data(description, columns)
        df_synthetic = process_generated_data(generated_data, columns)
        if df_synthetic is not None and not df_synthetic.empty:
            data_frames.append(df_synthetic)
        else:
            print("Skipping invalid generation.")
    if data_frames:
        return pd.concat(data_frames, ignore_index=True)
    else:
        print("No valid data frames to concatenate.")
        return pd.DataFrame(columns=columns)

@app.route('/generate', methods=['POST'])
def generate():
    data = request.json
    description = data.get('description')
    columns = data.get('columns')
    num_rows = data.get('num_rows', 1000)
    
    if not description or not columns:
        return jsonify({"error": "Please provide 'description' and 'columns' in the request."}), 400
    
    df_synthetic = generate_large_synthetic_data(description, columns, num_rows=num_rows)
    
    if df_synthetic is not None and not df_synthetic.empty:
        file_path = 'synthetic_data.csv'
        df_synthetic.to_csv(file_path, index=False)
        return send_file(file_path, as_attachment=True)
    else:
        return jsonify({"error": "Failed to generate a valid synthetic dataset."}), 500

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