from fastapi import FastAPI, HTTPException, File, UploadFile
from fastapi.responses import FileResponse
from preprocessing import data_quality, standardize_data_types, handle_missing_data, handle_outliers, generate_final_report, save_cleaned_data
import pandas as pd
import io

app = FastAPI(title="Data Preprocessing")

@app.get("/")
async def root():
    return {"message": "Welcome to the Data Preprocessing API!"}

@app.post("/preprocess_data/")
async def upload_csv(upload_file: UploadFile = File(...)):
    try:
        if not upload_file.filename.endswith('.csv'):
            raise HTTPException(status_code=400, detail="File must be in CSV format!")

        content = await upload_file.read()
        df = pd.read_csv(io.BytesIO(content), encoding_errors="replace")

        if df.empty:
            raise HTTPException(status_code=400, detail="File is empty, upload the correct file")

        data_quality(df)
        df = standardize_data_types(df)
        df = handle_missing_data(df)
        df = handle_outliers(df)

        REPORT_PATH = "output/preprocessing_report.txt"
        generate_final_report(df, REPORT_PATH)

        CLEANED_DATA_PATH = "output/cleaned_dataset.csv"
        save_cleaned_data(df, CLEANED_DATA_PATH)

        return FileResponse(CLEANED_DATA_PATH, media_type="text/csv", filename="cleaned_dataset.csv")

    except Exception as e:
        raise HTTPException(status_code=400, detail=f"Error processing file: {str(e)}")