from fastapi import FastAPI, File, UploadFile, HTTPException
from fastapi.responses import StreamingResponse
from PIL import Image
import io

app = FastAPI(title="Advanced Image Converter")

ALLOWED_OUTPUT_FORMATS = ["jpeg", "png", "gif", "bmp", "tiff", "webp"]

@app.post("/convert_image/")
async def convert_image(
    file: UploadFile = File(...),
    output_format: str = "jpeg",
    quality: int = 95  # For JPEG/WebP, adjust compression quality (0-100)
):
    """
    Converts an uploaded image to the specified format.

    - Supports common image formats as input.
    - Output formats: JPEG, PNG, GIF, BMP, TIFF, WebP.
    - For JPEG and WebP, you can adjust the `quality` (0-100).
    """
    if output_format.lower() not in ALLOWED_OUTPUT_FORMATS:
        raise HTTPException(
            status_code=400,
            detail=f"Invalid output format. Allowed formats: {', '.join(ALLOWED_OUTPUT_FORMATS)}",
        )

    if output_format.lower() in ["jpeg", "webp"] and not (0 <= quality <= 100):
        raise HTTPException(
            status_code=400, detail="Quality must be between 0 and 100 for JPEG and WebP."
        )

    try:
        image = Image.open(io.BytesIO(await file.read()))
    except Exception as e:
        raise HTTPException(status_code=400, detail="Invalid image file.") from e

    output_io = io.BytesIO()
    try:
        save_kwargs = {}
        if output_format.lower() in ["jpeg", "webp"]:
            save_kwargs["quality"] = quality
        image.save(output_io, format=output_format.upper(), **save_kwargs)
    except KeyError:
        raise HTTPException(
            status_code=400, detail=f"Conversion to {output_format} failed."
        )
    except Exception as e:
        raise HTTPException(status_code=500, detail=f"Image processing error: {e}")

    output_io.seek(0)
    media_type = f"image/{output_format.lower()}"
    if output_format.lower() == "tiff":
        media_type = "image/tiff"  # Special case for TIFF

    return StreamingResponse(output_io, media_type=media_type)