import asyncio
from fastapi import FastAPI, UploadFile, File, HTTPException

from ocr.gemini_service import parse_pan
from ocr.gemini_aadhar_service import parse_aadhar
from ocr.gemini_face_extractor import detect_face
from utils.crop import crop_face
from utils.pdf import pdf_to_image_bytes

app = FastAPI()

SUPPORTED_TYPES = {"image/jpeg", "image/png", "image/webp", "application/pdf"}


def _resolve_image(raw_bytes: bytes, content_type: str) -> bytes:
    if content_type == "application/pdf":
        return pdf_to_image_bytes(raw_bytes)
    return raw_bytes


@app.post("/kyc/pan")
async def process_pan(file: UploadFile = File(...)):
    if file.content_type not in SUPPORTED_TYPES:
        raise HTTPException(
            status_code=415,
            detail=f"Unsupported file type '{file.content_type}'. Upload a JPEG, PNG, WebP, or PDF.",
        )

    raw_bytes = await file.read()

    try:
        image_bytes = _resolve_image(raw_bytes, file.content_type)
    except ValueError as e:
        raise HTTPException(status_code=422, detail=str(e))

    try:
        pan_result, face_result = await asyncio.gather(
            asyncio.to_thread(parse_pan, image_bytes),
            asyncio.to_thread(detect_face, image_bytes),
        )
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e))

    face_bbox = face_result.get("box_2d")
    if face_bbox is None:
        raise HTTPException(status_code=422, detail="Could not detect face on the PAN card.")

    face_image = crop_face(image_bytes, face_bbox)

    return {
        "success": True,
        "parsed_data": pan_result.get("data"),
        "face_image": face_image,
        "engine_used": pan_result.get("engine_used"),
    }


@app.post("/kyc/aadhar")
async def process_aadhar(file: UploadFile = File(...)):
    if file.content_type not in SUPPORTED_TYPES:
        raise HTTPException(
            status_code=415,
            detail=f"Unsupported file type '{file.content_type}'. Upload a JPEG, PNG, WebP, or PDF.",
        )

    raw_bytes = await file.read()

    try:
        image_bytes = _resolve_image(raw_bytes, file.content_type)
    except ValueError as e:
        raise HTTPException(status_code=422, detail=str(e))

    # Face detection is best-effort — back side of Aadhaar has no photo.
    # return_exceptions=True prevents one failure from cancelling the other.
    ocr_result, face_result = await asyncio.gather(
        asyncio.to_thread(parse_aadhar, image_bytes),
        asyncio.to_thread(detect_face, image_bytes),
        return_exceptions=True,
    )

    if isinstance(ocr_result, Exception):
        raise HTTPException(status_code=500, detail=str(ocr_result))

    data = ocr_result.get("data", {})
    address_found = data.get("address_found", False)

    # Attempt to crop face; silently skip if detection failed (e.g. back side)
    face_image = None
    if not isinstance(face_result, Exception):
        face_bbox = face_result.get("box_2d")
        if face_bbox:
            try:
                face_image = crop_face(image_bytes, face_bbox)
            except Exception:
                pass

    return {
        "success": True,
        "parsed_data": data,
        "face_image": face_image,
        "face_found": face_image is not None,
        "address_found": address_found,
        "engine_used": ocr_result.get("engine_used"),
    }