from fastapi import APIRouter, UploadFile, File, Form
from fastapi.responses import StreamingResponse, JSONResponse
import io
import traceback

from shadow_generator import initialize_once, generate_shadow_rgba

router = APIRouter()

# initialize on import / startup
initialize_once()

@router.get("/health")
async def health():
    return {"ok": True}

@router.get("/params")
async def params_info():
    return {
        "angle_deg": "float. 0 = right, 90 = down. default 135.0",
        "distance": "float px offset of shadow. default 40.0",
        "softness": "float blur radius. default 25.0",
        "opacity": "float 0..1. default 0.7",
        "color": "hex color for shadow. default '#000000'",
        "spread": "float px. positive expands alpha, negative contracts. default 0.0",
        "shadow_type": "string. 'drop' or 'contact'. default 'drop'",
    }

@router.post("/generate-shadow")
async def generate_shadow_endpoint(
    image: UploadFile = File(..., description="RGBA PNG with transparent background"),
    angle_deg: float = Form(135.0),
    distance: float = Form(40.0),
    softness: float = Form(25.0),
    opacity: float = Form(0.7),
    color: str = Form("#000000"),
    spread: float = Form(0.0),
    shadow_type: str = Form("drop"),
    use_ssn: bool = Form(True)
):
    """
    Returns: PNG (RGBA) bytes stream containing object + generated shadow.
    """
    try:
        data = await image.read()
        params = {
            "angle_deg": angle_deg,
            "distance": distance,
            "softness": softness,
            "opacity": opacity,
            "color": color,
            "spread": spread,
            "shadow_type": shadow_type,
            "prefer_ssn": use_ssn
        }
        out_bytes = generate_shadow_rgba(data, params=params)
        return StreamingResponse(io.BytesIO(out_bytes), media_type="image/png")
    except Exception as exc:
        traceback.print_exc()
        return JSONResponse(status_code=500, content={"error": str(exc)})