from __future__ import annotations

import numpy as np
from fastapi import APIRouter, HTTPException
from fastapi.responses import Response

from ..schemas import DepthRequest
from ..services.depth_io import depth_to_png16_bytes
from ..services.image_io import b64_to_pil_image
from ..services.predictors import get_depth_predictor

router = APIRouter(tags=["depth"])


@router.post("/depth")
def depth(req: DepthRequest):
    """
    计算深度并直接返回二进制 PNG（16-bit 灰度）。

    约束：
    - 前端不传/不选模型；模型选择写死在后端 config.py
    - 成功：HTTP 200 + Content-Type: image/png
    - 失败：HTTP 500，detail 为错误信息
    """
    try:
        pil = b64_to_pil_image(req.image_b64).convert("RGB")
        predictor = get_depth_predictor()
        depth_arr = predictor(pil)  # type: ignore[misc]
        png_bytes = depth_to_png16_bytes(np.asarray(depth_arr))
        return Response(content=png_bytes, media_type="image/png")
    except Exception as e:
        raise HTTPException(status_code=500, detail=str(e)) from e