"""Baidu intelligent cutout fallback for transparent PNG assets."""

import base64
import io
import json
import time
import urllib.parse
import urllib.request
import urllib.error

from PIL import Image

import config


TOKEN_URL = "https://aip.baidubce.com/oauth/2.0/token"
SEGMENT_URL = "https://aip.baidubce.com/rest/2.0/image-process/v1/segment"
_TOKEN_CACHE = {"token": "", "expires_at": 0.0}


def _post_json(url, payload, timeout=60):
    data = json.dumps(payload).encode("utf-8")
    req = urllib.request.Request(
        url,
        data=data,
        headers={"Content-Type": "application/json; charset=UTF-8"},
        method="POST",
    )
    try:
        with urllib.request.urlopen(req, timeout=timeout) as res:
            return json.loads(res.read().decode("utf-8", "ignore"))
    except urllib.error.HTTPError as e:
        body = e.read().decode("utf-8", "ignore")[:800]
        raise RuntimeError(f"Baidu HTTP {e.code}: {body}")


def _get_access_token():
    now = time.time()
    if _TOKEN_CACHE["token"] and _TOKEN_CACHE["expires_at"] > now + 60:
        return _TOKEN_CACHE["token"]
    api_key = config.get("BAIDU_IMAGEPROCESS_API_KEY", "")
    secret_key = config.get("BAIDU_IMAGEPROCESS_SECRET_KEY", "")
    if not api_key or not secret_key:
        raise RuntimeError("missing BAIDU_IMAGEPROCESS_API_KEY / BAIDU_IMAGEPROCESS_SECRET_KEY")
    query = urllib.parse.urlencode({
        "grant_type": "client_credentials",
        "client_id": api_key,
        "client_secret": secret_key,
    })
    with urllib.request.urlopen(TOKEN_URL + "?" + query, timeout=30) as res:
        data = json.loads(res.read().decode("utf-8", "ignore"))
    token = data.get("access_token")
    if not token:
        raise RuntimeError(f"Baidu token response missing access_token: {json.dumps(data, ensure_ascii=False)[:500]}")
    _TOKEN_CACHE["token"] = token
    _TOKEN_CACHE["expires_at"] = now + int(data.get("expires_in", 2592000))
    return token


def remove_background(img, label="", log=print):
    """Return a PNG RGBA image with transparent background using Baidu segment."""
    token = _get_access_token()
    buf = io.BytesIO()
    img.convert("RGBA").save(buf, format="PNG")
    payload = {
        "image": base64.b64encode(buf.getvalue()).decode("ascii"),
        "method": "auto",
        "refine_mask": "true",
        "return_form": "rgba",
    }
    if log:
        log(f"🧠 [{label}] 百度智能抠图：提交自动主体抠图…")
    data = _post_json(SEGMENT_URL + "?access_token=" + urllib.parse.quote(token), payload, timeout=120)
    if data.get("error_code"):
        raise RuntimeError(f"Baidu segment error {data.get('error_code')}: {data.get('error_msg')}")
    raw_b64 = data.get("image")
    if not raw_b64:
        raise RuntimeError(f"Baidu segment response missing image: {json.dumps(data, ensure_ascii=False)[:500]}")
    out = Image.open(io.BytesIO(base64.b64decode(raw_b64))).convert("RGBA")
    if log:
        log(f"✅ [{label}] 百度智能抠图完成：{out.width}×{out.height}")
    return out