#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
推送层 —— 直连局域网墨水屏设备（喵喵固件，仅用标准库 urllib，无第三方依赖）。
固件开源：https://gitee.com/gxp666111/miaomiao（web/ 为设备自带管理页，可在浏览器打开
http://<EPD_HOST>/ 调试同一套接口）。
"""
import json
import time
import urllib.parse
import urllib.request
import urllib.error

import config

# 局域网 mDNS（.local）域名解析基于组播 UDP，偶发瞬时失败正常，重试即可恢复。
RETRY_TIMES = 2
RETRY_DELAY = 2


def _request(method, path, headers=None, body=None):
    url = f"http://{config.EPD_HOST}{path}"
    req = urllib.request.Request(url, data=body, headers=headers or {}, method=method)
    for attempt in range(RETRY_TIMES + 1):
        try:
            with urllib.request.urlopen(req, timeout=30) as resp:
                return resp.read().decode("utf-8", "ignore")
        except urllib.error.HTTPError as e:
            raise RuntimeError(f"HTTP {e.code}: {e.read().decode('utf-8', 'ignore')}") from e
        except urllib.error.URLError:
            if attempt == RETRY_TIMES:
                raise
            time.sleep(RETRY_DELAY)


def _list_gallery_names():
    text = _request("GET", "/images")
    return [item["name"] for item in json.loads(text).get("items", [])]


def _clear_gallery():
    """设备画廊按追加保存，用完即删，使其始终只留最新一张。
    清理是锦上添花，不是推送的必要条件——拉列表或单张删除失败都不能阻塞后续上传。"""
    try:
        names = _list_gallery_names()
    except Exception as e:
        print(f"[推送] 拉取画廊列表失败，跳过本次清理：{e}")
        return
    for name in names:
        try:
            _request("POST", f"/delete_image?name={urllib.parse.quote(name)}")
        except Exception as e:
            print(f"[推送] 清理画廊旧图 {name} 失败：{e}")


def push_image(image_path):
    """推送图片到局域网墨水屏设备：先清空画廊旧图，再上传新图触发显示刷新。"""
    _clear_gallery()
    with open(image_path, "rb") as fp:
        content = fp.read()
    resp = _request("POST", "/upload", headers={"Content-Type": "image/png"}, body=content)
    return config.EPD_HOST, resp