import threading
import time
import re
import traceback
import paho.mqtt.client as mqtt
from flask import Blueprint, Response, session

from app.glo import *

# ==================== 全局配置 ====================
mqtt_client = None
MQTT_SUB_TOPIC = ""
latest_frame_cache = {}
cache_lock = threading.Lock()
mqtt_sub_lock = threading.Lock()

wrobot_cam = Blueprint('wrobot_cam', __name__)


# ==================== MQTT 核心逻辑 ====================
def on_mqtt_connect(client, userdata, flags, rc):
    """MQTT连接成功回调：此时暂不订阅（等第一次页面访问时再订阅）"""
    if rc == 0:
        print("MQTT连接成功（暂未订阅任何主题，等待页面访问）")
    else:
        print(f"MQTT连接失败  错误码: {rc}")

def on_mqtt_message(client, userdata, message):
    """MQTT消息回调：仅处理已订阅的主题"""
    try:
        if not MQTT_SUB_TOPIC or message.topic != MQTT_SUB_TOPIC:
            return
        
        device_id = message.topic.split('/')[0]
        if len(message.payload) < 100:
            return
        
        with cache_lock:
            latest_frame_cache[device_id] = message.payload

    except Exception as e:
        print(f"MQTT消息处理异常: {e}")
        traceback.print_exc()

def start_mqtt_background():
    """启动MQTT客户端（仅连接，不订阅）"""
    global mqtt_client
    if mqtt_client is not None:
        return

    mqtt_client = mqtt.Client()
    mqtt_client.on_connect = on_mqtt_connect
    mqtt_client.on_message = on_mqtt_message

    try:
        mqtt_client.connect(MQTT_BROKER, MQTT_PORT, keepalive=60)
        mqtt_client.loop_start()
        print(f"MQTT客户端已启动 🚀（仅连接，未订阅主题）")
    except Exception as e:
        print(f"MQTT启动失败: {e}")
        traceback.print_exc()

def subscribe_first_topic(new_topic):
    """第一次订阅主题（初始化订阅）"""
    global MQTT_SUB_TOPIC
    if not mqtt_client or not mqtt_client.is_connected():
        raise RuntimeError("MQTT客户端未连接")

    with mqtt_sub_lock:
        MQTT_SUB_TOPIC = new_topic
        mqtt_client.subscribe(MQTT_SUB_TOPIC)
        print(f"MQTT首次订阅: {MQTT_SUB_TOPIC}")

def update_mqtt_subscription(new_topic):
    """更新订阅主题（非首次）"""
    global MQTT_SUB_TOPIC
    if not mqtt_client or not mqtt_client.is_connected():
        raise RuntimeError("MQTT客户端未连接")

    with mqtt_sub_lock:
        # 取消旧主题订阅
        mqtt_client.unsubscribe(MQTT_SUB_TOPIC)
        print(f"MQTT取消订阅: {MQTT_SUB_TOPIC}")
        
        # 订阅新主题
        MQTT_SUB_TOPIC = new_topic
        mqtt_client.subscribe(MQTT_SUB_TOPIC)
        print(f"MQTT重新订阅: {MQTT_SUB_TOPIC}")

# ==================== Flask 路由核心逻辑 ====================
def generate_video_frame(device_id):
    """生成视频流"""
    blank_jpeg = b'\xff\xd8\xff\xe0\x00\x10JFIF\x00\x01\x01\x00\x00\x01\x00\x01\x00\x00\xff\xd9'
    
    while True:
        try:
            with cache_lock:
                frame_data = latest_frame_cache.get(device_id, blank_jpeg)
            
            yield (b'--frame\r\n'
                   b'Content-Type: image/jpeg\r\n\r\n' + frame_data + b'\r\n')
            
            time.sleep(0.01)
        
        except GeneratorExit:
            break
        except Exception as e:
            print(f"视频流生成异常: {e}")
            yield (b'--frame\r\n'
                   b'Content-Type: image/jpeg\r\n\r\n' + blank_jpeg + b'\r\n')
            time.sleep(0.1)

@wrobot_cam.route('/wrobot_cam/<string:device_id>')
@wrobot_cam.route('/wrobot_cam')
def main(device_id=None):
    """核心逻辑：第一次访问时初始化订阅，后续访问时更新订阅"""
    # 1. 校验设备ID（无参数时直接报错，因为启动时未知默认设备）
    if not device_id:
        return Response("必须指定设备ID（访问方式：/wrobot_cam/设备ID）", status=400, mimetype='text/plain')
    
    device_list = GetUserDeviceIdList(session['user']['user_id'])
    if device_id not in device_list:
        return Response(f"设备ID不合法", status=400, mimetype='text/plain')

    
    # 2. 构建真实主题
    new_mqtt_topic = f"{device_id}/head_video"
    
    # 3. 区分「首次订阅」和「更新订阅」
    try:
        if not MQTT_SUB_TOPIC:  # 初始值为空 → 第一次访问，初始化订阅
            threading.Thread(target=subscribe_first_topic, args=(new_mqtt_topic,), daemon=True).start()
        elif new_mqtt_topic != MQTT_SUB_TOPIC:  # 非首次，更新订阅
            threading.Thread(target=update_mqtt_subscription, args=(new_mqtt_topic,), daemon=True).start()
    except RuntimeError as e:
        return Response(f"MQTT客户端异常：{str(e)}", status=500, mimetype='text/plain')

    # 4. 返回视频流
    return Response(
        generate_video_frame(device_id),
        mimetype='multipart/x-mixed-replace; boundary=frame'
    )

# ==================== 启动初始化 ====================
start_mqtt_background()