/*
   程序来源:  EMQX
   https://www.emqx.com/zh/blog/esp32-connects-to-the-free-public-mqtt-broker
  
*/

//首先我们将导入 WiFi 和 PubSubClient 库，
//WiFi 库能够将 ESP32 连接到 Wi-Fi 网络，
//PubSubClient 库能使 ESP32 连接到 MQTT 服务器发布消息及订阅主题。

#include <WiFi.h>
#include <PubSubClient.h>

//设置 Wi-Fi 名称和密码，以及 MQTT 服务器连接地址和端口，并这是 topic 为 "esp32/test"
// WiFi
const char *ssid = "fly"; // Enter your WiFi name   ChinaNet-axHs
const char *password = "00001111";  // Enter WiFi password    y8lbj5lg 

// MQTT Broker
const char *mqtt_broker = "broker.emqx.io";
const char *topic = "esp32/test";
const char *mqtt_username = "emqx";
const char *mqtt_password = "public";
const int mqtt_port = 1883;

WiFiClient espClient;
PubSubClient client(espClient);

void setup() {
 //打开一个串行连接，以便于输出程序的结果并且连接到 Wi-Fi 网络
 // Set software serial baud to 115200;
 Serial.begin(115200);
  pinMode(2, OUTPUT);
  pinMode(15, OUTPUT);
  digitalWrite(2,0);
  digitalWrite(15,0);
  int timeDelay = 1000; // 毫秒
  vTaskDelay(timeDelay / portTICK_PERIOD_MS); // 除以每个tack的毫秒
  digitalWrite(2,!digitalRead(2));
  digitalWrite(15,1);

 // connecting to a WiFi network
 WiFi.begin(ssid, password);
 while (WiFi.status() != WL_CONNECTED) {
     delay(500);
     Serial.println("Connecting to WiFi..");
  }
 Serial.println("Connected to the WiFi network");
 //使用 PubSubClient 连接到公共 MQTT Broker。
 //connecting to a mqtt broker
 client.setServer(mqtt_broker, mqtt_port);
 client.setCallback(callback);

 while (!client.connected()) {
     String client_id = "esp32-client-";
     client_id += String(WiFi.macAddress());
     Serial.printf("The client %s connects to the public mqtt broker\n", client_id.c_str());
     if (client.connect(client_id.c_str(), mqtt_username, mqtt_password)) {
         Serial.println("Public emqx mqtt broker connected");
     } else {
         Serial.print("failed with state ");
         Serial.print(client.state());
         delay(2000);
     }
 }
 //MQTT 服务器连接成功后，ESP32 将向 MQTT 服务器 esp/test 发布消息和订阅 esp/test 主题消息。
 // publish and subscribe
 client.publish(topic, "Hi EMQ X I'm ESP32 ^^");
 client.subscribe(topic);
}
//设置回调函数将主题名称打印到串行端口并打印从 esp32/test 主题接收的消息。
void callback(char *topic, byte *payload, unsigned int length) {
 Serial.print("Message arrived in topic: ");
 Serial.println(topic);
 Serial.print("Message:");
 for (int i = 0; i < length; i++) {
     Serial.print((char) payload[i]);
 }
 Serial.println();
 Serial.println("-----------------------");
}

void loop() {
 client.loop();
}