/*********
  Rui Santos
  Complete project details at https://randomnerdtutorials.com
*********/

#include <WiFi.h>
extern "C" {
  #include "freertos/FreeRTOS.h"
  #include "freertos/timers.h"
}
#include <AsyncMqttClient.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
#define OLED_RESET     4 // Reset pin # (or -1 if sharing Arduino reset pin)
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

// Change the credentials below, so your ESP32 connects to your router
#define WIFI_SSID "MYSSID"
#define WIFI_PASSWORD "MYPWD"

// Change the MQTT_HOST variable to your Raspberry Pi IP address,
// so it connects to your Mosquitto MQTT broker
#define MQTT_HOST IPAddress(192, 168, 1, NNN)
#define MQTT_PORT 1883

// Create objects to handle MQTT client
AsyncMqttClient mqttClient;
TimerHandle_t mqttReconnectTimer;
TimerHandle_t wifiReconnectTimer;

// Define GPIO where the pushbutton is connected to
const int buttonPin = 32;
int buttonState;                      // current reading from the input pin (pushbutton)
int lastButtonState = LOW;            // previous reading from the input pin (pushbutton)
unsigned long lastDebounceTime = 0;   // the last time the output pin was toggled
unsigned long debounceDelay = 50;     // the debounce time; increase if the output flickers

void connectToWifi() {
  Serial.println("Connecting to Wi-Fi...");
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
}

void connectToMqtt() {
  Serial.println("Connecting to MQTT...");
  mqttClient.connect();
}

void WiFiEvent(WiFiEvent_t event) {
  Serial.printf("[WiFi-event] event: %d\n", event);
  switch(event) {
    case SYSTEM_EVENT_STA_GOT_IP:
      Serial.println("WiFi connected");
      Serial.println("IP address: ");
      Serial.println(WiFi.localIP());
      connectToMqtt();
      break;
    case SYSTEM_EVENT_STA_DISCONNECTED:
      Serial.println("WiFi lost connection");
      xTimerStop(mqttReconnectTimer, 0); // ensure we don't reconnect to MQTT while reconnecting to Wi-Fi
      xTimerStart(wifiReconnectTimer, 0);
      break;
  }
}

// Add more topics that want your ESP32 to be subscribed to
void onMqttConnect(bool sessionPresent) {
  Serial.println("Connected to MQTT.");
  Serial.print("Session present: ");
  Serial.println(sessionPresent);
  uint16_t packetIdSub = mqttClient.subscribe("esp32/temperature", 0);
  Serial.print("Subscribing at QoS 0, packetId: ");
  Serial.println(packetIdSub);
}

void onMqttDisconnect(AsyncMqttClientDisconnectReason reason) {
  Serial.println("Disconnected from MQTT.");
  if (WiFi.isConnected()) {
    xTimerStart(mqttReconnectTimer, 0);
  }
}

void onMqttSubscribe(uint16_t packetId, uint8_t qos) {
  Serial.println("Subscribe acknowledged.");
  Serial.print("  packetId: ");
  Serial.println(packetId);
  Serial.print("  qos: ");
  Serial.println(qos);
}

void onMqttUnsubscribe(uint16_t packetId) {
  Serial.println("Unsubscribe acknowledged.");
  Serial.print("  packetId: ");
  Serial.println(packetId);
}

void onMqttPublish(uint16_t packetId) {
  Serial.println("Publish acknowledged.");
  Serial.print("  packetId: ");
  Serial.println(packetId);
}

// You can modify this function to handle what happens when you receive a certain message in a specific topic
void onMqttMessage(char* topic, char* payload, AsyncMqttClientMessageProperties properties, size_t len, size_t index, size_t total) {
  String messageTemp;
  for (int i = 0; i < len; i++) {
    //Serial.print((char)payload[i]);
    messageTemp += (char)payload[i];
  }
  if (strcmp(topic, "esp32/temperature") == 0) {

//    display.clearDisplay();
//    display.setTextSize(1);             // Normal 1:1 pixel scale
//    display.setTextColor(SSD1306_WHITE);        // Draw white text
//    display.setCursor(0,0);             // Start at top-left corner
//    display.println(F("Temperature:"));
//    display.setTextColor(SSD1306_WHITE);        // Draw white text
//    display.print(messageTemp);
//    display.display();
    testdrawstyles();
  }

  Serial.println("Publish received.");
  Serial.print("  message: ");
  Serial.println(messageTemp);
  Serial.print("  topic: ");
  Serial.println(topic);
  Serial.print("  qos: ");
  Serial.println(properties.qos);
  Serial.print("  dup: ");
  Serial.println(properties.dup);
  Serial.print("  retain: ");
  Serial.println(properties.retain);
  Serial.print("  len: ");
  Serial.println(len);
  Serial.print("  index: ");
  Serial.println(index);
  Serial.print("  total: ");
  Serial.println(total);
}

void setup() {

  Serial.begin(115200);

  // SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
  if(!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) { // Address 0x3D for 128x64
    Serial.println(F("SSD1306 allocation failed"));
    for(;;); // Don't proceed, loop forever
  }

  // Define buttonPin as an INPUT
  pinMode(buttonPin, INPUT);


  mqttReconnectTimer = xTimerCreate("mqttTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToMqtt));
  wifiReconnectTimer = xTimerCreate("wifiTimer", pdMS_TO_TICKS(2000), pdFALSE, (void*)0, reinterpret_cast<TimerCallbackFunction_t>(connectToWifi));

  WiFi.onEvent(WiFiEvent);

  mqttClient.onConnect(onMqttConnect);
  mqttClient.onDisconnect(onMqttDisconnect);
  mqttClient.onSubscribe(onMqttSubscribe);
  mqttClient.onUnsubscribe(onMqttUnsubscribe);
  mqttClient.onMessage(onMqttMessage);
  mqttClient.onPublish(onMqttPublish);
  mqttClient.setServer(MQTT_HOST, MQTT_PORT);

  connectToWifi();
}

void loop() {
  // Read the state of the pushbutton and save it in a local variable
  int reading = digitalRead(buttonPin);

  // If the pushbutton state changed (due to noise or pressing it), reset the timer
  if (reading != lastButtonState) {
    // Reset the debouncing timer
    lastDebounceTime = millis();
  }

  // If the button state has changed, after the debounce time
  if ((millis() - lastDebounceTime) > debounceDelay) {
    // And if the current reading is different than the current buttonState
    if (reading != buttonState) {
      buttonState = reading;
      // Publish an MQTT message on topic esp32/led to toggle the LED (turn the LED on or off)P
      if (buttonState == HIGH) {
        mqttClient.publish("esp32/led", 0, true, "toggle");
        Serial.println("Publishing on topic esp32/led topic at QoS 0");
      }
    }
  }
  // Save the reading. Next time through the loop, it'll be the lastButtonState
  lastButtonState = reading;
}

void testdrawstyles(void) {
  display.clearDisplay();
  display.setTextSize(1);             // Normal 1:1 pixel scale
  display.setTextColor(SSD1306_WHITE);        // Draw white text
  display.setCursor(0,0);             // Start at top-left corner
  display.println(F("Hello, world!"));

  display.setTextColor(SSD1306_BLACK, SSD1306_WHITE); // Draw 'inverse' text
  display.println(3.141592);

  display.setTextSize(2);             // Draw 2X-scale text
  display.setTextColor(SSD1306_WHITE);
  display.print("0x"); display.println(0xDEADBEEF, HEX);

  display.display();
  delay(2000);
}