/* Includes, defines, const values */
// Includes
#include <ESP8266WiFi.h>

// Used pins
#define PIR_PIN (2U)
#define BUZZER_PIN (3U)
#define LED_PIN (4U)

// WiFi credentials
#define WIFI_SSID "<<wifi_ssid>>"
#define WIFI_PASSWORD "<<wifi_password>>"

// Host IP
#define HOST_IP "<<host_ip>>"

// Define WiFi client - WiFi API
WiFiClient client;

// Global variables
volatile byte alarm_state = LOW;
volatile byte led_state = LOW;
unsigned long alarm_tstamp = 0U;
unsigned long led_tstamp = 0U;

// Function declarations
void set_alarm();
bool msecs_passed(int msecs, unsigned long *tstamp);


/* Arduino setup function */
void setup() {
  pinMode(PIR_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);

  attachInterrupt(digitalPinToInterrupt(PIR_PIN), set_alarm, RISING);
  
  Serial.begin(9600);
  delay(10);
  
  Serial.println();
  Serial.print("Connecting to: ");
  Serial.println(WIFI_SSID);
  
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);
  
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  
  Serial.println("");
  Serial.println("Connected to ");
  Serial.println(WIFI_SSID);
  Serial.println(" successfully!");
}

/* Arduino loop function */ 
void loop() {
  if (alarm_state == HIGH) {

    // Flip led every 200 msec so it blinks
    if (true == msecs_passed(200, &led_tstamp)){
      led_state = !led_state;
      digitalWrite(LED_PIN, led_state);
    }

    // Turn off alarm after 2 seconds
    if (true == msecs_passed(2000, &alarm_tstamp)){
      digitalWrite(LED_PIN, LOW);
      noTone(BUZZER_PIN);
      alarm_state = LOW;
      // Send info to host
      if (client.connect(HOST_IP, 80)) {
          Serial.println("Sending alarm info");
          client.println("GET /alarm.php?status=off HTTP/1.1");
          client.println("Host: ");
          client.println(HOST_IP)
          client.println("Connection: close");
          client.println();
      }
    }
  }
}

/* Interrupt function */ 
void set_alarm(){
  alarm_state = HIGH;

  Serial.println("Alarm triggered!");

  // Send info to host
  if (client.connect(HOST_IP, 80)) {
      Serial.println("Sending alarm info");
      client.println("GET /alarm.php?status=on HTTP/1.1");
      client.println("Host: ");
      client.println(HOST_IP)
      client.println("Connection: close");
      client.println();
    }

  // Set timetamps for checking alarm and led 
  alarm_tstamp = millis();
  led_tstamp = millis();

  // Turn on buzzer and led
  digitalWrite(LED_PIN, HIGH);
  tone(BUZZER_PIN, 1000);
}


bool msecs_passed(int msecs, unsigned long *tstamp){
  bool ret_val = false;

  if ((millis() - *tstamp) >= msecs)
  {
    *tstamp = millis();
    ret_val = true;
  }

  return ret_val;
}