#include <Wire.h>
#include <SparkFunTMP102.h>

TMP102 sensor0;

#define HIGH_TEMPERATURE 28.0
#define LOW_TEMPERATURE 26.0
const int SamplePeriod_ms = 5000;

// Helpers for ExpressLink command processing

typedef enum response_codes
{
  EL_OK, EL_OVERFLOW, EL_PARSE_ERROR, EL_COMMAND_NOT_FOUND, EL_PARAMETER_ERROR,
  EL_INVALID_ESCAPE, EL_NO_CONNECTION, EL_TOPIC_OUT_OF_RANGE, EL_TOPIC_UNDEFINED,
  EL_INVALID_KEY_LENGTH, EL_INVALID_KEY_NAME, EL_UNKNOWN_KEY, EL_KEY_READONLY,
  EL_KEY_WRITEONLY, EL_UNABLE_TO_CONNECT, EL_TIME_NOT_AVAILABLE, EL_LOCATION_NOT_AVAILABLE,
  EL_MODE_NOT_AVAILABLE, EL_ACTIVE_CONNECTION, EL_HOST_IMAGE_NOT_AVAILABLE, EL_INVALID_ADDRESS,
  EL_INVALID_OTA_UPDATE, EL_INVALID_QUERY, EL_INVALID_SIGNATURE
}response_codes_t;

typedef enum alarm_s
{
  AL_NONE, AL_HIGH, AL_LOW, AL_OK
} alarm_t;
const char *alarmStrings[] = {"", "HIGH", "LOW","OK" };

#define expresslink_com Serial1

// Send a command and retrieve the response
String SendCommand(String command)
{
  expresslink_com.print(command+"\n");
  String response = expresslink_com.readString();
  return response;
}

// Get the response code from the begining of an ExpressLink response
response_codes_t checkResponse(String response)
{
  if(response.indexOf("OK")!= -1) return EL_OK;
  int errPosition = response.indexOf("ERR");
  response_codes_t errCode =  (response_codes_t) response.substring(3).toInt();
  return errCode;
}

void expressLinkConnect()
{
  String response;
  bool finished = false;

  response = SendCommand("AT+CONNECT?");
  if(response.indexOf("OK 1")==-1)
  {
    SerialUSB.println("Connecting ExpressLink");
    do{
      response = SendCommand("AT+CONNECT");
      if(checkResponse(response) == EL_OK)
      {
        finished = true;
      }
      else
      {
        SerialUSB.println(response);
      }
    }while(!finished);
    SerialUSB.println("Connected to ExpressLink");
  }
}

// application

void setup() {
  delay(500);
  SerialUSB.begin(115200);
  while (!SerialUSB);
  
  Wire.begin();

  SerialUSB.println("checking the connection");
  
  if(!sensor0.begin())
  {
    SerialUSB.println("Cannot connect to TMP102.");
    SerialUSB.println("Check your connections.");
    while(1);
  }

  SerialUSB.println("Connected to TMP102!");

  expresslink_com.begin(115200);

  SendCommand("AT+CONF Topic1=temperature");
  SendCommand("AT+CONF Topic2=alarm");

  expressLinkConnect();  

}

float collectData()
{
  sensor0.wakeup();
  float temperature = sensor0.readTempC();
  sensor0.sleep();
  return temperature;
}

alarm_t checkAlarm(float data, float high_limit, float low_limit)
{
  static alarm_t alarm_pv = AL_NONE;
  alarm_t alarm_value = AL_NONE;
  
  if(data > high_limit)
  {
    alarm_value = AL_HIGH;
  }
  else if(data < low_limit)
  {
    alarm_value = AL_LOW;
  }
  else if(alarm_pv != AL_NONE)
  {
    alarm_value = AL_OK;
  }
  alarm_pv = alarm_value;
  return alarm_value;
}

void loop() {

  static int lastSampleTime_ms = 0;
  static bool alert_pv = false;
  String alarmString = "";
  alarm_t alarm;
  int now = millis();

  if( (now - SamplePeriod_ms) >= lastSampleTime_ms)
  {
    lastSampleTime_ms = now;
    
    expressLinkConnect(); // ensure we are still connected to the cloud

    float temperature = collectData();
    alarm = checkAlarm(temperature, HIGH_TEMPERATURE, LOW_TEMPERATURE);
    
    SendCommand("AT+SEND1 "+String(temperature));
    if(alarm != AL_NONE)
    {
      SendCommand("AT+SEND2 {\"alarm\":\"" + String(alarmStrings[alarm]) + "\"}");
      alarmString = " - alarm : " + String(alarmStrings[alarm]);
    }
    
    SerialUSB.println("Temperature : " + String(temperature) + alarmString);
  }
}