#include <OneWire.h>
#include <DallasTemperature.h>
#include <ESP8266WiFi.h>
#include <ModbusIP_ESP8266.h>
#include "config.h"
#include "LittleFS.h"
#include <LiquidCrystal_I2C.h>

// Display
#define LCD_COLUMNS 16
#define LCD_ROWS 2
#define LCD_ADDRESS 0x27

#define RELAY_PIN D3
#define TEMP_SENSOR_PIN D5
// network
// After how much time without connection we will 
// reboot (in millis)
#define NON_CONNECTED_REBOOT_TIMEOUT 60000 
#define RECONNECT_TIMEOUT 10000

IPAddress my_ip(MY_IP);
IPAddress gateway(MY_GW);
IPAddress subnet(MY_NET);

// modbus consts and works
#define TCP_PORT 15000
#define T_UPDATE_INTERVAL 1000

#define REGISTER_TARGET_T 0
#define REGISTER_HYSTERESIS 1
#define REGISTER_CUR_TEMP 2
#define REGISTER_CUR_STATE 3

ModbusIP mb;
OneWire oneWire(TEMP_SENSOR_PIN);
DallasTemperature sensor(&oneWire);

LiquidCrystal_I2C lcd(LCD_ADDRESS, LCD_COLUMNS, LCD_ROWS);

long last_poll;
long last_update;

int t_target = 7000;
int hyst = 200;
int cur_t = 0;
int cur_state = 0;

bool TryLoad(char *filename)
{
  File f = LittleFS.open(filename, "r");
	if (!f) return false;
	String s = f.readStringUntil('\n');
	t_target = atoi(s.c_str());
  s = f.readStringUntil('\n');
	hyst = atoi(s.c_str());
  f.close();
  if (t_target == 0) return false;
	return true;
}

void LoadState()
{
  if (TryLoad("/settings.txt")) return;
  TryLoad("/settings.txt.bak");
}

void SaveTo(char *filename)
{
  File f = LittleFS.open(filename, "w");
	if (!f) return;
	f.println(t_target);
  f.println(hyst);
	f.close();
}

void SaveState()
{
  SaveTo("/settings.txt");
	SaveTo("/settings.txt.bak");
}


void setup() 
{
  lcd.init();                     
  lcd.backlight();
  lcd.setCursor(0, 0);
	if (!LittleFS.begin())
	{
		Serial.println("Unable to mount the filesystem");
    lcd.print("ERR: FS");
		ESP.restart();
	}
	LoadState();
	pinMode(RELAY_PIN, OUTPUT);
  pinMode(TEMP_SENSOR_PIN, INPUT);
	Serial.begin(115200);
	Serial.println("Initialised...");

	WiFi.mode(WIFI_STA);
	WiFi.config(my_ip, gateway, subnet);
	WiFi.setAutoReconnect(true);
	WiFi.begin(WIFI_NAME, WIFI_PASS);
	Serial.print("Connecting");
  lcd.print("Connecting...");
	delay(500);
	Serial.println();

	last_poll = millis();
	
	mb.server(15000);
	mb.addHreg(REGISTER_TARGET_T, t_target);
	mb.addHreg(REGISTER_HYSTERESIS, hyst);
	mb.addHreg(REGISTER_CUR_TEMP, cur_t);
	mb.addHreg(REGISTER_CUR_STATE, cur_state);
  //
  sensor.begin();
  sensor.setResolution(12);
}

void UpdateCurrent()
{
  sensor.requestTemperatures();
	cur_t = int(sensor.getTempCByIndex(0) * 100);
	last_update = millis();
}

unsigned long last_connected = 0;
unsigned long last_connecting = 0;

void loop() 
{
	unsigned long current = millis();
	int u = 0;
	if (current < last_update || current - last_update >= T_UPDATE_INTERVAL)
	{
		UpdateCurrent();
		u = 1;
	}
	mb.task();
	t_target = mb.Hreg(REGISTER_TARGET_T);
	hyst = mb.Hreg(REGISTER_HYSTERESIS);
	if (cur_t < t_target - hyst) cur_state = 1;
	else if (cur_t > t_target + hyst) cur_state = 0;
	mb.Hreg(REGISTER_CUR_STATE, cur_state);
	digitalWrite(RELAY_PIN, cur_state);
	if (u) 
	{
    SaveState();
		Serial.println("Cur state");
		Serial.println(cur_state);
    Serial.println(cur_t);
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("T: ");
    lcd.print((cur_t) / 100.0, 2);
    lcd.print(" (");
    lcd.print(t_target / 100);
    lcd.print(")");
    lcd.setCursor(0, 1);
    lcd.print("S: ");
    lcd.print(cur_state);
    lcd.print("WiFi: ");
    lcd.print(WiFi.status());
	}
	mb.Hreg(REGISTER_TARGET_T, t_target);
	mb.Hreg(REGISTER_HYSTERESIS, hyst);
	mb.Hreg(REGISTER_CUR_TEMP, cur_t);
	mb.Hreg(REGISTER_CUR_STATE, cur_state);
	if (WiFi.status() != WL_CONNECTED)
	{
		if (current < last_connecting || current - last_connecting > RECONNECT_TIMEOUT)
	  {   
        WiFi.reconnect();
        last_connecting = current;
    }
	}
	else
	{
		last_connected = current;
	}
	if (current < last_connected || current - last_connected > NON_CONNECTED_REBOOT_TIMEOUT)
	{
    SaveState();
		ESP.restart();
	}
}