#include <Wire.h>
#include "SSD1306Ascii.h"
#include "SSD1306AsciiWire.h"
#include <EEPROM.h>
#include <dht.h>



dht DHT;   // just testing
#define DHT22_PIN 11


// UPS (un-interruptible supply) software
// Peter Scargill 2017  - https://tech.scargill.net
//
// This Atmega 328 low cost solution powers up with an SSD1306 display, showing the
// battery voltage (needs dividers - I used 2k2 ground to input, 10k input to battery)
// with programmable offset to compensate for resistor variation.
// Averages voltage over 8 seconds to avoid spikes and save hardware filtering
//
// Starts up - if voltage above upper threshold for a while turns
// output bit on - that controls a P-channel MOSFET on output
// of voltage booster - power the board from booster BEFORE the MOSFET
// There is a warning bit- to warn micro of impending
// shutdown. Shutdown when LOW.
//
// Shuts down power after giving load time to respond and turn off
// also shuts down after this point EVEN if the power came back on after warning bit
// went low. While off uses minimal display area to save current (OLED)
// Then turns back on when battery is up to it. Big programmable hysteresis between
// shutdown voltage and wakeup voltage
//
// Additional functionality:
// - long-press UP to trigger orderly shutdown. In that state press DOWN to restore
// - long-press DOWN to trigger test voltage reset. Sets average voltage to ZERO
//     temporarily - this triggers warning and shutdown - and eventual reboot
// - Added optional, programmable warning beeper (Piezo)
// - Added serial JSON (optional) monitor
// - Watchdog timeout from 1 minute through 255 minutes - change of state pin WATCHDOG
//  In normal operation shows total on time and total off time
// = new logging graphics - long-press SET button to see 0-5v battery over time
//
// Use 328-based board similar regulator (pref low loss) and no USB chip. If possible
// run OLED off 3v3.
//
// Blog has more - as does this video https://www.youtube.com/watch?v=44Lvdf7o4GQ
// Now set up for the 32-pixel displays - got everything down to 4 lines

#define VER "v1.14"
struct
{
  uint16_t check;
  float highV;
  float lowV;
  uint8_t startTimeout;
  uint8_t goodTimeout;
  uint8_t warningTimeout;
  uint8_t offTimeout;
  int16_t batteryOffset;
  uint16_t tone;
  uint8_t smon;
  uint8_t watchdog;
  uint16_t pause;
  uint8_t twarn;

} eeSave;




// Device address for the SSD1306 display
#define I2C_ADDRESS 0x3C
#define OPTIMIZE_I2C 1

SSD1306AsciiWire oled;

#define POWER 12  // inverted - ON - power available for my cheap version
#define WARNING 5 // inverted
#define TONE 13   // optional piezo beeper on warning
#define WATCHDOG 11  //  watchdog in

#define POWERUP_STATE 0
#define GOOD_STATE 1
#define TIMEOUT_STATE 2
#define OFF_STATE 3
#define SHUTDOWN_STATE 4

#define WAITING 60      // wait before actually turning off "relay" after
#define ONDELAY 20      // delay before turning on

#define SWITCHON 3.7    // defaults for hysteresis voltage
#define SWITCHOFF 3.1

#define LONGPRESS_UP 20   // 10ths of second before long presson UP triggers shutdown
#define LONGPRESS_DOWN 20 // 10ths of second before battery fail test
#define LONGPRESS_SET 20 // 10ths of second before graphics display
#define SHOWGRAPH 10     // 10 seconds showing graphical info
#define SHUTDOWN_PERIOD 20

#define SET 4
#define UP 6
#define DOWN 7

#define VOLTAGE A7

uint8_t showGraph = 0;

uint32_t secs = 0;
uint32_t upSecs = 0;
uint32_t downSecs = 0;

uint8_t triggerShutdown = 0;

uint32_t mySecs = 0;
uint8_t watchdogTrigger = 0;
uint8_t watchdogTimer = 0;
uint8_t watchdogState = 0;
uint8_t secondsCounter = 0;
uint8_t refresh = 0;

void LcdP(char *fmt, ...)
{
  char buf[22]; // resulting string limited to 128 chars
  va_list args;
  va_start(args, fmt);
  vsnprintf(buf, 128, fmt, args);
  va_end(args);
  oled.print(buf);
}

uint32_t mymillis = 0;
uint32_t my100millis = 0;
uint8_t lightState = 0;
uint8_t state = 0; // 0 is power up, 1 is on, 2 is turning off
uint8_t stateCounter = 0; // might want to stay in a state for some time
uint8_t startCounter = 0; // startup fallover into OFF state
float vol;
uint8_t onDelay = 0;

uint16_t average;
int temperatureReading;
int humidityReading;
uint8_t updateTimeout = 0;

char *theState = "standby";

uint8_t instate = 0;
uint8_t updated = 0;
uint8_t sKeypressed = 0;
uint8_t uKeypressed = 0;
uint8_t dKeypressed = 0;

uint8_t logit[128];
uint16_t logPause = 0;

void gotoXY(int x, int y)
{
  oled.setCursor(x, y);
}

//------------------------------------------------------------------------------
void setup()
{
  EEPROM.get(0, eeSave);
  analogReference(INTERNAL);
  if (eeSave.check != 0x52d1)
  {
    eeSave.check = 0x52d1;

    eeSave.highV = SWITCHON;
    eeSave.lowV = SWITCHOFF;
    eeSave.startTimeout = 5;
    eeSave.goodTimeout = 5;
    eeSave.warningTimeout = 25;
    eeSave.offTimeout = 20;
    eeSave.batteryOffset = 400;
    eeSave.tone = 0;
    eeSave.smon = 0;
    eeSave.watchdog = 0;
    eeSave.pause = 0;
    eeSave.twarn = 40;
    EEPROM.put(0, eeSave);
  }

  Wire.begin();
  oled.begin(&Adafruit128x32, I2C_ADDRESS);
  oled.set400kHz();
  oled.setFont(Adafruit5x7);
  uint32_t m = micros();

  Serial.begin(115200); // serial JSON data out if set

#define POWERON LOW
#define POWEROFF HIGH
#define WARNINGON LOW
#define WARNINGOFF HIGH

  digitalWrite(POWER, POWEROFF);   pinMode(POWER, OUTPUT);
  digitalWrite(WARNING, WARNINGOFF); pinMode(WARNING, OUTPUT);
  digitalWrite(TONE, 0); pinMode(TONE, OUTPUT);
  pinMode(SET, INPUT_PULLUP);
  pinMode(UP, INPUT_PULLUP);
  pinMode(DOWN, INPUT_PULLUP);
  pinMode(WATCHDOG, INPUT_PULLUP);
  average = analogRead(VOLTAGE); // we start off with read value;
  oled.clear();
  my100millis = millis() + 1000;
  state = 0;
  stateCounter = eeSave.startTimeout;
  watchdogState = digitalRead(WATCHDOG);
}

/*
  // Float to ASCII conversion
  char *ftoa(char *a, double f, int precision)
  {
	long p[] = {0,10,100,1000,10000,100000,1000000,10000000,100000000};

	char *ret = a;
	long heiltal = (long)f;
	itoa(heiltal, a, 10);
	while (*a != '\0') a++;
	a++ = '.';
	long desimal = abs((long)((f - heiltal) * p[precision]));
	itoa(desimal, a, 10);
	return ret;

  }
*/


void showBattery(void)
{
  LcdP("%d.%02dv", int(vol), ((int(vol * 100)) % 100)); oled.clearToEOL();
}
//------------------------------------------------------------------------------
void loop()
{
  // main loop

  if (my100millis <= millis()) // 100ms for key check
  {
    my100millis += 100;
    if ((eeSave.watchdog) && (watchdogTrigger == 0))
    {
      if (watchdogState != digitalRead(WATCHDOG)) {
        watchdogTimer = eeSave.watchdog;
        watchdogTrigger = 0;
        watchdogState = digitalRead(WATCHDOG);
      }
    }
    if (digitalRead(SET) == 1)
    {
      if (sKeypressed)
      { if (sKeypressed < LONGPRESS_SET)
        {
          if (showGraph) {
            showGraph = 0;
            oled.clear();
            instate = 255              ;
            sKeypressed = 0;
            refresh = 1;
          }
          instate++;
          updated = 0;
          updateTimeout = 100;
        }
        sKeypressed = 0;
      }
    }
    else
    {
      sKeypressed++;
      if (sKeypressed == LONGPRESS_SET) showGraph = SHOWGRAPH;
      if (sKeypressed >> LONGPRESS_SET) sKeypressed--;
    }


    if (digitalRead(UP) == 1) // special case long press is reset...
    {
      if (uKeypressed)
      {
        if (uKeypressed < LONGPRESS_UP)
        {
          switch (instate)
          {
            case 1 : if (eeSave.highV < 4.3) eeSave.highV += 0.1; break;
            case 2 : if (eeSave.lowV < 4.2) eeSave.lowV += 0.1; break;
            case 3 : eeSave.startTimeout++; break;
            case 4 : eeSave.goodTimeout++; break;
            case 5 : eeSave.warningTimeout++; break;
            case 6 : eeSave.offTimeout++; break;
            case 7 : eeSave.batteryOffset++; break;
            case 8 : if (eeSave.tone < 5000) eeSave.tone += 500; else eeSave.tone = 0; break;
            case 9 : eeSave.smon = 1; break;
            case 10 : eeSave.watchdog++;
              watchdogTimer = eeSave.watchdog; watchdogTrigger = 0; break;
            case 11: if (eeSave.pause < 5) eeSave.pause++; break;
            case 12: if (eeSave.twarn < 99) eeSave.twarn++; break;
          }
          updated = 0;
          updateTimeout = 100;
        }
        uKeypressed = 0;
      }
    }
    else
    {
      uKeypressed++;
      if (uKeypressed == LONGPRESS_UP) triggerShutdown = 1;
      if (uKeypressed > LONGPRESS_UP) uKeypressed--;
    }

    if (digitalRead(DOWN) == 1)
    {
      if (dKeypressed)
      {
        if (dKeypressed < LONGPRESS_DOWN)
        {
          switch (instate)
          {
            case 1 : if (eeSave.highV > 2.3) eeSave.highV -= 0.1; break;
            case 2 : if (eeSave.lowV > 2.2) eeSave.lowV -= 0.1; break;
            case 3 : eeSave.startTimeout--; break;
            case 4 : eeSave.goodTimeout--; break;
            case 5 : eeSave.warningTimeout--; break;
            case 6 : eeSave.offTimeout--; break;
            case 7 : eeSave.batteryOffset--; break;
            case 8 : if (eeSave.tone >= 500) eeSave.tone -= 500; break;
            case 9 : eeSave.smon = 0; break;
            case 10 : if (eeSave.watchdog) eeSave.watchdog--;
              watchdogTimer = eeSave.watchdog; watchdogTrigger = 0; break;
            case 11 : if (eeSave.pause) eeSave.pause--; break;
            case 12 : if (eeSave.twarn) eeSave.twarn--; break;
          }
          updated = 0;
          updateTimeout = 100;
        }
        dKeypressed = 0;
      }
    }
    else
    {
      dKeypressed++;
      if (dKeypressed == LONGPRESS_DOWN) average = 0;
      if (dKeypressed > LONGPRESS_DOWN) dKeypressed--;
    }

    if (eeSave.highV <= eeSave.lowV) eeSave.highV = eeSave.lowV + 0.1;
    if (eeSave.lowV >= eeSave.highV) eeSave.lowV = eeSave.highV - 0.1;
    switch (instate)
    {
      case 0:  if (updated == 0)
        {
          gotoXY(0, 3);
          oled.clearToEOL();
          updated = 1;
        }
        break;
      case 1:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("SET: HiV=%d.%d   ", int(eeSave.highV), ((int(eeSave.highV * 100)) % 100) / 10); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 2:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("SET: LoV=%d.%d   ", int(eeSave.lowV), ((int(eeSave.lowV * 100)) % 100) / 10); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 3:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("SET: Start=%d secs", eeSave.startTimeout); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 4:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("SET: Good=%d secs", eeSave.goodTimeout); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 5:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("SET: Warn=%d secs", eeSave.warningTimeout); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 6:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("SET: Off=%d secs", eeSave.offTimeout); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 7:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("SET: Boffs=%d", eeSave.batteryOffset - 400); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 8: if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("Warning tone=%dHz", eeSave.tone); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 9: if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("Serial mon On/Off: %d", eeSave.smon); oled.clearToEOL();
          updated = 1;
        }

        break;
      case 10: if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("Watchdog=%d mins", eeSave.watchdog); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 11:  if (updated == 0)
        {
          gotoXY(0, 3);
          switch (eeSave.pause)
          {
            case 0 : LcdP("Log period=NONE"); break;
            case 1 : LcdP("Log period=1 sec"); break;
            case 2 : LcdP("Log period=10 secs"); break;
            case 3 : LcdP("Log period=1 min"); break;
            case 4 : LcdP("Log period=10 mins"); break;
            case 5 : LcdP("Log period=1 hr"); break;
            default : LcdP("Log period=??"); break;
          }
          oled.clearToEOL();
          updated = 1;
        }
        break;
      case 12: if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("Twarning=%d%%", eeSave.twarn); oled.clearToEOL();
          updated = 1;
        }
        break;        
      case 13:  if (updated == 0)
        {
          gotoXY(0, 3);
          LcdP("Version=%s", VER); oled.clearToEOL();
          updated = 1;
        }
        break;
      case 14:  updated = 0; instate = 0; break;
    }

    if (updateTimeout)
    {
      if (--updateTimeout == 0)
      {
        instate = 0;
        updated = 0;
        EEPROM.put(0, eeSave);
      }
    }
  }

  // main 1 second loop here for determining where we are
  if (mymillis <= millis())
  {
    mymillis += 1000; // every second we do this

    int chk = DHT.read22(DHT22_PIN);

    average = ((average * 7) + analogRead(VOLTAGE)) / 8; //i.e. average over 8 seconds 0-1023 = 0-5v - might make testing longer in the end
    vol = (((float)average) * 5.0 / 824.0) * (float)eeSave.batteryOffset / 400.0; //10k/2k2

    if (eeSave.pause) {
      if ((mySecs % 60) == 0) logPause++;
    } else logPause++;

    if (eeSave.pause == 1) {
      logPause++;  // 1 second
    }
    else if (eeSave.pause == 2) {
      if ((mySecs % 10) == 0) logPause++;  // 10 seconds
    }
    else if (eeSave.pause == 3) {
      if ((mySecs % 60) == 0) logPause++;  // 1 minute
    }
    else if (eeSave.pause == 4) {
      if ((mySecs % 600) == 0) logPause++;  // 10 minutes
    }
    else if (eeSave.pause == 5) {
      if ((mySecs % 3600) == 0) logPause++;  // 1 hour
    }

    mySecs++;
    if (logPause > eeSave.pause) // log 128 values 0-30 = 0-5v  -  2 secs updating for testing
    {
      logPause = 0;
      for (int a = 0; a < 127; a++) logit[a] = logit[a + 1];
      logit[126] = ((int)(vol * 6.0));
    }

    if (triggerShutdown) {
      triggerShutdown = 0;
      state = SHUTDOWN_STATE;
      stateCounter = SHUTDOWN_PERIOD;
    }

    char bString[64];
    sprintf(bString, "{\"state\": %d,\"battery\": %d.%02d,\"upsecs\":%ld,\"downsecs\":%ld}", state, int(vol), (int)(vol * 100) % 100, upSecs, downSecs);

    if (eeSave.smon) Serial.println(bString);

    if (showGraph)
    {
      if (showGraph == SHOWGRAPH)
      {
        uint8_t val;
        oled.clear();
        oled.setCursor(0, 0);
        for (int a = 0; a < 128; a++)
        {
          //uint32_t point=(0x80000000>>logit[a])|0x80000001;

          uint32_t point = (((0x80000000 >> logit[a]) - 1) ^ 0xffffffff) | 0x80000001;

          if ((a == 0) || (a == 127)) point = 0xffffffff;
          oled.setCursor(a, 0); oled.ssd1306WriteRamBuf((uint8_t)((point) & 255));
          oled.setCursor(a, 1); oled.ssd1306WriteRamBuf((uint8_t)((point >> 8) & 255));;
          oled.setCursor(a, 2); oled.ssd1306WriteRamBuf((uint8_t)((point >> 16) & 255));
          oled.setCursor(a, 3); oled.ssd1306WriteRamBuf((uint8_t)((point >> 24) & 255));
        }
        oled.setCursor(0, 0);
      }
      showGraph--; if (showGraph == 0) refresh = 1;
    }
    else
    {
      switch (state)
      {
        case POWERUP_STATE : // powered up everything off
          secondsCounter = 0;
          if ((stateCounter == eeSave.startTimeout) || (refresh)) {
            refresh = 0;
            gotoXY(0, 0);
            LcdP("Starting up..");
            oled.clearToEOL();
          }
          if (stateCounter) --stateCounter;
          gotoXY(0, 1); LcdP("Bat="); showBattery();
          gotoXY(0, 2); LcdP("Wait=%03d secs", stateCounter); oled.clearToEOL();
          digitalWrite(WARNING, WARNINGON); // no warning
          digitalWrite(POWER, POWEROFF);
          if (vol > eeSave.highV)
          {
            if (stateCounter == 0) {
              stateCounter = eeSave.goodTimeout;
              state = GOOD_STATE;
            }
          } else
          {
            if (stateCounter == 0) {
              stateCounter = eeSave.offTimeout;
              state = OFF_STATE;
            }
          }
          break;

        case GOOD_STATE :  // battery is above upper threshold
          if ((stateCounter == eeSave.goodTimeout) || (refresh)) {
            refresh = 0;
            gotoXY(0, 0);
            LcdP("** Pi Power %s **", VER);
            oled.clearToEOL();
            watchdogTimer = eeSave.watchdog;
          }
          if (stateCounter) --stateCounter;
          if (++secondsCounter == 60)
          {
            secondsCounter = 0;
            if (watchdogTimer) {
              watchdogTimer--;  // only do this when battery is ok
              if (watchdogTimer == 0) watchdogTrigger = 1;
            }
          }
          if (watchdogTrigger) {
            watchdogTrigger = 0;  // reboot
            stateCounter = eeSave.warningTimeout;
            state = TIMEOUT_STATE;
          }

          gotoXY(0, 1); 
          if (watchdogTimer) LcdP("WDT: %d:%02d ", watchdogTimer, 59 - secondsCounter);
          else
          {
            temperatureReading = (int)DHT.temperature;
            humidityReading = (int)DHT.humidity;
            if (chk==DHTLIB_OK)
            {
              if (mySecs & 2) LcdP("Tem=%dc ", temperatureReading); else LcdP("Hum=%d%% ", humidityReading);
              if (temperatureReading>eeSave.twarn) tone(TONE, eeSave.tone, 100);
            }
          }
          LcdP("Bat="); showBattery();
          gotoXY(0, 2); LcdP("HiV=%d.%dv LoV=%d.%dv", int(eeSave.highV), ((int(eeSave.highV * 100)) % 100) / 10, int(eeSave.lowV), ((int(eeSave.lowV * 100)) % 100) / 10); oled.clearToEOL();
          digitalWrite(WARNING, WARNINGOFF); // no warning
          digitalWrite(POWER, POWERON);
          if (vol < eeSave.lowV)
          {
            gotoXY(0, 3); LcdP("Wait=%03d secs", stateCounter); oled.clearToEOL();
            if (stateCounter == 0) {
              stateCounter = eeSave.warningTimeout;
              state = TIMEOUT_STATE;
            }
          } else
          {
            stateCounter = eeSave.goodTimeout - 1;
            if ((instate == 0) && (vol >= eeSave.lowV))
            {
              gotoXY(0, 3);
              if (mySecs & 2) {
                LcdP("On= %04ldd %02ld:%02ld:%02ld", upSecs / 86400, (upSecs / 3600) % 24, (upSecs % 3600) / 60, upSecs % 60);
                oled.clearToEOL();
              }
              else          {
                LcdP("Off=%04ldd %02ld:%02ld:%02ld", downSecs / 86400, (downSecs / 3600) % 24 , (downSecs % 3600) / 60, downSecs % 60);
                oled.clearToEOL();
              }
            }
          }
          ++upSecs;
          break;

        case TIMEOUT_STATE : // battery has dropped below upper threshold - ALWAYS timeout to OFF_STATE
          secondsCounter = 0;
          if ((stateCounter == eeSave.warningTimeout) || (refresh)) {
            refresh = 0;
            oled.clear();
          }
          gotoXY(0, 0); LcdP("Timoutout. Bat="); showBattery();
          gotoXY(0, 1); LcdP("Wait=%03d secs", stateCounter); oled.clearToEOL();
          digitalWrite(WARNING, WARNINGON); // warning
          digitalWrite(POWER, POWERON);
          if (eeSave.tone) tone(TONE, eeSave.tone, 100);
          if (stateCounter) --stateCounter;
          if (stateCounter == 0 ) {
            stateCounter = eeSave.offTimeout;
            state = OFF_STATE;
          }
          ++upSecs;
          break;

        case OFF_STATE : // everything off
          secondsCounter = 0;
          if ((stateCounter == eeSave.offTimeout) || (refresh)) {
            refresh = 0;
            oled.clear();
          }
          if (stateCounter) --stateCounter;
          if (vol <= eeSave.highV)  {
            gotoXY(0, 0);
            LcdP("Stdby. Bat=");
            showBattery();
          }
          digitalWrite(WARNING, WARNINGON); // LEAVE ON ie LOW
          digitalWrite(POWER, POWEROFF);
          if (vol > eeSave.highV)
          {
            gotoXY(0, 0); LcdP("Warming up. Bat=");  showBattery();
            gotoXY(0, 1); LcdP("Wait=%03d secs", stateCounter); oled.clearToEOL();
            if (stateCounter == 0) {
              stateCounter = eeSave.goodTimeout;
              state = GOOD_STATE;
            }
          } else
          {
            stateCounter = eeSave.offTimeout - 1; // avoid clearscreen
            //  gotoXY(0, 3); oled.clearToEOL();
          }
          ++downSecs;
          break;

        case SHUTDOWN_STATE: // everything off and stays off... hold the SET button.... set state to SHUTDOWN_STATE and stateCounter to SHUTDOWN_PERIOD
          secondsCounter = 0;
          if ((stateCounter == SHUTDOWN_PERIOD) || (refresh))
          {
            refresh = 0;
            oled.clear();
            gotoXY(0, 2); LcdP("Shutdown commencing.."); oled.clearToEOL();
            digitalWrite(WARNING, WARNINGON); // warning
          }
          if (stateCounter)
          { --stateCounter;
            if (stateCounter == 0)
            {
              gotoXY(0, 2); LcdP("Shutdown COMPLETE"); oled.clearToEOL();
              digitalWrite(WARNING, WARNINGON); // LEAVE ON ie LOW
              digitalWrite(POWER, POWEROFF);
            }
          }
          else if (digitalRead(DOWN) == 0)   {
            oled.clear();
            state = POWERUP_STATE;
            stateCounter = eeSave.startTimeout;
          }
      }
    }
  }
}