/*

  AirQuality.ino
  
  ATMEGA328 (Arduino UNO) only

  Universal 8bit Graphics Library (https://github.com/olikraus/u8g2/)

  Copyright (c) 2018, olikraus@gmail.com
  All rights reserved.

  Redistribution and use in source and binary forms, with or without modification, 
  are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright notice, this list 
    of conditions and the following disclaimer.
    
  * Redistributions in binary form must reproduce the above copyright notice, this 
    list of conditions and the following disclaimer in the documentation and/or other 
    materials provided with the distribution.

  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND 
  CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, 
  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 
  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 
  DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR 
  CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 
  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
  CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 
  STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 
  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 
  ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.  
  
*/

#include <Arduino.h>
#include <Wire.h>
#include <U8g2lib.h>
#include <Adafruit_SGP30.h>
#include <Adafruit_SHT31.h>
#include <avr/sleep.h> 



U8G2_SSD1306_128X64_NONAME_1_HW_I2C u8g2(U8G2_R0, /* reset=*/ U8X8_PIN_NONE);
Adafruit_SHT31 sht31 = Adafruit_SHT31();	// temperature & humidity sensor
Adafruit_SGP30 sgp;						// air quality sensor

U8G2LOG u8g2log;

// setup the terminal (U8G2LOG) and connect to u8g2 for automatic refresh of the display
// The size (width * height) depends on the selected font and the display

#define U8LOG_WIDTH 25
#define U8LOG_HEIGHT 9
uint8_t u8log_buffer[U8LOG_WIDTH*U8LOG_HEIGHT];

//===================================================


#define FONT_SMALL u8g2_font_helvB08_tf
#define FONT_MED_NUM u8g2_font_helvB14_tn
//#define FONT_BIG u8g2_font_inr49_mn
#define FONT_BIG u8g2_font_logisoso38_tn

//===================================================

#define HIST_CNT 64
#define HIST_VAUES 5
#define TEMP_LOW -20
#define TEMP_HIGH (TEMP_LOW+120)

uint8_t hist_start = 0;
uint8_t hist_end = 1;
uint8_t hist_last = 0;


void hist_append(void)
{
  hist_last = hist_end;
  
  if ( hist_end == hist_start )	
  {	// history is full
    hist_start++;
    if ( hist_start >= HIST_CNT )
      hist_start = 0;
  }
  
    
  hist_end++;
  if ( hist_end >= HIST_CNT )
  {
    hist_end = 0;
  }
}

uint16_t hist_eco2_max[HIST_CNT];
uint16_t hist_eco2_min[HIST_CNT];

uint8_t hist_temp_max[HIST_CNT];
uint8_t hist_temp_min[HIST_CNT];

uint8_t hist_rh_max[HIST_CNT];
uint8_t hist_rh_min[HIST_CNT];



//===================================================
// http://shelvin.de/arduino-in-den-sleep_mode_pwr_down-schlaf-modus-setzen/


// define startup calibration time: 2h
#define STARTUP_TIME ((60*60*2)/2)

// define startup calibration time: 30 seconds
#define DISPLAY_TIME ((30))

// Datasheet, page 8:
// For the first 15s after the “Init_air_quality” command  the  sensor  
// is  in  an  initialization  phase  during  which  a  “Measure_air_quality”  
// command  returns  fixed  values
// --> sensor warmup time
#define SENSOR_WARMUP_TIME ((16))

#define SENSOR_MEASURE_TIME (14)

#define SENSOR_SAMPLE_TIME (2*60)


// count WDT interrupts. Interrupt will happen every 4 seconds, so overflow happens after 544 years
volatile uint32_t wdt_count = 0;

volatile uint16_t startup_timer = 0;
volatile uint16_t sensor_sample_timer = SENSOR_SAMPLE_TIME;
volatile uint8_t is_sensor_sample_timer_alarm = 0;
volatile uint8_t display_timer = 0;
volatile uint8_t sensor_warmup_timer = 0;
volatile uint8_t sensor_measure_timer = 0;

ISR(WDT_vect) 
{
  wdt_count++; 
  if ( startup_timer > 0 )
    startup_timer--;
  if ( display_timer > 0 )
    display_timer--;
  if ( sensor_warmup_timer > 0 )
    sensor_warmup_timer--;
  if ( sensor_measure_timer > 0 )
    sensor_measure_timer--;
  if ( sensor_sample_timer > 0 )
  {
    sensor_sample_timer--;
  }
  else
  {
    sensor_sample_timer = SENSOR_SAMPLE_TIME;
    is_sensor_sample_timer_alarm = 1;
  }
}

void enableWDT() 
{
  MCUSR = 0;			// clear all reset flags including the WDT flag
  WDTCSR = B00011000; // enable bit 4 (WDCE) and bit 3 (WDE) to change the prescalar
  WDTCSR = B01000110; // Enable watchdog IRQ  and set prescaler to 128k --> 1 sec
}

void reducePower(void)
{
  ADCSRA = ADCSRA & B01111111; // ADC abschalten, ADEN bit7 zu 0
  ACSR = B10000000; // Analogen Comparator abschalten, ACD bit7 zu 1
  //DIDR0 = DIDR0 | B00111111; // Digitale Eingangspuffer ausschalten, analoge Eingangs Pins 0-5 auf 1
}

//===================================================


void setup(void) {
  reducePower();

  u8g2.begin();  
  u8g2.enableUTF8Print();
  
  u8g2.setFont(u8g2_font_5x7_mr);	// set the font for the terminal window
  u8g2log.begin(u8g2, U8LOG_WIDTH, U8LOG_HEIGHT, u8log_buffer);
  u8g2log.setLineHeightOffset(0);	// set extra space between lines in pixel, this can be negative
  u8g2log.setRedrawMode(0);		// 0: Update screen with newline, 1: Update screen for every char  

  
  u8g2log.print(F("Air Quality\n"));
  if (sht31.begin(0x44)) {   				// 0x45 for alternate i2c addr
    u8g2log.print(F("SHT31 found at 0x44\n"));
  } else {
    u8g2log.print(F("SHT31 not found\n"));
    while (1);
  }

  if (sgp.begin()) {   				
    u8g2log.print(F("SGP30 found\n"));
  } else {
    u8g2log.print(F("SGP30 not found\n"));
    while (1);
  }
  
  u8g2log.print(F("SGP #"));
  u8g2log.print(sgp.serialnumber[0], HEX);
  u8g2log.print(sgp.serialnumber[1], HEX);
  u8g2log.println(sgp.serialnumber[2], HEX);

  delay(1000);
  
  enableWDT();
}

/* 
  Calculate absolute humidity [mg/m^3]
  Args: Temperature [°C], humidity [%RH]
*/

uint32_t getAbsoluteHumidity(float temperature, float humidity) {
    // approximation formula from Sensirion SGP30 Driver Integration chapter 3.15
    const float absoluteHumidity = 216.7f * ((humidity / 100.0f) * 6.112f * exp((17.62f * temperature) / (243.12f + temperature)) / (273.15f + temperature)); // [g/m^3]
    const uint32_t absoluteHumidityScaled = static_cast<uint32_t>(1000.0f * absoluteHumidity); // [mg/m^3]
    return absoluteHumidityScaled;
}


float temperature_raw;
float humidity_raw;
uint8_t temperature;	/* with offset and multiplied by 2 */
uint8_t humidity;		/* *2 */
uint16_t tvoc_raw;
uint16_t tvoc_lp;
uint16_t eco2_raw;
uint16_t eco2_lp;
int is_air_quality_available = 0;


void startAirQuality(void)
{
}

void readAirQuality(void)
{
  uint8_t i;
  int32_t tvoc_coeff = 7;	// 1..32
  int32_t eco2_coeff = 7;	// 1..32
  
  temperature_raw = sht31.readTemperature();
  
  if ( temperature_raw <= (float)TEMP_LOW )
  {
    temperature = 0;
  }
  else if ( temperature_raw >= (float)TEMP_HIGH )
  {
    temperature = TEMP_HIGH - TEMP_LOW;
    temperature *= 2;
  }
  else
  {
    temperature = (uint8_t)((temperature_raw-(float)TEMP_LOW)*2.0);
  }
  
  humidity_raw = sht31.readHumidity();
  humidity = (uint8_t)((humidity_raw)*2.0);

  sgp.setHumidity(getAbsoluteHumidity(temperature_raw, humidity_raw));
  is_air_quality_available = sgp.IAQmeasure();

  if ( is_air_quality_available )
  {
    tvoc_raw = sgp.TVOC;
    eco2_raw = sgp.eCO2;
  }
  else
  {
    tvoc_raw = 0;
    eco2_raw = 400;
  }
}


uint16_t maximum(uint16_t a, uint16_t b)
{
  if ( a < b )
    return b;
  return a;
}

uint16_t minimum(uint16_t a, uint16_t b)
{
  if ( a > b )
    return b;
  return a;
}


/* append current values to last history entry */
void add_hist_minmax(void)
{
  
  hist_eco2_max[hist_last] = maximum(hist_eco2_max[hist_last], eco2_raw);
  hist_eco2_min[hist_last] = minimum(hist_eco2_min[hist_last], eco2_raw);

  hist_temp_max[hist_last] = maximum(hist_temp_max[hist_last], temperature);
  hist_temp_min[hist_last] = minimum(hist_temp_min[hist_last], temperature);

  hist_rh_max[hist_last] = maximum(hist_rh_max[hist_last], humidity);
  hist_rh_min[hist_last] = minimum(hist_rh_min[hist_last], humidity);
}

void add_hist_new(void)
{
  hist_append();

  hist_eco2_max[hist_last] = eco2_raw;
  hist_eco2_min[hist_last] = eco2_raw;

  hist_temp_max[hist_last] = temperature;
  hist_temp_min[hist_last] = temperature;

  hist_rh_max[hist_last] = humidity;
  hist_rh_min[hist_last] = humidity;

}

uint16_t get_uint8(void *ptr, uint8_t pos)
{
  return ((uint8_t *)ptr)[pos];
}

uint16_t get_uint16(void *ptr, uint8_t pos)
{
  return ((uint16_t *)ptr)[pos];
}

void draw_temperature(uint16_t x)
{
  uint8_t frac;
  frac = x & 1;
  x >>= 1;
  x += TEMP_LOW;
  x = x & 0x0ff;
  u8g2.print(x);
  u8g2.print('.');
  if ( frac ) 
    u8g2.print('5');
  else
    u8g2.print('0');
}

void draw_humidity(uint16_t x)
{
  uint8_t frac;
  frac = x & 1;
  x >>= 1;
  u8g2.print(x);
  u8g2.print('.');
  if ( frac ) 
    u8g2.print('5');
  else
    u8g2.print('0');
}

void draw_16bit(uint16_t x)
{
  u8g2.print(x);
}

void draw_graph( uint16_t (*get_val)(void *ptr, uint8_t pos), void *min_array, void *max_array, void (*draw_value)(uint16_t x))
{
  uint8_t i, ii, x;
  uint16_t max = 0;
  uint16_t min = 0x0ffff;
  uint16_t delta;
  uint8_t ymin, ymax;
  i = hist_start;
  for(;;)
  {
    ii = i;
    i++;
    if ( i >= HIST_CNT )
      i = 0;
    if ( i == hist_end )
      break;
    if ( min > get_val(min_array, ii) )
      min = get_val(min_array, ii);
    if ( max < get_val(max_array, ii) )
      max = get_val(max_array, ii);
  }
  if ( min > max )
    return;
  if ( min + 32 >= max )
    max = min + 32;
    
  if ( max - min < 100 )
  {
    max += 19;
    max /= 20;
    max *= 20;
    
    min /= 20;
    min *= 20;
  }
  else
  {
    max += 199;
    max /= 200;
    max *= 200;
    
    min /= 200;
    min *= 200;
  }
    
  delta = max-min;

  i = hist_start;
  x = 127-HIST_CNT;
  
  for(;;)
  {
    ii = i;
    i++;
    if ( i >= HIST_CNT )
      i = 0;
    if ( i == hist_end )
      break;
    ymin = ((unsigned long)(get_val(min_array, ii) - min)*32UL)/delta;
    ymax = ((unsigned long)(get_val(max_array, ii) - min)*32UL)/delta;
    u8g2.drawVLine(x, 63-ymax, ymax-ymin+1);
    x++;
  }
  u8g2.setCursor(0, 43);
  draw_value(max);
  u8g2.setCursor(0, 63);
  draw_value(min);
}

//===================================================

void draw_page1(void)
{
  u8g2.firstPage();
  do {
    u8g2.setFont(u8g2_font_helvB08_tf);
    u8g2.setCursor(0, 10);
    //u8g2.print(temperature_raw);
    draw_temperature(temperature);
    //u8g2.setCursor(33, 10);
    u8g2.print(F(" °C"));
    u8g2.setCursor(64, 10);
    draw_humidity(humidity);
    //u8g2.setCursor(98, 10);
    u8g2.print(F(" %RH"));

    //u8g2.setCursor(0, 20);
    //u8g2.print(eco2_base, HEX);
    //u8g2.print(" ");
    //u8g2.print(tvoc_base, HEX);


    if ( is_air_quality_available )
    {
      u8g2.setCursor(0, 30);
      u8g2.print(tvoc_raw);
      u8g2.print(" / ");
      u8g2.print(eco2_raw);
    }
      
    draw_graph( get_uint16, hist_eco2_min, hist_eco2_max, draw_16bit);
      
  } while ( u8g2.nextPage() );
}

//===================================================

void draw_eco2(void)
{
  u8g2.setFontMode(1);
  u8g2.firstPage();
  do {
    u8g2.setFont(FONT_SMALL);
    u8g2.setCursor(0, 10);
    //u8g2.print(temperature_raw);
    draw_temperature(temperature);
    //u8g2.setCursor(33, 10);
    u8g2.print(F(" °C"));
    u8g2.setCursor(64, 10);
    draw_humidity(humidity);
    //u8g2.setCursor(98, 10);
    u8g2.print(F(" %RH"));

    //u8g2.setCursor(0, 20);
    //u8g2.print(eco2_base, HEX);
    //u8g2.print(" ");
    //u8g2.print(tvoc_base, HEX);

    if ( is_air_quality_available )
    {
      u8g2.setFont(FONT_BIG);
      u8g2.setCursor(20, 63);
      u8g2.print(eco2_raw);
      
      u8g2.setFont(FONT_SMALL);
      u8g2.setCursor(0, 25);
      u8g2.print(F("CO"));
      u8g2.setCursor(17, 30);
      u8g2.print(F("²"));
      
      //u8g2.print(tvoc_raw);
    }
      
  } while ( u8g2.nextPage() );
}

//===================================================

void draw_1_4_temperature(u8g2_uint_t x, u8g2_uint_t y)
{
    u8g2.setFont(FONT_MED_NUM);
    
    u8g2.setCursor(x, 28+y);
    draw_temperature(temperature);

    u8g2.setFont(FONT_SMALL);
    
    u8g2.setCursor(x, 10+y);
    u8g2.print(F("°C"));
}

void draw_1_4_humidity(u8g2_uint_t x, u8g2_uint_t y)
{
  u8g2.setFont(FONT_MED_NUM);
  u8g2.setCursor(x, 28+y);
  draw_humidity(humidity);
  
  u8g2.setFont(FONT_SMALL);
  u8g2.setCursor(x, 10+y);
  u8g2.print(F("%RH"));
}

void draw_1_4_eco2(u8g2_uint_t x, u8g2_uint_t y)
{
  u8g2.setFont(FONT_SMALL);

  u8g2.setCursor(x, y+45-32);
  u8g2.print(F("ppm CO"));
  u8g2.setCursor(x+40, y+50-32);
  u8g2.print(F("²"));

  u8g2.setFont(FONT_MED_NUM);

  u8g2.setCursor(x, y+63-32);
  u8g2.print(eco2_raw);
}

void draw_1_4_tvoc(u8g2_uint_t x, u8g2_uint_t y)
{
  u8g2.setFont(FONT_SMALL);
  u8g2.setCursor(x, y+45-32);
  u8g2.print(F("ppb TVOC"));

  u8g2.setFont(FONT_MED_NUM);

  u8g2.setCursor(x, y+63-32);
  u8g2.print(tvoc_raw);
}

void draw_1_4_wdt_count(u8g2_uint_t x, u8g2_uint_t y)
{
  u8g2.setFont(FONT_SMALL);
  u8g2.setCursor(x, y+45-32);
  u8g2.print(F("WDT Count"));

  u8g2.setFont(FONT_MED_NUM);

  u8g2.setCursor(x, y+63-32);
  u8g2.print(wdt_count);
}

void draw_1_4_emoticon(u8g2_uint_t x, u8g2_uint_t y)
{
  uint8_t tvoc_idx, eco2_idx, emo_idx;
  if ( tvoc_raw <= 75 )
    tvoc_idx = 1;
  else if ( tvoc_raw <= 150 )
    tvoc_idx = 2;
  else if ( tvoc_raw <= 300 )
    tvoc_idx = 3;
  else if ( tvoc_raw <= 500 )
    tvoc_idx = 4;
  else if ( tvoc_raw <= 1000 )
    tvoc_idx = 5;
  else if ( tvoc_raw <= 1500 )
    tvoc_idx = 6;
  else if ( tvoc_raw <= 3000 )
    tvoc_idx = 7;
  else if ( tvoc_raw <= 5000 )
    tvoc_idx = 8;
  else
    tvoc_idx = 9;

  if ( eco2_raw <= 500 )
    eco2_idx = 1;
  else if ( eco2_raw <= 600 )
    eco2_idx = 2;
  else if ( eco2_raw <= 800 )
    eco2_idx = 3;
  else if ( eco2_raw <= 1000 )
    eco2_idx = 4;
  else if ( eco2_raw <= 1200 )
    eco2_idx = 5;
  else if ( eco2_raw <= 1400 )
    eco2_idx = 6;
  else if ( eco2_raw <= 5000 )
    eco2_idx = 7;
  else if ( eco2_raw <= 10000 )
    eco2_idx = 8;
  else
    eco2_idx = 9;

  emo_idx = tvoc_idx;
  if ( emo_idx < eco2_idx )
    emo_idx = eco2_idx;
  u8g2.setFont(u8g2_font_emoticons21_tr);
  u8g2.drawGlyph(x+20, y+21+6, 32+emo_idx);
}

//===================================================

void draw_all_numbers(void)
{
  u8g2.setFontMode(1);
  u8g2.firstPage();
  do {
    u8g2.drawHLine(0, 32, 128);
    u8g2.drawVLine(62, 0, 64);
  
    
    draw_1_4_temperature(1, 0);
    draw_1_4_humidity(66, 0);

    if ( is_air_quality_available )
    {
      draw_1_4_eco2(1, 32);
      draw_1_4_tvoc(66, 32);
    }
      
  } while ( u8g2.nextPage() );
}


void draw_with_emo(void)
{
  u8g2.setFontMode(1);
  u8g2.firstPage();
  do {
    u8g2.drawHLine(0, 32, 128);
    u8g2.drawVLine(62, 0, 64);
  
    
    draw_1_4_temperature(1, 0);
    draw_1_4_humidity(66, 0);
    //draw_1_4_wdt_count(66, 0);

    if ( is_air_quality_available )
    {
      draw_1_4_eco2(1, 32);
      draw_1_4_emoticon(66, 32);
    }
      
  } while ( u8g2.nextPage() );
}

//===================================================

#define STATE_RESET 0
#define STATE_STARTUP_DISP_ON 1
#define STATE_STARTUP_DISP_OFF 2
#define STATE_WARMUP_DISP_ON 11
#define STATE_WARMUP_DISP_OFF 12
#define STATE_MEASURE_DISP_ON 21
#define STATE_MEASURE_DISP_OFF 22
#define STATE_SENSOR_SLEEP_DISP_OFF 32

uint8_t state = STATE_STARTUP_DISP_ON;

void next_state(void)
{
  switch(state)
  {
    case STATE_RESET:
      startup_timer = STARTUP_TIME;
      state = STATE_STARTUP_DISP_ON;
      break;
    case STATE_STARTUP_DISP_ON:
      if ( display_timer == 0 )
      {
	state = STATE_STARTUP_DISP_OFF;
      }
      else
      {
      }
      break;
    case STATE_STARTUP_DISP_OFF:
    
      break;
    case STATE_WARMUP_DISP_ON:
      if ( display_timer == 0 )
      {
	state = STATE_WARMUP_DISP_OFF;
      }
      else
      {
      }
      break;
    case STATE_WARMUP_DISP_OFF:
      break;
    case STATE_MEASURE_DISP_ON:
      if ( display_timer == 0 )
      {
	state = STATE_MEASURE_DISP_OFF;
      }
      else
      {
      }
      break;
    case STATE_MEASURE_DISP_OFF:
      break;
    case STATE_SENSOR_SLEEP_DISP_OFF.
      break;
    default:
      state = STATE_RESET;
      break;
  }
}




//===================================================


uint16_t eco2_base;
uint16_t tvoc_base;

uint8_t new_counter = 0; 

void loop(void) {
  uint8_t i;
  u8g2_uint_t g;
  
  
  readAirQuality();
  if ( (new_counter & 3) == 0 )
    add_hist_new();
  else
    add_hist_minmax();
  new_counter++;
  
  sgp.getIAQBaseline(&eco2_base, &tvoc_base);
  draw_with_emo();

  set_sleep_mode(SLEEP_MODE_PWR_DOWN); 
  sleep_enable(); 
  sleep_mode(); 
  sleep_disable(); 
}