#include <Wire.h>
#include <TimeLib.h>
#include <DS1307RTC.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_I2CDevice.h>

#include "images.h"

#define LONGPRESSTHRESHOLD  5000
#define TIME_BASEPOSITION   32
#define DATE_BASEPOSITION   48
#define X_BASEPOSITION      64
#define SERIALRATE          115200
#define USEEXPO             0

Adafruit_SSD1306 display(128, 64, &Wire, -1, 888888);       // Define Display

int textSizeTime = 2;
int textSizeDate = 1;
int animState = 1, animCounter = 0;
float animProgress = 25;
bool USBSyncMode = false;

#ifdef USEEXPO
  float easeInOut(float x) { return x == 0 ? 0 : powf(2, 10 * x - 10); }
#else
  float easeInOut(float x) { return powf(x, 4); }
#endif

void setup() {
  display.begin(SSD1306_SWITCHCAPVCC, 0x3C);        // Begin I2C Communication With Display

  display.clearDisplay();                           // Clear Display Buffer
  display.setTextColor(SSD1306_BLACK);
  display.println("READY.");
  display.display();                                // Display On Screen

  pinMode(13, OUTPUT);
  pinMode(10, INPUT);
  pinMode(9, INPUT);
  pinMode(8, INPUT);

  updateStates();
}

tmElements_t tm;
String currTime;
float a;
int l, pl; int s, ps; int r, pr; int lr, plr;
uint32_t framec = 0;
uint32_t longPressStart = 0;
bool longPressCanStart = true;

void loop() {
  updateStates();

  if (!(animState == 0 && animProgress >= 26) && USBSyncMode == false) {
    display.clearDisplay();

    if (animState == 0) {
      a = easeInOut(animProgress / 25) *32;
      if (animProgress <= 25) animProgress++; 
    } else if (animState == 1) {
      a = easeInOut(animProgress / 25) *32;
      if (animProgress > 0) animProgress--;

      animCounter++;
      if (animCounter > 200) { animState = 0; }
    }
  
    if (RTC.read(tm)) {
      display.setTextColor(SSD1306_BLACK);
      display.fillRoundRect(0, a, 128, 64-(a*2), 10, SSD1306_WHITE);

      currTime = DuoDigit(String(tm.Hour)) + ":" + DuoDigit(String(tm.Minute)) + ":" + DuoDigit(String(tm.Second));
      display.setTextSize(textSizeTime);
      display.setCursor(
        X_BASEPOSITION - ((5 * textSizeTime)*(currTime.length() +1.5) / 2),
        TIME_BASEPOSITION - (7*textSizeTime / 2) - (7*textSizeDate / 2)
      );
      display.print(currTime);
      
      currTime = DuoDigit(String(tm.Day)) + "/" + DuoDigit(String(tm.Month)) + "/" + DuoDigit(String(tm.Year));
      display.setTextSize(textSizeDate);
      display.setCursor(
        X_BASEPOSITION - ((5 * textSizeDate)*(currTime.length() +1) / 2),
        DATE_BASEPOSITION - (7*textSizeDate / 2) - (7*textSizeTime / 2)
      );
      display.print(currTime);

    } else {
      display.drawBitmap(0, 0, warning, 72, 64, SSD1306_WHITE);
      display.setTextSize(1);
      display.setTextColor(SSD1306_WHITE);
      display.setCursor(55, 0);

      if (RTC.chipPresent()) {
        display.println("RTC Module");
        display.setCursor(61, 10);
        display.print("Has Stopped");
      } else {
        display.print("RTC Not");
        display.setCursor(61, 10);
        display.print("Detected");
      }
    }
    
    display.display();

  } else if (USBSyncMode) { // USB Sync Mode
    display.clearDisplay();
    Serial.begin(SERIALRATE);
    Serial.println("\nHH:MM:SS DD/MM/YYYY");

    bool Error = !RTC.read(tm);

    drawUSBSyncInterface();
    if (Error) display.println("RTC Error");
    else display.println("Waiting for Serial...");
    display.display();

    if (Error) { while(!(s < ps)) updateStates(); USBSyncMode = false; }

    int h = tm.Hour;
    int m = tm.Minute;
    int s = tm.Second;
    int d = tm.Day;
    int mo = tm.Month;
    int y = tm.Year;

    while(USBSyncMode) {
      updateStates();

      if (Serial.available() > 0) {
        String rectime = Serial.readStringUntil('\n');
        Serial.println(rectime);

        display.clearDisplay();
        drawUSBSyncInterface();
        display.println("Select to confirm");
        
        h = rectime.substring(0, 2).toInt();
        m = rectime.substring(3, 5).toInt();
        s = rectime.substring(6, 8).toInt();
        d = rectime.substring(9, 11).toInt();
        mo = rectime.substring(12, 14).toInt();
        y = rectime.substring(15, 19).toInt();

        tmElements_t tm2;
        tm2.Hour = h; tm2.Minute = m; tm2.Second = s; tm2.Day = d; tm2.Month = mo; tm2.Year = y;
        int unix = makeTime(tm2);
        //Serial.println(unixTime);

        //display.println("unix:   " + String(unix));
        display.println("hour:   " + String(h));
        display.println("minute: " + String(m));
        display.println("second: " + String(s));
        
        display.display();
      }
    }

  } else {
    if (bitRead(framec, 16) == 1) { display.display(); framec = 0; /*digitalWrite(13, !digitalRead(13)); <-- debug feature*/ }
    framec++;
  }
}

String DuoDigit(String v) {
  return v.length() < 2 ? "0" + v : v;
}

void updateStates() {
  pl = l;
  ps = s;
  pr = r;
  plr = lr;

  l = digitalRead(8);
  s = digitalRead(9);
  r = digitalRead(10);
  lr = !l && !r;

  if (s < ps && animState != 1) { animState = 1; animProgress = 25; animCounter = 0; framec = 0; }

  if (plr < lr) longPressStart = millis();
  else if (lr < plr) longPressCanStart = true;

  if (lr && (millis() - longPressStart) > LONGPRESSTHRESHOLD && longPressCanStart) {
    longPressStart = millis();
    if (USBSyncMode) Serial.end();
    USBSyncMode = !USBSyncMode;
    longPressCanStart = false;
  }
}

void drawUSBSyncInterface() {
  display.drawBitmap(0, 0, usb, 48, 23, SSD1306_WHITE);
  display.setTextColor(SSD1306_WHITE);
  display.setCursor(52, 2); display.print("USB Sync");
  display.setCursor(52, 12); display.print(SERIALRATE);
  display.setCursor(0, 25);
}