// C++ code
//

#include <Wire.h>
#include <Adafruit_PCF8575.h>
#include <Adafruit_GFX.h>
#include <Adafruit_LEDBackpack.h>
#include <Adafruit_LiquidCrystal.h>

//0x26 Create PCF8574 object with I2C address 0x20
Adafruit_PCF8575 pcf(0x26); 
// PCF8574 pin connections
#define ROW1 P0
#define ROW2 P1
#define ROW3 P2
#define ROW4 P3
#define COL1 P4
#define COL2 P5
#define COL3 P6
#define COL4 P7

//0x27 Initialize the I2C LCD with its I2C address (e.g., 0x27)
Adafruit_LiquidCrystal lcd(0x27);

//0x70 Create an instance of the LED backpack
Adafruit_7segment matrix = Adafruit_7segment();  

// Inintialise Variables
  //CONST
  	const int resetButtonPin = 2;   // Pin for the reset button
	const int buzzerPin = 9;
	const int maxDisplayValue = 10000; // Max Display Value
	const int T_1000 = 1000;           // 1000ms
	const unsigned long debouncePeriod_200 = 200;
	const unsigned long debouncePeriod_500 = 500;
    // Keypad layout
    const char keys[4][4] = {
      {'1', '2', '3', 'A'},
      {'4', '5', '6', 'B'},
      {'7', '8', '9', 'C'},
      {'*', '0', '#', 'D'}
    };

  //STATIC
	static unsigned long lastDisplayUpdate = 0;
	static unsigned long lastDebounceTime = 0;

  //OTHER
    unsigned long elapsedMillis  = 0;
    //Timer
    unsigned long TimerReset     = 0;  // = Timer Set actual Millis()
    unsigned int TimerElapsed    = 0;  // = Timer Calculate time since last Reset
    unsigned int TimerMin        = 0;  // = Timer Minutes
    unsigned int TimerSec        = 0;  // = Timer Seconds 
    //Conter
    unsigned long CounterReset   = 0;  // = Counter Set actual Millis()
    unsigned int CounterElapsed  = 0;  // = Counter Calculate time since last Reset
    unsigned int CounterMin      = 0;  // = Counter Minutes
    unsigned int CounterSec      = 0;  // = Counter Seconds



void setup() {
  // Initialize Serial communication for debugging
    Serial.begin(9600);
    Serial.println("Scanning for I2C devices...");
  // Initialize I2C
  	Wire.begin();
  // Initialize PCF8574 with I2C
  	pcf.begin();
    for (int i = 0; i < 4; i++) {
      pcf.pinMode(i, OUTPUT);      // Row pins (P0 to P3) as outputs
      pcf.digitalWrite(i, HIGH);  // Set rows HIGH initially
    }
    for (int i = 4; i < 8; i++) {
      pcf.pinMode(i, INPUT_PULLUP);       // Column pins (P4 to P7) as inputs +Enable pull-up resistors on columns
    }
  // Initialize the LCD display with I2C
    lcd.begin(16, 2);
    lcd.setBacklight(1);
  // Initialize the LED 7 Segment display
  	matrix.begin(0x70); // Use the default I2C address
  
  //Buton Setup
    pinMode(resetButtonPin, INPUT_PULLUP); // Configure button pin with pull-up resistor
    pinMode(buzzerPin, OUTPUT);

  // Scan for I2C devices
    for (byte address = 1; address < 127; address++) {
      Wire.beginTransmission(address);
      if (Wire.endTransmission() == 0) {
        Serial.print("I2C device found at address 0x");
        Serial.println(address, HEX);
        delay(debouncePeriod_500);
      }
    }
  
  //Start Menu
    lcd.setCursor(0, 0);
    lcd.print("Menu:...[Select]");       // Print a message
  
  // Short delay before starting the main loop
    delay(debouncePeriod_200);  
}

void loop() {

  // Check Overflow
  if ( TimerReset > millis() || CounterReset > millis() ){
    TimerReset     = 0;
    CounterReset   = 0;
  }
  
  // Check if the reset button is pressed (with non-blocking debounce)
  if (digitalRead(resetButtonPin) == LOW) {
    if (millis() - lastDebounceTime > debouncePeriod_200) { // 200ms debounce period
      TimerReset = millis();
      CounterReset = millis();
      lastDebounceTime = millis();
    }
  }
  // Calculate elapsed time
  TimerElapsed   = (millis() - TimerReset  ) /T_1000;	// Elapsed time in seconds
  CounterElapsed = (millis() - CounterReset) /T_1000;	// Elapsed time in seconds
  
  //Display Time every 1000ms
  if (millis() - lastDisplayUpdate >= T_1000) {
    lastDisplayUpdate = millis();
    // Display a number on the 7-segment display
    matrix.print(maxDisplayValue-TimerElapsed);   // Display elapsed time in seconds
    matrix.writeDisplay();              // Update the display
  
    // Move the cursor to the second row, first column
    lcd.setCursor(0,1);
    lcd.print(TimerElapsed);     // Display elapsed time in seconds

    elapsedMillis = TimerElapsed;
    CounterMin = elapsedMillis / 60;    // Extract minutes
    CounterSec = elapsedMillis % 60;	// Extract seconds 
  
    lcd.setCursor(11,1);
    if (CounterMin < 10) { lcd.print("0"); }
    lcd.print(CounterMin);
    lcd.print(":");
    if (CounterSec < 10) { lcd.print("0"); }
    lcd.print(CounterSec);
    
  	
  }
  
  /* 
  tone(buzzerPin, 1000); // Generate a 1kHz sound
  delay(1000);           // Sound for 1 second
  noTone(buzzerPin);     // Stop the sound
  delay(1000);           // Wait 1 second	
  */
}


/*
Display 7s

Clear the display
  matrix.clear();
  matrix.writeDisplay();
  
*/


/*
LCD display:
1. Direct Connection (Without I2C Module)
  LCD Pin	Label	Connection to Arduino
  1	GND	GND
  2	VCC	5V
  3	V0 (Contrast)	Connect to a 10kΩ potentiometer (middle pin)
  4	RS (Register Select)	Digital Pin (e.g., D7)
  5	RW (Read/Write)	GND (set to Write mode)
  6	E (Enable)	Digital Pin (e.g., D8)
  7–10	D0–D3	Leave unconnected (used in 4-bit mode)
  11	D4	Digital Pin (e.g., D9)
  12	D5	Digital Pin (e.g., D10)
  13	D6	Digital Pin (e.g., D11)
  14	D7	Digital Pin (e.g., D12)
  15	LED+ (Backlight)	220Ω resistor to 5V
  16	LED- (Backlight)	GND

  >> LiquidCrystal lcd(7, 8, 9, 10, 11, 12); // RS, E, D4, D5, D6, D7
  lcd.begin(16, 2);           (Setup) Set up the LCD's number of columns and rows
  lcd.setCursor(column, row); Moves the cursor to the specified column (0–15) and row (0–1).
  lcd.clear();                Clears the entire display and resets the cursor to (0, 0).
  lcd.home();                 Moves the cursor back to (0, 0) without clearing the screen.
  lcd.print();                Display data or "text"
  
2. Using an I2C Module (Recommended)  
  I2C Module Pin	Connection to Arduino
  GND	GND
  VCC	5V
  SDA	A4 (Uno) or SDA pin
  SCL	A5 (Uno) or SCL pin
  
  >> LiquidCrystal_I2C lcd(0x27, 16, 2);   // Initialize the I2C LCD with its I2C address (e.g., 0x27)
  lcd.init();                      (Setup) Initialize the LCD
  lcd.Backlight();                 (Setup) Turn on the backlight
  lcd.noBacklight();               to toggle the backlight.
  lcd.setCursor(column, row);      Moves the cursor to the specified column (0–15) and row (0–1).
  lcd.print();                     Display data or "text"
  
*/

/*
I2C Address Table
A2	A1	A0	I2C Address
0	0	0	0x70
0	0	1	0x71
0	1	0	0x72
0	1	1	0x73
1	0	0	0x74
1	0	1	0x75
1	1	0	0x76
1	1	1	0x77
*/

/*
void setup()
{
  pinMode(A0, INPUT);
  pinMode(8, OUTPUT);
  pinMode(A1, INPUT);
  pinMode(A2, INPUT);
}

void loop()
{
  // if button press on A0 is detected
  if (digitalRead(A0) == HIGH) {
    tone(8, 440, 100); // play tone 57 (A4 = 440 Hz)
  }
  // if button press on A1 is detected
  if (digitalRead(A1) == HIGH) {
    tone(8, 494, 100); // play tone 59 (B4 = 494 Hz)
  }
  // if button press on A0 is detected
  if (digitalRead(A2) == HIGH) {
    tone(8, 523, 100); // play tone 60 (C5 = 523 Hz)
  }
  delay(10); // Delay a little bit to improve simulation performance
}*/