#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ILI9341.h>

// TFT display pins
#define TFT_CS   15
#define TFT_DC   2
#define TFT_RST  4
Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC, TFT_RST);

// Joystick
const int joyX = 34;
const int joyY = 35;

// Buttons (active LOW)
const int btnConfirm = 32;
const int btnBack = 33;
const int btnExtra = 25;

// Buzzer
const int buzzerPin = 26;

// Debounce variables
bool lastConfirmState = HIGH;
bool lastBackState = HIGH;
bool lastExtraState = HIGH;
unsigned long lastConfirmTime = 0, lastBackTime = 0, lastExtraTime = 0;
const unsigned long debounceDelay = 200;

// Menu control
int menuIndex = 0;
const int menuLength = 2;
bool inSubMenu = false;

// Screen update
bool screenNeedsUpdate = true;

// Breathing Exercise variables
bool breathingExerciseActive = false;
unsigned long breathingStartTime = 0;
const unsigned long breathingDuration = 30000;
const unsigned long inhaleTime = 4000;
const unsigned long holdTime = 7000;
const unsigned long exhaleTime = 8000;
const unsigned long totalCycle = inhaleTime + holdTime + exhaleTime;
const int minRadius = 20;
const int maxRadius = 80;
const int circleX = 160;
const int circleY = 120;

// Stopwatch buffer
char stopwatchBuffer[9];

// Time Management variables
bool timeManagementActive = false;

// Example static task list (max 5 tasks)
const char* tasks[] = {
  "1. Buy groceries",
  "2. Finish project",
  "3. Call John",
  "4. Read book",
  "5. Workout"
};
const int taskCount = 5;

// Current year and month for calendar display
int currentYear = 2025;
int currentMonth = 6; // June

// Joystick navigation timing
const int deadZone = 500, centerVal = 2048;
unsigned long lastNavTime = 0;
const unsigned long navDelay = 300;

// For time management screen refresh control
unsigned long lastTimeMgmtRefresh = 0;
const unsigned long timeMgmtRefreshInterval = 1000; // 1 second refresh interval

void setup() {
  Serial.begin(115200);
  tft.begin();
  tft.setRotation(1);
  tft.fillScreen(ILI9341_BLACK);

  pinMode(btnConfirm, INPUT_PULLUP);
  pinMode(btnBack, INPUT_PULLUP);
  pinMode(btnExtra, INPUT_PULLUP);
  pinMode(buzzerPin, OUTPUT);
}

void loop() {
  if (breathingExerciseActive) {
    runBreathingExercise();
    handleBackDuringBreathing();
  } else if (timeManagementActive) {
    runTimeManagement();
    handleBackDuringTimeManagement();
  } else {
    handleJoystick();
    handleConfirmButton();
    handleBackButton();
    handleExtraButton();

    if (screenNeedsUpdate) {
      updateDisplay();
      screenNeedsUpdate = false;
    }
  }
}

// ------------------- INPUT HANDLERS -------------------

void handleJoystick() {
  int yVal = analogRead(joyY);
  if (millis() - lastNavTime > navDelay && !inSubMenu) {
    if (yVal < centerVal - deadZone && menuIndex > 0) {
      menuIndex--;
      screenNeedsUpdate = true;
      lastNavTime = millis();
    } else if (yVal > centerVal + deadZone && menuIndex < menuLength - 1) {
      menuIndex++;
      screenNeedsUpdate = true;
      lastNavTime = millis();
    }
  }
}

void handleConfirmButton() {
  bool reading = digitalRead(btnConfirm);
  if (reading != lastConfirmState && millis() - lastConfirmTime > debounceDelay) {
    lastConfirmTime = millis();
    if (reading == LOW) {
      if (!inSubMenu) {
        inSubMenu = true;
      } else {
        if (menuIndex == 0) startBreathingExercise();
        else if (menuIndex == 1) startTimeManagement();
      }
      screenNeedsUpdate = true;
    }
  }
  lastConfirmState = reading;
}

void handleBackButton() {
  bool reading = digitalRead(btnBack);
  if (reading != lastBackState && millis() - lastBackTime > debounceDelay) {
    lastBackTime = millis();
    if (reading == LOW) {
      if (inSubMenu) {
        // If in submenu but no active feature, just go back to menu
        if (!breathingExerciseActive && !timeManagementActive) {
          inSubMenu = false;
          screenNeedsUpdate = true;
        }
      }
    }
  }
  lastBackState = reading;
}

void handleExtraButton() {
  bool reading = digitalRead(btnExtra);
  if (reading != lastExtraState && millis() - lastExtraTime > debounceDelay) {
    lastExtraTime = millis();
    if (reading == LOW) {
      // Placeholder for future features
    }
  }
  lastExtraState = reading;
}

void handleBackDuringBreathing() {
  bool reading = digitalRead(btnBack);
  if (reading != lastBackState && millis() - lastBackTime > debounceDelay) {
    lastBackTime = millis();
    if (reading == LOW) {
      breathingExerciseActive = false;
      inSubMenu = false;
      screenNeedsUpdate = true;
    }
  }
  lastBackState = reading;
}

void handleBackDuringTimeManagement() {
  bool reading = digitalRead(btnBack);
  if (reading != lastBackState && millis() - lastBackTime > debounceDelay) {
    lastBackTime = millis();
    if (reading == LOW) {
      timeManagementActive = false;
      inSubMenu = false;
      screenNeedsUpdate = true;
    }
  }
  lastBackState = reading;
}

// ------------------- MENU DISPLAY -------------------

void updateDisplay() {
  tft.fillScreen(ILI9341_BLACK);
  tft.setTextSize(2);
  tft.setCursor(10, 10);
  tft.setTextColor(ILI9341_WHITE);

  if (!inSubMenu) {
    tft.println("Menu:");
    drawOption(0, "Breathing Exercise", menuIndex == 0);
    drawOption(1, "Time Management", menuIndex == 1);
  } else {
    tft.println("Selected:");
    tft.setCursor(10, 50);
    tft.setTextColor(ILI9341_GREEN);
    if (menuIndex == 0) {
      tft.println("Breathing Exercise");
      tft.setCursor(10, 90);
      tft.setTextColor(ILI9341_WHITE);
      tft.println("Press Confirm to start");
    } else {
      tft.println("Time Management");
      tft.setCursor(10, 90);
      tft.setTextColor(ILI9341_WHITE);
      tft.println("Press Confirm to open");
    }
  }
}

void drawOption(int index, const char* label, bool selected) {
  int y = 40 + index * 30;
  tft.setCursor(10, y);
  tft.setTextColor(selected ? ILI9341_YELLOW : ILI9341_WHITE);
  tft.print(selected ? "> " : "  ");
  tft.println(label);
}

// ------------------- BREATHING EXERCISE -------------------

void startBreathingExercise() {
  breathingExerciseActive = true;
  breathingStartTime = millis();
  tft.fillScreen(ILI9341_BLACK);
}

void runBreathingExercise() {
  unsigned long now = millis();
  unsigned long elapsed = now - breathingStartTime;

  if (elapsed >= breathingDuration) {
    breathingExerciseActive = false;
    inSubMenu = false;
    screenNeedsUpdate = true;
    return;
  }

  unsigned long seconds = elapsed / 1000;
  sprintf(stopwatchBuffer, "%02lu:%02lu", seconds / 60, seconds % 60);
  unsigned long cycleTime = elapsed % totalCycle;
  int radius = minRadius;

  if (cycleTime < inhaleTime) {
    float progress = 1.0f - (float)cycleTime / inhaleTime;
    radius = minRadius + (maxRadius - minRadius) * progress;
    if (cycleTime < 50) tone(buzzerPin, 1000, 100);
  } else if (cycleTime < inhaleTime + holdTime) {
    radius = minRadius;
  } else {
    float progress = (float)(cycleTime - inhaleTime - holdTime) / exhaleTime;
    radius = minRadius + (maxRadius - minRadius) * progress;
    if (cycleTime < inhaleTime + holdTime + 50) tone(buzzerPin, 1000, 100);
  }

  // Only redraw circle and text to reduce flicker
  tft.fillRect(0, 0, 320, 240, ILI9341_BLACK);
  tft.fillCircle(circleX, circleY, radius, ILI9341_BLUE);

  const char* phaseText;
  if (cycleTime < inhaleTime) phaseText = "Inhale";
  else if (cycleTime < inhaleTime + holdTime) phaseText = "Hold";
  else phaseText = "Exhale";

  tft.setTextSize(3);
  tft.setTextColor(ILI9341_WHITE);
  int16_t x1, y1;
  uint16_t w, h;
  tft.getTextBounds(phaseText, 0, 0, &x1, &y1, &w, &h);
  tft.setCursor((320 - w) / 2, circleY - radius - h - 10);
  tft.print(phaseText);

  tft.setTextSize(2);
  tft.setTextColor(ILI9341_GREEN);
  tft.getTextBounds(stopwatchBuffer, 0, 0, &x1, &y1, &w, &h);
  tft.setCursor((320 - w) / 2, circleY + radius + 10);
  tft.print(stopwatchBuffer);

  delay(20);
}

// ------------------- TIME MANAGEMENT -------------------

void startTimeManagement() {
  timeManagementActive = true;
  lastTimeMgmtRefresh = 0;  // force immediate redraw
  tft.fillScreen(ILI9341_BLACK);  // Clear entire screen once
  drawCalendarAndTasks();
}

void runTimeManagement() {
  if (millis() - lastTimeMgmtRefresh > timeMgmtRefreshInterval) {
    drawCalendarAndTasks();
    lastTimeMgmtRefresh = millis();
  }
}

void drawCalendarAndTasks() {
  // Instead of clearing the entire screen, clear only calendar and task areas

  // Clear calendar area
  int calWidth = 224;
  int calHeight = 240;
  tft.fillRect(0, 0, calWidth, calHeight, ILI9341_BLACK);

  // Clear task list area
  int taskX = calWidth + 1;
  int taskWidth = 96;
  tft.fillRect(taskX, 0, taskWidth, calHeight, ILI9341_BLACK);

  drawCalendar(0, 0, calWidth, calHeight, currentYear, currentMonth);
  drawTaskList(taskX, 0, taskWidth, calHeight);
}

void drawCalendar(int x, int y, int w, int h, int year, int month) {
  tft.drawRect(x, y, w, h, ILI9341_WHITE);

  // Month title
  tft.setTextSize(2);
  tft.setTextColor(ILI9341_YELLOW);
  tft.setCursor(x + 10, y + 5);
  const char* monthNames[12] = {"Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep","Oct","Nov","Dec"};
  char header[20];
  sprintf(header, "%s %d", monthNames[month-1], year);
  tft.print(header);

  // Weekday names individually aligned centered in each cell
  const char* weekdays[7] = {"Su", "Mo", "Tu", "We", "Th", "Fr", "Sa"};
  int cellW = 30;  
  int startX = x + 10;
  int headerY = y + 30;

  tft.setTextSize(1);
  tft.setTextColor(ILI9341_WHITE);
  for (int i = 0; i < 7; i++) {
    int textX = startX + i * cellW + 9; // center approx (30/2 - 3 char width/2)
    tft.setCursor(textX, headerY);
    tft.print(weekdays[i]);
  }

  // Days grid
  int startY = y + 45;
  int cellH = 24;

  int firstDay = dayOfWeek(year, month, 1); // Sunday=0
  int daysInMonth = getDaysInMonth(year, month);

  int day = 1;
  for (int row = 0; row < 6; row++) {
    for (int col = 0; col < 7; col++) {
      int posX = startX + col * cellW;
      int posY = startY + row * cellH;

      if (row == 0 && col < firstDay) {
        // Empty cells before first day
        continue;
      }

      if (day <= daysInMonth) {
        // Highlight day 4 as red
        if (day == 4) tft.setTextColor(ILI9341_RED);
        else tft.setTextColor(ILI9341_WHITE);

        // Center day numbers in cells by adding horizontal offset
        int textX = posX + 10;
        tft.setCursor(textX, posY);
        if(day < 10) tft.print(' ');    // Padding for single-digit numbers
        tft.print(day);
        day++;
      }
    }
  }
}

void drawTaskList(int x, int y, int w, int h) {
  tft.drawRect(x, y, w, h, ILI9341_WHITE);
  tft.setTextSize(2);
  tft.setTextColor(ILI9341_CYAN);
  tft.setCursor(x + 5, y + 5);
  tft.println("Tasks:");

  tft.setTextSize(1);
  tft.setTextColor(ILI9341_WHITE);

  int startY = y + 30;
  for (int i = 0; i < taskCount; i++) {
    tft.setCursor(x + 5, startY + i * 20);
    tft.println(tasks[i]);
  }
}

// Utility functions:

int dayOfWeek(int year, int month, int day) {
  // Zeller's Congruence (0=Saturday, so shift)
  if (month < 3) {
    month += 12;
    year--;
  }
  int K = year % 100;
  int J = year / 100;
  int h = (day + 13*(month+1)/5 + K + K/4 + J/4 + 5*J) % 7;
  // Convert: 0=Saturday to 0=Sunday
  int d = (h + 6) % 7;
  return d;
}

int getDaysInMonth(int year, int month) {
  if (month == 2) {
    // Leap year check
    bool leap = (year % 4 == 0 && (year % 100 != 0 || year % 400 == 0));
    return leap ? 29 : 28;
  }
  if (month == 4 || month == 6 || month == 9 || month == 11) return 30;
  return 31;
}