#include <Adafruit_GFX.h>    // Core graphics library
#include <SPI.h>             // Needed for display
#include <Adafruit_ILI9341.h>
#include <FS.h>
#include <SD.h>

#define TFT_CS   10
#define TFT_DC   2

// SD Card configuration
#define SD_CS    9

// Button matrix pin definitions
#define COL1 16
#define COL2 17
#define ROW1 45
#define ROW2 48

// Define button actions
enum ButtonAction {
  NONE,
  UP,
  DOWN,
  SELECT,
  BACK
};

// TFT and SD card initialization
Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC);

// Variables for file navigation
File currentFile;
String fileList[10]; // Holds up to 10 file names
int fileCount = 0;
int selectedIndex = 0;
bool viewingFile = false;

void setup() {
  Serial.begin(115200);
  Serial.println("Initializing...");

  // Set up button matrix pins
  pinMode(COL1, OUTPUT);
  pinMode(COL2, OUTPUT);
  pinMode(ROW1, INPUT_PULLUP);
  pinMode(ROW2, INPUT_PULLUP);

  // Initialize TFT
  tft.begin();
  tft.fillScreen(ILI9341_BLACK);
  tft.setCursor(0, 0);
  tft.setTextColor(ILI9341_WHITE);
  tft.setTextSize(2);

  // Initialize SD card
  if (!SD.begin(SD_CS)) {
    tft.println("SD init failed!");
    return;
  }

  // List files on SD card
  listFiles("/");
}

void loop() {
  ButtonAction action = readButtonMatrix();
  
  if (!viewingFile) {
    // Navigation mode
    handleNavigation(action);
  } else {
    // Viewing file mode
    if (action == BACK) {
      tft.fillScreen(ILI9341_BLACK);
      tft.setCursor(0, 0);
      viewingFile = false;
      displayFileList();
    }
  }
}

// Function to list files in a directory
void listFiles(const char *dirname) {
  File root = SD.open(dirname);
  if (!root) {
    tft.println("Failed to open dir");
    return;
  }
  fileCount = 0;
  File file = root.openNextFile();
  while (file && fileCount < 10) {
    if (!file.isDirectory() && String(file.name()).endsWith(".txt")) {
      fileList[fileCount++] = String(file.name());
    }
    file.close();
    file = root.openNextFile();
  }
  displayFileList();
}

// Function to display file list on TFT
void displayFileList() {
  tft.fillScreen(ILI9341_BLACK);
  tft.setCursor(0, 0);
  for (int i = 0; i < fileCount; i++) {
    if (i == selectedIndex) {
      tft.print("> ");
    } else {
      tft.print("  ");
    }
    tft.println(fileList[i]);
  }
}

// Function to handle navigation
void handleNavigation(ButtonAction action) {
  if (action == UP && selectedIndex > 0) {
    selectedIndex--;
    displayFileList();
  } else if (action == DOWN && selectedIndex < fileCount - 1) {
    selectedIndex++;
    displayFileList();
  } else if (action == SELECT) {
    viewFile(fileList[selectedIndex]);
  }
}

// Function to view the content of a file
// Function to view the content of a file
void viewFile(String filename) {
  String filePath = "/" + filename;  // Construct the full path
  
  currentFile = SD.open(filePath.c_str(), FILE_READ);  // Use FILE_READ mode
  if (!currentFile) {
    tft.fillScreen(ILI9341_BLACK);
    tft.setCursor(0, 0);
    tft.println("Failed to open file");
    return;
  }

  viewingFile = true;
  tft.fillScreen(ILI9341_BLACK);
  tft.setCursor(0, 0);

  // Read the file in smaller chunks to handle memory limitations
  while (currentFile.available()) {
    char c = currentFile.read();
    tft.print(c);

    // Handle display overflow by scrolling
    if (tft.getCursorY() > tft.height() - 20) {
      tft.fillScreen(ILI9341_BLACK);
      tft.setCursor(0, 0);
    }
  }

  currentFile.close();
}


// Function to read button matrix
ButtonAction readButtonMatrix() {
  for (int col = 0; col < 2; col++) {
    digitalWrite(COL1, col == 0 ? LOW : HIGH);
    digitalWrite(COL2, col == 1 ? LOW : HIGH);

    if (digitalRead(ROW1) == LOW) {
      delay(200); // Debounce
      return col == 0 ? UP : SELECT;
    }
    if (digitalRead(ROW2) == LOW) {
      delay(200); // Debounce
      return col == 0 ? DOWN : BACK;
    }
  }
  return NONE;
}