#include <SD.h>
#include <LiquidCrystal_I2C.h>
#include <ezButton.h>
#include "lcd_custom_character.h"

File file;

int book_num = 0;
int book_state = 0;
int prev_book_num = -1;
int page_num = 0, prev_page_num = -1;
String display_text = "";

ezButton next(2);
ezButton prev(3);
ezButton select_book(4);
ezButton open_book(5);

LiquidCrystal_I2C lcd(0x27, 20, 4);

void setup() {
  Serial.begin(9600);
  SD.begin();

  next.setDebounceTime(50);
  prev.setDebounceTime(50);
  select_book.setDebounceTime(50);
  open_book.setDebounceTime(50);

  lcd.init();
  lcd.backlight();
  lcd.clear();

  welcome();
  animate();
}

void lcd_print(int x, int y, String message) {
  lcd.setCursor(x, y);
  lcd.print(message);
}

void display_char(int x, int y, int id) {
  lcd.setCursor(x, y);
  lcd.write(id);
}

void animate() {
  lcd.createChar(0, left_stick);
  lcd.createChar(1, right_stick);
  lcd.createChar(2, open_eye);
  lcd.createChar(3, middle_stick);
  lcd.createChar(4, closed_eye);

  for (int i = 0; i < 5; i++) {
    display_char(11, 3, 1);
    display_char(9, 3, 3);
    display_char(7, 3, 0);
    if (i % 2 == 0) {
      display_char(8, 3, 2);
      display_char(10, 3, 2);
      delay(500);
    }
    else {
      display_char(8, 3, 4);
      display_char(10, 3, 4);
      delay(50);
    }
  }

}

void welcome() {
  lcd_print(1, 0, "Welcome");
  delay(200);
  lcd_print(8, 1, "To");
  delay(200);
  lcd_print(10, 2, "Digi Book");
  delay(100);
}

void loop() {
  next.loop();
  prev.loop();
  select_book.loop();
  open_book.loop();

  if (next.isPressed()) {
    if (book_state) page_num++;
    else book_num++;
  }
  else if (prev.isPressed()) {
    if (book_state) page_num--;
    else book_num--;
  }
  else if (select_book.isPressed()) {
    book_state = 0;
    prev_book_num = -1;
    page_num = 0;
    prev_page_num = -1;
  }
  else if (open_book.isPressed()) {
    book_state = 1;
  }

  book_num = constrain(book_num, 0, 1);
  if (page_num < 0) page_num = 0;
  check_book();
  read_book();

  delay(50);
}

void check_book() {
  if (prev_book_num != book_num) {
    prev_book_num = book_num;
    lcd.clear();
    if (book_num) {
      lcd_print(0, 0, "Think and Grow Rich");
    }
    else {
      lcd_print(0, 0, "Harry Potter");
    }
  }
}

void read_book() {
  if (book_state) {
    if (book_num) file = SD.open("think.txt", FILE_READ);
    else file = SD.open("harry.txt", FILE_READ);

    int total_pages = file.size() / 80;
    page_num = constrain(page_num, 0, total_pages);
    int pointer = page_num * 80;

    if (file) {
      if (prev_page_num != page_num) {
        prev_page_num = page_num;
        file.seek(pointer);
        display_text = "";
        while (display_text.length() != 80) {
          char data = file.read();
          display_text.concat(data);
        }
      }
    }
  }
  file.close();
}

void page_print() {
  lcd.clear();
  for (int i = 0; i < 4; i++) {
    lcd_print(0, i, display_text.substring(i*20, (i+1)*20));
  }
}