import curses
import os
import textwrap

def read_file(filename):
    with open(filename, 'r', encoding='utf-8') as f:
        return f.read()

def main(stdscr):
    curses.curs_set(0)  # Hide cursor
    stdscr.keypad(1)  # Enable special keys
    stdscr.timeout(100)  # Set timeout for getch

    current_chapter = 0
    offset = 0  # To keep track of scrolling
    update_needed = True  # Flag to check whether an update is needed

    while True:
        # Only clear and refresh the screen if an update is needed
        if update_needed:
            stdscr.clear()

            # Read the file
            if current_chapter == 0:
                text = read_file('chapters/title.txt')
            else:
                text = read_file(f'chapters/chapter{current_chapter}.txt')

            # Split text by lines, then wrap each line
            max_y, max_x = stdscr.getmaxyx()
            lines = text.split('\n')
            wrapped_lines = [textwrap.fill(line, width=max_x) for line in lines]
            final_text = '\n'.join(wrapped_lines)
            final_lines = final_text.split('\n')

            # Display text
            for i, line in enumerate(final_lines[offset:]):
                if i >= max_y - 1:
                    break
                stdscr.addstr(i, 0, line)

            stdscr.refresh()
            update_needed = False  # Reset the flag after updating

        # Get user input
        c = stdscr.getch()

        # Scroll up/down
        if c == curses.KEY_UP and offset > 0:
            offset -= 1
            update_needed = True
        elif c == curses.KEY_DOWN and offset < len(final_lines) - max_y:
            offset += 1
            update_needed = True
        # Skip a whole screen up/down
        elif c == curses.KEY_SR and offset > 0:  # Ctrl+Up
            offset = max(0, offset - max_y)
            update_needed = True
        elif c == curses.KEY_SF and offset < len(final_lines) - max_y:  # Ctrl+Down
            offset = min(len(final_lines) - max_y, offset + max_y)
            update_needed = True
        # Change chapters
        elif c == curses.KEY_RIGHT:
            current_chapter += 1
            if not os.path.exists(f'chapters/chapter{current_chapter}.txt'):
                current_chapter -= 1
            offset = 0
            update_needed = True
        elif c == curses.KEY_LEFT and current_chapter > 0:
            current_chapter -= 1
            offset = 0
            update_needed = True
        # Quit
        elif c == ord('q'):
            break  # No need to set update_needed since we are exiting

curses.wrapper(main)