import curses

def hex_to_text(hex_str):
    """
    Convert a hex string to text, replacing non-printable characters with '*'.
    """
    text = ''
    for i in range(0, len(hex_str), 2):
        try:
            byte = int(hex_str[i:i+2], 16)
            if chr(byte) in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-{}:.,;!?() ":
                text += chr(byte)
            else:
                text += '*'
        except ValueError:
            text += '*'
    return text

def xor_column(cursor_x, cursor_y, new_char, lines, file_name):
    # Find the character in the position x, y in the original file
    try:
        with open(file_name, 'r') as file:
            orig_hexlines = file.readlines()
    except FileNotFoundError:
        print("File not found.")
        return

    #matrix of the original file containing the numerical values of the characters
    orig_lines = [[int(hex_str[i:i+2], 16) for i in range(0, len(hex_str), 2)] for hex_str in orig_hexlines]
    original_char = chr(orig_lines[cursor_y][cursor_x])

    # XOR it with the new character to get the key
    key = ord(original_char) ^ ord(new_char)

    # XOR the key with the corresponding character in the other lines to get the plaintext
    for row in range(len(lines)):
        if row != cursor_y:
            char = lines[row][cursor_x]
            xor_char = chr(ord(char) ^ key)
            lines[row] = lines[row][:cursor_x] + xor_char + lines[row][cursor_x+1:]

    return lines

def main(stdscr):
    curses.curs_set(1)  # Set cursor to visible
    stdscr.clear()
    stdscr.refresh()

    file_name = "message.enc"
    try:
        with open(file_name, 'r') as file:
            hex_lines = file.readlines()
    except FileNotFoundError:
        print("File not found.")
        return

    lines = [hex_to_text(line.strip()) for line in hex_lines]

    cursor_y, cursor_x = 0, 0

    #enable keypad
    stdscr.keypad(True)

    while True:
        stdscr.clear()

        for i, line in enumerate(lines):
            if 0 <= i < curses.LINES:
                stdscr.addstr(i, 0, line)
        stdscr.move(cursor_y, cursor_x)
        stdscr.refresh()

        key = stdscr.getch()

        if key == 450:
            cursor_y = max(0, cursor_y - 1)
        elif key == 456:
            cursor_y = min(len(lines) - 1, cursor_y + 1)
        elif key == 452:
            cursor_x = max(0, cursor_x - 1)
        elif key == 454:
            cursor_x = min(len(lines[cursor_y]) - 1, cursor_x + 1)
        else:
            if chr(key) in "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789_-{}:.,;!?() ":
                try:
                    lines[cursor_y] = lines[cursor_y][:cursor_x] + chr(key) + lines[cursor_y][cursor_x+1:]
                    lines = xor_column(cursor_x, cursor_y, chr(key), lines, file_name)
                    cursor_x = min(len(lines[cursor_y]), cursor_x + 1)

                except ValueError:
                    pass

curses.wrapper(main)