#/usr/bin/env python

import fcntl
import os
import pty
import sys
import struct
import termios

# return dimensions (cols x rows)
def load_dimensions():
    # default to 80x24
    dims = 80, 24

    if not os.path.exists('.theme'):
        return dims

    try:
        with open('.theme', 'rb') as f:
            data = f.read(8)
            if len(data) < 8:
                return dims
            vals = struct.unpack('HHHBB', data)
            x, y = int(vals[3]), int(vals[4])
            if x < 80 or y < 24 or x > 200 or y > 100:
                print('invalid width/height: %d/%d' % (x, y))
                sys.exit(1)
            dims = x, y
    except Exception(e):
        print('error in .theme file: %s' % e)
        sys.exit(1)
    return dims

def main():

    # check usage
    args = sys.argv[1:]
    if len(args) < 1:
        print('usage: %s ROM')
        print('')
        print('  ROM: the rom file to launch')
        sys.exit(1)

    # either detect dimensions from theme or use 80x24
    cols, rows = load_dimensions()

    # path to rom to run
    rom = args[0]

    # fork with a new pty
    pid, fd = pty.fork()

    if pid == 0:
        # set TERM to something we can (mostly) handle
        env = dict(os.environ)
        env['TERM'] = 'ansi'
        os.execvpe('bash', ['bash'], env)
    else:
        # set the terminal size
        size = struct.pack("HHHH", rows, cols, 8, 12)
        fcntl.ioctl(fd, termios.TIOCSWINSZ, size)

        # use fd for the terminals stdin/stdout
        os.dup2(fd, sys.stdin.fileno())
        os.dup2(os.dup(fd), sys.stdout.fileno())
        os.execvp('uxnemu', ['uxnemu', rom] + args[1:])

if __name__ == "__main__":
    main()