import builtins
import os
import sys
import _sitebuiltins


def read_user_env_vars():
    try:
        with open(os.path.expanduser('~/Library/Preferences/calibre/macos-env.txt'), 'rb') as f:
            raw = f.read().decode('utf-8', 'replace')
    except EnvironmentError:
        return
    for line in raw.splitlines():
        if line.startswith('#'):
            continue
        parts = line.split('=', 1)
        if len(parts) == 2:
            key, val = parts
            os.environ[key] = os.path.expandvars(os.path.expanduser(val))


def nuke_stdout():
    # Redirect stdout, stdin and stderr to /dev/null
    from calibre.constants import plugins
    plugins['speedup'][0].detach(os.devnull)


def set_helper():
    builtins.help = _sitebuiltins._Helper()


def set_quit():
    eof = 'Ctrl-D (i.e. EOF)'
    builtins.quit = _sitebuiltins.Quitter('quit', eof)
    builtins.exit = _sitebuiltins.Quitter('exit', eof)


def main():
    sys.argv[0] = sys.calibre_basename
    try:
        read_user_env_vars()
    except Exception as err:
        try:
            print('Failed to read user env vars with error:', err, file=sys.stderr)
            sys.stderr.flush()
        except Exception:
            pass

    set_helper()
    set_quit()
    if sys.gui_app and not (
        sys.stdout.isatty() or sys.stderr.isatty() or sys.stdin.isatty()
    ):
        nuke_stdout()
    mod = __import__(sys.calibre_module, fromlist=[1])
    func = getattr(mod, sys.calibre_function)
    return func()


if __name__ == '__main__':
    main()