"""Entry point: converts either direction, the way `sedonac.exe <file>` does --
the input's extension decides.

    python sab2sax.py [in.sax|in.sab] [out]

    .sax in -> .sab out    (sab.encode)
    .sab in -> .sax out    (sax.decode)

Omit the input and a file chooser opens; omit the output and a save dialog opens
next to the input, pre-filled with a timestamped name. Sedona home comes from
system.properties (see config.py).
"""
import os, sys
import config, sab, sax


def convert(in_path, out_path=None, home=None):
    """Convert `in_path` by extension, no dialogs. Returns (out_path, bytes written).

    With no `out_path`, writes a timestamped name next to the input."""
    ext = os.path.splitext(in_path)[1].lower()
    if ext not in (".sax", ".sab"):
        raise Exception("don't know what to do with %s -- expected .sax or .sab" % in_path)
    if out_path is None:
        name = sab.default_sab_name(in_path) if ext == ".sax" else sax.default_sax_name(in_path)
        out_path = os.path.join(os.path.dirname(os.path.abspath(in_path)), name)
    if ext == ".sax":
        return out_path, sab.encode(in_path, home, out_path)
    return out_path, sax.decode(in_path, home, out_path)


def main(argv):
    home = config.get_sedona_home()

    in_path = argv[1] if len(argv) > 1 else config.choose_input_file()
    if not in_path:
        raise SystemExit("no input file selected")
    in_path = os.path.abspath(in_path)
    if not os.path.isfile(in_path):
        raise SystemExit("no such file: " + in_path)

    ext = os.path.splitext(in_path)[1].lower()
    if ext not in (".sax", ".sab"):
        raise SystemExit("don't know what to do with %s -- expected .sax or .sab" % in_path)

    if len(argv) > 2:
        out_path = argv[2]
    elif ext == ".sax":
        out_path = config.choose_sab_file(initialfile=sab.default_sab_name(in_path),
                                          initial=os.path.dirname(in_path))
    else:
        out_path = config.choose_sax_output(initialfile=sax.default_sax_name(in_path),
                                            initial=os.path.dirname(in_path))
    if not out_path:
        raise SystemExit("no output file selected")

    if ext == ".sax":
        n = sab.encode(in_path, home, out_path)
    else:
        n = sax.decode(in_path, home, out_path)
    print("wrote %d bytes to %s" % (n, out_path))


if __name__ == "__main__":
    main(sys.argv)