import glob
import os.path

import urwid


class _PathCompleter:
    def __init__(self, _testing=False):
        """
            _testing: disables reloading of the lookup table to make testing
            possible.
        """
        self.lookup, self.offset = None, None
        self.final = None
        self._testing = _testing

    def reset(self):
        self.lookup = None
        self.offset = -1

    def complete(self, txt):
        """
            Returns the next completion for txt, or None if there is no
            completion.
        """
        path = os.path.expanduser(txt)
        if not self.lookup:
            if not self._testing:
                # Lookup is a set of (display value, actual value) tuples.
                self.lookup = []
                if os.path.isdir(path):
                    files = glob.glob(os.path.join(path, "*"))
                    prefix = txt
                else:
                    files = glob.glob(path + "*")
                    prefix = os.path.dirname(txt)
                prefix = prefix or "./"
                for f in files:
                    display = os.path.join(prefix, os.path.basename(f))
                    if os.path.isdir(f):
                        display += "/"
                    self.lookup.append((display, f))
            if not self.lookup:
                self.final = path
                return path
            self.lookup.sort()
            self.offset = -1
            self.lookup.append((txt, txt))
        self.offset += 1
        if self.offset >= len(self.lookup):
            self.offset = 0
        ret = self.lookup[self.offset]
        self.final = ret[1]
        return ret[0]


class PathEdit(urwid.Edit, _PathCompleter):
    def __init__(self, *args, **kwargs):
        urwid.Edit.__init__(self, *args, **kwargs)
        _PathCompleter.__init__(self)

    def keypress(self, size, key):
        if key == "tab":
            comp = self.complete(self.get_edit_text())
            self.set_edit_text(comp)
            self.set_edit_pos(len(comp))
        else:
            self.reset()
        return urwid.Edit.keypress(self, size, key)
