# Python imports
import re

# Lib imports
import gi
gi.require_version('Gdk', '3.0')
from gi.repository import Gdk

# Application imports
from .singleton import Singleton



def logger(log = ""):
    print(log)


class KeymapError(Exception):
    """ Custom exception for errors in keybinding configurations """

MODIFIER = re.compile('<([^<]+)>')
class Keybindings(Singleton):
    """ Class to handle loading and lookup of Terminator keybindings """

    modifiers = {
        'ctrl':     Gdk.ModifierType.CONTROL_MASK,
        'control':  Gdk.ModifierType.CONTROL_MASK,
        'primary':  Gdk.ModifierType.CONTROL_MASK,
        'shift':    Gdk.ModifierType.SHIFT_MASK,
        'alt':      Gdk.ModifierType.MOD1_MASK,
        'super':    Gdk.ModifierType.SUPER_MASK,
        'hyper':    Gdk.ModifierType.HYPER_MASK,
        'mod2':	    Gdk.ModifierType.MOD2_MASK
    }

    empty   = {}
    keys    = None
    _masks  = None
    _lookup = None

    def __init__(self):
        self.keymap = Gdk.Keymap.get_default()
        self.configure({})

    def print_keys(self):
        print(self.keys)

    def append_bindings(self, combos):
        """ Accept new binding(s) and reload """
        for item in combos:
            method, keys = item.split(":")
            self.keys[method] = keys

        self.reload()

    def configure(self, bindings):
        """ Accept new bindings and reconfigure with them """
        self.keys = bindings
        self.reload()

    def reload(self):
        """ Parse bindings and mangle into an appropriate form """
        self._lookup = {}
        self._masks  = 0

        for action, bindings in list(self.keys.items()):
            if isinstance(bindings, list):
                bindings = (*bindings,)
            elif not isinstance(bindings, tuple):
                bindings = (bindings,)


            for binding in bindings:
                if not binding or binding == "None":
                    continue

                try:
                    keyval, mask = self._parsebinding(binding)
                    # Does much the same, but with worse error handling.
                    # keyval, mask = Gtk.accelerator_parse(binding)
                except KeymapError as e:
                  logger(f"Keybinding reload failed to parse binding '{binding}': {e}")
                else:
                    if mask & Gdk.ModifierType.SHIFT_MASK:
                        if keyval == Gdk.KEY_Tab:
                            keyval = Gdk.KEY_ISO_Left_Tab
                            mask &= ~Gdk.ModifierType.SHIFT_MASK
                        else:
                            keyvals = Gdk.keyval_convert_case(keyval)
                            if keyvals[0] != keyvals[1]:
                                keyval = keyvals[1]
                                mask &= ~Gdk.ModifierType.SHIFT_MASK
                    else:
                        keyval = Gdk.keyval_to_lower(keyval)

                    self._lookup.setdefault(mask, {})
                    self._lookup[mask][keyval] = action
                    self._masks |= mask

    def _parsebinding(self, binding):
        """ Parse an individual binding using Gtk's binding function """
        mask = 0
        modifiers = re.findall(MODIFIER, binding)

        if modifiers:
            for modifier in modifiers:
                mask |= self._lookup_modifier(modifier)

        key = re.sub(MODIFIER, '', binding)
        if key == '':
            raise KeymapError('No key found!')

        keyval = Gdk.keyval_from_name(key)

        if keyval == 0:
            raise KeymapError(f"Key '{key}' is unrecognised...")
        return (keyval, mask)

    def _lookup_modifier(self, modifier):
        """ Map modifier names to gtk values """
        try:
            return self.modifiers[modifier.lower()]
        except KeyError:
            raise KeymapError(f"Unhandled modifier '<{modifier}>'")

    def lookup(self, event):
        """ Translate a keyboard event into a mapped key """
        try:
            _found, keyval, _egp, _lvl, consumed = self.keymap.translate_keyboard_state(
                                              event.hardware_keycode,
                                              Gdk.ModifierType(event.get_state() & ~Gdk.ModifierType.LOCK_MASK),
                                              event.group)
        except TypeError:
            logger(f"Keybinding lookup failed to translate keyboard event: {dir(event)}")
            return None

        mask = (event.get_state() & ~consumed) & self._masks
        return self._lookup.get(mask, self.empty).get(keyval, None)
