Mini Shell

import os

from .screen import Screen
from .defs import KEYMAP as _KEYMAP


# Standard widget result actions (as return from .loop())
ACTION_OK = 1000
ACTION_CANCEL = 1001
ACTION_NEXT = 1002
ACTION_PREV = 1003

class Widget(Screen):

    def __init__(self):
        self.kbuf = b""
        self.signals = {}

    def set_xy(self, x, y):
        self.x = x
        self.y = y

    def inside(self, x, y):
        return self.y <= y < self.y + self.h and self.x <= x < self.x + self.w

    def signal(self, sig):
        if sig in self.signals:
            self.signals[sig](self)

    def on(self, sig, handler):
        self.signals[sig] = handler

    @staticmethod
    def longest(items):
        if not items:
            return 0
        return max((len(t) for t in items))

    def set_cursor(self):
        # By default, a widget doesn't use text cursor, so disables it
        self.cursor(False)

    def get_input(self):
        if self.kbuf:
            key = self.kbuf[0:1]
            self.kbuf = self.kbuf[1:]
        else:
            key = os.read(0, 32)
            if key[0] != 0x1b:
                key = key.decode()
                self.kbuf = key[1:].encode()
                key = key[0:1].encode()
        key = _KEYMAP.get(key, key)

        if isinstance(key, bytes) and key.startswith(b"\x1b[M") and len(key) == 6:
            if key[3] != 32:
                return None
            row = key[5] - 33
            col = key[4] - 33
            return [col, row]

        return key

    def handle_input(self, inp):
        if isinstance(inp, list):
            res = self.handle_mouse(inp[0], inp[1])
        else:
            res = self.handle_key(inp)
        return res

    def loop(self):
        self.redraw()
        while True:
            key = self.get_input()
            if key is None:
                continue
            res = self.handle_input(key)

            if res is not None and res is not True:
                return res


class FocusableWidget(Widget):
    # If set to non-False, pressing Enter on this widget finishes
    # dialog, with Dialog.loop() return value being this value.
    finish_dialog = False


class EditableWidget(FocusableWidget):

    def get(self):
        raise NotImplementedError


class ChoiceWidget(EditableWidget):

    def __init__(self, choice):
        super().__init__()
        self.choice = choice

    def get(self):
        return self.choice


# Widget with few internal selectable items
class ItemSelWidget(ChoiceWidget):

    def __init__(self, items):
        super().__init__(0)
        self.items = items

    def move_sel(self, direction):
        self.choice = (self.choice + direction) % len(self.items)
        self.redraw()
        self.signal("changed")