__init__.py

import sys

from blessed import Terminal

from inquirer import errors
from inquirer import events
from inquirer import themes
from inquirer.render.console._text import Text
from inquirer.render.console._editor import Editor
from inquirer.render.console._password import Password
from inquirer.render.console._confirm import Confirm
from inquirer.render.console._list import List
from inquirer.render.console._keyed_list import KeyedList
from inquirer.render.console._checkbox import Checkbox
from inquirer.render.console._path import Path


class ConsoleRender:
    def __init__(self, event_generator=None, theme=None, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self._event_gen = event_generator or events.KeyEventGenerator()
        self.terminal = Terminal()
        self._previous_error = None
        self._position = 0
        self._theme = theme or themes.Default()

    def render(self, question, answers=None):
        question.answers = answers or {}

        if question.ignore:
            return question.default

        clazz = self.render_factory(question.kind)
        render = clazz(question, terminal=self.terminal, theme=self._theme, show_default=question.show_default)

        self.clear_eos()

        try:
            return self._event_loop(render)
        finally:
            print("")

    def _event_loop(self, render):
        try:
            while True:
                self._relocate()
                self._print_status_bar(render)

                self._print_header(render)
                self._print_options(render)

                self._process_input(render)
                self._force_initial_column()
        except errors.EndOfInput as e:
            self._go_to_end(render)
            return e.selection

    def _print_status_bar(self, render):
        if self._previous_error is None:
            self.clear_bottombar()
            return

        self.render_error(self._previous_error)
        self._previous_error = None

    def _print_options(self, render):
        for message, symbol, color in render.get_options():
            if hasattr(message, "decode"):  # python 2
                message = message.decode("utf-8")
            self.print_line(" {color}{s} {m}{t.normal}", m=message, color=color, s=symbol)

    def _print_header(self, render):
        base = render.get_header()

        header = base[: self.width - 9] + "..." if len(base) > self.width - 6 else base
        default_value = " ({color}{default}{normal})".format(
            default=render.question.default, color=self._theme.Question.default_color, normal=self.terminal.normal
        )
        show_default = render.question.default and render.show_default
        header += default_value if show_default else ""
        msg_template = (
            "{t.move_up}{t.clear_eol}{tq.brackets_color}[" "{tq.mark_color}?{tq.brackets_color}]{t.normal} {msg}"
        )

        # ensure any user input with { or } will not cause a formatting error
        escaped_current_value = str(render.get_current_value()).replace("{", "{{").replace("}", "}}")
        self.print_str(
            f"\n{msg_template}: {escaped_current_value}",
            msg=header,
            lf=not render.title_inline,
            tq=self._theme.Question,
        )

    def _process_input(self, render):
        try:
            ev = self._event_gen.next()
            if isinstance(ev, events.KeyPressed):
                render.process_input(ev.value)
        except errors.ValidationError as e:
            self._previous_error = e.value
        except errors.EndOfInput as e:
            try:
                render.question.validate(e.selection)
                raise
            except errors.ValidationError as e:
                self._previous_error = render.handle_validation_error(e)

    def _relocate(self):
        print(self._position * self.terminal.move_up, end="")
        self._force_initial_column()
        self._position = 0

    def _go_to_end(self, render):
        positions = len(list(render.get_options())) - self._position
        if positions > 0:
            print(self._position * self.terminal.move_down, end="")
        self._position = 0

    def _force_initial_column(self):
        self.print_str("\r")

    def render_error(self, message):
        if message:
            symbol = ">> "
            size = len(symbol) + 1
            length = len(message)
            message = message.rstrip()
            message = message if length + size < self.width else message[: self.width - (size + 3)] + "..."

            self.render_in_bottombar(
                "{t.red}{s}{t.normal}{t.bold}{msg}{t.normal} ".format(msg=message, s=symbol, t=self.terminal)
            )

    def render_in_bottombar(self, message):
        with self.terminal.location(0, self.height - 2):
            self.clear_eos()
            self.print_str(message)

    def clear_bottombar(self):
        with self.terminal.location(0, self.height - 2):
            self.clear_eos()

    def render_factory(self, question_type):
        matrix = {
            "text": Text,
            "editor": Editor,
            "password": Password,
            "confirm": Confirm,
            "list": List,
            "keyed_list": KeyedList,
            "checkbox": Checkbox,
            "path": Path,
        }

        if question_type not in matrix:
            raise errors.UnknownQuestionTypeError()
        return matrix.get(question_type)

    def print_line(self, base, lf=True, **kwargs):
        self.print_str(base + self.terminal.clear_eol(), lf=lf, **kwargs)

    def print_str(self, base, lf=False, **kwargs):
        if lf:
            self._position += 1

        print(base.format(t=self.terminal, **kwargs), end="\n" if lf else "")
        sys.stdout.flush()

    def clear_eos(self):
        print(self.terminal.clear_eos(), end="")

    @property
    def width(self):
        return self.terminal.width or 80

    @property
    def height(self):
        return self.terminal.width or 24