"""
This module contains implementations for the termui module. To keep the
import time of Click down, some infrequently used functionality is
placed in this module and only imported as needed.
"""

from __future__ import annotations

import collections.abc as cabc
import contextlib
import math
import os
import shlex
import sys
import time
import typing as t
from gettext import gettext as _
from io import StringIO
from pathlib import Path
from types import TracebackType

from ._compat import _default_text_stdout
from ._compat import CYGWIN
from ._compat import get_best_encoding
from ._compat import isatty
from ._compat import strip_ansi
from ._compat import term_len
from ._compat import WIN
from .exceptions import ClickException
from .utils import echo

V = t.TypeVar("V")


if os.name == "nt":
    BEFORE_BAR = "\r"
    AFTER_BAR = "\n"
else:
    BEFORE_BAR = "\r\033[?25l"
    AFTER_BAR = "\033[?25h\n"


class ProgressBar(t.Generic[V]):
    def __init__(
        self,
        iterable: cabc.Iterable[V] | None,
        length: int | None = None,
        fill_char: str = "#",
        empty_char: str = " ",
        bar_template: str = "%(bar)s",
        info_sep: str = "  ",
        hidden: bool = False,
        show_eta: bool = True,
        show_percent: bool | None = None,
        show_pos: bool = False,
        item_show_func: t.Callable[[V | None], str | None] | None = None,
        label: str | None = None,
        file: t.TextIO | None = None,
        color: bool | None = None,
        update_min_steps: int = 1,
        width: int = 30,
    ) -> None:
        self.fill_char = fill_char
        self.empty_char = empty_char
        self.bar_template = bar_template
        self.info_sep = info_sep
        self.hidden = hidden
        self.show_eta = show_eta
        self.show_percent = show_percent
        self.show_pos = show_pos
        self.item_show_func = item_show_func
        self.label: str = label or ""

        if file is None:
            file = _default_text_stdout()

            # There are no standard streams attached to write to. For example,
            # pythonw on Windows.
            if file is None:
                file = StringIO()

        self.file = file
        self.color = color
        self.update_min_steps = update_min_steps
        self._completed_intervals = 0
        self.width: int = width
        self.autowidth: bool = width == 0

        if length is None:
            from operator import length_hint

            length = length_hint(iterable, -1)

            if length == -1:
                length = None
        if iterable is None:
            if length is None:
                raise TypeError("iterable or length is required")
            iterable = t.cast("cabc.Iterable[V]", range(length))
        self.iter: cabc.Iterable[V] = iter(iterable)
        self.length = length
        self.pos: int = 0
        self.avg: list[float] = []
        self.last_eta: float
        self.start: float
        self.start = self.last_eta = time.time()
        self.eta_known: bool = False
        self.finished: bool = False
        self.max_width: int | None = None
        self.entered: bool = False
        self.current_item: V | None = None
        self._is_atty = isatty(self.file)
        self._last_line: str | None = None

    def __enter__(self) -> ProgressBar[V]:
        self.entered = True
        self.render_progress()
        return self

    def __exit__(
        self,
        exc_type: type[BaseException] | None,
        exc_value: BaseException | None,
        tb: TracebackType | None,
    ) -> None:
        self.render_finish()

    def __iter__(self) -> cabc.Iterator[V]:
        if not self.entered:
            raise RuntimeError("You need to use progress bars in a with block.")
        self.render_progress()
        return self.generator()

    def __next__(self) -> V:
        # Iteration is defined in terms of a generator function,
        # returned by iter(self); use that to define next(). This works
        # because `self.iter` is an iterable consumed by that generator,
        # so it is re-entry safe. Calling `next(self.generator())`
        # twice works and does "what you want".
        return next(iter(self))

    def render_finish(self) -> None:
        # Steps stay pending until they add up to update_min_steps, so a length
        # that is not a multiple of it keeps a sub-threshold remainder that
        # never reaches pos. Apply it so the bar settles on its true position.
        if self._completed_intervals:
            self.make_step(self._completed_intervals)
            self._completed_intervals = 0
            self.render_progress()

        if self.hidden or not self._is_atty:
            return
        self.file.write(AFTER_BAR)
        self.file.flush()

    @property
    def pct(self) -> float:
        if self.finished:
            return 1.0
        return min(self.pos / (float(self.length or 1) or 1), 1.0)

    @property
    def time_per_iteration(self) -> float:
        if not self.avg:
            return 0.0
        return sum(self.avg) / float(len(self.avg))

    @property
    def eta(self) -> float:
        if self.length is not None and not self.finished:
            return self.time_per_iteration * (self.length - self.pos)
        return 0.0

    def format_eta(self) -> str:
        if self.eta_known:
            t = int(self.eta)
            seconds = t % 60
            t //= 60
            minutes = t % 60
            t //= 60
            hours = t % 24
            t //= 24
            if t > 0:
                return "{d}{day_label} {h:02}:{m:02}:{s:02}".format(
                    d=t,
                    day_label=_("d"),
                    h=hours,
                    m=minutes,
                    s=seconds,
                )
            else:
                return f"{hours:02}:{minutes:02}:{seconds:02}"
        return ""

    def format_pos(self) -> str:
        pos = str(self.pos)
        if self.length is not None:
            pos += f"/{self.length}"
        return pos

    def format_pct(self) -> str:
        return f"{int(self.pct * 100): 4}%"[1:]

    def format_bar(self) -> str:
        if self.length is not None:
            bar_length = int(self.pct * self.width)
            bar = self.fill_char * bar_length
            bar += self.empty_char * (self.width - bar_length)
        elif self.finished:
            bar = self.fill_char * self.width
        else:
            chars = list(self.empty_char * (self.width or 1))
            if self.time_per_iteration != 0:
                chars[
                    int(
                        (math.cos(self.pos * self.time_per_iteration) / 2.0 + 0.5)
                        * self.width
                    )
                ] = self.fill_char
            bar = "".join(chars)
        return bar

    def format_progress_line(self) -> str:
        show_percent = self.show_percent

        info_bits = []
        if self.length is not None and show_percent is None:
            show_percent = not self.show_pos

        if self.show_pos:
            info_bits.append(self.format_pos())
        if show_percent:
            info_bits.append(self.format_pct())
        if self.show_eta and self.eta_known and not self.finished:
            info_bits.append(self.format_eta())
        if self.item_show_func is not None:
            item_info = self.item_show_func(self.current_item)
            if item_info is not None:
                info_bits.append(item_info)

        return (
            self.bar_template
            % {
                "label": self.label,
                "bar": self.format_bar(),
                "info": self.info_sep.join(info_bits),
            }
        ).rstrip()

    def render_progress(self) -> None:
        if self.hidden:
            return

        if not self._is_atty:
            # Only output the label once if the output is not a TTY.
            if self._last_line != self.label:
                self._last_line = self.label
                echo(self.label, file=self.file, color=self.color)
            return

        buf = []
        # Update width in case the terminal has been resized
        if self.autowidth:
            import shutil

            old_width = self.width
            self.width = 0
            clutter_length = term_len(self.format_progress_line())
            new_width = max(0, shutil.get_terminal_size().columns - clutter_length)
            if new_width < old_width and self.max_width is not None:
                buf.append(BEFORE_BAR)
                buf.append(" " * self.max_width)
                self.max_width = new_width
            self.width = new_width

        clear_width = self.width
        if self.max_width is not None:
            clear_width = self.max_width

        buf.append(BEFORE_BAR)
        line = self.format_progress_line()
        line_len = term_len(line)
        if self.max_width is None or self.max_width < line_len:
            self.max_width = line_len

        buf.append(line)
        buf.append(" " * (clear_width - line_len))
        line = "".join(buf)
        # Render the line only if it changed.

        if line != self._last_line:
            self._last_line = line
            echo(line, file=self.file, color=self.color, nl=False)
            self.file.flush()

    def make_step(self, n_steps: int) -> None:
        self.pos += n_steps
        if self.length is not None and self.pos >= self.length:
            self.finished = True

        if (time.time() - self.last_eta) < 1.0:
            return

        self.last_eta = time.time()

        # self.avg is a rolling list of length <= 7 of steps where steps are
        # defined as time elapsed divided by the total progress through
        # self.length.
        if self.pos:
            step = (time.time() - self.start) / self.pos
        else:
            step = time.time() - self.start

        self.avg = self.avg[-6:] + [step]

        self.eta_known = self.length is not None

    def update(self, n_steps: int, current_item: V | None = None) -> None:
        """Update the progress bar by advancing a specified number of
        steps, and optionally set the ``current_item`` for this new
        position.

        :param n_steps: Number of steps to advance.
        :param current_item: Optional item to set as ``current_item``
            for the updated position.

        .. versionchanged:: 8.0
            Added the ``current_item`` optional parameter.

        .. versionchanged:: 8.0
            Only render when the number of steps meets the
            ``update_min_steps`` threshold.
        """
        if current_item is not None:
            self.current_item = current_item

        self._completed_intervals += n_steps

        if self._completed_intervals >= self.update_min_steps:
            self.make_step(self._completed_intervals)
            self.render_progress()
            self._completed_intervals = 0

    def finish(self) -> None:
        self.eta_known = False
        self.current_item = None
        self.finished = True

    def generator(self) -> cabc.Iterator[V]:
        """Return a generator which yields the items added to the bar
        during construction, and updates the progress bar *after* the
        yielded block returns.
        """
        # WARNING: the iterator interface for `ProgressBar` relies on
        # this and only works because this is a simple generator which
        # doesn't create or manage additional state. If this function
        # changes, the impact should be evaluated both against
        # `iter(bar)` and `next(bar)`. `next()` in particular may call
        # `self.generator()` repeatedly, and this must remain safe in
        # order for that interface to work.
        if not self.entered:
            raise RuntimeError("You need to use progress bars in a with block.")

        if not self._is_atty:
            yield from self.iter
        else:
            for rv in self.iter:
                self.current_item = rv

                # This allows show_item_func to be updated before the
                # item is processed. Only trigger at the beginning of
                # the update interval.
                if self._completed_intervals == 0:
                    self.render_progress()

                yield rv
                self.update(1)

            self.finish()
            self.render_progress()


class _PagerWriter:
    """Wrap a pager's output stream to strip ANSI styling when colors are
    disabled.

    The wrapped stream is owned by the pager strategy that produced it, so this
    wrapper never closes it: ``_pipepager`` closes its pipe to signal EOF to the
    pager process, ``_tempfilepager`` closes and removes its temporary file, and
    ``_nullpager`` leaves an external stream such as ``sys.stdout`` untouched.

    The ``color`` attribute lets :func:`click.echo` detect that ANSI stripping
    is handled here, so it doesn't strip a second time (see
    :func:`._compat.should_strip_ansi`).
    """

    def __init__(self, stream: t.TextIO, color: bool) -> None:
        self._stream = stream
        self.color = color

    def write(self, text: str) -> int:
        if not self.color:
            text = strip_ansi(text)

        return self._stream.write(text)

    def writelines(self, lines: cabc.Iterable[str]) -> None:
        for line in lines:
            self.write(line)

    def flush(self) -> None:
        self._stream.flush()

    def close(self) -> None:
        # The pager strategy owns the stream's lifecycle. Flush pending output,
        # but never close the underlying stream from here.
        self._stream.flush()

    def __getattr__(self, name: str) -> t.Any:
        return getattr(self._stream, name)


def _resolve_pager_command(cmd_parts: list[str]) -> tuple[Path, list[str]] | None:
    """Resolve a pager ``argv`` to an absolute command path and its parameters.

    The command is looked up with :func:`shutil.which`, which the
    :mod:`subprocess` docs recommend on every platform for an unqualified name:
    https://docs.python.org/3/library/subprocess.html#popen-constructor

    Returns ``None`` when there is no command to run or it is not on the path,
    leaving the caller to pick a fallback.
    """
    if not cmd_parts:
        return None

    import shutil

    cmd_filepath = shutil.which(cmd_parts[0])

    if not cmd_filepath:
        return None

    # Normalize to an absolute path without resolving symlinks: multi-call
    # binaries such as busybox derive their identity from the link they are
    # invoked through, so resolving less -> busybox makes them misbehave.
    # See https://github.com/pallets/click/issues/2943 and
    # https://github.com/pallets/click/pull/2944
    return Path(cmd_filepath).absolute(), cmd_parts[1:]


def _pager_contextmanager(
    color: bool | None = None,
) -> t.ContextManager[tuple[t.TextIO, bool | None]]:
    """Decide what method to use for paging through text."""
    stdout = _default_text_stdout()

    # There are no standard streams attached to write to. For example,
    # pythonw on Windows.
    if stdout is None:
        stdout = StringIO()

    if not isatty(sys.stdin) or not isatty(stdout):
        return _nullpager(stdout, color)

    # Split using POSIX mode (the default) so that quote characters are
    # stripped from tokens and quoted Windows paths are preserved.
    # Non-POSIX mode retains quotes in tokens, and wrapping tokens
    # with shlex.quote re-introduces quoting issues on Windows.
    pager_cmd_parts = shlex.split(os.environ.get("PAGER", ""))

    if pager_cmd_parts:
        # Piping to `more` on Windows adds spurious \r\n, so it gets the temp
        # file strategy whatever the user asked for.
        use_tempfile = WIN
    else:
        if os.environ.get("TERM") in ("dumb", "emacs"):
            return _nullpager(stdout, color)

        use_tempfile = WIN or sys.platform.startswith("os2")
        pager_cmd_parts = ["more"] if use_tempfile else ["less"]

    resolved = _resolve_pager_command(pager_cmd_parts)

    if resolved is None:
        # Page through stdout, which _nullpager leaves open for its owner.
        return _nullpager(stdout, color)

    cmd_path, cmd_params = resolved

    if use_tempfile:
        return _tempfilepager(cmd_path, cmd_params, color)

    return _pipepager(cmd_path, cmd_params, color)


@contextlib.contextmanager
def get_pager_file(color: bool | None = None) -> t.Generator[t.TextIO, None, None]:
    """Context manager.

    Yields a writable file-like object which can be used as an output pager.

    .. versionadded:: 8.4.0

    :param color: controls if the pager supports ANSI colors or not.  The
                  default is autodetection.
    """
    with _pager_contextmanager(color=color) as (stream, color):
        # Every pager strategy yields a text stream, so the only thing left to
        # do is strip ANSI styling when colors are disabled. A strategy yields
        # None when it has no opinion on colors, which settles as off here. The
        # wrapper does not close the stream: each strategy owns its stream's
        # lifecycle.
        writer = _PagerWriter(stream, color=bool(color))
        try:
            yield t.cast(t.TextIO, writer)
        finally:
            writer.flush()


def _less_uses_raw_mode(less_env: str, cmd_params: list[str]) -> bool:
    """Detect a raw-control-characters request in a ``less`` invocation.

    Parses the tokens of the ``LESS`` environment variable and the command
    line: only short-option clusters (``-R``, ``-rX``, ``-XrY``) and the
    ``--raw-control-chars`` long option request raw mode. Filenames and
    long-option values may carry the letter ``r`` without being such a
    request.
    """
    try:
        env_tokens = shlex.split(less_env)
    except ValueError:
        # Unbalanced quotes make ``LESS`` unparsable: fall back to whitespace
        # splitting rather than failing the pager over it.
        env_tokens = less_env.split()
    tokens = env_tokens + cmd_params

    for token in tokens:
        if token.startswith("--"):
            if token.casefold() == "--raw-control-chars":
                return True
        elif token.startswith("-") and len(token) > 1:
            if "r" in token[1:].casefold():
                return True

    return False


@contextlib.contextmanager
def _pipepager(
    cmd_path: Path, cmd_params: list[str], color: bool | None = None
) -> t.Iterator[tuple[t.TextIO, bool | None]]:
    """Page through text by feeding it to another program.

    Invokes the pager via :class:`subprocess.Popen` with an ``argv`` list.

    Invoking a pager through this might support colors: if piping to
    ``less`` and the user hasn't decided on colors, ``LESS=-R`` is set
    automatically.
    """
    import subprocess

    # Make a local copy of the environment to not affect the global one.
    env = dict(os.environ)

    # If we're piping to less and the user hasn't decided on colors, we enable
    # them: either the invocation already requests raw control characters, or
    # ``LESS=-R`` is injected. Match on the stem so a resolved ``less.exe`` is
    # recognized like bare ``less``, case-insensitively on Windows since its
    # filesystems are. POSIX keeps an exact match.
    cmd_name = cmd_path.stem
    if WIN:
        # ``_pager_contextmanager`` currently routes every Windows invocation
        # to ``_tempfilepager``, so this branch is not reachable on Windows
        # today: it keeps the detection correct should that routing ever
        # change.
        cmd_name = cmd_name.casefold()

    if color is None and cmd_name == "less":
        less_env = os.environ.get("LESS", "")
        if _less_uses_raw_mode(less_env, cmd_params):
            color = True
        elif not less_env and not cmd_params:
            env["LESS"] = "-R"
            color = True

    c = subprocess.Popen(
        [str(cmd_path)] + cmd_params,
        shell=False,
        stdin=subprocess.PIPE,
        env=env,
        errors="replace",
        text=True,
    )
    # With ``text=True``, ``c.stdin`` is already a text stream that encodes
    # writes for the pager process (honoring ``errors="replace"``).
    stdin = t.cast(t.TextIO, c.stdin)
    try:
        yield stdin, color
    except BrokenPipeError:
        # In case the pager exited unexpectedly, ignore the broken pipe error.
        pass
    except Exception as e:
        # In case there is an exception we want to close the pager immediately
        # and let the caller handle it.
        # Otherwise the pager will keep running, and the user may not notice
        # the error message, or worse yet it may leave the terminal in a broken state.
        c.terminate()
        raise e
    finally:
        # We must close stdin and wait for the pager to exit before we continue
        try:
            stdin.close()
        # Close implies flush, so it might throw a BrokenPipeError if the pager
        # process exited already.
        except BrokenPipeError:
            pass

        # Less doesn't respect ^C, but catches it for its own UI purposes (aborting
        # search or other commands inside less).
        #
        # That means when the user hits ^C, the parent process (click) terminates,
        # but less is still alive, paging the output and messing up the terminal.
        #
        # If the user wants to make the pager exit on ^C, they should set
        # `LESS='-K'`. It's not our decision to make.
        while True:
            try:
                c.wait()
            except KeyboardInterrupt:
                pass
            else:
                break


@contextlib.contextmanager
def _tempfilepager(
    cmd_path: Path, cmd_params: list[str], color: bool | None = None
) -> t.Iterator[tuple[t.TextIO, bool | None]]:
    """Page through text by invoking a program on a temporary file.

    Used as the primary pager strategy on Windows (where piping to
    ``more`` adds spurious ``\\r\\n``), and as a fallback on other
    platforms. The command is invoked with any parameters from ``PAGER``
    followed by the temporary file name.
    """
    import subprocess
    import tempfile

    encoding = get_best_encoding(sys.stdout)
    # On Windows, NamedTemporaryFile cannot be opened by another process
    # while Python still has it open, so we use delete=False and clean up manually
    # rather than using a contextmanager here.
    f = tempfile.NamedTemporaryFile(
        mode="w", encoding=encoding, errors="replace", delete=False
    )
    try:
        yield t.cast(t.TextIO, f), color
        f.flush()
        f.close()
        subprocess.call([str(cmd_path), *cmd_params, f.name])
    finally:
        # An error raised while paging skips the close() above, and Windows
        # refuses to unlink a file the process still holds open. Closing here
        # keeps that PermissionError from replacing the original exception.
        # close() is idempotent, so this is a no-op on the success path.
        f.close()
        os.unlink(f.name)


@contextlib.contextmanager
def _nullpager(
    stream: t.TextIO, color: bool | None = None
) -> t.Iterator[tuple[t.TextIO, bool | None]]:
    """Simply print unformatted text. This is the ultimate fallback.

    The stream comes from elsewhere (typically ``sys.stdout``), so its lifecycle
    is left untouched: :class:`_PagerWriter` never closes what it wraps, and it
    is the only thing :func:`get_pager_file` hands to the caller.
    """
    yield stream, color


class Editor:
    def __init__(
        self,
        editor: str | None = None,
        env: cabc.Mapping[str, str] | None = None,
        require_save: bool = True,
        extension: str = ".txt",
    ) -> None:
        self.editor = editor
        self.env = env
        self.require_save = require_save
        self.extension = extension

    def get_editor(self) -> str:
        if self.editor is not None:
            return self.editor
        for key in "VISUAL", "EDITOR":
            rv = os.environ.get(key)
            if rv:
                return rv
        if WIN:
            return "notepad"

        from shutil import which

        for editor in "sensible-editor", "vim", "nano":
            if which(editor) is not None:
                return editor
        return "vi"

    def edit_files(self, filenames: cabc.Iterable[str | os.PathLike[str]]) -> None:
        """Open files in the user's editor."""
        import shlex
        import subprocess

        editor = self.get_editor()
        environ: dict[str, str] | None = None

        if self.env:
            environ = os.environ.copy()
            environ.update(self.env)

        try:
            # Split in POSIX mode (the default) for the same reasons as
            # in pager(): strips quotes from tokens and preserves quoted
            # Windows paths.
            c = subprocess.Popen(
                args=shlex.split(editor) + list(filenames),
                env=environ,
            )
            exit_code = c.wait()
            if exit_code != 0:
                raise ClickException(
                    _("{editor}: Editing failed").format(editor=editor)
                )
        except OSError as e:
            raise ClickException(
                _("{editor}: Editing failed: {e}").format(editor=editor, e=e)
            ) from e

    @t.overload
    def edit(self, text: bytes | bytearray) -> bytes | None: ...

    # We cannot know whether or not the type expected is str or bytes when None
    # is passed, so str is returned as that was what was done before.
    @t.overload
    def edit(self, text: str | None) -> str | None: ...

    def edit(self, text: str | bytes | bytearray | None) -> str | bytes | None:
        import tempfile

        if text is None:
            data: bytes | bytearray = b""
        elif isinstance(text, (bytes, bytearray)):
            data = text
        else:
            if text and not text.endswith("\n"):
                text += "\n"

            if WIN:
                data = text.replace("\n", "\r\n").encode("utf-8-sig")
            else:
                data = text.encode("utf-8")

        fd, name = tempfile.mkstemp(prefix="editor-", suffix=self.extension)
        f: t.BinaryIO

        try:
            with os.fdopen(fd, "wb") as f:
                f.write(data)

            # If the filesystem resolution is 1 second, like Mac OS
            # 10.12 Extended, or 2 seconds, like FAT32, and the editor
            # closes very fast, require_save can fail. Set the modified
            # time to be 2 seconds in the past to work around this.
            os.utime(name, (os.path.getatime(name), os.path.getmtime(name) - 2))
            # Depending on the resolution, the exact value might not be
            # recorded, so get the new recorded value.
            timestamp = os.path.getmtime(name)

            self.edit_files((name,))

            if self.require_save and os.path.getmtime(name) == timestamp:
                return None

            with open(name, "rb") as f:
                rv = f.read()

            if isinstance(text, (bytes, bytearray)):
                return rv

            return rv.decode("utf-8-sig").replace("\r\n", "\n")
        finally:
            os.unlink(name)


def open_url(url: str, wait: bool = False, locate: bool = False) -> int:
    import subprocess

    def _unquote_file(url: str) -> str:
        from urllib.parse import unquote

        if url.startswith("file://"):
            url = unquote(url[7:])

        return url

    if sys.platform == "darwin":
        args = ["open"]
        if wait:
            args.append("-W")
        if locate:
            args.append("-R")
        args.append(_unquote_file(url))
        null = open("/dev/null", "w")
        try:
            return subprocess.Popen(args, stderr=null).wait()
        finally:
            null.close()
    elif WIN:
        if locate:
            url = _unquote_file(url)
            args = ["explorer", "/select,", url]
            try:
                return subprocess.call(args)
            except OSError:
                return 127
        else:
            try:
                os.startfile(url)  # type: ignore[attr-defined]
            except OSError:
                return 127
            return 0
    elif CYGWIN:
        if locate:
            url = _unquote_file(url)
            args = ["cygstart", os.path.dirname(url)]
        else:
            args = ["cygstart"]
            if wait:
                args.append("-w")
            args.append(url)
        try:
            return subprocess.call(args)
        except OSError:
            # Command not found
            return 127

    try:
        if locate:
            url = os.path.dirname(_unquote_file(url)) or "."
        else:
            url = _unquote_file(url)
        c = subprocess.Popen(["xdg-open", url])
        if wait:
            return c.wait()
        return 0
    except OSError:
        if url.startswith(("http://", "https://")) and not locate and not wait:
            import webbrowser

            webbrowser.open(url)
            return 0
        return 1


def _translate_ch_to_exc(ch: str) -> None:
    if ch == "\x03":
        raise KeyboardInterrupt()

    if ch == "\x04" and not WIN:  # Unix-like, Ctrl+D
        raise EOFError()

    if ch == "\x1a" and WIN:  # Windows, Ctrl+Z
        raise EOFError()


if sys.platform == "win32":
    import msvcrt

    @contextlib.contextmanager
    def raw_terminal() -> cabc.Iterator[int]:
        yield -1

    def getchar(echo: bool) -> str:
        # The function `getch` will return a bytes object corresponding to
        # the pressed character. Since Windows 10 build 1803, it will also
        # return \x00 when called a second time after pressing a regular key.
        #
        # `getwch` does not share this probably-bugged behavior. Moreover, it
        # returns a Unicode object by default, which is what we want.
        #
        # Either of these functions will return \x00 or \xe0 to indicate
        # a special key, and you need to call the same function again to get
        # the "rest" of the code. The fun part is that \u00e0 is
        # "latin small letter a with grave", so if you type that on a French
        # keyboard, you _also_ get a \xe0.
        # E.g., consider the Up arrow. This returns \xe0 and then \x48. The
        # resulting Unicode string reads as "a with grave" + "capital H".
        # This is indistinguishable from when the user actually types
        # "a with grave" and then "capital H".
        #
        # When \xe0 is returned, we assume it's part of a special-key sequence
        # and call `getwch` again, but that means that when the user types
        # the \u00e0 character, `getchar` doesn't return until a second
        # character is typed.
        # The alternative is returning immediately, but that would mess up
        # cross-platform handling of arrow keys and others that start with
        # \xe0. Another option is using `getch`, but then we can't reliably
        # read non-ASCII characters, because return values of `getch` are
        # limited to the current 8-bit codepage.
        #
        # Anyway, Click doesn't claim to do this Right(tm), and using `getwch`
        # is doing the right thing in more situations than with `getch`.

        if echo:
            func = t.cast(t.Callable[[], str], msvcrt.getwche)
        else:
            func = t.cast(t.Callable[[], str], msvcrt.getwch)

        rv = func()

        if rv in ("\x00", "\xe0"):
            # \x00 and \xe0 are control characters that indicate special key,
            # see above.
            rv += func()

        _translate_ch_to_exc(rv)
        return rv

else:
    import termios
    import tty

    @contextlib.contextmanager
    def raw_terminal() -> cabc.Iterator[int]:
        f: t.TextIO | None
        fd: int

        if not isatty(sys.stdin):
            f = open("/dev/tty")
            fd = f.fileno()
        else:
            fd = sys.stdin.fileno()
            f = None

        try:
            old_settings = termios.tcgetattr(fd)

            try:
                tty.setraw(fd)
                yield fd
            finally:
                termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
                sys.stdout.flush()

                if f is not None:
                    f.close()
        except termios.error:
            pass

    def getchar(echo: bool) -> str:
        with raw_terminal() as fd:
            ch = os.read(fd, 32).decode(get_best_encoding(sys.stdin), "replace")

            if echo and isatty(sys.stdout):
                sys.stdout.write(ch)

            _translate_ch_to_exc(ch)
            return ch