utils.py

import os
import re
import sys
import typing as t
from functools import update_wrapper
from types import ModuleType

from ._compat import _default_text_stderr
from ._compat import _default_text_stdout
from ._compat import _find_binary_writer
from ._compat import auto_wrap_for_ansi
from ._compat import binary_streams
from ._compat import get_filesystem_encoding
from ._compat import open_stream
from ._compat import should_strip_ansi
from ._compat import strip_ansi
from ._compat import text_streams
from ._compat import WIN
from .globals import resolve_color_default

if t.TYPE_CHECKING:
    import typing_extensions as te

F = t.TypeVar("F", bound=t.Callable[..., t.Any])


def _posixify(name: str) -> str:
    return "-".join(name.split()).lower()


def safecall(func: F) -> F:
    """Wraps a function so that it swallows exceptions."""

    def wrapper(*args, **kwargs):  # type: ignore
        try:
            return func(*args, **kwargs)
        except Exception:
            pass

    return update_wrapper(t.cast(F, wrapper), func)


def make_str(value: t.Any) -> str:
    """Converts a value into a valid string."""
    if isinstance(value, bytes):
        try:
            return value.decode(get_filesystem_encoding())
        except UnicodeError:
            return value.decode("utf-8", "replace")
    return str(value)


def make_default_short_help(help: str, max_length: int = 45) -> str:
    """Returns a condensed version of help string."""
    # Consider only the first paragraph.
    paragraph_end = help.find("\n\n")

    if paragraph_end != -1:
        help = help[:paragraph_end]

    # Collapse newlines, tabs, and spaces.
    words = help.split()

    if not words:
        return ""

    # The first paragraph started with a "no rewrap" marker, ignore it.
    if words[0] == "\b":
        words = words[1:]

    total_length = 0
    last_index = len(words) - 1

    for i, word in enumerate(words):
        total_length += len(word) + (i > 0)

        if total_length > max_length:  # too long, truncate
            break

        if word[-1] == ".":  # sentence end, truncate without "..."
            return " ".join(words[: i + 1])

        if total_length == max_length and i != last_index:
            break  # not at sentence end, truncate with "..."
    else:
        return " ".join(words)  # no truncation needed

    # Account for the length of the suffix.
    total_length += len("...")

    # remove words until the length is short enough
    while i > 0:
        total_length -= len(words[i]) + (i > 0)

        if total_length <= max_length:
            break

        i -= 1

    return " ".join(words[:i]) + "..."


class LazyFile:
    """A lazy file works like a regular file but it does not fully open
    the file but it does perform some basic checks early to see if the
    filename parameter does make sense.  This is useful for safely opening
    files for writing.
    """

    def __init__(
        self,
        filename: str,
        mode: str = "r",
        encoding: t.Optional[str] = None,
        errors: t.Optional[str] = "strict",
        atomic: bool = False,
    ):
        self.name = filename
        self.mode = mode
        self.encoding = encoding
        self.errors = errors
        self.atomic = atomic
        self._f: t.Optional[t.IO]

        if filename == "-":
            self._f, self.should_close = open_stream(filename, mode, encoding, errors)
        else:
            if "r" in mode:
                # Open and close the file in case we're opening it for
                # reading so that we can catch at least some errors in
                # some cases early.
                open(filename, mode).close()
            self._f = None
            self.should_close = True

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

    def __repr__(self) -> str:
        if self._f is not None:
            return repr(self._f)
        return f"<unopened file '{self.name}' {self.mode}>"

    def open(self) -> t.IO:
        """Opens the file if it's not yet open.  This call might fail with
        a :exc:`FileError`.  Not handling this error will produce an error
        that Click shows.
        """
        if self._f is not None:
            return self._f
        try:
            rv, self.should_close = open_stream(
                self.name, self.mode, self.encoding, self.errors, atomic=self.atomic
            )
        except OSError as e:  # noqa: E402
            from .exceptions import FileError

            raise FileError(self.name, hint=e.strerror) from e
        self._f = rv
        return rv

    def close(self) -> None:
        """Closes the underlying file, no matter what."""
        if self._f is not None:
            self._f.close()

    def close_intelligently(self) -> None:
        """This function only closes the file if it was opened by the lazy
        file wrapper.  For instance this will never close stdin.
        """
        if self.should_close:
            self.close()

    def __enter__(self) -> "LazyFile":
        return self

    def __exit__(self, exc_type, exc_value, tb):  # type: ignore
        self.close_intelligently()

    def __iter__(self) -> t.Iterator[t.AnyStr]:
        self.open()
        return iter(self._f)  # type: ignore


class KeepOpenFile:
    def __init__(self, file: t.IO) -> None:
        self._file = file

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

    def __enter__(self) -> "KeepOpenFile":
        return self

    def __exit__(self, exc_type, exc_value, tb):  # type: ignore
        pass

    def __repr__(self) -> str:
        return repr(self._file)

    def __iter__(self) -> t.Iterator[t.AnyStr]:
        return iter(self._file)


def echo(
    message: t.Optional[t.Any] = None,
    file: t.Optional[t.IO[t.Any]] = None,
    nl: bool = True,
    err: bool = False,
    color: t.Optional[bool] = None,
) -> None:
    """Print a message and newline to stdout or a file. This should be
    used instead of :func:`print` because it provides better support
    for different data, files, and environments.

    Compared to :func:`print`, this does the following:

    -   Ensures that the output encoding is not misconfigured on Linux.
    -   Supports Unicode in the Windows console.
    -   Supports writing to binary outputs, and supports writing bytes
        to text outputs.
    -   Supports colors and styles on Windows.
    -   Removes ANSI color and style codes if the output does not look
        like an interactive terminal.
    -   Always flushes the output.

    :param message: The string or bytes to output. Other objects are
        converted to strings.
    :param file: The file to write to. Defaults to ``stdout``.
    :param err: Write to ``stderr`` instead of ``stdout``.
    :param nl: Print a newline after the message. Enabled by default.
    :param color: Force showing or hiding colors and other styles. By
        default Click will remove color if the output does not look like
        an interactive terminal.

    .. versionchanged:: 6.0
        Support Unicode output on the Windows console. Click does not
        modify ``sys.stdout``, so ``sys.stdout.write()`` and ``print()``
        will still not support Unicode.

    .. versionchanged:: 4.0
        Added the ``color`` parameter.

    .. versionadded:: 3.0
        Added the ``err`` parameter.

    .. versionchanged:: 2.0
        Support colors on Windows if colorama is installed.
    """
    if file is None:
        if err:
            file = _default_text_stderr()
        else:
            file = _default_text_stdout()

    # Convert non bytes/text into the native string type.
    if message is not None and not isinstance(message, (str, bytes, bytearray)):
        out: t.Optional[t.Union[str, bytes]] = str(message)
    else:
        out = message

    if nl:
        out = out or ""
        if isinstance(out, str):
            out += "\n"
        else:
            out += b"\n"

    if not out:
        file.flush()
        return

    # If there is a message and the value looks like bytes, we manually
    # need to find the binary stream and write the message in there.
    # This is done separately so that most stream types will work as you
    # would expect. Eg: you can write to StringIO for other cases.
    if isinstance(out, (bytes, bytearray)):
        binary_file = _find_binary_writer(file)

        if binary_file is not None:
            file.flush()
            binary_file.write(out)
            binary_file.flush()
            return

    # ANSI style code support. For no message or bytes, nothing happens.
    # When outputting to a file instead of a terminal, strip codes.
    else:
        color = resolve_color_default(color)

        if should_strip_ansi(file, color):
            out = strip_ansi(out)
        elif WIN:
            if auto_wrap_for_ansi is not None:
                file = auto_wrap_for_ansi(file)  # type: ignore
            elif not color:
                out = strip_ansi(out)

    file.write(out)  # type: ignore
    file.flush()


def get_binary_stream(name: "te.Literal['stdin', 'stdout', 'stderr']") -> t.BinaryIO:
    """Returns a system stream for byte processing.

    :param name: the name of the stream to open.  Valid names are ``'stdin'``,
                 ``'stdout'`` and ``'stderr'``
    """
    opener = binary_streams.get(name)
    if opener is None:
        raise TypeError(f"Unknown standard stream '{name}'")
    return opener()


def get_text_stream(
    name: "te.Literal['stdin', 'stdout', 'stderr']",
    encoding: t.Optional[str] = None,
    errors: t.Optional[str] = "strict",
) -> t.TextIO:
    """Returns a system stream for text processing.  This usually returns
    a wrapped stream around a binary stream returned from
    :func:`get_binary_stream` but it also can take shortcuts for already
    correctly configured streams.

    :param name: the name of the stream to open.  Valid names are ``'stdin'``,
                 ``'stdout'`` and ``'stderr'``
    :param encoding: overrides the detected default encoding.
    :param errors: overrides the default error mode.
    """
    opener = text_streams.get(name)
    if opener is None:
        raise TypeError(f"Unknown standard stream '{name}'")
    return opener(encoding, errors)


def open_file(
    filename: str,
    mode: str = "r",
    encoding: t.Optional[str] = None,
    errors: t.Optional[str] = "strict",
    lazy: bool = False,
    atomic: bool = False,
) -> t.IO:
    """Open a file, with extra behavior to handle ``'-'`` to indicate
    a standard stream, lazy open on write, and atomic write. Similar to
    the behavior of the :class:`~click.File` param type.

    If ``'-'`` is given to open ``stdout`` or ``stdin``, the stream is
    wrapped so that using it in a context manager will not close it.
    This makes it possible to use the function without accidentally
    closing a standard stream:

    .. code-block:: python

        with open_file(filename) as f:
            ...

    :param filename: The name of the file to open, or ``'-'`` for
        ``stdin``/``stdout``.
    :param mode: The mode in which to open the file.
    :param encoding: The encoding to decode or encode a file opened in
        text mode.
    :param errors: The error handling mode.
    :param lazy: Wait to open the file until it is accessed. For read
        mode, the file is temporarily opened to raise access errors
        early, then closed until it is read again.
    :param atomic: Write to a temporary file and replace the given file
        on close.

    .. versionadded:: 3.0
    """
    if lazy:
        return t.cast(t.IO, LazyFile(filename, mode, encoding, errors, atomic=atomic))

    f, should_close = open_stream(filename, mode, encoding, errors, atomic=atomic)

    if not should_close:
        f = t.cast(t.IO, KeepOpenFile(f))

    return f


def format_filename(
    filename: t.Union[str, bytes, os.PathLike], shorten: bool = False
) -> str:
    """Formats a filename for user display.  The main purpose of this
    function is to ensure that the filename can be displayed at all.  This
    will decode the filename to unicode if necessary in a way that it will
    not fail.  Optionally, it can shorten the filename to not include the
    full path to the filename.

    :param filename: formats a filename for UI display.  This will also convert
                     the filename into unicode without failing.
    :param shorten: this optionally shortens the filename to strip of the
                    path that leads up to it.
    """
    if shorten:
        filename = os.path.basename(filename)

    return os.fsdecode(filename)


def get_app_dir(app_name: str, roaming: bool = True, force_posix: bool = False) -> str:
    r"""Returns the config folder for the application.  The default behavior
    is to return whatever is most appropriate for the operating system.

    To give you an idea, for an app called ``"Foo Bar"``, something like
    the following folders could be returned:

    Mac OS X:
      ``~/Library/Application Support/Foo Bar``
    Mac OS X (POSIX):
      ``~/.foo-bar``
    Unix:
      ``~/.config/foo-bar``
    Unix (POSIX):
      ``~/.foo-bar``
    Windows (roaming):
      ``C:\Users\<user>\AppData\Roaming\Foo Bar``
    Windows (not roaming):
      ``C:\Users\<user>\AppData\Local\Foo Bar``

    .. versionadded:: 2.0

    :param app_name: the application name.  This should be properly capitalized
                     and can contain whitespace.
    :param roaming: controls if the folder should be roaming or not on Windows.
                    Has no affect otherwise.
    :param force_posix: if this is set to `True` then on any POSIX system the
                        folder will be stored in the home folder with a leading
                        dot instead of the XDG config home or darwin's
                        application support folder.
    """
    if WIN:
        key = "APPDATA" if roaming else "LOCALAPPDATA"
        folder = os.environ.get(key)
        if folder is None:
            folder = os.path.expanduser("~")
        return os.path.join(folder, app_name)
    if force_posix:
        return os.path.join(os.path.expanduser(f"~/.{_posixify(app_name)}"))
    if sys.platform == "darwin":
        return os.path.join(
            os.path.expanduser("~/Library/Application Support"), app_name
        )
    return os.path.join(
        os.environ.get("XDG_CONFIG_HOME", os.path.expanduser("~/.config")),
        _posixify(app_name),
    )


class PacifyFlushWrapper:
    """This wrapper is used to catch and suppress BrokenPipeErrors resulting
    from ``.flush()`` being called on broken pipe during the shutdown/final-GC
    of the Python interpreter. Notably ``.flush()`` is always called on
    ``sys.stdout`` and ``sys.stderr``. So as to have minimal impact on any
    other cleanup code, and the case where the underlying file is not a broken
    pipe, all calls and attributes are proxied.
    """

    def __init__(self, wrapped: t.IO) -> None:
        self.wrapped = wrapped

    def flush(self) -> None:
        try:
            self.wrapped.flush()
        except OSError as e:
            import errno

            if e.errno != errno.EPIPE:
                raise

    def __getattr__(self, attr: str) -> t.Any:
        return getattr(self.wrapped, attr)


def _detect_program_name(
    path: t.Optional[str] = None, _main: t.Optional[ModuleType] = None
) -> str:
    """Determine the command used to run the program, for use in help
    text. If a file or entry point was executed, the file name is
    returned. If ``python -m`` was used to execute a module or package,
    ``python -m name`` is returned.

    This doesn't try to be too precise, the goal is to give a concise
    name for help text. Files are only shown as their name without the
    path. ``python`` is only shown for modules, and the full path to
    ``sys.executable`` is not shown.

    :param path: The Python file being executed. Python puts this in
        ``sys.argv[0]``, which is used by default.
    :param _main: The ``__main__`` module. This should only be passed
        during internal testing.

    .. versionadded:: 8.0
        Based on command args detection in the Werkzeug reloader.

    :meta private:
    """
    if _main is None:
        _main = sys.modules["__main__"]

    if not path:
        path = sys.argv[0]

    # The value of __package__ indicates how Python was called. It may
    # not exist if a setuptools script is installed as an egg. It may be
    # set incorrectly for entry points created with pip on Windows.
    if getattr(_main, "__package__", None) is None or (
        os.name == "nt"
        and _main.__package__ == ""
        and not os.path.exists(path)
        and os.path.exists(f"{path}.exe")
    ):
        # Executed a file, like "python app.py".
        return os.path.basename(path)

    # Executed a module, like "python -m example".
    # Rewritten by Python from "-m script" to "/path/to/script.py".
    # Need to look at main module to determine how it was executed.
    py_module = t.cast(str, _main.__package__)
    name = os.path.splitext(os.path.basename(path))[0]

    # A submodule like "example.cli".
    if name != "__main__":
        py_module = f"{py_module}.{name}"

    return f"python -m {py_module.lstrip('.')}"


def _expand_args(
    args: t.Iterable[str],
    *,
    user: bool = True,
    env: bool = True,
    glob_recursive: bool = True,
) -> t.List[str]:
    """Simulate Unix shell expansion with Python functions.

    See :func:`glob.glob`, :func:`os.path.expanduser`, and
    :func:`os.path.expandvars`.

    This is intended for use on Windows, where the shell does not do any
    expansion. It may not exactly match what a Unix shell would do.

    :param args: List of command line arguments to expand.
    :param user: Expand user home directory.
    :param env: Expand environment variables.
    :param glob_recursive: ``**`` matches directories recursively.

    .. versionchanged:: 8.1
        Invalid glob patterns are treated as empty expansions rather
        than raising an error.

    .. versionadded:: 8.0

    :meta private:
    """
    from glob import glob

    out = []

    for arg in args:
        if user:
            arg = os.path.expanduser(arg)

        if env:
            arg = os.path.expandvars(arg)

        try:
            matches = glob(arg, recursive=glob_recursive)
        except re.error:
            matches = []

        if not matches:
            out.append(arg)
        else:
            out.extend(matches)

    return out