def download_file(url, dest=None, chunk_size=1024, replace="ask",
                  label="Downloading {dest_basename} ({size:.2f}MB)",
                  expected_extension=None):
    """Download a file from a given URL and display progress.

    :param dest: If the destination exists and is a directory, the filename
        will be guessed from the Content-Disposition header. If the destination
        is an existing file, the user will either be prompted to overwrite, or
        the file will be replaced (depending on the value of **replace**). If
        the destination does not exist, it will be used as the filename.
    :param int chunk_size: bytes read in at a time.
    :param replace: If `False`, an existing destination file will not be
        overwritten.
    :param label: a string which is formatted and displayed as the progress bar
        label. Variables provided include *dest_basename*, *dest*, and *size*.
    :param expected_extension: if set, the filename will be sanitized to ensure
        it has the given extension. The extension should not start with a dot
        (`.`).
    """
    dest = Path(dest or url.split("/")[-1])
    response = get(url, stream=True)
    if (dest.exists()
            and dest.is_dir()
            and "Content-Disposition" in response.headers):
        content_disposition = rfc6266.parse_requests_response(response)
        if expected_extension is not None:
            filename = content_disposition.filename_sanitized(
                expected_extension)
        filename = secure_filename(filename)
        dest = dest / filename
    if dest.exists() and not dest.is_dir():
        if (replace is False
                or replace == "ask"
                and not click.confirm("Replace {}?".format(dest))):
            return str(dest)
    size = int(response.headers.get("content-length", 0))
    label = label.format(dest=dest, dest_basename=dest.name,
                         size=size/1024.0/1024)
    with click.open_file(str(dest), "wb") as f:
        content_iter = response.iter_content(chunk_size=chunk_size)
        with click.progressbar(content_iter, length=size/1024,
                               label=label) as bar:
            for chunk in bar:
                if chunk:
                    f.write(chunk)
                    f.flush()
    return str(dest)
def install(self, spec, prefix):
        """Install under the projectdir"""
        mkdirp(self.projectdir)
        projdir = os.path.basename(self.projectdir)
        # Filtering: bashrc, cshrc
        edits = {
            'WM_PROJECT_INST_DIR': os.path.dirname(self.projectdir),
            'WM_PROJECT_DIR': join_path('$WM_PROJECT_INST_DIR', projdir),
        }

        # All top-level files, except spack build info and possibly Allwmake
        if '+source' in spec:
            ignored = re.compile(r'^spack-.*')
        else:
            ignored = re.compile(r'^(Allwmake|spack-).*')

        files = [
            f for f in glob.glob("*")
            if os.path.isfile(f) and not ignored.search(f)
        ]
        for f in files:
            install(f, self.projectdir)

        # Having wmake and ~source is actually somewhat pointless...
        # Install 'etc' before 'bin' (for symlinks)
        # META-INFO for 1812 and later (or backported)
        dirs = ['META-INFO', 'etc', 'bin', 'wmake']
        if '+source' in spec:
            dirs.extend(['applications', 'src', 'tutorials'])

        for d in dirs:
            if os.path.isdir(d):
                install_tree(
                    d,
                    join_path(self.projectdir, d),
                    symlinks=True)

        dirs = ['platforms']
        if '+source' in spec:
            dirs.extend(['doc'])

        # Install platforms (and doc) skipping intermediate targets
        relative_ignore_paths = ['src', 'applications', 'html', 'Guides']
        ignore = lambda p: p in relative_ignore_paths
        for d in dirs:
            install_tree(
                d,
                join_path(self.projectdir, d),
                ignore=ignore,
                symlinks=True)

        etc_dir = join_path(self.projectdir, 'etc')
        rewrite_environ_files(  # Adjust etc/bashrc and etc/cshrc
            edits,
            posix=join_path(etc_dir, 'bashrc'),
            cshell=join_path(etc_dir, 'cshrc'))
        self.install_links()