# Copyright (C) 2009 Google Inc. All rights reserved.
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# in the documentation and/or other materials provided with the
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import errno
import os
import path


class MockFileSystem(object):
    def __init__(self, files=None):
        """Initializes a "mock" filesystem that can be used to completely
        stub out a filesystem.

        Args:
            files: a dict of filenames -> file contents. A file contents
                value of None is used to indicate that the file should
                not exist.
        """
        self.files = files or {}

    def exists(self, path):
        return self.isfile(path) or self.isdir(path)

    def isfile(self, path):
        return path in self.files and self.files[path] is not None

    def isdir(self, path):
        if path in self.files:
            return False
        if not path.endswith('/'):
            path += '/'
        return any(f.startswith(path) for f in self.files)

    def join(self, *comps):
        return '/'.join(comps)

    def listdir(self, path):
        if not self.isdir(path):
            raise OSError("%s is not a directory" % path)

        if not path.endswith('/'):
            path += '/'

        dirs = []
        files = []
        for f in self.files:
            if self.exists(f) and f.startswith(path):
                remaining = f[len(path):]
                if '/' in remaining:
                    dir = remaining[:remaining.index('/')]
                    if not dir in dirs:
                        dirs.append(dir)
                else:
                    files.append(remaining)
        return dirs + files

    def maybe_make_directory(self, *path):
        # FIXME: Implement such that subsequent calls to isdir() work?
        pass

    def read_text_file(self, path):
        return self.read_binary_file(path)

    def read_binary_file(self, path):
        if path in self.files:
            if self.files[path] is None:
                raise IOError(errno.ENOENT, path, os.strerror(errno.ENOENT))
            return self.files[path]

    def write_text_file(self, path, contents):
        return self.write_binary_file(path, contents)

    def write_binary_file(self, path, contents):
        self.files[path] = contents

    def copyfile(self, source, destination):
        if not self.exists(source):
            raise IOError(errno.ENOENT, source, os.strerror(errno.ENOENT))
        if self.isdir(source):
            raise IOError(errno.EISDIR, source, os.strerror(errno.ISDIR))
        if self.isdir(destination):
            raise IOError(errno.EISDIR, destination, os.strerror(errno.ISDIR))

        self.files[destination] = self.files[source]