# Copyright (C) 2010 Google Inc. All rights reserved.
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"""Wrapper object for the file system / source tree."""

from __future__ import with_statement

import codecs
import errno
import exceptions
import glob
import os
import shutil
import tempfile
import time

from webkitpy.common.system import ospath

class FileSystem(object):
    """FileSystem interface for webkitpy.

    Unless otherwise noted, all paths are allowed to be either absolute
    or relative."""
    def __init__(self):
        self._sep = os.sep

    def _get_sep(self):
        return self._sep

    sep = property(_get_sep, doc="pathname separator")

    def abspath(self, path):
        return os.path.abspath(path)

    def basename(self, path):
        """Wraps os.path.basename()."""
        return os.path.basename(path)

    def chdir(self, path):
        """Wraps os.chdir()."""
        return os.chdir(path)

    def copyfile(self, source, destination):
        """Copies the contents of the file at the given path to the destination
        path."""
        shutil.copyfile(source, destination)

    def dirname(self, path):
        """Wraps os.path.dirname()."""
        return os.path.dirname(path)

    def exists(self, path):
        """Return whether the path exists in the filesystem."""
        return os.path.exists(path)

    def files_under(self, path, dirs_to_skip=[], file_filter=None):
        """Return the list of all files under the given path in topdown order.

        Args:
            dirs_to_skip: a list of directories to skip over during the
                traversal (e.g., .svn, resources, etc.)
            file_filter: if not None, the filter will be invoked
                with the filesystem object and the dirname and basename of
                each file found. The file is included in the result if the
                callback returns True.
        """
        def filter_all(fs, dirpath, basename):
            return True

        file_filter = file_filter or filter_all
        files = []
        if self.isfile(path):
            if file_filter(self, self.dirname(path), self.basename(path)):
                files.append(path)
            return files

        if self.basename(path) in dirs_to_skip:
            return []

        for (dirpath, dirnames, filenames) in os.walk(path):
            for d in dirs_to_skip:
                if d in dirnames:
                    dirnames.remove(d)

            for filename in filenames:
                if file_filter(self, dirpath, filename):
                    files.append(self.join(dirpath, filename))
        return files

    def getcwd(self):
        """Wraps os.getcwd()."""
        return os.getcwd()

    def glob(self, path):
        """Wraps glob.glob()."""
        return glob.glob(path)

    def isabs(self, path):
        """Return whether the path is an absolute path."""
        return os.path.isabs(path)

    def isfile(self, path):
        """Return whether the path refers to a file."""
        return os.path.isfile(path)

    def isdir(self, path):
        """Return whether the path refers to a directory."""
        return os.path.isdir(path)

    def join(self, *comps):
        """Return the path formed by joining the components."""
        return os.path.join(*comps)

    def listdir(self, path):
        """Return the contents of the directory pointed to by path."""
        return os.listdir(path)

    def mkdtemp(self, **kwargs):
        """Create and return a uniquely named directory.

        This is like tempfile.mkdtemp, but if used in a with statement
        the directory will self-delete at the end of the block (if the
        directory is empty; non-empty directories raise errors). The
        directory can be safely deleted inside the block as well, if so
        desired.

        Note that the object returned is not a string and does not support all of the string
        methods. If you need a string, coerce the object to a string and go from there.
        """
        class TemporaryDirectory(object):
            def __init__(self, **kwargs):
                self._kwargs = kwargs
                self._directory_path = tempfile.mkdtemp(**self._kwargs)

            def __str__(self):
                return self._directory_path

            def __enter__(self):
                return self._directory_path

            def __exit__(self, type, value, traceback):
                # Only self-delete if necessary.

                # FIXME: Should we delete non-empty directories?
                if os.path.exists(self._directory_path):
                    os.rmdir(self._directory_path)

        return TemporaryDirectory(**kwargs)

    def maybe_make_directory(self, *path):
        """Create the specified directory if it doesn't already exist."""
        try:
            os.makedirs(self.join(*path))
        except OSError, e:
            if e.errno != errno.EEXIST:
                raise

    def move(self, source, destination):
        shutil.move(source, destination)

    def mtime(self, path):
        return os.stat(path).st_mtime

    def normpath(self, path):
        """Wraps os.path.normpath()."""
        return os.path.normpath(path)

    def open_binary_tempfile(self, suffix):
        """Create, open, and return a binary temp file. Returns a tuple of the file and the name."""
        temp_fd, temp_name = tempfile.mkstemp(suffix)
        f = os.fdopen(temp_fd, 'wb')
        return f, temp_name

    def open_text_file_for_writing(self, path, append=False):
        """Returns a file handle suitable for writing to."""
        mode = 'w'
        if append:
            mode = 'a'
        return codecs.open(path, mode, 'utf8')

    def open_binary_file_for_reading(self, path):
        return codecs.open(path, 'rb')

    def read_binary_file(self, path):
        """Return the contents of the file at the given path as a byte string."""
        with file(path, 'rb') as f:
            return f.read()

    def read_text_file(self, path):
        """Return the contents of the file at the given path as a Unicode string.

        The file is read assuming it is a UTF-8 encoded file with no BOM."""
        with codecs.open(path, 'r', 'utf8') as f:
            return f.read()

    def relpath(self, path, start='.'):
        return ospath.relpath(path, start)

    class _WindowsError(exceptions.OSError):
        """Fake exception for Linux and Mac."""
        pass

    def remove(self, path, osremove=os.remove):
        """On Windows, if a process was recently killed and it held on to a
        file, the OS will hold on to the file for a short while.  This makes
        attempts to delete the file fail.  To work around that, this method
        will retry for a few seconds until Windows is done with the file."""
        try:
            exceptions.WindowsError
        except AttributeError:
            exceptions.WindowsError = FileSystem._WindowsError

        retry_timeout_sec = 3.0
        sleep_interval = 0.1
        while True:
            try:
                osremove(path)
                return True
            except exceptions.WindowsError, e:
                time.sleep(sleep_interval)
                retry_timeout_sec -= sleep_interval
                if retry_timeout_sec < 0:
                    raise e

    def rmtree(self, path):
        """Delete the directory rooted at path, empty or no."""
        shutil.rmtree(path, ignore_errors=True)

    def read_binary_file(self, path):
        """Return the contents of the file at the given path as a byte string."""
        with file(path, 'rb') as f:
            return f.read()

    def read_text_file(self, path):
        """Return the contents of the file at the given path as a Unicode string.

        The file is read assuming it is a UTF-8 encoded file with no BOM."""
        with codecs.open(path, 'r', 'utf8') as f:
            return f.read()

    def splitext(self, path):
        """Return (dirname + os.sep + basename, '.' + ext)"""
        return os.path.splitext(path)

    def write_binary_file(self, path, contents):
        """Write the contents to the file at the given location."""
        with file(path, 'wb') as f:
            f.write(contents)

    def write_text_file(self, path, contents):
        """Write the contents to the file at the given location.

        The file is written encoded as UTF-8 with no BOM."""
        with codecs.open(path, 'w', 'utf8') as f:
            f.write(contents)