# -*- coding: utf-8 -*-
"""

The `utils` module provides a number of utility functions that don't belong
in the Filesystem interface. Generally the functions in this module work with
multiple Filesystems, for instance moving and copying between non-similar Filesystems.

"""


__all__ = ['copyfile',
           'movefile',
           'movedir',
           'copydir',
           'countbytes',
           'isfile',
           'isdir',
           'find_duplicates',
           'print_fs',
           'open_atomic_write']

import os
import sys
import stat
import six
from six import PY3

from fs.mountfs import MountFS
from fs.path import pathjoin
from fs.errors import DestinationExistsError, RemoveRootError
from fs.base import FS


def copyfile(src_fs, src_path, dst_fs, dst_path, overwrite=True, chunk_size=64*1024):
    """Copy a file from one filesystem to another. Will use system copyfile, if both files have a syspath.
    Otherwise file will be copied a chunk at a time.

    :param src_fs: Source filesystem object
    :param src_path: -- Source path
    :param dst_fs: Destination filesystem object
    :param dst_path: Destination filesystem object
    :param chunk_size: Size of chunks to move if system copyfile is not available (default 64K)

    """

    # If the src and dst fs objects are the same, then use a direct copy
    if src_fs is dst_fs:
        src_fs.copy(src_path, dst_path, overwrite=overwrite)
        return

    src_syspath = src_fs.getsyspath(src_path, allow_none=True)
    dst_syspath = dst_fs.getsyspath(dst_path, allow_none=True)

    if not overwrite and dst_fs.exists(dst_path):
        raise DestinationExistsError(dst_path)

    # System copy if there are two sys paths
    if src_syspath is not None and dst_syspath is not None:
        FS._shutil_copyfile(src_syspath, dst_syspath)
        return

    src_lock = getattr(src_fs, '_lock', None)

    if src_lock is not None:
        src_lock.acquire()

    try:
        src = None
        try:
            src = src_fs.open(src_path, 'rb')
            dst_fs.setcontents(dst_path, src, chunk_size=chunk_size)
        finally:
            if src is not None:
                src.close()
    finally:
        if src_lock is not None:
            src_lock.release()


def copyfile_non_atomic(src_fs, src_path, dst_fs, dst_path, overwrite=True, chunk_size=64*1024):
    """A non atomic version of copyfile (will not block other threads using src_fs or dst_fst)

    :param src_fs: Source filesystem object
    :param src_path: -- Source path
    :param dst_fs: Destination filesystem object
    :param dst_path: Destination filesystem object
    :param chunk_size: Size of chunks to move if system copyfile is not available (default 64K)

    """

    if not overwrite and dst_fs.exists(dst_path):
        raise DestinationExistsError(dst_path)

    src = None
    dst = None
    try:
        src = src_fs.open(src_path, 'rb')
        dst = dst_fs.open(dst_path, 'wb')
        write = dst.write
        read = src.read
        chunk = read(chunk_size)
        while chunk:
            write(chunk)
            chunk = read(chunk_size)
    finally:
        if src is not None:
            src.close()
        if dst is not None:
            dst.close()


def movefile(src_fs, src_path, dst_fs, dst_path, overwrite=True, chunk_size=64*1024):
    """Move a file from one filesystem to another. Will use system copyfile, if both files have a syspath.
    Otherwise file will be copied a chunk at a time.

    :param src_fs: Source filesystem object
    :param src_path: Source path
    :param dst_fs: Destination filesystem object
    :param dst_path: Destination filesystem object
    :param chunk_size: Size of chunks to move if system copyfile is not available (default 64K)

    """
    src_syspath = src_fs.getsyspath(src_path, allow_none=True)
    dst_syspath = dst_fs.getsyspath(dst_path, allow_none=True)

    if not overwrite and dst_fs.exists(dst_path):
        raise DestinationExistsError(dst_path)

    if src_fs is dst_fs:
        src_fs.move(src_path, dst_path, overwrite=overwrite)
        return

    # System copy if there are two sys paths
    if src_syspath is not None and dst_syspath is not None:
        FS._shutil_movefile(src_syspath, dst_syspath)
        return

    src_lock = getattr(src_fs, '_lock', None)

    if src_lock is not None:
        src_lock.acquire()

    try:
        src = None
        try:
            # Chunk copy
            src = src_fs.open(src_path, 'rb')
            dst_fs.setcontents(dst_path, src, chunk_size=chunk_size)
        except:
            raise
        else:
            src_fs.remove(src_path)
        finally:
            if src is not None:
                src.close()
    finally:
        if src_lock is not None:
            src_lock.release()


def movefile_non_atomic(src_fs, src_path, dst_fs, dst_path, overwrite=True, chunk_size=64*1024):
    """A non atomic version of movefile (wont block other threads using src_fs or dst_fs)

    :param src_fs: Source filesystem object
    :param src_path: Source path
    :param dst_fs: Destination filesystem object
    :param dst_path: Destination filesystem object
    :param chunk_size: Size of chunks to move if system copyfile is not available (default 64K)

    """

    if not overwrite and dst_fs.exists(dst_path):
        raise DestinationExistsError(dst_path)

    src = None
    dst = None
    try:
        # Chunk copy
        src = src_fs.open(src_path, 'rb')
        dst = dst_fs.open(dst_path, 'wb')
        write = dst.write
        read = src.read
        chunk = read(chunk_size)
        while chunk:
            write(chunk)
            chunk = read(chunk_size)
    except:
        raise
    else:
        src_fs.remove(src_path)
    finally:
        if src is not None:
            src.close()
        if dst is not None:
            dst.close()


def movedir(fs1, fs2, create_destination=True, ignore_errors=False, chunk_size=64*1024):
    """Moves contents of a directory from one filesystem to another.

    :param fs1: A tuple of (<filesystem>, <directory path>)
    :param fs2: Destination filesystem, or a tuple of (<filesystem>, <directory path>)
    :param create_destination: If True, the destination will be created if it doesn't exist
    :param ignore_errors: If True, exceptions from file moves are ignored
    :param chunk_size: Size of chunks to move if a simple copy is used

    """
    if not isinstance(fs1, tuple):
        raise ValueError("first argument must be a tuple of (<filesystem>, <path>)")

    fs1, dir1 = fs1
    parent_fs1 = fs1
    parent_dir1 = dir1
    fs1 = fs1.opendir(dir1)

    if parent_dir1 in ('', '/'):
        raise RemoveRootError(dir1)

    if isinstance(fs2, tuple):
        fs2, dir2 = fs2
        if create_destination:
            fs2.makedir(dir2, allow_recreate=True, recursive=True)
        fs2 = fs2.opendir(dir2)

    mount_fs = MountFS(auto_close=False)
    mount_fs.mount('src', fs1)
    mount_fs.mount('dst', fs2)

    mount_fs.copydir('src', 'dst',
                     overwrite=True,
                     ignore_errors=ignore_errors,
                     chunk_size=chunk_size)
    parent_fs1.removedir(parent_dir1, force=True)


def copydir(fs1, fs2, create_destination=True, ignore_errors=False, chunk_size=64*1024):
    """Copies contents of a directory from one filesystem to another.

    :param fs1: Source filesystem, or a tuple of (<filesystem>, <directory path>)
    :param fs2: Destination filesystem, or a tuple of (<filesystem>, <directory path>)
    :param create_destination: If True, the destination will be created if it doesn't exist
    :param ignore_errors: If True, exceptions from file moves are ignored
    :param chunk_size: Size of chunks to move if a simple copy is used

    """
    if isinstance(fs1, tuple):
        fs1, dir1 = fs1
        fs1 = fs1.opendir(dir1)
    if isinstance(fs2, tuple):
        fs2, dir2 = fs2
        if create_destination:
            fs2.makedir(dir2, allow_recreate=True, recursive=True)
        fs2 = fs2.opendir(dir2)

    mount_fs = MountFS(auto_close=False)
    mount_fs.mount('src', fs1)
    mount_fs.mount('dst', fs2)
    mount_fs.copydir('src', 'dst',
                     overwrite=True,
                     ignore_errors=ignore_errors,
                     chunk_size=chunk_size)


def copydir_progress(progress_callback, fs1, fs2, create_destination=True, ignore_errors=False, chunk_size=64*1024):
    """
    Copies the contents of a directory from one fs to another, with a callback function to display progress.

    `progress_callback` should be a function with two parameters; `step` and `num_steps`.

    `num_steps` is the number of steps in the copy process, and `step` is the current step. `num_steps` may be None if the number
    of steps is still being calculated.

    """
    if isinstance(fs1, tuple):
        fs1, dir1 = fs1
        fs1 = fs1.opendir(dir1)
    if isinstance(fs2, tuple):
        fs2, dir2 = fs2
        if create_destination:
            fs2.makedir(dir2, allow_recreate=True, recursive=True)
        fs2 = fs2.opendir(dir2)

    def do_callback(step, num_steps):
        try:
            progress_callback(step, num_steps)
        except:
            pass

    do_callback(0, None)

    file_count = 0
    copy_paths = []
    for dir_path, file_paths in fs1.walk():
        copy_paths.append((dir_path, file_paths))
        file_count += len(file_paths)
        do_callback(0, file_count)

    step = 0
    for i, (dir_path, file_paths) in enumerate(copy_paths):
        try:
            fs2.makedir(dir_path, allow_recreate=True)
            for path in file_paths:
                copy_path = pathjoin(dir_path, path)
                with fs1.open(copy_path, 'rb') as src_file:
                    fs2.setcontents(copy_path, src_file, chunk_size=chunk_size)
                step += 1
        except:
            if ignore_errors:
                continue
            raise
        do_callback(step, file_count)


def remove_all(fs, path):
    """Remove everything in a directory. Returns True if successful.

    :param fs: A filesystem
    :param path: Path to a directory

    """
    sub_fs = fs.opendir(path)
    for sub_path in sub_fs.listdir():
        if sub_fs.isdir(sub_path):
            sub_fs.removedir(sub_path, force=True)
        else:
            sub_fs.remove(sub_path)
    return fs.isdirempty(path)


def copystructure(src_fs, dst_fs):
    """Copies the directory structure from one filesystem to another, so that
    all directories in `src_fs` will have a corresponding directory in `dst_fs`

    :param src_fs: Filesystem to copy structure from
    :param dst_fs: Filesystem to copy structure to

    """

    for path in src_fs.walkdirs():
        dst_fs.makedir(path, allow_recreate=True)


def countbytes(fs):
    """Returns the total number of bytes contained within files in a filesystem.

    :param fs: A filesystem object

    """
    total = sum(fs.getsize(f) for f in fs.walkfiles())
    return total


def isdir(fs,path,info=None):
    """Check whether a path within a filesystem is a directory.

    If you're able to provide the info dict for the path, this may be possible
    without querying the filesystem (e.g. by checking st_mode).
    """
    if info is not None:
        st_mode = info.get("st_mode")
        if st_mode:
            if stat.S_ISDIR(st_mode):
                return True
            if stat.S_ISREG(st_mode):
                return False
    return fs.isdir(path)


def isfile(fs,path,info=None):
    """Check whether a path within a filesystem is a file.

    If you're able to provide the info dict for the path, this may be possible
    without querying the filesystem (e.g. by checking st_mode).
    """
    if info is not None:
        st_mode = info.get("st_mode")
        if st_mode:
            if stat.S_ISREG(st_mode):
                return True
            if stat.S_ISDIR(st_mode):
                return False
    return fs.isfile(path)

def contains_files(fs, path='/'):
    """Check if there are any files in the filesystem"""
    try:
        next(iter(fs.walkfiles(path)))
    except StopIteration:
        return False
    return True

def find_duplicates(fs,
                    compare_paths=None,
                    quick=False,
                    signature_chunk_size=16*1024,
                    signature_size=10*16*1024):
    """A generator that yields the paths of duplicate files in an FS object.
    Files are considered identical if the contents are the same (dates or
    other attributes not take in to account).

    :param fs: A filesystem object
    :param compare_paths: An iterable of paths within the FS object, or all files if omitted
    :param quick: If set to True, the quick method of finding duplicates will be used, which can potentially return false positives if the files have the same size and start with the same data. Do not use when deleting files!
    :param signature_chunk_size: The number of bytes to read before generating a signature checksum value
    :param signature_size: The total number of bytes read to generate a signature

    For example, the following will list all the duplicate .jpg files in "~/Pictures"::

        >>> from fs.utils import find_duplicates
        >>> from fs.osfs import OSFS
        >>> fs = OSFS('~/Pictures')
        >>> for dups in find_duplicates(fs, fs.walkfiles('*.jpg')):
        ...     print(list(dups))

    """

    from collections import defaultdict
    from zlib import crc32

    if compare_paths is None:
        compare_paths = fs.walkfiles()

    # Create a dictionary that maps file sizes on to the paths of files with
    # that filesize. So we can find files of the same size with a quick lookup
    file_sizes = defaultdict(list)
    for path in compare_paths:
        file_sizes[fs.getsize(path)].append(path)

    size_duplicates = [paths for paths in file_sizes.values() if len(paths) > 1]

    signatures = defaultdict(list)

    # A signature is a tuple of CRC32s for each 4x16K of the file
    # This allows us to find potential duplicates with a dictionary lookup
    for paths in size_duplicates:
        for path in paths:
            signature = []
            fread = None
            bytes_read = 0
            try:
                fread = fs.open(path, 'rb')
                while signature_size is None or bytes_read < signature_size:
                    data = fread.read(signature_chunk_size)
                    if not data:
                        break
                    bytes_read += len(data)
                    signature.append(crc32(data))
            finally:
                if fread is not None:
                    fread.close()
            signatures[tuple(signature)].append(path)

    # If 'quick' is True then the signature comparison is adequate (although
    # it may result in false positives)
    if quick:
        for paths in signatures.values():
            if len(paths) > 1:
                yield paths
        return

    def identical(p1, p2):
        """ Returns True if the contents of two files are identical. """
        f1, f2 = None, None
        try:
            f1 = fs.open(p1, 'rb')
            f2 = fs.open(p2, 'rb')
            while True:
                chunk1 = f1.read(16384)
                if not chunk1:
                    break
                chunk2 = f2.read(16384)
                if chunk1 != chunk2:
                    return False
            return True
        finally:
            if f1 is not None:
                f1.close()
            if f2 is not None:
                f2.close()

    # If we want to be accurate then we need to compare suspected duplicates
    # byte by byte.
    # All path groups in this loop have the same size and same signature, so are
    # highly likely to be identical.
    for paths in signatures.values():

        while len(paths) > 1:

            test_p = paths.pop()
            dups = [test_p]

            for path in paths:
                if identical(test_p, path):
                    dups.append(path)

            if len(dups) > 1:
                yield dups

            paths = list(set(paths).difference(dups))


def print_fs(fs,
             path='/',
             max_levels=5,
             file_out=None,
             terminal_colors=None,
             hide_dotfiles=False,
             dirs_first=False,
             files_wildcard=None,
             dirs_only=False):
    """Prints a filesystem listing to stdout (including sub directories).

    This mostly useful as a debugging aid.
    Be careful about printing a OSFS, or any other large filesystem.
    Without max_levels set, this function will traverse the entire directory tree.

    For example, the following will print a tree of the files under the current working directory::

        >>> from fs.osfs import *
        >>> from fs.utils import *
        >>> fs = OSFS('.')
        >>> print_fs(fs)


    :param fs: A filesystem object
    :param path: Path of a directory to list (default "/")
    :param max_levels: Maximum levels of dirs to list (default 5), set to None for no maximum
    :param file_out: File object to write output to (defaults to sys.stdout)
    :param terminal_colors: If True, terminal color codes will be written, set to False for non-console output.
        The default (None) will select an appropriate setting for the platform.
    :param hide_dotfiles: if True, files or directories beginning with '.' will be removed

    """

    if file_out is None:
        file_out = sys.stdout

    file_encoding = getattr(file_out, 'encoding', 'utf-8') or 'utf-8'
    file_encoding = file_encoding.upper()

    if terminal_colors is None:
        if sys.platform.startswith('win'):
            terminal_colors = False
        else:
            terminal_colors = hasattr(file_out, 'isatty') and file_out.isatty()

    def write(line):
        if PY3:
            file_out.write((line + '\n'))
        else:
            file_out.write((line + '\n').encode(file_encoding, 'replace'))

    def wrap_prefix(prefix):
        if not terminal_colors:
            return prefix
        return '\x1b[32m%s\x1b[0m' % prefix

    def wrap_dirname(dirname):
        if not terminal_colors:
            return dirname
        return '\x1b[1;34m%s\x1b[0m' % dirname

    def wrap_error(msg):
        if not terminal_colors:
            return msg
        return '\x1b[31m%s\x1b[0m' % msg

    def wrap_filename(fname):
        if not terminal_colors:
            return fname
        if fname.startswith('.'):
            fname = '\x1b[33m%s\x1b[0m' % fname
        return fname
    dircount = [0]
    filecount = [0]
    def print_dir(fs, path, levels=[]):
        if file_encoding == 'UTF-8' and terminal_colors:
            char_vertline = '│'
            char_newnode = '├'
            char_line = '──'
            char_corner = '╰'
        else:
            char_vertline = '|'
            char_newnode = '|'
            char_line = '--'
            char_corner = '`'

        try:
            dirs = fs.listdir(path, dirs_only=True)
            if dirs_only:
                files = []
            else:
                files = fs.listdir(path, files_only=True, wildcard=files_wildcard)
            dir_listing = ( [(True, p) for p in dirs] +
                            [(False, p) for p in files] )
        except Exception as e:
            prefix = ''.join([(char_vertline + '   ', '    ')[last] for last in levels]) + '   '
            write(wrap_prefix(prefix[:-1] + '    ') + wrap_error("unable to retrieve directory list (%s) ..." % str(e)))
            return 0

        if hide_dotfiles:
            dir_listing = [(isdir, p) for isdir, p in dir_listing if not p.startswith('.')]

        if dirs_first:
            dir_listing.sort(key = lambda isdir_p:(not isdir_p[0], isdir_p[1].lower()))
        else:
            dir_listing.sort(key = lambda isdir_p1:isdir_p1[1].lower())

        for i, (is_dir, item) in enumerate(dir_listing):
            if is_dir:
                dircount[0] += 1
            else:
                filecount[0] += 1
            is_last_item = (i == len(dir_listing) - 1)
            prefix = ''.join([(char_vertline + '   ', '    ')[last] for last in levels])
            if is_last_item:
                prefix += char_corner
            else:
                prefix += char_newnode

            if is_dir:
                write('%s %s' % (wrap_prefix(prefix + char_line), wrap_dirname(item)))
                if max_levels is not None and len(levels) + 1 >= max_levels:
                    pass
                    #write(wrap_prefix(prefix[:-1] + '       ') + wrap_error('max recursion levels reached'))
                else:
                    print_dir(fs, pathjoin(path, item), levels[:] + [is_last_item])
            else:
                write('%s %s' % (wrap_prefix(prefix + char_line), wrap_filename(item)))

        return len(dir_listing)

    print_dir(fs, path)
    return dircount[0], filecount[0]


class AtomicWriter(object):
    """Context manager to perform atomic writes"""

    def __init__(self, fs, path, mode='w'):
        self.fs = fs
        self.path = path
        self.mode = mode
        self.tmp_path = path + '~'
        self._f = None

    def __enter__(self):
        self._f = self.fs.open(self.tmp_path, self.mode)
        return self._f

    def __exit__(self, exc_type, exc_value, traceback):
        if exc_type is None:
            if self._f is not None:
                if hasattr('_f', 'flush'):
                    self._f.flush()
                if hasattr(self._f, 'fileno'):
                    os.fsync(self._f.fileno())
                self._f.close()
                self._f = None
                self.fs.rename(self.tmp_path, self.path)
        else:
            if self._f is not None:
                self._f.close()


def open_atomic_write(fs, path, mode='w'):
    """Open a file for 'atomic' writing

    This returns a context manager which ensures that a file is written in its entirety or not at all.

    """
    return AtomicWriter(fs, path, mode=mode)




if __name__ == "__main__":
    from fs.tempfs import TempFS
    from six import b
    t1 = TempFS()
    t1.setcontents("foo", b("test"))
    t1.makedir("bar")
    t1.setcontents("bar/baz", b("another test"))

    t1.tree()

    t2 = TempFS()
    print(t2.listdir())
    movedir(t1, t2)

    print(t2.listdir())
    t1.tree()
    t2.tree()

