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

# Copyright 2015-2016 Jaap Karssenberg <jaap.karssenberg@gmail.com>

'''Mock objects for file system classes

Since the file system is an external resource that assumes an
underlying reality, it is a hard thing to mock in test cases.
However it is also relatively slow, so having a good mock makes
good test cases much more usable.
Therefore we go to great lenght here to have a full set of mock
classes for all file system related objects.
'''

from __future__ import with_statement

import os
import time

from .base import *
from .base import _EOL, _SEP


__all__ = ('MockFolder', 'MockFile')


def clone_mock_object(source, target):
	'''Similar to C{copyto}, but used to copy to a mock object
	that belongs to another mock filesystem hierarchy.
	@param source: a L{MockFile} or L{MockFolder}
	@param target: another L{MockFile} or L{MockFolder}
	'''
	assert source.__class__ is target.__class__
	mynode = source._node()
	newnode = target._fs.touch(target.pathnames, mynode.deepcopy_data())
	newnode.ctime = mynode.ctime
	newnode.mtime = mynode.mtime


def os_native_path(unixpath):
	'''Adapts unix style paths for windows if needed
	Used for convenience to of writing cross-platform test cases
	Called automatically when constructing a L{MockFile} or L{MockFolder} object
	Does not modify URLs
	@param unixpath: the (mock) unix path as a string
	'''
	assert isinstance(unixpath, basestring)
	if os.name == 'nt' and not is_url_re.match(unixpath):
		if unixpath.startswith('/'):
			unixpath = 'M:' + unixpath # arbitrary drive letter, should be OK for mock
		return unixpath.replace('/', '\\')
	else:
		return unixpath


class MockFSNode(object):

	__slots__ = ('ctime', 'mtime', 'size', 'data', 'isdir')

	def __init__(self, data):
		assert isinstance(data, (basestring, dict))
		self.ctime = None
		self.mtime = None
		self.size = None
		self.isdir = isinstance(data, dict)
		self.data = data
		self.on_changed()

	def deepcopy_data(self):
		if self.isdir:
			new = {}
			for name, node in self.data.items():
				new[name] = MockFSNode(node.deepcopy_data()) # recurs
				new[name].ctime = node.ctime
				new[name].mtime = node.mtime
			return new
		else:
			return self.data

	def on_changed(self):
		# Called after change of data attribute to update
		# mtime, ctime and size attributes
		old = self.mtime
		self.mtime = time.time()
		if old and "%.2f" % self.mtime == "%.2f" % old:
			self.mtime += 0.01 # Hack to make tests pass ..
		if self.ctime is None:
			self.ctime = self.mtime
		self.size = len(self.data) if self.data else 0


class MockFS(MockFSNode):
	# Special node object that has some filesystem-like functions

	def __init__(self):
		MockFSNode.__init__(self, {})

	def tree(self):
		def walk(prefix, node):
			for name in node.data:
				yield prefix + name
				if node.data[name].isdir:
					for line in walk(prefix + name + '/', node.data[name]):
						yield line

		return walk('', self)

	def stat(self, names):
		# Find node below or self if 'names' is empty
		node = self
		for i, name in enumerate(names):
			parent = node
			if not parent.isdir:
				raise AssertionError, 'Not a folder: %s' % _SEP.join(names[:i+1])
			else:
				try:
					node = parent.data[name]
				except KeyError:
					raise FileNotFoundError(_SEP.join(names))
		return node

	def touch(self, names, data):
		# Walk nodes below and create new where needed
		if not names:
			return self # toplevel always exists

		node = self
		for i, name in enumerate(names[:-1]):
			parent = node
			if not name in parent.data:
				parent.data[name] = MockFSNode({}) # new folder
				parent.on_changed()
			node = parent.data[name]
			if not node.isdir:
				raise AssertionError, 'Not a folder: %s' % _SEP.join(names[:i+1])

		parent, basename = node, names[-1]
		if basename not in parent.data:
			parent.data[basename] = MockFSNode(data)
			parent.on_changed()

		return parent.data[basename]


class MockFSObjectBase(FSObjectBase):
	# Base class for MockFolder and MockFile. It uses an internal
	# structure of MockFSNode objects to represent a file tree. Between
	# external facing objects this internal structure is passed on.
	# The result is that there is persistency as long as any of the
	# file or folder objects created is alive. Also multiple objects
	# can refer to the same resource; same as with a real external
	# file system.

	def __init__(self, path, watcher=None, _fs=None):
		if isinstance(path, basestring):
			path = os_native_path(path) # make test syntax easier
		FSObjectBase.__init__(self, path, watcher=watcher)
		if not _fs:
			_fs = MockFS()
		self._fs = _fs
		assert isinstance(self._fs, MockFS)

	def __eq__(self, other):
		return FilePath.__eq__(self, other) and other._fs is self._fs

	def _set_mtime(self, mtime):
		assert isinstance(mtime, (int, float))
		node = self._node()
		node.mtime = mtime

	def _node(self):
		raise NotImplemented

	def parent(self):
		dirname = self.dirname
		if dirname is None:
			raise ValueError, 'Can not get parent of root'
		else:
			return MockFolder(dirname, watcher=self.watcher, _fs=self._fs)

	def exists(self):
		try:
			self._node()
		except FileNotFoundError:
			return False
		else:
			return True

	def iswritable(self):
		return True

	def isequal(self, other):
		return isinstance(other, self.__class__) \
			and self._fs is other._fs \
			and self.path == other.path

	def ctime(self):
		return self._node().ctime

	def mtime(self):
		return self._node().mtime

	def moveto(self, other):
		if isinstance(self, File) and isinstance(other, Folder):
			other = other.file(self.basename)

		if not isinstance(other, MockFSObjectBase):
			raise NotImplementedError, 'TODO: support cross object type move'

		self._mock_copyto(other)
		self._remove(removechildren=True)
		if self.watcher:
			self.watcher.emit('moved', self, other)

		self._cleanup()
		return other

	def copyto(self, other):
		if isinstance(self, File) and isinstance(other, Folder):
			other = other.file(self.basename)

		if isinstance(other, MockFSObjectBase):
			self._mock_copyto(other)
		else:
			assert isinstance(other, (File, Folder))
			self._copyto(other)

		if self.watcher:
			self.watcher.emit('created', other)
		return other

	def _mock_copyto(self, other):
		assert other._fs is self._fs
		assert not other.path == self.path

		if isinstance(self, File):
			assert isinstance(other, File)
		else:
			assert isinstance(other, Folder)

		try:
			node = self._fs.stat(other.pathnames)
		except FileNotFoundError:
			mynode = self._node()
			newnode = self._fs.touch(other.pathnames, mynode.deepcopy_data())
			newnode.ctime = mynode.ctime
			newnode.mtime = mynode.mtime
		else:
			raise FileExistsError(other)

	def remove(self):
		if self.exists():
			self._remove()
			if self.watcher:
				self.watcher.emit('removed', self)

		self._cleanup()

	def _remove(self, removechildren=False):
		node = self._node()
		if node.isdir and node.data and not removechildren:
			raise FolderNotEmptyError(self)

		parentnode = self._fs.stat(self.pathnames[:-1])
		parentnode.data.pop(self.pathnames[-1])
		parentnode.on_changed()


class MockFolder(MockFSObjectBase, Folder):

	def _node(self):
		node = self._fs.stat(self.pathnames)
		if not node.isdir:
			raise AssertionError, 'Not a folder: %s' % self.path
		return node

	def exists(self):
		try:
			return self._node().isdir
		except:
			return False

	def touch(self):
		if not self.exists():
			try:
				self.parent().touch()
			except ValueError:
				pass

			node = self._fs.touch(self.pathnames, {})
			if not node.isdir:
				raise AssertionError, 'Not a folder: %s' % self.path

			if self.watcher:
				self.watcher.emit('created', self)

	def __iter__(self):
		children = self._node().data
		return self._object_iter(children, True, True)

	def list_files(self):
		children = self._node().data
		return self._object_iter(children, True, False)

	def list_folders(self):
		children = self._node().data
		return self._object_iter(children, False, True)

	def _object_iter(self, children, showfile, showdir):
		# inner iter to force FileNotFoundError on call instead of first iter call
		for name, node in sorted(children.items()):
			if node.isdir:
				if showdir:
					yield self.folder(name)
			else:
				if showfile:
					yield self.file(name)

	def list_names(self):
		children = self._node().data
		return sorted(children.keys())

	def file(self, path):
		return MockFile(self.get_childpath(path), watcher=self.watcher, _fs=self._fs)

	def folder(self, path):
		return MockFolder(self.get_childpath(path), watcher=self.watcher, _fs=self._fs)

	def child(self, path):
		# Will raise if path does not exist
		p = self.get_childpath(path)
		node = self._fs.stat(p.pathnames)
		if node.isdir:
			return self.folder(path)
		else:
			return self.file(path)


class MockFile(MockFSObjectBase, File):

	def __init__(self, path, endofline=_EOL, watcher=None, _fs=None):
		assert endofline in ('dos', 'unix')
		MockFSObjectBase.__init__(self, path, watcher=watcher, _fs=_fs)
		self._mimetype = None
		self.endofline = endofline # attribute not used in this mock ..

	def _node(self):
		node = self._fs.stat(self.pathnames)
		if node.isdir:
			raise AssertionError, 'Not a file: %s' % self.path
		return node

	def size(self):
		return self._node().size

	def read_binary(self):
		return self._node().data

	def read(self):
		return self._node().data

	def readlines(self):
		return self.read().splitlines(True)

	def write(self, text):
		assert isinstance(text, basestring)

		with self._write_decoration():
			try:
				node = self._node()
			except FileNotFoundError:
				self._fs.touch(self.pathnames, text)
			else:
				node.data = text
				node.on_changed()

	write_binary = write

	def writelines(self, lines):
		self.write(''.join(lines))
