#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# Copyright (C) 2011 Yesudeep Mangalapilly <yesudeep@gmail.com>
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.


from watchdog.utils import platform

if platform.is_windows():
    import ctypes

    from watchdog.observers.winapi import \
        FILE_FLAG_BACKUP_SEMANTICS, \
        FILE_FLAG_OVERLAPPED, \
        FILE_SHARE_READ, \
        FILE_SHARE_WRITE, \
        FILE_SHARE_DELETE, \
        FILE_NOTIFY_CHANGE_FILE_NAME, \
        FILE_NOTIFY_CHANGE_DIR_NAME, \
        FILE_NOTIFY_CHANGE_ATTRIBUTES, \
        FILE_NOTIFY_CHANGE_SIZE, \
        FILE_NOTIFY_CHANGE_LAST_WRITE, \
        FILE_NOTIFY_CHANGE_SECURITY, \
        FILE_NOTIFY_CHANGE_LAST_ACCESS, \
        FILE_NOTIFY_CHANGE_CREATION, \
        FILE_ACTION_CREATED, \
        FILE_ACTION_DELETED, \
        FILE_ACTION_MODIFIED, \
        FILE_LIST_DIRECTORY, \
        OPEN_EXISTING, \
        INVALID_HANDLE_VALUE, \
        CreateFileW, \
        ReadDirectoryChangesW, \
        CreateIoCompletionPort, \
        CloseHandle
    from watchdog.events import \
        DirDeletedEvent, \
        DirCreatedEvent, \
        DirModifiedEvent, \
        FileDeletedEvent, \
        FileCreatedEvent, \
        FileModifiedEvent

    # We don't need to recalculate these flags every time a call is made to
    # the win32 API functions.
    WATCHDOG_FILE_FLAGS = FILE_FLAG_BACKUP_SEMANTICS
    WATCHDOG_FILE_FLAGS_ASYNC = FILE_FLAG_BACKUP_SEMANTICS | FILE_FLAG_OVERLAPPED
    WATCHDOG_FILE_SHARE_FLAGS = reduce(lambda x, y: x | y, [
        FILE_SHARE_READ,
        FILE_SHARE_WRITE,
        FILE_SHARE_DELETE,
    ])
    WATCHDOG_FILE_NOTIFY_FLAGS = reduce(lambda x, y: x | y, [
        FILE_NOTIFY_CHANGE_FILE_NAME,
        FILE_NOTIFY_CHANGE_DIR_NAME,
        FILE_NOTIFY_CHANGE_ATTRIBUTES,
        FILE_NOTIFY_CHANGE_SIZE,
        FILE_NOTIFY_CHANGE_LAST_WRITE,
        FILE_NOTIFY_CHANGE_SECURITY,
        FILE_NOTIFY_CHANGE_LAST_ACCESS,
        FILE_NOTIFY_CHANGE_CREATION,
    ])


    # HACK:
    WATCHDOG_TRAVERSE_MOVED_DIR_DELAY = 1   # seconds

    BUFFER_SIZE = 2048

    # Moved event is handled explicitly in the emitter thread.
    DIR_ACTION_EVENT_MAP = {
        FILE_ACTION_CREATED: DirCreatedEvent,
        FILE_ACTION_DELETED: DirDeletedEvent,
        FILE_ACTION_MODIFIED: DirModifiedEvent,
    }
    FILE_ACTION_EVENT_MAP = {
        FILE_ACTION_CREATED: FileCreatedEvent,
        FILE_ACTION_DELETED: FileDeletedEvent,
        FILE_ACTION_MODIFIED: FileModifiedEvent,
    }


    def get_directory_handle(path, file_flags):
        """Returns a Windows handle to the specified directory path."""
        handle = CreateFileW(path,
                             FILE_LIST_DIRECTORY,
                             WATCHDOG_FILE_SHARE_FLAGS,
                             None,
                             OPEN_EXISTING,
                             file_flags,
                             None)
        return handle


    def close_directory_handle(handle):
        CloseHandle(handle)


    def read_directory_changes(handle, event_buffer, recursive):
        """Read changes to the directory using the specified directory handle.

        http://timgolden.me.uk/pywin32-docs/win32file__ReadDirectoryChangesW_meth.html
        """
        nbytes = ctypes.wintypes.DWORD()
        ReadDirectoryChangesW(handle,
                              ctypes.byref(event_buffer),
                              len(event_buffer),
                              recursive,
                              WATCHDOG_FILE_NOTIFY_FLAGS,
                              ctypes.byref(nbytes),
                              None,
                              None)
        # get_FILE_NOTIFY_INFORMATION expects nBytes to be long.
        return event_buffer.raw, long(nbytes.value)


    def create_io_completion_port():
        """
        http://timgolden.me.uk/pywin32-docs/win32file__CreateIoCompletionPort_meth.html
        """
        return CreateIoCompletionPort(INVALID_HANDLE_VALUE, None, 0, 0)
