#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
    openslides.utils.main
    ~~~~~~~~~~~~~~~~~~~~~

    Some functions for OpenSlides.

    :copyright: 2011–2013 by OpenSlides team, see AUTHORS.
    :license: GNU GPL, see LICENSE for more details.
"""

import os
import sys
import ctypes
import tempfile


UNIX_VERSION = 'Unix Version'
WINDOWS_VERSION = 'Windows Version'
WINDOWS_PORTABLE_VERSION = 'Windows Portable Version'

class PortableDirNotWritable(Exception):
    pass

def filesystem2unicode(path):
    """
    Transforms a path string to unicode according to the filesystem's encoding.
    """
    # TODO: Delete this function after switch to Python 3.
    if not isinstance(path, unicode):
        filesystem_encoding = sys.getfilesystemencoding() or sys.getdefaultencoding()
        path = path.decode(filesystem_encoding)
    return path


def detect_openslides_type():
    """
    Returns the type of this version.
    """
    if sys.platform == 'win32':
        if os.path.basename(sys.executable).lower() == 'openslides.exe':
            # Note: sys.executable is the path of the *interpreter*
            #       the portable version embeds python so it *is* the interpreter.
            #       The wrappers generated by pip and co. will spawn the usual
            #       python(w).exe, so there is no danger of mistaking them
            #       for the portable even though they may also be called
            #       openslides.exe
            openslides_type = WINDOWS_PORTABLE_VERSION
        else:
            openslides_type = WINDOWS_VERSION
    else:
        openslides_type = UNIX_VERSION
    return openslides_type


def is_portable():
    """
    Helper function just for the GUI.
    """
    # TODO: Remove this function.
    return detect_openslides_type() == WINDOWS_PORTABLE_VERSION


def get_win32_app_data_path():
    """
    Returns the path to Windows' AppData directory.
    """
    shell32 = ctypes.WinDLL("shell32.dll")
    SHGetFolderPath = shell32.SHGetFolderPathW
    SHGetFolderPath.argtypes = (
        ctypes.c_void_p, ctypes.c_int, ctypes.c_void_p, ctypes.c_uint32,
        ctypes.c_wchar_p)
    SHGetFolderPath.restype = ctypes.c_uint32

    CSIDL_LOCAL_APPDATA = 0x001c
    MAX_PATH = 260

    buf = ctypes.create_unicode_buffer(MAX_PATH)
    res = SHGetFolderPath(0, CSIDL_LOCAL_APPDATA, 0, 0, buf)
    if res != 0:
        raise Exception("Could not deterime APPDATA path")

    return buf.value


def get_win32_portable_path():
    """
    Returns the path to the Windows portable version.
    """
    # NOTE: sys.executable will be the path to openslides.exe
    #       since it is essentially a small wrapper that embeds the
    #       python interpreter
    portable_path = filesystem2unicode(os.path.dirname(os.path.abspath(sys.executable)))
    try:
        fd, test_file = tempfile.mkstemp(dir=portable_path)
    except OSError:
        raise PortableDirNotWritable(
            'Portable directory is not writeable. '
            'Please choose another directory for settings and local files.')
    else:
        os.close(fd)
        os.unlink(test_file)
    return portable_path


def get_portable_paths(name):
    """
    Returns the paths for the Windows portable version on runtime for the
    SQLite3 database and the media directory. The argument 'name' can be
    'database' or 'media'.
    """
    if name == 'database':
        path = os.path.join(get_win32_portable_path(), 'openslides', 'database.sqlite')
    elif name == 'media':
        path = os.path.join(get_win32_portable_path(), 'openslides', 'media', '')
    else:
        raise TypeError('Unknow type %s' % name)
    return path