# Copyright (C) 2008-2010 Adam Olsen
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2, or (at your option)
# any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
#
#
# The developers of the Exaile media player hereby grant permission
# for non-GPL compatible GStreamer and Exaile plugins to be used and
# distributed together with GStreamer and Exaile. This permission is
# above and beyond the permissions granted by the GPL license by which
# Exaile is covered. If you modify this code, you may extend this
# exception to your version of the code, but you are not obligated to
# do so. If you do not wish to do so, delete this exception statement
# from your version.

"""
    General functions and classes shared in the codebase
"""

from __future__ import with_statement

import inspect
import gio
import glib
import gobject
import logging
import os
import random
import string
import subprocess
import sys
import threading
import traceback
import urllib2
import urlparse
from functools import wraps, partial
from collections import deque
from UserDict import DictMixin

logger = logging.getLogger(__name__)

#TODO: get rid of this. only plugins/cd/ uses it.
VALID_TAGS = (
    # Ogg Vorbis spec tags
    "title version album tracknumber artist genre performer copyright "
    "license organization description location contact isrc date "

    # Other tags we like
    "arranger author composer conductor lyricist discnumber labelid part "
    "website language encodedby bpm albumartist originaldate originalalbum "
    "originalartist recordingdate"
    ).split()

PICKLE_PROTOCOL=2

# Default tags for track sorting. Unless you have good reason to do
# otherwise, use this.
# TODO: make this a setting?
BASE_SORT_TAGS=('albumartist', 'date', 'album', 'discnumber', 'tracknumber', 'title')

# use this for general logging of exceptions
def log_exception(log=logger, message="Exception caught!"):
    """
        Convenience function to log an exception + traceback

        :param log: the logger object to use.  important to specify
            so that it will be logged under the right module name.
        :param message: a message describing the error condition.
    """
    log.debug(message + "\n" + traceback.format_exc())

def to_unicode(x, default_encoding=None):
    """Force getting a unicode string from any object."""
    if isinstance(x, unicode):
        return x
    elif default_encoding and isinstance(x, str):
        # This unicode constructor only accepts "string or buffer".
        return unicode(x, default_encoding)
    else:
        return unicode(x)

def clamp(value, minimum, maximum):
    """
        Clamps a value to the given boundaries

        :param value: the value to clamp
        :param minimum: the minimum value to return
        :param maximum: the maximum value to return
    """
    return max(minimum, min(value, maximum))

def enum(**enums):
    """
        Creates an enum type

        :see: http://stackoverflow.com/a/1695250
    """
    return type('Enum', (), enums)

def sanitize_url(url):
    """
        Removes the password part from an url

        :param url: the URL to sanitize
        :type url: string
        :returns: the sanitized url
    """
    try:
        components = list(urlparse.urlparse(url))
        auth, host = components[1].split('@')
        username, password = auth.split(':')
    except (AttributeError, ValueError):
        pass
    else:
        # Replace password with fixed amount of "*"
        auth = ':'.join((username, 5 * '*'))
        components[1] = '@'.join((auth, host))
        url = urlparse.urlunparse(components)

    return url

def get_url_contents(url, user_agent):
    '''
        Retrieves data from a URL and sticks a user-agent on it. You can use
        exaile.get_user_agent_string(pluginname) to get this.
        
        Added in Exaile 3.4
        
        :returns: Contents of page located at URL
        :raises: urllib2.URLError
    '''
    
    headers = {'User-Agent': user_agent}
    req = urllib2.Request(url, None, headers)
    fp = urllib2.urlopen(req)
    data = fp.read()
    fp.close()
    
    return data

def threaded(func):
    """
        A decorator that will make any function run in a new thread

        :param func: the function to run threaded
    """
    @wraps(func)
    def wrapper(*args, **kwargs):
        t = threading.Thread(target=func, args=args, kwargs=kwargs)
        t.daemon = True
        t.start()

    return wrapper

def synchronized(func):
    """
        A decorator to make a function synchronized - which means only one
        thread is allowed to access it at a time.
        
        This only works on class functions, and creates a variable in 
        the instance called _sync_lock. 
        
        If this function is used on multiple functions in an object, they
        will be locked with respect to each other. The lock is re-entrant.
    """
    @wraps(func)
    def wrapper(self, *__args, **__kw):
        try:
            rlock = self._sync_lock
        except AttributeError:
            from threading import RLock
            rlock = self.__dict__.setdefault('_sync_lock', RLock())
        rlock.acquire()
        try:
            return func(self, *__args, **__kw)
        finally:
            rlock.release()
    return wrapper
    

def _idle_callback(func, callback, *args, **kwargs):
    value = func(*args, **kwargs)
    if callback and callable(callback):
        callback(value)

def idle_add(callback=None):
    """
        A decorator that will wrap the function in a glib.idle_add call

        NOTE: Although this decorator will probably work in more cases than
        the gtkrun decorator does, you CANNOT expect to get a return value
        from the function that calls a function with this decorator.  Instead,
        you must use the callback parameter.  If the wrapped function returns
        a value, it will be passed in as a parameter to the callback function.

        @param callback: optional callback that will be called when the
            wrapped function is done running
    """
    def wrap(f):
        def wrapped(*args, **kwargs):
            glib.idle_add(_idle_callback, f, callback,
                *args, **kwargs)

        return wrapped
    return wrap

def _glib_wait_inner(timeout, glib_timeout_func):
    id = [None] # Have to hold the value in a mutable structure because
                # python's scoping rules prevent us assigning to an
                # outer scope directly.
    def waiter(function):
        def delayer(*args, **kwargs):
            if id[0]: glib.source_remove(id[0])
            id[0] = glib_timeout_func(timeout, function, *args, **kwargs)
        return delayer
    return waiter

def glib_wait(timeout):
    """
        Decorator to make a function run only after 'timeout'
        milliseconds have elapsed since the most recent call to the
        function.

        For example, if a function was given a timeout of 1000 and
        called once, then again half a second later, it would run
        only once, 1.5 seconds after the first call to it.

        Arguments are supported, but which call's set of arguments
        is used is undefined, so this is not useful for much beyond
        passing in unchanging arguments like 'self' or 'cls'.

        If the function returns a value that evaluates to True, it
        will be called again under the same timeout rules.
    """
    # 'undefined' is a bit of a white lie - it's always the most
    # recent call's args. However, I'm reserving the right to change
    # the implementation later for the moment, and really I don't
    # think it makes sense to use functions that have changing args
    # with this decorator.
    return _glib_wait_inner(timeout, glib.timeout_add)

def glib_wait_seconds(timeout):
    """
        Same as glib_wait, but uses glib.timeout_add_seconds instead
        of glib.timeout_add and takes its timeout in seconds. See the
        glib documention for why you might want to use one over the
        other.
    """
    return _glib_wait_inner(timeout, glib.timeout_add_seconds)

def profileit(func):
    """
        Decorator to profile a function
    """
    import hotshot, hotshot.stats
    @wraps(func)
    def wrapper(*args, **kwargs):
        prof = hotshot.Profile("profiling.data")
        res = prof.runcall(func, *args, **kwargs)
        prof.close()
        stats = hotshot.stats.load("profiling.data")
        stats.strip_dirs()
        stats.sort_stats('time', 'calls')
        print ">>>---- Begin profiling print"
        stats.print_stats()
        print ">>>---- End profiling print"
        return res
    return wrapper

class classproperty(object):
    """
        Decorator allowing for class property access
    """
    def __init__(self, function):
        self.function = function

    def __get__(self, obj, type):
        return self.function(type)

class VersionError(Exception):
    """
       Represents version discrepancies
    """
    #: the error message
    message = None

    def __init__(self, message):
        Exception.__init__(self)
        self.message = message

    def __str__(self):
        return repr(self.message)

def open_file(path):
    """
        Opens a file or folder using the system configured program
    """
    platform = sys.platform
    if platform == 'win32':
        # pylint will error here on non-windows platforms unless we do this
        # pylint: disable-msg=E1101
        os.startfile(path)
        # pylint: enable-msg=E1101
    elif platform == 'darwin':
        subprocess.Popen(["open", path])
    else:
        subprocess.Popen(["xdg-open", path])

def open_file_directory(path):
    """
        Opens the parent directory of a file, selecting the file if possible.
    """
    import gio
    f = gio.File(path)
    platform = sys.platform
    if platform == 'win32':
        # Normally we can just run `explorer /select, filename`, but Python 2
        # always calls CreateProcessA, which doesn't support Unicode. We could 
        # call CreateProcessW with ctypes, but the following is more robust.
        import ctypes
        ctypes.windll.ole32.CoInitialize(None)
        # Not sure why this is always UTF-8.
        upath = f.get_path().decode('utf-8')
        pidl = ctypes.windll.shell32.ILCreateFromPathW(upath)
        ctypes.windll.shell32.SHOpenFolderAndSelectItems(pidl, 0, None, 0)
        ctypes.windll.shell32.ILFree(pidl)
        ctypes.windll.ole32.CoUninitialize()
    elif platform == 'darwin':
        subprocess.Popen(["open", f.get_parent().get_parse_name()])
    else:
        subprocess.Popen(["xdg-open", f.get_parent().get_parse_name()])

class LimitedCache(DictMixin):
    """
        Simple cache that acts much like a dict, but has a maximum # of items
    """
    def __init__(self, limit):
        self.limit = limit
        self.order = deque()
        self.cache = dict()

    def __iter__(self):
        return self.cache.__iter__()

    def __contains__(self, item):
        return self.cache.__contains__(item)

    def __delitem__(self, item):
        del self.cache[item]
        self.order.remove(item)

    def __getitem__(self, item):
        val = self.cache[item]
        self.order.remove(item)
        self.order.append(item)
        return val

    def __setitem__(self, item, value):
        self.cache[item] = value
        if item in self.order:
            self.order.remove(item)
        self.order.append(item)
        while len(self) > self.limit:
            del self.cache[self.order.popleft()]

    def __repr__(self):
        '''prevent repr(self) from changing cache order'''
        return repr(self.cache)
        
    def __str__(self):
        '''prevent str(self) from changing cache order'''
        return str(self.cache)

    def keys(self):
        return self.cache.keys()

class cached(object):
    """
        Decorator to make a function's results cached
        does not cache if there is an exception.

        .. note:: This probably breaks on functions that modify their arguments
    """
    def __init__(self, limit):
        self.limit = limit

    @staticmethod
    def _freeze(d):
        return frozenset(d.iteritems())

    def __call__(self, f):
        try:
            f._cache
        except AttributeError:
            f._cache = LimitedCache(self.limit)
        @wraps(f)
        def wrapper(*args, **kwargs):
            try:
                return f._cache[(args, self._freeze(kwargs))]
            except KeyError:
                pass
            ret = f(*args, **kwargs)
            try:
                f._cache[(args, self._freeze(kwargs))] = ret
            except TypeError: # args can't be hashed
                pass
            return ret
        return wrapper
        
    def __get__(self, obj, objtype):
        """Support instance methods."""
        return partial(self.__call__, obj)

def walk(root):
    """
        Walk through a Gio directory, yielding each file

        Files are enumerated in the following order: first the
        directory, then the files in that directory. Once one
        directory's files have all been listed, it moves on to
        the next directory. Order of files within a directory
        and order of directory traversal is not specified.

        :param root: a :class:`gio.File` representing the
            directory to walk through
        :returns: a generator object
        :rtype: :class:`gio.File`
    """
    queue = deque()
    queue.append(root)

    while len(queue) > 0:
        dir = queue.pop()
        yield dir
        try:
            for fileinfo in dir.enumerate_children("standard::type,"
                    "standard::is-symlink,standard::name,"
                    "standard::symlink-target,time::modified"):
                fil = dir.get_child(fileinfo.get_name())
                # FIXME: recursive symlinks could cause an infinite loop
                if fileinfo.get_is_symlink():
                    target = fileinfo.get_symlink_target()
                    if not "://" in target and not os.path.isabs(target):
                        fil2 = dir.get_child(target)
                    else:
                        fil2 = gio.File(target)
                    # already in the collection, we'll get it anyway
                    if fil2.has_prefix(root):
                        continue
                type = fileinfo.get_file_type()
                if type == gio.FILE_TYPE_DIRECTORY:
                    queue.append(fil)
                elif type == gio.FILE_TYPE_REGULAR:
                    yield fil
        except gio.Error, e: # why doesnt gio offer more-specific errors?
            log_exception(log=logger, message="Unhandled exception while walking on %s." % dir)

def walk_directories(root):
    """
        Walk through a Gio directory, yielding each subdirectory

        :param root: a :class:`gio.File` representing the
            directory to walk through
        :returns: a generator object
        :rtype: :class:`gio.File`
    """
    yield root
    directory = None
    subdirectory = None

    try:
        for fileinfo in root.enumerate_children(
                'standard::name,standard::type'):
            if fileinfo.get_file_type() == gio.FILE_TYPE_DIRECTORY:
                directory = root.get_child(fileinfo.get_name())

                for subdirectory in walk_directories(directory):
                    yield subdirectory
    except gio.Error, e:
        log_exception(log=logger, message="Unhandled exception while walking dirs on %s, %s, %s" % (root, directory, subdirectory))

class TimeSpan:
    """
        Calculates the number of days, hours, minutes,
        and seconds in a time span
    """
    #: number of days
    days = 0
    #: number of hours
    hours = 0
    #: number of minutes
    minutes = 0
    #: number of seconds
    seconds = 0

    def __init__(self, span):
        """
            :param span: Time span in seconds
            :type span: float
        """
        try:
            span = float(span)
        except (ValueError, TypeError):
            span = 0

        span, self.seconds = divmod(span, 60)
        span, self.minutes = divmod(span, 60)
        self.days, self.hours = divmod(span, 24)

    def __repr__(self):
        return str(self)

    def __str__(self):
        return '%dd, %dh, %dm, %ds' % (
            self.days, self.hours, self.minutes, self.seconds)

class MetadataList(object):
    """
        Like a list, but also associates an object of metadata
        with each entry.

        ``(get|set|del)_meta_key`` are the metadata interface - they
        allow the metadata to act much like a dictionary, with a few
        optimizations.

        List aspects that are not supported:
            * sort
            * comparisons other than equality
            * multiply
    """
    __slots__ = ['__list', 'metadata']

    def __init__(self, iterable=[], metadata=[]):
        self.__list = list(iterable)
        meta = list(metadata)
        if meta and len(meta) != len(self.__list):
            raise ValueError, "Length of metadata must match length of items."
        if not meta:
            meta = [None] * len(self.__list)
        self.metadata = meta

    def __repr__(self):
        return "MetadataList(%s)"%self.__list

    def __len__(self):
        return len(self.__list)

    def __iter__(self):
        return self.__list.__iter__()

    def __add__(self, other):
        l = MetadataList(self, self.metadata)
        l.extend(other)
        return l

    def __iadd__(self, other):
        self.extend(other)
        return self

    def __eq__(self, other):
        if isinstance(other, MetadataList):
            other = list(other)
        return self.__list == other

    def __getitem__(self, i):
        val = self.__list.__getitem__(i)
        if isinstance(i, slice):
            return MetadataList(val, self.metadata.__getitem__(i))
        else:
            return val

    def __setitem__(self, i, value):
        self.__list.__setitem__(i, value)
        if isinstance(value, MetadataList):
            metadata = list(value.metadata)
        else:
            metadata = [None]*len(value)
        self.metadata.__setitem__(i, metadata)

    def __delitem__(self, i):
        self.__list.__delitem__(i)
        self.metadata.__delitem__(i)

    def append(self, other, metadata=None):
        self.insert(len(self), other, metadata=metadata)

    def extend(self, other):
        self[len(self):len(self)] = other

    def insert(self, i, item, metadata=None):
        if i >= len(self):
            i = len(self)
            e = len(self)+1
        else:
            e = i
        self[i:e] = [item]
        self.metadata[i:e] = [metadata]

    def pop(self, i=-1):
        item = self[i]
        del self[i]
        return item

    def remove(self, item):
        del self[self.index(item)]

    def reverse(self):
        self.__list.reverse()
        self.metadata.reverse()

    def index(self, i, start=0, end=None):
        if end is None:
            return self.__list.index(i, start)
        else:
            return self.__list.index(i, start, end)

    def count(self, i):
        return self.__list.count(i)

    def get_meta_key(self, index, key, default=None):
        if not self.metadata[index]:
            return default
        return self.metadata[index].get(key, default)

    def set_meta_key(self, index, key, value):
        if not self.metadata[index]:
            self.metadata[index] = {}
        self.metadata[index][key] = value

    def del_meta_key(self, index, key):
        if not self.metadata[index]:
            raise KeyError, key
        del self.metadata[index][key]
        if not self.metadata[index]:
            self.metadata[index] = None

class ProgressThread(gobject.GObject, threading.Thread):
    """
        A basic thread with progress updates
    """
    __gsignals__ = {
        'progress-update': (
            gobject.SIGNAL_RUN_FIRST,
            gobject.TYPE_NONE,
            (gobject.TYPE_INT,)
        ),
        # TODO: Check if 'stopped' is required
        'done': (
            gobject.SIGNAL_RUN_FIRST,
            gobject.TYPE_NONE,
            ()
        )
    }

    def __init__(self):
        gobject.GObject.__init__(self)
        threading.Thread.__init__(self)
        self.setDaemon(True)

    def stop(self):
        """
            Stops the thread
        """
        self.emit('done')

    def run(self):
        """
            Override and make sure that the 'progress-update'
            signal is emitted regularly with the progress
        """
        pass


class PosetItem(object):
    def __init__(self, name, after, priority, value=None):
        """
            :param name: unique identifier for this item
            :type name: string
            :param after: which items this item comes after
            :type after: list of string
            :param priority: tiebreaker, higher values come later
            :type priority: int
            :param value: arbitrary data associated with the item
        """
        self.name = name
        self.after = list(after)
        self.priority = priority
        self.children = []
        self.value = value

def order_poset(items):
    """
        :param items: poset to order
        :type items: list of :class:`PosetItem`
    """
    items = dict([(i.name, i) for i in items])
    for name, item in items.iteritems():
        for after in item.after:
            i = items.get(after)
            if i:
                i.children.append(item)
            else:
                item.after.remove(after)
    result = []
    next = [i[1] for i in items.items() if not i[1].after]
    while next:
        current = [(i.priority, i.name, i) for i in next]
        current.sort()
        result.extend([i[2] for i in current])
        nextset = dict()
        for i in current:
            for c in i[2].children:
                nextset[c.name] = c
        removals = []
        for name, item in nextset.iteritems():
            for after in item.after:
                if after in nextset:
                    removals.append(name)
                    break
        for r in removals:
            del nextset[r]
        next = nextset.values()
    return result

class LazyDict(object):
    __slots__ = ['_dict', '_funcs', 'args', '_locks']
    def __init__(self, *args):
        self.args = args
        self._dict = {}
        self._funcs = {}
        self._locks = {}

    def __setitem__(self, item, value):
        if inspect.isfunction(value):
            self._funcs[item] = value
        else:
            self._dict[item] = value

    def __getitem__(self, item):
        lock = self._locks.get(item, threading.Lock())
        with lock:
            try:
                return self._dict[item]
            except KeyError:
                self._locks[item] = lock
                val = self._funcs[item](item, *self.args)
                self._dict[item] = val
                return val

    def get(self, item, default=None):
        try:
            return self[item]
        except KeyError:
            return default

# vim: et sts=4 sw=4
