# Copyright 2020 The GNOME Music developers
#
# GNOME Music 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 of the License, or
# (at your option) any later version.
#
# GNOME Music 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 GNOME Music; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
#
# The GNOME Music authors hereby grant permission for non-GPL compatible
# GStreamer plugins to be used and distributed together with GStreamer
# and GNOME Music.  This permission is above and beyond the permissions
# granted by the GPL license by which GNOME Music 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.

from __future__ import annotations
from typing import Optional, Union
import typing

from gi.repository import Adw, GObject, Gtk

from gnomemusic.asyncqueue import AsyncQueue
from gnomemusic.artcache import ArtCache
from gnomemusic.defaulticon import DefaultIcon
from gnomemusic.utils import ArtSize, DefaultIconType
if typing.TYPE_CHECKING:
    from gnomemusic.corealbum import CoreAlbum
    from gnomemusic.coreartist import CoreArtist
    from gnomemusic.coresong import CoreSong


if typing.TYPE_CHECKING:
    CoreObject = Union[CoreAlbum, CoreArtist, CoreSong]


class ArtStack(Gtk.Stack):
    """Provides a smooth transition between image states

    Uses a Gtk.Stack to provide an in-situ transition between an image
    state. Between the 'loading' and 'default' art state and in between
    songs.
    """

    __gtype_name__ = "ArtStack"

    _async_queue = AsyncQueue("ArtStack")

    def __init__(self, size: ArtSize = ArtSize.MEDIUM) -> None:
        """Initialize the ArtStack

        :param ArtSize size: The size of the art used for the cover
        """
        super().__init__()

        self._art_type = DefaultIconType.ALBUM
        self._cache = ArtCache(self)
        self._coreobject: Optional[CoreObject] = None
        self._handler_id = 0
        self._size = size
        self._thumbnail_id = 0

        self._cover_a = Gtk.Image()
        self._cover_a.props.visible = True
        self._cover_b = Gtk.Image()
        self._cover_b.props.visible = True

        self.add_named(self._cover_a, "A")
        self.add_named(self._cover_b, "B")

        self.props.size = size

        self.connect("destroy", self._on_destroy)
        Adw.StyleManager.get_default().connect(
            "notify::dark", self._on_dark_changed)

    @GObject.Property(type=object, flags=GObject.ParamFlags.READWRITE)
    def size(self) -> ArtSize:
        """Size of the cover

        :returns: The size used
        :rtype: ArtSize
        """
        return self._size

    @size.setter  # type: ignore
    def size(self, value: ArtSize) -> None:
        """Set the cover size

        :param ArtSize value: The size to use for the cover
        """
        self.set_size_request(value.width, value.height)
        self._size = value

    @GObject.Property(type=object, flags=GObject.ParamFlags.READWRITE)
    def art_type(self) -> DefaultIconType:
        """Type of the stack cover

        :returns: The type of the default icon
        :rtype: DefaultIconType
        """
        return self._art_type

    @art_type.setter  # type: ignore
    def art_type(self, value: DefaultIconType) -> None:
        """Set the stack cover type

        :param DefaultIconType value: The default icon type for the
            stack
        """
        self._art_type = value

        default_icon = DefaultIcon(self).get(self._art_type, self._size)

        self._swap_thumbnails(default_icon, False)

    @GObject.Property(type=object, default=None)
    def coreobject(self) -> Optional[CoreObject]:
        return self._coreobject

    @coreobject.setter  # type: ignore
    def coreobject(self, coreobject: CoreObject) -> None:
        if coreobject is self._coreobject:
            return

        if self._thumbnail_id != 0:
            self._coreobject.disconnect(self._thumbnail_id)
            self._thumbnail_id = 0

        self._coreobject = coreobject
        self._thumbnail_id = self._coreobject.connect(
            "notify::thumbnail", self._on_thumbnail_changed)

        if self._coreobject.props.thumbnail is not None:
            self._on_thumbnail_changed(self._coreobject, None)

    def _on_dark_changed(
            self, style_manager: Adw.StyleManager,
            pspec: GObject.ParamSpecBoolean) -> None:
        default_icon = DefaultIcon(self).get(self._art_type, self._size)

        if self._coreobject:
            if self._coreobject.props.thumbnail == "generic":
                self._swap_thumbnails(default_icon, False)
        else:
            self._swap_thumbnails(default_icon, False)

    def _on_thumbnail_changed(
            self, coreobject: CoreObject,
            uri: GObject.ParamSpecString) -> None:
        self._disconnect_cache()

        self._handler_id = self._cache.connect(
            "finished", self._on_cache_result)

        self._async_queue.queue(self._cache, coreobject, self._size)

    def _swap_thumbnails(
            self, paintable: Gtk.Paintable, animate: bool) -> None:
        if self.props.visible_child_name == "B":
            self._cover_a.props.paintable = paintable
            if animate:
                self.set_visible_child_full(
                    "A", Gtk.StackTransitionType.CROSSFADE)
            else:
                self.props.visible_child_name = "A"
        else:
            self._cover_b.props.paintable = paintable
            if animate:
                self.set_visible_child_full(
                    "B", Gtk.StackTransitionType.CROSSFADE)
            else:
                self.props.visible_child_name = "B"

    def _on_cache_result(
            self, cache: ArtCache, paintable: Gtk.Paintable) -> None:
        self._swap_thumbnails(paintable, True)

    def _on_destroy(self, widget: ArtStack) -> None:
        # If the stack is destroyed while the art is updated, an error
        # can occur once the art is retrieved because the ArtStack does
        # not have children anymore.
        self._disconnect_cache()

    def _disconnect_cache(self) -> None:
        if self._handler_id != 0:
            self._cache.disconnect(self._handler_id)
            self._handler_id = 0
