#!/usr/bin/env python3

#Libervia Desktop-Kivy
# Copyright (C) 2016-2021 Jérôme Poisson (goffi@goffi.org)

# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, 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 Affero General Public License for more details.

# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.


from libervia.backend.core import log as logging
from libervia.backend.core import exceptions
from libervia.frontends.quick_frontend import quick_widgets
from kivy.graphics import Color, Ellipse
from kivy.uix.layout import Layout
from kivy.uix.boxlayout import BoxLayout
from kivy.uix.stencilview import StencilView
from kivy.uix.carousel import Carousel
from kivy.uix.screenmanager import ScreenManager, Screen
from kivy.metrics import dp
from kivy import properties
from libervia.desktop_kivy import G
from .constants import Const as C
from . import cagou_widget

log = logging.getLogger(__name__)


REMOVE_WID_LIMIT = dp(50)
MIN_WIDTH = MIN_HEIGHT = dp(70)


class BoxStencil(BoxLayout, StencilView):
    pass


class WHWrapper(BoxLayout):
    main_container = properties.ObjectProperty(None)
    screen_manager = properties.ObjectProperty(None, allownone=True)
    carousel = properties.ObjectProperty(None, allownone=True)
    split_size = properties.NumericProperty(dp(1))
    split_margin = properties.NumericProperty(dp(2))
    split_color = properties.ListProperty([0.8, 0.8, 0.8, 1])
    split_color_move = C.COLOR_SEC_DARK
    split_color_del = properties.ListProperty([0.8, 0.0, 0.0, 1])
    # sp stands for "split point"
    sp_size = properties.NumericProperty(dp(1))
    sp_space = properties.NumericProperty(dp(4))
    sp_zone = properties.NumericProperty(dp(30))
    _split = properties.OptionProperty('None', options=['None', 'left', 'top'])
    _split_del = properties.BooleanProperty(False)

    def __init__(self, **kwargs):
        idx = kwargs.pop('_wid_idx')
        self._wid_idx = idx
        super(WHWrapper, self).__init__(**kwargs)
        self._left_wids = set()
        self._top_wids = set()
        self._right_wids = set()
        self._bottom_wids = set()
        self._clear_attributes()

    def _clear_attributes(self):
        self._former_slide = None

    def __repr__(self):
        return "WHWrapper_{idx}".format(idx=self._wid_idx)

    def _main_wid(self, wid_list):
        """return main widget of a side list

        main widget is either the widget currently splitted
        or any widget if none is split
        @return (WHWrapper, None): main widget or None
            if there is not widget
        """
        if not wid_list:
            return None
        for wid in wid_list:
            if wid._split != 'None':
                return wid
        return next(iter(wid_list))

    def on_parent(self, __, new_parent):
        if new_parent is None:
            # we detach all children so LiberviaDesktopKivyWidget.whwrapper won't link to this one
            # anymore
            self.clear_widgets()

    @property
    def _left_wid(self):
        return self._main_wid(self._left_wids)

    @property
    def _top_wid(self):
        return self._main_wid(self._top_wids)

    @property
    def _right_wid(self):
        return self._main_wid(self._right_wids)

    @property
    def _bottom_wid(self):
        return self._main_wid(self._bottom_wids)

    @property
    def current_slide(self):
        if (self.carousel is not None
            and (self.screen_manager is None or self.screen_manager.current == '')):
            return self.carousel.current_slide
        elif self.screen_manager is not None:
            # we should have exactly one children in current_screen, else there is a bug
            return self.screen_manager.current_screen.children[0]
        else:
            try:
                return self.main_container.children[0]
            except IndexError:
                log.error("No child found, this should not happen")
                return None

    @property
    def carousel_active(self):
        """Return True if Carousel is used and active"""
        if self.carousel is None:
            return False
        if self.screen_manager is not None and self.screen_manager.current != '':
            return False
        return True

    @property
    def former_screen_wid(self):
        """Return widget currently active for former screen"""
        if self.screen_manager is None:
            raise exceptions.InternalError(
                "former_screen_wid can only be used if ScreenManager is used")
        if self._former_screen_name is None:
            return None
        return self.get_screen_widget(self._former_screen_name)

    def get_screen_widget(self, screen_name):
        """Return screen main widget, handling carousel if necessary"""
        if self.carousel is not None and screen_name == '':
            return self.carousel.current_slide
        try:
            return self.screen_manager.get_screen(screen_name).children[0]
        except IndexError:
            return None

    def _draw_ellipse(self):
        """draw split ellipse"""
        color = self.split_color_del if self._split_del else self.split_color_move
        try:
            self.canvas.after.remove(self.ellipse)
        except AttributeError:
            pass
        if self._split == "top":
            with self.canvas.after:
                Color(*color)
                self.ellipse = Ellipse(angle_start=90, angle_end=270,
                               pos=(self.x + self.width/2 - self.sp_zone/2,
                                    self.y + self.height - self.sp_zone/2),
                               size=(self.sp_zone, self.sp_zone))
        elif self._split == "left":
            with self.canvas.after:
                Color(*color)
                self.ellipse = Ellipse(angle_end=180,
                               pos=(self.x + -self.sp_zone/2,
                                    self.y + self.height/2 - self.sp_zone/2),
                               size = (self.sp_zone, self.sp_zone))
        else:
            raise exceptions.InternalError('unexpected split value')

    def on_touch_down(self, touch):
        """activate split if touch is on a split zone"""
        if not self.collide_point(*touch.pos):
            return
        log.debug("WIDGET IDX: {} (left: {}, top: {}, right: {}, bottom: {}), pos: {}, size: {}".format(
            self._wid_idx,
            'None' if not self._left_wids else [w._wid_idx for w in self._left_wids],
            'None' if not self._top_wids else [w._wid_idx for w in self._top_wids],
            'None' if not self._right_wids else [w._wid_idx for w in self._right_wids],
            'None' if not self._bottom_wids else [w._wid_idx for w in self._bottom_wids],
            self.pos,
            self.size,
            ))
        touch_rx, touch_ry = self.to_widget(*touch.pos, relative=True)
        if (touch_ry <= self.height and
            touch_ry >= self.height - self.split_size - self.split_margin or
            touch_ry <= self.height and
            touch_ry >= self.height - self.sp_zone and
            touch_rx >= self.width//2 - self.sp_zone//2 and
            touch_rx <= self.width//2 + self.sp_zone//2):
            # split area is touched, we activate top split mode
            self._split = "top"
            self._draw_ellipse()
        elif (touch_rx >= 0 and
              touch_rx <= self.split_size + self.split_margin or
              touch_rx >= 0 and
              touch_rx <= self.sp_zone and
              touch_ry >= self.height//2 - self.sp_zone//2 and
              touch_ry <= self.height//2 + self.sp_zone//2):
            # split area is touched, we activate left split mode
            self._split = "left"
            touch.ud['ori_width'] = self.width
            self._draw_ellipse()
        else:
            if self.carousel_active and len(self.carousel.slides) <= 1:
                # we don't want swipe of carousel if there is only one slide
                return StencilView.on_touch_down(self.carousel, touch)
            else:
                return super(WHWrapper, self).on_touch_down(touch)

    def on_touch_move(self, touch):
        """handle size change and widget creation on split"""
        if self._split == 'None':
            return super(WHWrapper, self).on_touch_move(touch)

        elif self._split == 'top':
            new_height = touch.y - self.y

            if new_height < MIN_HEIGHT:
                return

            # we must not pass the top widget/border
            if self._top_wids:
                top = next(iter(self._top_wids))
                y_limit = top.y + top.height

                if top.height <= REMOVE_WID_LIMIT:
                    # we are in remove zone, we add visual hint for that
                    if not self._split_del and self._top_wids:
                        self._split_del = True
                        self._draw_ellipse()
                else:
                    if self._split_del:
                        self._split_del = False
                        self._draw_ellipse()
            else:
                y_limit = self.y + self.height

            if touch.y >= y_limit:
                return

            # all right, we can change size
            self.height = new_height
            self.ellipse.pos = (self.ellipse.pos[0], touch.y - self.sp_zone/2)

            if not self._top_wids:
                # we are the last widget on the top
                # so we create a new widget
                new_wid = self.parent.add_widget()
                self._top_wids.add(new_wid)
                new_wid._bottom_wids.add(self)
                for w in self._right_wids:
                    new_wid._right_wids.add(w)
                    w._left_wids.add(new_wid)
                for w in self._left_wids:
                    new_wid._left_wids.add(w)
                    w._right_wids.add(new_wid)

        elif self._split == 'left':
            ori_width = touch.ud['ori_width']
            new_x = touch.x
            new_width = ori_width - (touch.x - touch.ox)

            if new_width < MIN_WIDTH:
                return

            # we must not pass the left widget/border
            if self._left_wids:
                left = next(iter(self._left_wids))
                x_limit = left.x

                if left.width <= REMOVE_WID_LIMIT:
                    # we are in remove zone, we add visual hint for that
                    if not self._split_del and self._left_wids:
                        self._split_del = True
                        self._draw_ellipse()
                else:
                    if self._split_del:
                        self._split_del = False
                        self._draw_ellipse()
            else:
                x_limit = self.x

            if new_x <= x_limit:
                return

            # all right, we can change position/size
            self.x = new_x
            self.width = new_width
            self.ellipse.pos = (touch.x - self.sp_zone/2, self.ellipse.pos[1])

            if not self._left_wids:
                # we are the last widget on the left
                # so we create a new widget
                new_wid = self.parent.add_widget()
                self._left_wids.add(new_wid)
                new_wid._right_wids.add(self)
                for w in self._top_wids:
                    new_wid._top_wids.add(w)
                    w._bottom_wids.add(new_wid)
                for w in self._bottom_wids:
                    new_wid._bottom_wids.add(w)
                    w._top_wids.add(new_wid)

        else:
            raise Exception.InternalError('invalid _split value')

    def on_touch_up(self, touch):
        if self._split == 'None':
            return super(WHWrapper, self).on_touch_up(touch)
        if self._split == 'top':
            # we remove all top widgets in delete zone,
            # and update there side widgets list
            for top in self._top_wids.copy():
                if top.height <= REMOVE_WID_LIMIT:
                    G.host._remove_visible_widget(top.current_slide)
                    for w in top._top_wids:
                        w._bottom_wids.remove(top)
                        w._bottom_wids.update(top._bottom_wids)
                    for w in top._bottom_wids:
                        w._top_wids.remove(top)
                        w._top_wids.update(top._top_wids)
                    for w in top._left_wids:
                        w._right_wids.remove(top)
                    for w in top._right_wids:
                        w._left_wids.remove(top)
                    self.parent.remove_widget(top)
        elif self._split == 'left':
            # we remove all left widgets in delete zone,
            # and update there side widgets list
            for left in self._left_wids.copy():
                if left.width <= REMOVE_WID_LIMIT:
                    G.host._remove_visible_widget(left.current_slide)
                    for w in left._left_wids:
                        w._right_wids.remove(left)
                        w._right_wids.update(left._right_wids)
                    for w in left._right_wids:
                        w._left_wids.remove(left)
                        w._left_wids.update(left._left_wids)
                    for w in left._top_wids:
                        w._bottom_wids.remove(left)
                    for w in left._bottom_wids:
                        w._top_wids.remove(left)
                    self.parent.remove_widget(left)
        self._split = 'None'
        self.canvas.after.remove(self.ellipse)
        del self.ellipse

    def clear_widgets(self):
        current_slide = self.current_slide
        if current_slide is not None:
            G.host._remove_visible_widget(current_slide, ignore_missing=True)

        super().clear_widgets()

        self.screen_manager = None
        self.carousel = None
        self._clear_attributes()

    def set_widget(self, wid, index=0):
        assert len(self.children) == 0

        if wid.collection_carousel or wid.global_screen_manager:
            self.main_container = self
        else:
            self.main_container = BoxStencil()
            self.add_widget(self.main_container)

        if self.carousel is not None:
            return self.carousel.add_widget(wid, index)

        if wid.global_screen_manager:
            if self.screen_manager is None:
                self.screen_manager = ScreenManager()
                self.main_container.add_widget(self.screen_manager)
                parent = Screen()
                self.screen_manager.add_widget(parent)
                self._former_screen_name = ''
                self.screen_manager.bind(current=self.on_screen_change)
                wid.screen_manager_init(self.screen_manager)
        else:
            parent = self.main_container

        if wid.collection_carousel:
            # a Carousel is requested, and this is the first widget that we add
            # so we need to create the carousel
            self.carousel = Carousel(
                direction = "right",
                ignore_perpendicular_swipes = True,
                loop = True,
            )
            self._slides_update_lock = 0
            self.carousel.bind(current_slide=self.on_slide_change)
            parent.add_widget(self.carousel)
            self.carousel.add_widget(wid, index)
        else:
            # no Carousel requested, we add the widget as a direct child
            parent.add_widget(wid)
            G.host._add_visible_widget(wid)

    def change_widget(self, new_widget):
        """Change currently displayed widget

        slides widgets will be updated
        """
        if (self.carousel is not None
            and self.carousel.current_slide.__class__ == new_widget.__class__):
            # we have the same class, we reuse carousel and screen manager setting

            if self.carousel.current_slide != new_widget:
                # slides update need to be blocked to avoid the update in on_slide_change
                # which would mess the removal of current widgets
                self._slides_update_lock += 1
                new_wid = None
                for w in self.carousel.slides[:]:
                    if w.widget_hash == new_widget.widget_hash:
                        new_wid = w
                        continue
                    self.carousel.remove_widget(w)
                    if isinstance(w, quick_widgets.QuickWidget):
                        G.host.widgets.delete_widget(w)
                if new_wid is None:
                    new_wid = G.host.get_or_clone(new_widget)
                    self.carousel.add_widget(new_wid)
                self._update_hidden_slides()
                self._slides_update_lock -= 1

            if self.screen_manager is not None:
                self.screen_manager.clear_widgets([
                    s for s in self.screen_manager.screens if s.name != ''])
                new_wid.screen_manager_init(self.screen_manager)
        else:
            # else, we restart fresh
            self.clear_widgets()
            self.set_widget(G.host.get_or_clone(new_widget))

    def on_screen_change(self, screen_manager, new_screen):
        try:
            new_screen_wid = self.current_slide
        except IndexError:
            new_screen_wid = None
            log.warning("Switching to a screen without children")
        if new_screen == '' and self.carousel is not None:
            # carousel may have been changed in the background, so we update slides
            self._update_hidden_slides()
        former_screen_wid = self.former_screen_wid
        if isinstance(former_screen_wid, cagou_widget.LiberviaDesktopKivyWidget):
            G.host._remove_visible_widget(former_screen_wid)
        if isinstance(new_screen_wid, cagou_widget.LiberviaDesktopKivyWidget):
            G.host._add_visible_widget(new_screen_wid)
        self._former_screen_name = new_screen
        G.host.selected_widget = new_screen_wid

    def on_slide_change(self, handler, new_slide):
        if self._former_slide is new_slide:
            # FIXME: workaround for Kivy a95d67f (and above?), Carousel.current_slide
            #        binding now calls on_slide_change twice with the same widget (here
            #        "new_slide"). To be checked with Kivy team.
            return
        log.debug(f"Slide change: new_slide = {new_slide}")
        if self._former_slide is not None:
            G.host._remove_visible_widget(self._former_slide, ignore_missing=True)
        self._former_slide = new_slide
        if self.carousel_active:
            G.host.selected_widget = new_slide
            if new_slide is not None:
                G.host._add_visible_widget(new_slide)
                self._update_hidden_slides()

    def hidden_list(self, visible_list, ignore=None):
        """return widgets of same class as carousel current one, if they are hidden

        @param visible_list(list[QuickWidget]): widgets visible
        @param ignore(QuickWidget, None): do no return this widget
        @return (iter[QuickWidget]): widgets hidden
        """
        # we want to avoid recreated widgets
        added = [w.widget_hash for w in visible_list]
        current_slide = self.carousel.current_slide
        for w in G.host.widgets.get_widgets(current_slide.__class__,
                                           profiles=current_slide.profiles):
            wid_hash = w.widget_hash
            if w in visible_list or wid_hash in added:
                continue
            if wid_hash == ignore.widget_hash:
                continue
            yield w


    def _update_hidden_slides(self):
        """adjust carousel slides according to visible widgets"""
        if self._slides_update_lock or not self.carousel_active:
            return
        current_slide = self.carousel.current_slide
        if not isinstance(current_slide, quick_widgets.QuickWidget):
            return
        # lock must be used here to avoid recursions
        self._slides_update_lock += 1
        visible_list = G.host.get_visible_list(current_slide.__class__)
        # we ignore current_slide as it may not be visible yet (e.g. if an other
        # screen is shown
        hidden = list(self.hidden_list(visible_list, ignore=current_slide))
        slides_sorted =  sorted(set(hidden + [current_slide]))
        to_remove = set(self.carousel.slides).difference({current_slide})
        for w in to_remove:
            self.carousel.remove_widget(w)
        if hidden:
            # no need to add more than two widgets (next and previous),
            # as the list will be updated on each new visible widget
            current_idx = slides_sorted.index(current_slide)
            try:
                next_slide = slides_sorted[current_idx+1]
            except IndexError:
                next_slide = slides_sorted[0]
            self.carousel.add_widget(G.host.get_or_clone(next_slide))
            if len(hidden)>1:
                previous_slide = slides_sorted[current_idx-1]
                self.carousel.add_widget(G.host.get_or_clone(previous_slide))

        self._slides_update_lock -= 1


class WidgetsHandlerLayout(Layout):
    count = 0

    def __init__(self, **kwargs):
        super(WidgetsHandlerLayout, self).__init__(**kwargs)
        self._layout_size = None  # size used for the last layout
        fbind = self.fbind
        update = self._trigger_layout
        fbind('children', update)
        fbind('parent', update)
        fbind('size', self.adjust_prop)
        fbind('pos', update)

    @property
    def default_widget(self):
        return G.host.default_wid['factory'](G.host.default_wid, None, None)

    def adjust_prop(self, handler, new_size):
        """Adjust children proportion

        useful when this widget is resized (e.g. when going to fullscreen)
        """
        if len(self.children) > 1:
            old_width, old_height = self._layout_size
            if not old_width or not old_height:
                # we don't want division by zero
                return self._trigger_layout(handler, new_size)
            width_factor = float(self.width) / old_width
            height_factor = float(self.height) / old_height
            for child in self.children:
                child.width *= width_factor
                child.height *= height_factor
                child.x *= width_factor
                child.y *= height_factor
        self._trigger_layout(handler, new_size)

    def do_layout(self, *args):
        self._layout_size = self.size[:]
        for child in self.children:
            # XXX: left must be calculated before right and bottom before top
            #      because they are the pos, and are used to caculate size (right and top)
            # left
            left = child._left_wid
            left_end_x = self.x-1 if left is None else left.right
            if child.x != left_end_x + 1 and child._split == "None":
                child.x = left_end_x + 1
            # right
            right = child._right_wid
            right_x = self.right + 1 if right is None else right.x
            if child.right != right_x - 1:
                child.width = right_x - child.x - 1
            # bottom
            bottom = child._bottom_wid
            if bottom is None:
                if child.y != self.y:
                    child.y = self.y
            else:
                if child.y != bottom.top + 1:
                    child.y = bottom.top + 1
            # top
            top = child._top_wid
            top_y = self.top+1 if top is None else top.y
            if child.top != top_y - 1:
                if child._split == "None":
                    child.height = top_y - child.y - 1

    def remove_widget(self, wid):
        super(WidgetsHandlerLayout, self).remove_widget(wid)
        log.debug("widget deleted ({})".format(wid._wid_idx))

    def add_widget(self, wid=None, index=0):
        WidgetsHandlerLayout.count += 1
        if wid is None:
            wid = self.default_widget
        if G.host.selected_widget is None:
            G.host.selected_widget = wid
        wrapper = WHWrapper(_wid_idx=WidgetsHandlerLayout.count)
        log.debug("WHWrapper created ({})".format(wrapper._wid_idx))
        wrapper.set_widget(wid)
        super(WidgetsHandlerLayout, self).add_widget(wrapper, index)
        return wrapper


class WidgetsHandler(WidgetsHandlerLayout):

    def __init__(self, **kw):
        super(WidgetsHandler, self).__init__(**kw)
        self.add_widget()