# Portions Copyright 2017 Canonical, Ltd.
#
# 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/>.

# This is adapted from
# https://github.com/pimutils/khal/commit/bd7c5f928a7670de9afae5657e66c6dc846688ac, which has this license:
#
# Copyright (c) 2013-2015 Christian Geier et al.
#
# Permission is hereby granted, free of charge, to any person obtaining a copy of
# this software and associated documentation files (the "Software"), to deal in
# the Software without restriction, including without limitation the rights to
# use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
# the Software, and to permit persons to whom the Software is furnished to do so,
# subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
# FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

import logging

import urwid

log = logging.getLogger('subiquitycore.ui.container')


def _maybe_call(w, methname):
    if w is None:
        return
    m = getattr(w.base_widget, methname, None)
    if m is not None:
        m()


class TabCyclingMixin:
    """Tab-cycling implementation that works with Pile and Columns."""

    def _select_first_selectable(self):
        """Select first selectable child (possibily recursively)."""
        for i, (w, o) in enumerate(self.contents):
            if w.selectable():
                self.set_focus(i)
                _maybe_call(w, "_select_first_selectable")
                return

    def _select_last_selectable(self):
        """Select last selectable child (possibily recursively)."""
        for i, (w, o) in reversed(list(enumerate(self.contents))):
            if w.selectable():
                self.set_focus(i)
                _maybe_call(w, "_select_last_selectable")
                return

    def keypress(self, size, key):
        key = super(TabCyclingMixin, self).keypress(size, key)

        if len(self.contents) == 0:
            return key

        if self._command_map[key] == 'next selectable':
            next_fp = self.focus_position + 1
            for i, (w, o) in enumerate(self._contents[next_fp:], next_fp):
                if w.selectable():
                    self.set_focus(i)
                    _maybe_call(w, "_select_first_selectable")
                    return
            self._select_first_selectable()
            return key
        elif self._command_map[key] == 'prev selectable':
            for i, (w, o) in reversed(list(enumerate(self._contents[:self.focus_position]))):
                if w.selectable():
                    self.set_focus(i)
                    _maybe_call(w, "_select_last_selectable")
                    return
            self._select_last_selectable()
            return key
        else:
            return key

enter_advancing_command_map = urwid.command_map.copy()
enter_advancing_command_map['enter'] = 'next selectable'

class TabCyclingPile(TabCyclingMixin, urwid.Pile):
    _command_map = enter_advancing_command_map
    pass

class TabCyclingColumns(TabCyclingMixin, urwid.Columns):
    pass


class TabCyclingListBox(urwid.ListBox):
    _command_map = enter_advancing_command_map
    # It feels like it ought to be possible to write TabCyclingMixin
    # so it works for a ListBox as well, but it seems to be just
    # awkward enough to make the repeated code the easier and clearer
    # option.

    def __init__(self, body):
        # urwid.ListBox converts an arbitrary sequence argument to a
        # PollingListWalker, which doesn't work with the below code.
        if getattr(body, 'get_focus', None) is None:
            body = urwid.SimpleFocusListWalker(body)
        super().__init__(body)

    def _set_focus_no_move(self, i):
        # We call set_focus twice because otherwise the listbox
        # attempts to do the minimal amount of scrolling required to
        # get the new focus widget into view, which is not what we
        # want, as if our first widget is a compound widget it results
        # its last widget being focused -- in fact the opposite of
        # what we want!
        self.set_focus(i)
        self.set_focus(i)
        # I don't really understand why this is required but it seems it is.
        self._invalidate()

    def _select_first_selectable(self):
        """Select first selectable child (possibily recursively)."""
        for i, w in enumerate(self.body):
            if w.selectable():
                self._set_focus_no_move(i)
                _maybe_call(w, "_select_first_selectable")
                return

    def _select_last_selectable(self):
        """Select last selectable child (possibily recursively)."""
        for i, w in reversed(list(enumerate(self.body))):
            if w.selectable():
                self._set_focus_no_move(i)
                _maybe_call(w, "_select_last_selectable")
                return

    def keypress(self, size, key):
        key = super(TabCyclingListBox, self).keypress(size, key)

        if len(self.body) == 0:
            return key

        if self._command_map[key] == 'next selectable':
            next_fp = self.focus_position + 1
            for i, w in enumerate(self.body[next_fp:], next_fp):
                if w.selectable():
                    self._set_focus_no_move(i)
                    _maybe_call(w, "_select_first_selectable")
                    return
            self._select_first_selectable()
            return key
        elif self._command_map[key] == 'prev selectable':
            for i, w in reversed(list(enumerate(self.body[:self.focus_position]))):
                if w.selectable():
                    self._set_focus_no_move(i)
                    _maybe_call(w, "_select_last_selectable")
                    return
            self._select_last_selectable()
            return key
        else:
            return key


class FocusTrackingMixin:

    def __init__(self, *args, **kw):
        super().__init__(*args, **kw)
        self._contents.set_focus_changed_callback(self._focus_changed)

    def lost_focus(self):
        try:
            cur_focus = self.focus
        except IndexError:
            pass
        else:
            _maybe_call(cur_focus, 'lost_focus')

    def gained_focus(self):
        _maybe_call(self.focus, 'gained_focus')

    def _focus_changed(self, new_focus):
        #log.debug("_focus_changed %s", self)
        try:
            cur_focus = self.focus
        except IndexError:
            pass
        else:
            _maybe_call(cur_focus, 'lost_focus')
        _maybe_call(self[new_focus], 'gained_focus')
        self._invalidate()


class FocusTrackingColumns(FocusTrackingMixin, TabCyclingColumns):
    pass


class FocusTrackingPile(FocusTrackingMixin, TabCyclingPile):
    pass


class FocusTrackingListBox(TabCyclingListBox):

    def __init__(self, *args, **kw):
        super().__init__(*args, **kw)
        self.body.set_focus_changed_callback(self._focus_changed)

    def _focus_changed(self, new_focus):
        log.debug("_focus_changed %s", self)
        _maybe_call(self.focus, 'lost_focus')
        _maybe_call(self.body[new_focus], 'gained_focus')
        self._invalidate()

    def lost_focus(self):
        _maybe_call(self.focus, 'lost_focus')

    def gained_focus(self):
        _maybe_call(self.focus, 'gained_focus')


Columns = FocusTrackingColumns
Pile = FocusTrackingPile


class ScrollBarListBox(FocusTrackingListBox):

    def __init__(self, walker=None):
        def f(char, attr):
            return urwid.AttrMap(urwid.SolidFill(char), attr)
        self.bar = Pile([
            ('weight', 1, f("\N{BOX DRAWINGS LIGHT VERTICAL}", 'scrollbar_bg')),
            ('weight', 1, f("\N{FULL BLOCK}", 'scrollbar_fg')),
            ('weight', 1, f("\N{BOX DRAWINGS LIGHT VERTICAL}", 'scrollbar_bg')),
            ])
        super().__init__(walker)

    def render(self, size, focus=False):
        visible = self.ends_visible(size, focus)
        if len(visible) == 2:
            return super().render(size, focus)
        else:
            # This implementation assumes that the number of rows is
            # not too large (and in particular is finite). That's the
            # case for all the listboxes we have in subiquity today.
            maxcol, maxrow = size

            offset, inset = self.get_focus_offset_inset((maxcol - 1, maxrow))

            seen_focus = False
            height = height_before_focus = 0
            focus_widget, focus_pos = self.body.get_focus()
            # Scan through the rows calculating total height and the
            # height of the rows before the focus widget.
            for widget in self.body:
                rows = widget.rows((maxcol - 1,))
                if widget is focus_widget:
                    seen_focus = True
                elif not seen_focus:
                    height_before_focus += rows
                height += rows

            # Calculate the number of rows off the top and bottom of
            # the listbox.
            if 'top' in visible:
                top = 0
            else:
                top = height_before_focus + inset - offset
            if 'bottom' in visible:
                bottom = 0
            else:
                bottom = height - top - maxrow

            # Prevent the box from being squished to 0 rows (if it
            # gets ('weight', maxrow) gets round(maxrow / (top +
            # maxrow + bottom)) and that being < 1 simplifies to the
            # below).
            if maxrow*maxrow < height:
                boxopt = self.bar.options('given', 1)
            else:
                boxopt = self.bar.options('weight', maxrow)

            self.bar.contents[:] = [
                (self.bar.contents[0][0], self.bar.options('weight', top)),
                (self.bar.contents[1][0], boxopt),
                (self.bar.contents[2][0], self.bar.options('weight', bottom)),
                ]
            canvases = [
                (super().render((maxcol - 1, maxrow), focus), self.focus_position, True, maxcol - 1),
                (self.bar.render((1, maxrow)), None, False, 1)
                ]
            return urwid.CanvasJoin(canvases)


ListBox = ScrollBarListBox