# Copyright 2015 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/>.

import datetime
import logging

import yaml

from urwid import (
    AttrMap,
    CheckBox,
    LineBox,
    ListBox as UrwidListBox,
    RadioButton,
    SelectableIcon,
    SimpleFocusListWalker,
    Text,
    )

from subiquitycore.async_helpers import schedule_task
from subiquitycore.ui.buttons import ok_btn, cancel_btn, other_btn
from subiquitycore.ui.container import (
    Columns,
    ListBox,
    Pile,
    ScrollBarListBox,
    WidgetWrap,
    )
from subiquitycore.ui.spinner import Spinner
from subiquitycore.ui.table import (
    AbstractTable,
    ColSpec,
    TablePile,
    TableRow,
    )
from subiquitycore.ui.utils import (
    button_pile,
    Color,
    Padding,
    screen,
    )
from subiquitycore.view import BaseView

from subiquity.models.filesystem import humanize_size
from subiquity.models.snaplist import SnapSelection

log = logging.getLogger("subiquity.views.snaplist")


class StarRadioButton(RadioButton):
    states = {
        True: SelectableIcon("(*)"),
        False: SelectableIcon("( )"),
        }


class NoTabCyclingTableListBox(AbstractTable):

    def _make(self, rows):
        body = SimpleFocusListWalker(rows)
        return ScrollBarListBox(UrwidListBox(body))


def format_datetime(d):
    delta = datetime.datetime.now() - d
    if delta.total_seconds() < 60:
        return _("just now")
    elif delta.total_seconds() < 60*60:
        amount = int(delta.total_seconds()/60)
        if amount == 1:
            unit = _("minute")
        else:
            unit = _("minutes")
    elif delta.total_seconds() < 60*60*24:
        amount = int(delta.total_seconds()/(60*60))
        if amount == 1:
            unit = _("hour")
        else:
            unit = _("hours")
    elif delta.days < 30:
        amount = delta.days
        if amount == 1:
            unit = _("day")
        else:
            unit = _("days")
    else:
        return str(d.date())
    return _("{amount:2} {unit} ago").format(amount=amount, unit=unit)


class SnapInfoView(WidgetWrap):

    # This is mostly like a Pile but it tries to be a bit smart about
    # how to distribute space between the description and channel list
    # (which can both be arbitrarily long or short). If both are long,
    # the channel list is given a third of the space. If there is
    # space for both, they are packed into the upper part of the view.

    def __init__(self, parent, snap, cur_channel):
        self.parent = parent
        self.snap = snap
        self.needs_focus = True

        self.description = Text(snap.description.replace('\r', '').strip())
        self.lb_description = ListBox([self.description])

        latest_update = datetime.datetime.min
        radio_group = []
        channel_rows = []
        for csi in snap.channels:
            latest_update = max(latest_update, csi.released_at)
            btn = StarRadioButton(
                radio_group,
                csi.channel_name,
                state=csi.channel_name == cur_channel,
                on_state_change=self.state_change,
                user_data=SnapSelection(
                    channel=csi.channel_name,
                    is_classic=csi.confinement == "classic"))
            channel_rows.append(Color.menu_button(TableRow([
                btn,
                Text(csi.version),
                Text("(" + csi.revision + ")"),
                Text(humanize_size(csi.size)),
                Text(format_datetime(csi.released_at)),
                Text(csi.confinement),
            ])))

        first_info_row = TableRow([
            (3, Text(
                [
                    ('info_minor', _("LICENSE: ")),
                    snap.license,
                ], wrap='clip')),
            (3, Text(
                [
                    ('info_minor', _("LAST UPDATED: ")),
                    format_datetime(latest_update),
                ])),
            ])
        heading_row = Color.info_minor(TableRow([
            Text(_("CHANNEL")),
            (2, Text(_("VERSION"))),
            Text(_("SIZE")),
            Text(_("PUBLISHED")),
            Text(_("CONFINEMENT")),
            ]))
        colspecs = {
            1: ColSpec(can_shrink=True),
            }
        info_table = TablePile(
            [
                first_info_row,
                TableRow([Text("")]),
                heading_row,
            ],
            spacing=2, colspecs=colspecs)
        self.lb_channels = NoTabCyclingTableListBox(
            channel_rows,
            spacing=2, colspecs=colspecs)
        info_table.bind(self.lb_channels)
        self.info_padding = Padding.pull_1(info_table)

        publisher = [('info_minor', _("by: ")), snap.publisher]
        if snap.verified:
            publisher.append(('verified', ' \N{check mark}'))

        title = Columns([
            Text(snap.name),
            ('pack', Text(publisher, align='right')),
            ], dividechars=1)

        contents = [
            ('pack',      title),
            ('pack',      Text("")),
            ('pack',      Text(snap.summary)),
            ('pack',      Text("")),
            self.lb_description,  # overwritten in render()
            ('pack',      Text("")),
            ('pack',      self.info_padding),
            ('pack',      Text("")),
            ('weight', 1, self.lb_channels),
            ]
        self.description_index = contents.index(self.lb_description)
        self.pile = Pile(contents)
        super().__init__(self.pile)

    def state_change(self, sender, state, selection):
        if state:
            log.debug(
                "selecting %s from %s", self.snap.name, selection.channel)
            self.parent.snap_boxes[self.snap.name].set_state(True)
            self.parent.to_install[self.snap.name] = selection

    def render(self, size, focus):
        maxcol, maxrow = size

        rows_available = maxrow
        pack_option = self.pile.options('pack')
        for w, o in self.pile.contents:
            if o == pack_option:
                rows_available -= w.rows((maxcol,), focus)

        rows_wanted_description = self.description.rows((maxcol-1,), False)
        rows_wanted_channels = 0
        for row in self.lb_channels._w.original_widget.body:
            rows_wanted_channels += row.rows((maxcol,), False)

        if rows_wanted_channels + rows_wanted_description <= rows_available:
            description_rows = rows_wanted_description
            channel_rows = rows_wanted_channels
        else:
            if rows_wanted_description < 2*rows_available/3:
                description_rows = rows_wanted_description
                channel_rows = rows_available - description_rows
            else:
                channel_rows = max(
                    min(rows_wanted_channels, int(rows_available/3)), 3)
                description_rows = rows_available - channel_rows

        self.pile.contents[self.description_index] = (
            self.lb_description, self.pile.options('given', description_rows))
        if description_rows >= rows_wanted_description:
            self.lb_description.base_widget._selectable = False
        else:
            self.lb_description.base_widget._selectable = True
        if channel_rows >= rows_wanted_channels:
            self.info_padding.right = 0
        else:
            self.info_padding.right = 1
        if self.needs_focus:
            self.pile._select_first_selectable()
            self.needs_focus = False
        return self.pile.render(size, focus)


class FetchingInfo(WidgetWrap):

    def __init__(self, parent, snap, aio_loop):
        self.parent = parent
        self.spinner = Spinner(aio_loop, style='dots')
        self.spinner.start()
        self.closed = False
        text = _("Fetching info for {}").format(snap.name)
        # | text |
        # 12    34
        self.width = len(text) + 4
        cancel = cancel_btn(label=_("Cancel"), on_press=self.close)
        super().__init__(
            LineBox(
                Pile([
                    ('pack', Text(' ' + text)),
                    ('pack', self.spinner),
                    ('pack', button_pile([cancel])),
                    ])))

    def close(self, sender=None):
        if self.closed:
            return
        self.closed = True
        self.spinner.stop()
        self.parent.remove_overlay()


class FetchingFailed(WidgetWrap):

    def __init__(self, row, snap):
        self.row = row
        self.closed = False
        text = _("Fetching info for {} failed").format(snap.name)
        # | text |
        # 12    34
        self.width = len(text) + 4
        retry = other_btn(label=_("Try again"), on_press=self.load)
        cancel = cancel_btn(label=_("Cancel"), on_press=self.close)
        super().__init__(
            LineBox(
                Pile([
                    ('pack', Text(' ' + text)),
                    ('pack', button_pile([retry, cancel])),
                    ])))

    def load(self, sender=None):
        self.close()
        self.row.load_info()

    def close(self, sender=None):
        if self.closed:
            return
        self.closed = True
        self.row.parent.remove_overlay()


class SnapCheckBox(CheckBox):
    states = {
        True: SelectableIcon("[*]"),
        False: SelectableIcon("[ ]"),
        }

    def __init__(self, parent, snap, state):
        self.parent = parent
        self.snap = snap
        super().__init__(
            snap.name, state=state, on_state_change=self.state_change)

    def loaded(self):
        if len(self.snap.channels) == 0:  # or other indication of failure
            ff = FetchingFailed(self, self.snap)
            self.parent.show_overlay(ff, width=ff.width)
        else:
            cur_chan = None
            if self.snap.name in self.parent.to_install:
                cur_chan = self.parent.to_install[self.snap.name].channel
            siv = SnapInfoView(self.parent, self.snap, cur_chan)
            self.parent.show_screen(screen(
                siv,
                [other_btn(
                    label=_("Close"),
                    on_press=self.parent.show_main_screen)],
                focus_buttons=False))

    async def wait(self, t, fi):
        await t
        fi.close()
        self.loaded()

    def load_info(self):
        t = self.parent.controller.get_snap_info_task(self.snap)

        if t.done():
            self.loaded()
            return
        fi = FetchingInfo(
            self.parent, self.snap, self.parent.controller.app.aio_loop)
        self.parent.show_overlay(fi, width=fi.width)
        schedule_task(self.wait(t, fi))

    def keypress(self, size, key):
        if key.startswith("enter"):
            self.load_info()
        else:
            return super().keypress(size, key)

    def state_change(self, sender, new_state):
        if new_state:
            log.debug("selecting %s", self.snap.name)
            self.parent.to_install[self.snap.name] = SnapSelection(
                channel='stable',
                is_classic=self.snap.confinement == "classic")
        else:
            log.debug("unselecting %s", self.snap.name)
            self.parent.to_install.pop(self.snap.name, None)


class SnapListView(BaseView):

    title = _("Featured Server Snaps")

    def __init__(self, model, controller):
        self.model = model
        self.controller = controller
        self.to_install = model.to_install.copy()
        self.load()

    def loaded(self):
        snap_list = self.model.get_snap_list()
        if len(snap_list) == 0:
            self.offer_retry()
        else:
            self.make_main_screen(snap_list)
            self.show_main_screen()

    async def _wait(self, t, spinner):
        spinner.stop()
        await t
        self.loaded()

    def load(self, sender=None):
        t = self.controller.get_snap_list_task()
        if t.done():
            self.loaded()
            return
        spinner = Spinner(self.controller.app.aio_loop, style='dots')
        spinner.start()
        self._w = screen(
            [spinner], [ok_btn(label=_("Continue"), on_press=self.done)],
            excerpt=_("Loading server snaps from store, please wait..."))
        schedule_task(self._wait(t, spinner))

    def offer_retry(self):
        self._w = screen(
            [Text(_("Sorry, loading snaps from the store failed."))],
            [
                other_btn(label=_("Try again"), on_press=self.load),
                ok_btn(label=_("Continue"), on_press=self.done),
            ])

    def show_main_screen(self, sender=None):
        self._w = self._main_screen

    def show_screen(self, screen):
        self._w = screen

    def get_seed_yaml(self):
        if self.controller.opts.dry_run:
            return '''snaps:
  -
    name: core
    channel: stable
    file: core_4486.snap
  -
    name: lxd
    channel: stable/ubuntu-18.04
    file: lxd_59.snap
'''
        seed_location = '/media/filesystem/var/lib/snapd/seed/seed.yaml'
        content = ""
        try:
            with open(seed_location, encoding='utf-8', errors='replace') as fp:
                content = fp.read()
        except FileNotFoundError:
            log.exception("could not find source at %r", seed_location)
        return content

    def get_preinstalled_snaps(self):
        try:
            seed = yaml.safe_load(self.get_seed_yaml())
        except yaml.YAMLError:
            log.exception("failed to parse seed.yaml")
            return set()
        names = set()
        for snap in seed.get('snaps', []):
            name = snap.get('name')
            if name:
                names.add(name)
        log.debug("pre-seeded snaps %s", names)
        return names

    def make_main_screen(self, snap_list):
        self.snap_boxes = {}
        body = []
        preinstalled = self.get_preinstalled_snaps()
        for snap in snap_list:
            if snap.name in preinstalled:
                log.debug("not offering preseeded snap %r", snap.name)
                continue
            box = self.snap_boxes[snap.name] = SnapCheckBox(
                self, snap, snap.name in self.to_install)
            publisher = snap.publisher
            if snap.verified:
                publisher = [publisher, ('verified', '\N{check mark}')]
            row = [
                box,
                Text(publisher),
                Text(snap.summary, wrap='clip'),
                Text("\N{BLACK RIGHT-POINTING SMALL TRIANGLE}")
                ]
            body.append(AttrMap(
                TableRow(row),
                'menu_button',
                {None: 'menu_button focus', 'verified': 'verified focus'},
                ))
        table = NoTabCyclingTableListBox(
            body,
            colspecs={
                1: ColSpec(omittable=True),
                2: ColSpec(pack=False, min_width=40),
                })
        ok = ok_btn(label=_("Done"), on_press=self.done)
        cancel = cancel_btn(label=_("Back"), on_press=self.cancel)
        self._main_screen = screen(
            table, [ok, cancel],
            focus_buttons=False,
            excerpt=_(
                "These are popular snaps in server environments. Select or "
                "deselect with SPACE, press ENTER to see more details of the "
                "package, publisher and versions available."))

    def done(self, sender=None):
        log.debug("snaps to install %s", self.to_install)
        self.controller.done(self.to_install)

    def cancel(self, sender=None):
        if self._w is self._main_screen:
            self.controller.cancel()
        else:
            self.show_main_screen()
