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# Copyright 2015 Canonical, Ltd.
#
# 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, version 3.
#
# 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, see <http://www.gnu.org/licenses/>.

import asyncio
import fcntl
import json
import logging
import os
import struct
import sys

import urwid
import yaml

from subiquitycore.async_helpers import schedule_task
from subiquitycore.context import (
    Context,
    )
from subiquitycore.controller import (
    Skip,
    )
from subiquitycore.palette import PALETTE_COLOR, PALETTE_MONO
from subiquitycore.controllerset import ControllerSet
from subiquitycore.prober import Prober
from subiquitycore.screen import is_linux_tty, make_screen
from subiquitycore.signals import Signal
from subiquitycore.ui.frame import SubiquityCoreUI
from subiquitycore.utils import arun_command

log = logging.getLogger('subiquitycore.core')


# /usr/include/linux/kd.h
K_RAW = 0x00
K_XLATE = 0x01
K_MEDIUMRAW = 0x02
K_UNICODE = 0x03
K_OFF = 0x04

KDGKBMODE = 0x4B44  # gets current keyboard mode
KDSKBMODE = 0x4B45  # sets current keyboard mode


def extend_dec_special_charmap():
    urwid.escape.DEC_SPECIAL_CHARMAP.update({
        ord('\N{BLACK RIGHT-POINTING SMALL TRIANGLE}'): '>',
        ord('\N{BLACK LEFT-POINTING SMALL TRIANGLE}'): '<',
        ord('\N{BLACK DOWN-POINTING SMALL TRIANGLE}'): 'v',
        ord('\N{BLACK UP-POINTING SMALL TRIANGLE}'): '^',
        ord('\N{check mark}'): '+',
        ord('\N{bullet}'): '*',
        ord('\N{lower half block}'): '=',
        ord('\N{upper half block}'): '=',
        ord('\N{FULL BLOCK}'): urwid.escape.DEC_SPECIAL_CHARMAP[
            ord('\N{BOX DRAWINGS LIGHT VERTICAL}')],
    })


class KeyCodesFilter:
    """input_filter that can pass (medium) raw keycodes to the application

    See http://lct.sourceforge.net/lct/x60.html for terminology.

    Call enter_keycodes_mode()/exit_keycodes_mode() to switch into and
    out of keycodes mode. In keycodes mode, the only events passed to
    the application are "press $N" / "release $N" where $N is the
    keycode the user pressed or released.

    Much of this is cribbed from the source of the "showkeys" utility.
    """

    def __init__(self):
        self._fd = os.open("/proc/self/fd/"+str(sys.stdin.fileno()), os.O_RDWR)
        self.filtering = False

    def enter_keycodes_mode(self):
        log.debug("enter_keycodes_mode")
        self.filtering = True
        # Read the old keyboard mode (it will proably always be K_UNICODE but
        # well).
        o = bytearray(4)
        fcntl.ioctl(self._fd, KDGKBMODE, o)
        self._old_mode = struct.unpack('i', o)[0]
        # Set the keyboard mode to K_MEDIUMRAW, which causes the keyboard
        # driver in the kernel to pass us keycodes.
        fcntl.ioctl(self._fd, KDSKBMODE, K_MEDIUMRAW)

    def exit_keycodes_mode(self):
        log.debug("exit_keycodes_mode")
        self.filtering = False
        fcntl.ioctl(self._fd, KDSKBMODE, self._old_mode)

    def filter(self, keys, codes):
        # Luckily urwid passes us the raw results from read() we can
        # turn into keycodes.
        if self.filtering:
            i = 0
            r = []
            n = len(codes)
            while i < len(codes):
                # This is straight from showkeys.c.
                if codes[i] & 0x80:
                    p = 'release '
                else:
                    p = 'press '
                if i + 2 < n and (codes[i] & 0x7f) == 0:
                    if (codes[i + 1] & 0x80) != 0:
                        if (codes[i + 2] & 0x80) != 0:
                            kc = (((codes[i + 1] & 0x7f) << 7) |
                                  (codes[i + 2] & 0x7f))
                            i += 3
                else:
                    kc = codes[i] & 0x7f
                    i += 1
                r.append(p + str(kc))
            return r
        else:
            return keys


class DummyKeycodesFilter:
    # A dummy implementation of the same interface as KeyCodesFilter
    # we can use when not running in a linux tty.

    def enter_keycodes_mode(self):
        pass

    def exit_keycodes_mode(self):
        pass

    def filter(self, keys, codes):
        return keys


class AsyncioEventLoop(urwid.AsyncioEventLoop):
    # This is fixed in the latest urwid.

    def _exception_handler(self, loop, context):
        exc = context.get('exception')
        if exc:
            log.debug("_exception_handler %r", exc)
            loop.stop()
            if not isinstance(exc, urwid.ExitMainLoop):
                # Store the exc_info so we can re-raise after the loop stops
                self._exc_info = (type(exc), exc, exc.__traceback__)
        else:
            loop.default_exception_handler(context)


class Application:

    # A concrete subclass must set project and controllers attributes, e.g.:
    #
    # project = "subiquity"
    # controllers = [
    #         "Welcome",
    #         "Network",
    #         "Filesystem",
    #         "Identity",
    #         "InstallProgress",
    # ]
    # The 'next_screen' and 'prev_screen' methods move through the list of
    # controllers in order, calling the start_ui method on the controller
    # instance.

    make_ui = SubiquityCoreUI

    def __init__(self, opts):
        self.debug_flags = ()
        if opts.dry_run:
            # Recognized flags are:
            #  - install-fail: makes curtin install fail by replaying curtin
            #    events from a failed installation, see
            #    subiquity/controllers/installprogress.py
            #  - bpfail-full, bpfail-restricted: makes block probing fail, see
            #    subiquitycore/prober.py
            #  - copy-logs-fail: makes post-install copying of logs fail, see
            #    subiquity/controllers/installprogress.py
            self.debug_flags = os.environ.get('SUBIQUITY_DEBUG', '').split(',')

        prober = Prober(opts.machine_config, self.debug_flags)

        self.ui = self.make_ui()
        self.opts = opts
        opts.project = self.project

        self.root = '/'
        if opts.dry_run:
            self.root = '.subiquity'
        self.state_dir = os.path.join(self.root, 'run', self.project)
        os.makedirs(self.state_path('states'), exist_ok=True)

        self.answers = {}
        if opts.answers is not None:
            self.answers = yaml.safe_load(opts.answers.read())
            log.debug("Loaded answers %s", self.answers)
            if not opts.dry_run:
                open('/run/casper-no-prompt', 'w').close()

        # Set rich_mode to the opposite of what we want, so we can
        # call toggle_rich to get the right things set up.
        self.rich_mode = opts.run_on_serial

        if is_linux_tty():
            self.input_filter = KeyCodesFilter()
        else:
            self.input_filter = DummyKeycodesFilter()

        self.scale_factor = float(
            os.environ.get('SUBIQUITY_REPLAY_TIMESCALE', "1"))
        self.updated = os.path.exists(self.state_path('updating'))
        self.signal = Signal()
        self.prober = prober
        self.new_event_loop()
        self.urwid_loop = None
        controllers_mod = __import__(
            '{}.controllers'.format(self.project), None, None, [''])
        self.controllers = ControllerSet(
            controllers_mod, self.controllers, init_args=(self,))
        self.context = Context.new(self)

    def new_event_loop(self):
        new_loop = asyncio.new_event_loop()
        asyncio.set_event_loop(new_loop)
        self.aio_loop = new_loop

    def run_command_in_foreground(self, cmd, before_hook=None, after_hook=None,
                                  **kw):
        screen = self.urwid_loop.screen

        async def _run():
            await arun_command(
                cmd, stdin=None, stdout=None, stderr=None, **kw)
            screen.start()
            if after_hook is not None:
                after_hook()

        screen.stop()
        urwid.emit_signal(
            screen, urwid.display_common.INPUT_DESCRIPTORS_CHANGED)
        if before_hook is not None:
            before_hook()
        schedule_task(_run())

    def _connect_base_signals(self):
        """Connect signals used in the core controller."""
        # Registers signals from each controller
        for controller in self.controllers.instances:
            controller.register_signals()
        log.debug("known signals: %s", self.signal.known_signals)

    def state_path(self, *parts):
        return os.path.join(self.state_dir, *parts)

    def save_state(self):
        cur = self.controllers.cur
        if cur is None:
            return
        with open(self.state_path('states', cur.name), 'w') as fp:
            json.dump(cur.serialize(), fp)

    def select_screen(self, new):
        new.context.enter("starting UI")
        if self.opts.screens and new.name not in self.opts.screens:
            raise Skip
        try:
            new.start_ui()
        except Skip:
            new.context.exit("(skipped)")
            raise
        with open(self.state_path('last-screen'), 'w') as fp:
            fp.write(new.name)

    def _move_screen(self, increment):
        self.save_state()
        old = self.controllers.cur
        if old is not None:
            old.context.exit("completed")
            old.end_ui()
        cur_index = self.controllers.index
        while True:
            self.controllers.index += increment
            if self.controllers.index < 0:
                self.controllers.index = cur_index
                return
            if self.controllers.index >= len(self.controllers.instances):
                self.exit()
            new = self.controllers.cur
            try:
                self.select_screen(new)
            except Skip:
                log.debug("skipping screen %s", new.name)
                continue
            else:
                return

    def next_screen(self, *args):
        self._move_screen(1)

    def prev_screen(self, *args):
        self._move_screen(-1)

    def select_initial_screen(self, controller_index):
        self.controllers.index = controller_index - 1
        self.next_screen()

    def report_start_event(self, context, description):
        log = logging.getLogger(context.full_name())
        level = getattr(logging, context.level)
        log.log(level, "start: %s", description)

    def report_finish_event(self, context, description, status):
        log = logging.getLogger(context.full_name())
        level = getattr(logging, context.level)
        log.log(level, "finish: %s %s", description, status.name)

# EventLoop -------------------------------------------------------------------

    def _remove_last_screen(self):
        last_screen = self.state_path('last-screen')
        if os.path.exists(last_screen):
            os.unlink(last_screen)

    def exit(self):
        self._remove_last_screen()
        self.aio_loop.stop()

    def run_scripts(self, scripts):
        # run_scripts runs (or rather arranges to run, it's all async)
        # a series of python snippets in a helpful namespace. This is
        # all in aid of being able to test some part of the UI without
        # having to click the same buttons over and over again to get
        # the UI to the part you are working on.
        #
        # In the namespace are:
        #  * everything from view_helpers
        #  * wait, delay execution of subsequent scripts for a while
        #  * c, a function that finds a button and clicks it. uses
        #    wait, above to wait for the button to appear in case it
        #    takes a while.
        from subiquitycore.testing import view_helpers

        class ScriptState:
            def __init__(self):
                self.ns = view_helpers.__dict__.copy()
                self.waiting = False
                self.wait_count = 0
                self.scripts = scripts

        ss = ScriptState()

        def _run_script():
            log.debug("running %s", ss.scripts[0])
            exec(ss.scripts[0], ss.ns)
            if ss.waiting:
                return
            ss.scripts = ss.scripts[1:]
            if ss.scripts:
                self.aio_loop.call_soon(_run_script)

        def c(pat):
            but = view_helpers.find_button_matching(self.ui, '.*' + pat + '.*')
            if not but:
                ss.wait_count += 1
                if ss.wait_count > 10:
                    raise Exception("no button found matching %r after"
                                    "waiting for 10 secs" % pat)
                wait(1, func=lambda: c(pat))
                return
            ss.wait_count = 0
            view_helpers.click(but)

        def wait(delay, func=None):
            ss.waiting = True

            def next():
                ss.waiting = False
                if func is not None:
                    func()
                if not ss.waiting:
                    ss.scripts = ss.scripts[1:]
                    if ss.scripts:
                        _run_script()
            self.aio_loop.call_later(delay, next)

        ss.ns['c'] = c
        ss.ns['wait'] = wait
        ss.ns['ui'] = self.ui

        self.aio_loop.call_later(0.06, _run_script)

    def toggle_rich(self):
        if self.rich_mode:
            urwid.util.set_encoding('ascii')
            new_palette = PALETTE_MONO
            self.rich_mode = False
        else:
            urwid.util.set_encoding('utf-8')
            new_palette = PALETTE_COLOR
            self.rich_mode = True
        urwid.CanvasCache.clear()
        self.urwid_loop.screen.register_palette(new_palette)
        self.urwid_loop.screen.clear()

    def unhandled_input(self, key):
        if self.opts.dry_run and key == 'ctrl x':
            self.exit()
        elif key == 'f3':
            self.urwid_loop.screen.clear()
        elif self.opts.run_on_serial and key in ['ctrl t', 'f4']:
            self.toggle_rich()

    def start_controllers(self):
        log.debug("starting controllers")
        for controller in self.controllers.instances:
            controller.start()
        log.debug("controllers started")

    def load_serialized_state(self):
        for controller in self.controllers.instances:
            state_path = self.state_path('states', controller.name)
            if not os.path.exists(state_path):
                continue
            with open(state_path) as fp:
                controller.deserialize(json.load(fp))

        last_screen = None
        state_path = self.state_path('last-screen')
        if os.path.exists(state_path):
            with open(state_path) as fp:
                last_screen = fp.read().strip()
        controller_index = 0
        for i, controller in enumerate(self.controllers.instances):
            if controller.name == last_screen:
                controller_index = i
        # Screens that have already been seen should be marked as configured.
        for controller in self.controllers.instances[:controller_index]:
            controller.configured()
        return controller_index

    def make_screen(self, inputf=None, outputf=None):
        return make_screen(self.opts.ascii, inputf, outputf)

    def run(self, input=None, output=None):
        log.debug("Application.run")

        self.urwid_loop = urwid.MainLoop(
            self.ui, screen=self.make_screen(input, output),
            handle_mouse=False, pop_ups=True,
            input_filter=self.input_filter.filter,
            unhandled_input=self.unhandled_input,
            event_loop=AsyncioEventLoop(loop=self.aio_loop))

        extend_dec_special_charmap()

        self.toggle_rich()

        self.base_model = self.make_model()
        try:
            if self.opts.scripts:
                self.run_scripts(self.opts.scripts)

            self.controllers.load_all()

            initial_controller_index = 0

            if self.updated:
                initial_controller_index = self.load_serialized_state()

            self.aio_loop.call_soon(
                self.select_initial_screen, initial_controller_index)
            self._connect_base_signals()

            self.start_controllers()

            self.urwid_loop.run()
        except Exception:
            log.exception("Exception in controller.run():")
            raise