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

import urwid
import yaml

from subiquitycore.async_helpers import schedule_task
from subiquitycore.context import (
    Context,
    )
from subiquitycore.controller import (
    Skip,
    )
from subiquitycore.signals import Signal
from subiquitycore.prober import Prober
from subiquitycore.ui.frame import SubiquityCoreUI
from subiquitycore.utils import arun_command

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


# From uapi/linux/kd.h:
KDGKBTYPE = 0x4B33  # get keyboard type

GIO_CMAP = 0x4B70  # gets colour palette on VGA+
PIO_CMAP = 0x4B71  # sets colour palette on VGA+
UO_R, UO_G, UO_B = 0xe9, 0x54, 0x20

# /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


class TwentyFourBitScreen(urwid.raw_display.Screen):

    def __init__(self, _urwid_name_to_rgb, **kwargs):
        self._urwid_name_to_rgb = _urwid_name_to_rgb
        super().__init__(**kwargs)

    def _cc(self, color):
        """Return the "SGR" parameter for selecting color.

        See https://en.wikipedia.org/wiki/ANSI_escape_code#SGR for an
        explanation.  We use the basic codes for black/white/default for
        maximum compatibility; they are the only colors used when the
        mono palette is selected.
        """
        if color == 'white':
            return '7'
        elif color == 'black':
            return '0'
        elif color == 'default':
            return '9'
        else:
            # This is almost but not quite a ISO 8613-3 code -- that
            # would use colons to separate the rgb values instead. But
            # it's what xterm, and hence everything else, supports.
            return '8;2;{};{};{}'.format(*self._urwid_name_to_rgb[color])

    def _attrspec_to_escape(self, a):
        return '\x1b[0;3{};4{}m'.format(
            self._cc(a.foreground),
            self._cc(a.background))


def is_linux_tty():
    try:
        r = fcntl.ioctl(sys.stdout.fileno(), KDGKBTYPE, ' ')
    except IOError as e:
        log.debug("KDGKBTYPE failed %r", e)
        return False
    log.debug("KDGKBTYPE returned %r, is_linux_tty %s", r, r == b'\x02')
    return r == b'\x02'


urwid_8_names = (
    'black',
    'dark red',
    'dark green',
    'brown',
    'dark blue',
    'dark magenta',
    'dark cyan',
    'light gray',
)


def make_palette(colors, styles, ascii):
    """Return a palette to be passed to MainLoop.

    colors is a list of exactly 8 tuples (name, (r, g, b))

    styles is a list of tuples (stylename, fg_color, bg_color) where
    fg_color and bg_color are defined in 'colors'
    """
    # The part that makes this "fun" is that urwid insists on referring
    # to the basic colors by their "standard" names but we overwrite
    # these colors to mean different things.  So we convert styles into
    # an urwid palette by mapping the names in colors to the standard
    # name.
    if len(colors) != 8:
        raise Exception(
            "make_palette must be passed a list of exactly 8 colors")
    urwid_name = dict(zip([c[0] for c in colors], urwid_8_names))

    urwid_palette = []
    for name, fg, bg in styles:
        urwid_fg, urwid_bg = urwid_name[fg], urwid_name[bg]
        if ascii:
            # 24bit grey on colored background looks good
            # but in 16 colors it's unreadable
            # hence add more contrast
            if urwid_bg != 'black':
                urwid_fg = 'black'
            # Only frame_button doesn't match above rule
            # fix it to be brown-on-black black-on-brown
            if name == 'frame_button focus':
                urwid_fg, urwid_bg = 'brown', 'black'
        urwid_palette.append((name, urwid_fg, urwid_bg))

    return urwid_palette


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 ControllerSet:

    def __init__(self, app, names):
        self.app = app
        self.controller_names = names[:]
        self.index = -1
        self.instances = []
        self.controllers_mod = __import__(
            '{}.controllers'.format(self.app.project), None, None, [''])

    def _get_controller_class(self, name):
        return getattr(self.controllers_mod, name+"Controller")

    def load(self, name):
        self.controller_names.remove(name)
        log.debug("Importing controller: %s", name)
        klass = self._get_controller_class(name)
        if hasattr(self, name):
            c = 1
            for instance in self.instances:
                if isinstance(instance, klass):
                    c += 1
            rep_cls = self._get_controller_class("Repeated")
            inst = rep_cls(getattr(self, name), c)
            name = inst.name
        else:
            inst = klass(self.app)
        setattr(self, name, inst)
        self.instances.append(inst)

    def load_all(self):
        while self.controller_names:
            self.load(self.controller_names[0])

    @property
    def cur(self):
        if self.out_of_bounds():
            return None
        return self.instances[self.index]

    def out_of_bounds(self):
        return self.index < 0 or self.index >= len(self.instances)


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()

        self.is_color = False
        self.color_palette = make_palette(self.COLORS, self.STYLES, opts.ascii)

        self.is_linux_tty = is_linux_tty()

        if self.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
        self.controllers = ControllerSet(self, self.controllers)
        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

        # Calling screen.stop() sends the INPUT_DESCRIPTORS_CHANGED
        # signal. This calls _reset_input_descriptors() which calls
        # unhook_event_loop / hook_event_loop on the screen. But this all
        # happens before _started is set to False on the screen and so this
        # does not actually do anything -- we end up attempting to read from
        # stdin while in a background process group, something that gets the
        # kernel upset at us.
        #
        # The cleanest fix seems to be to just send the signal again once
        # stop() has returned which, now that screen._started is False,
        # correctly stops listening from stdin.
        #
        # There is an exactly analagous problem with screen.start() except
        # there the symptom is that we are running in the foreground but not
        # listening to stdin! The fix is the same.

        async def _run():
            await arun_command(
                cmd, stdin=None, stdout=None, stderr=None, **kw)
            screen.start()
            urwid.emit_signal(
                screen, urwid.display_common.INPUT_DESCRIPTORS_CHANGED)
            self.setraw()
            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_color(self):
        if self.is_color:
            new_palette = self.STYLES_MONO
            self.is_color = False
        else:
            new_palette = self.color_palette
            self.is_color = True
        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 key in ['ctrl t', 'f4']:
            self.toggle_color()

    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 setraw(self):
        fd = self.urwid_loop.screen._term_input_file.fileno()
        if os.isatty(fd):
            tty.setraw(fd)

    def make_screen(self, inputf=None, outputf=None):
        """Return a screen to be passed to MainLoop.

        colors is a list of exactly 8 tuples (name, (r, g, b)), the same as
        passed to make_palette.
        """
        # On the linux console, we overwrite the first 8 colors to be those
        # defined by colors. Otherwise, we return a screen that uses ISO
        # 8613-3ish codes to display the colors.
        if inputf is None:
            inputf = sys.stdin
        if outputf is None:
            outputf = sys.stdout

        if len(self.COLORS) != 8:
            raise Exception(
                "make_screen must be passed a list of exactly 8 colors")
        if self.is_linux_tty:
            # Perhaps we ought to return a screen subclass that does this
            # ioctl-ing in .start() and undoes it in .stop() but well.
            curpal = bytearray(16*3)
            fcntl.ioctl(sys.stdout.fileno(), GIO_CMAP, curpal)
            for i in range(8):
                for j in range(3):
                    curpal[i*3+j] = self.COLORS[i][1][j]
            fcntl.ioctl(sys.stdout.fileno(), PIO_CMAP, curpal)
            return urwid.raw_display.Screen(input=inputf, output=outputf)
        elif self.opts.ascii:
            return urwid.raw_display.Screen(input=inputf, output=outputf)
        else:
            _urwid_name_to_rgb = {}
            for i, n in enumerate(urwid_8_names):
                _urwid_name_to_rgb[n] = self.COLORS[i][1]
            return TwentyFourBitScreen(_urwid_name_to_rgb,
                                       input=inputf, output=outputf)

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

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

        if self.opts.ascii:
            urwid.util.set_encoding('ascii')

        extend_dec_special_charmap()

        self.toggle_color()

        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.setraw)
            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
