#
# This file is part of Plinth.
#
# 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/>.
#

"""
Framework for installing and updating distribution packages
"""

from django.contrib import messages
from django.utils.translation import ugettext as _
import functools
import logging
import threading

import plinth
from plinth.utils import import_from_gi
glib = import_from_gi('GLib', '2.0')
packagekit = import_from_gi('PackageKitGlib', '1.0')


logger = logging.getLogger(__name__)
transactions = {}
packages_resolved = {}


class PackageException(Exception):
    """A package operation has failed."""

    def __init__(self, error_string=None, error_details=None, *args, **kwargs):
        """Store packagekit error string and details."""
        super(PackageException, self).__init__(*args, **kwargs)

        self.error_string = error_string
        self.error_details = error_details

    def __str__(self):
        """Return the strin representation of the exception."""
        return 'PackageException(error_string="{0}", error_details="{1}")' \
            .format(self.error_string, self.error_details)


class Transaction(object):
    """Information about an ongoing transaction."""

    def __init__(self, package_names, before_install=None, on_install=None):
        """Initialize transaction object.

        Set most values to None until they are sent as progress update.
        """
        self.package_names = package_names
        # XXX: This is hack, remove after implementing proper setup mechanism.
        self.before_install = before_install
        self.on_install = on_install

        # Progress
        self.allow_cancel = None
        self.percentage = None
        self.status = None
        self.status_string = None
        self.flags = None
        self.package = None
        self.package_id = None
        self.item_progress = None
        self.role = None
        self.caller_active = None
        self.download_size_remaining = None
        self.speed = None

        # Completion
        self.is_finished = False
        self.exception = None

    def get_id(self):
        """Return a identifier to use as a key in a map of transactions."""
        return frozenset(self.package_names)

    def __str__(self):
        """Return the string representation of the object"""
        return ('Transaction(packages={0}, allow_cancel={1}, status={2}, '
                ' percentage={3}, package={4}, item_progress={5})').format(
                    self.package_names, self.allow_cancel, self.status_string,
                    self.percentage, self.package, self.item_progress)

    def start_install_in_thread(self):
        """Start a PackageKit transaction to install given list of packages.

        This operation is non-blocking at it spawns a new thread.
        """
        thread = threading.Thread(target=self.install)
        thread.start()

    def install(self):
        """Run a PackageKit transaction to install given packages."""
        try:
            if self.before_install:
                self.before_install()
        except Exception as exception:
            logger.exception('Error during setup before install - %s',
                             exception)
            self.finish(exception)
            return

        try:
            self._do_install()
        except PackageException as exception:
            self.finish(exception)
            return
        except glib.Error as exception:
            self.finish(PackageException(exception.message))
            return

        try:
            if self.on_install:
                self.on_install()
        except Exception as exception:
            logger.exception('Error during setup - %s', exception)
            self.finish(exception)
            return

        self.finish()

    def _do_install(self):
        """Run a PackageKit transaction to install given packages.

        Raise exception in case of error.
        """
        client = packagekit.Client()
        client.set_interactive(False)

        # Refresh package cache from all enabled repositories
        results = client.refresh_cache(
            False, None, self.progress_callback, self)
        self._assert_success(results)

        # Resolve packages again to get the latest versions after refresh
        results = client.resolve(packagekit.FilterEnum.INSTALLED,
                                 tuple(self.package_names) + (None, ),
                                 None, self.progress_callback, self)
        self._assert_success(results)

        for package in results.get_package_array():
            packages_resolved[package.get_name()] = package

        package_ids = []
        for package_name in self.package_names:
            if package_name not in packages_resolved or \
               not packages_resolved[package_name]:
                raise PackageException(_('packages not found'))

            package_ids.append(packages_resolved[package_name].get_id())

        # Start package installation
        results = client.install_packages(
            packagekit.TransactionFlagEnum.ONLY_TRUSTED, package_ids + [None],
            None, self.progress_callback, self)
        self._assert_success(results)

    def _assert_success(self, results):
        """Check that the most recent operation was a success."""
        if results and results.get_error_code() is not None:
            error = results.get_error_code()
            error_code = error.get_code() if error else None
            error_string = packagekit.ErrorEnum.to_string(error_code) \
                if error_code else None
            error_details = error.get_details() if error else None
            raise PackageException(error_string, error_details)

    def progress_callback(self, progress, progress_type, user_data):
        """Process progress updates on package resolve operation"""
        if progress_type == packagekit.ProgressType.PERCENTAGE:
            self.percentage = progress.props.percentage
        elif progress_type == packagekit.ProgressType.PACKAGE:
            self.package = progress.props.package
        elif progress_type == packagekit.ProgressType.ALLOW_CANCEL:
            self.allow_cancel = progress.props.allow_cancel
        elif progress_type == packagekit.ProgressType.PACKAGE_ID:
            self.package_id = progress.props.package_id
        elif progress_type == packagekit.ProgressType.ITEM_PROGRESS:
            self.item_progress = progress.props.item_progress
        elif progress_type == packagekit.ProgressType.STATUS:
            self.status = progress.props.status
            self.status_string = \
                packagekit.StatusEnum.to_string(progress.props.status)
        elif progress_type == packagekit.ProgressType.TRANSACTION_FLAGS:
            self.flags = progress.props.transaction_flags
        elif progress_type == packagekit.ProgressType.ROLE:
            self.role = progress.props.role
        elif progress_type == packagekit.ProgressType.CALLER_ACTIVE:
            self.caller_active = progress.props.caller_active
        elif progress_type == packagekit.ProgressType.DOWNLOAD_SIZE_REMAINING:
            self.download_size_remaining = \
                progress.props.download_size_remaining
        elif progress_type == packagekit.ProgressType.SPEED:
            self.speed = progress.props.speed
        else:
            logger.info('Unhandle packagekit progress callback - %s, %s',
                        progress, progress_type)

    def finish(self, exception=None):
        """Mark transaction as complected and store exception if any."""
        self.is_finished = True
        self.exception = exception

    def collect_result(self):
        """Retrieve the result of this transaction.

        Also remove self from global transactions list.
        """
        assert self.is_finished

        del transactions[self.get_id()]
        return self.exception


def required(package_names, before_install=None, on_install=None):
    """Decorate a view to check and install required packages."""

    def wrapper2(func):
        """Return a function to check and install packages."""

        @functools.wraps(func)
        def wrapper(request, *args, **kwargs):
            """Check and install packages required by a view."""
            if not _should_show_install_view(request, package_names):
                return func(request, *args, **kwargs)

            view = plinth.views.PackageInstallView.as_view()
            return view(request, package_names=package_names,
                        before_install=before_install, on_install=on_install,
                        *args, **kwargs)

        return wrapper

    return wrapper2


def _should_show_install_view(request, package_names):
    """Return whether the installation view should be shown."""
    transaction_id = frozenset(package_names)

    # No transaction in progress
    if transaction_id not in transactions:
        is_installed = check_installed(package_names)
        return not is_installed

    # Installing
    transaction = transactions[transaction_id]
    if not transaction.is_finished:
        return True

    # Transaction finished, waiting to show the result
    exception = transaction.collect_result()
    if not exception:
        messages.success(request,
                         _('Installed and configured packages successfully.'))
        return False
    else:
        error_string = getattr(exception, 'error_string', str(exception))
        error_details = getattr(exception, 'error_details', '')
        messages.error(request, _('Error installing packages: {string} {details}')
                       .format(string=error_string, details=error_details))
        return True


def check_installed(package_names):
    """Return a boolean installed status of package.

    This operation is blocking and waits until the check is finished.
    """
    def _callback(progress, progress_type, user_data):
        """Process progress updates on package resolve operation."""
        pass

    client = packagekit.Client()
    response = client.resolve(packagekit.FilterEnum.INSTALLED,
                              tuple(package_names) + (None, ), None,
                              _callback, None)

    installed_package_names = []
    for package in response.get_package_array():
        if package.get_info() == packagekit.InfoEnum.INSTALLED:
            installed_package_names.append(package.get_name())

        packages_resolved[package.get_name()] = package

    # When package names could not be resolved
    for package_name in package_names:
        if package_name not in packages_resolved:
            packages_resolved[package_name] = None

    return set(installed_package_names) == set(package_names)


def is_installing(package_names):
    """Return whether a set of packages are currently being installed."""
    return frozenset(package_names) in transactions


def start_install(package_names, before_install=None, on_install=None):
    """Start a PackageKit transaction to install given list of packages.

    This operation is non-blocking at it spawns a new thread.
    """
    transaction = Transaction(package_names,
                              before_install=before_install,
                              on_install=on_install)
    transactions[frozenset(package_names)] = transaction

    transaction.start_install_in_thread()