Synnefo

# Copyright 2012-2013 GRNET S.A. All rights reserved.

#

# Redistribution and use in source and binary forms, with or

# without modification, are permitted provided that the following

# conditions are met:

#

#   1. Redistributions of source code must retain the above

#      copyright notice, this list of conditions and the following

#      disclaimer.

#

#   2. Redistributions in binary form must reproduce the above

#      copyright notice, this list of conditions and the following

#      disclaimer in the documentation and/or other materials

#      provided with the distribution.

#

# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS

# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED

# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR

# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR

# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT

# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF

# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED

# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT

# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN

# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

# POSSIBILITY OF SUCH DAMAGE.

#

# The views and conclusions contained in the software and

# documentation are those of the authors and should not be

# interpreted as representing official policies, either expressed

# or implied, of GRNET S.A.

from optparse import make_option

from django.core.management.base import BaseCommand, CommandError

from django.core.exceptions import FieldError

from synnefo.webproject.management import util

from synnefo.management.common import UserCache

class ListCommand(BaseCommand):

    """Generic *-list management command.

    Management command to handle common tasks when implementing a -list

    management command. This class handles the following tasks:

    * Retrieving objects from database.

    The DB model class is declared in ``object_class`` class attribute. Also,

    results can be filter using either the ``filters`` and ``excludes``

    attribute or the "--filter-by" option.

    * Display specific fields of the database objects.

    List of available fields is defined in the ``FIELDS`` class attribute,

    which is a dictionary mapping from field names to tuples containing the

    way the field is retrieved and a text help message to display. The first

    field of the tuple is either a string containing a chain of attribute

    accesses (e.g. "machine.flavor.cpu") either a callable function, taking

    as argument the DB object and returning a single value.

    The fields that will be displayed be default is contained in the ``fields``

    class attribute. The user can specify different fields using the "--fields"

    option.

    * Handling of user UUIDs and names.

    If the ``user_uuid_field`` is declared, then "--user" and "--display-mails"

    options will become available. The first one allows filtering via either

    a user's UUID or display name. The "--displayname" option will append

    the displayname of ther user with "user_uuid_field" to the output.

    * Pretty printing output to a nice table.

    """

    # The following fields must be handled in the ListCommand subclasses!

    # The django DB model

    object_class = None

    # The name of the field containg the user ID of the user, if any.

    user_uuid_field = None

    # The name of the field containg the deleted flag, if any.

    deleted_field = None

    # Dictionary with all available fields

    FIELDS = {}

    # List of fields to display by default

    fields = []

    # Default filters and excludes

    filters = {}

    excludes = {}

    help = "Generic List Command"

    option_list = BaseCommand.option_list + (

        make_option(

            "-o", "--output",

            dest="fields",

            help="Comma-separated list of output fields"),

        make_option(

            "--list-fields",

            dest="list_fields",

            action="store_true",

            default=False,

            help="List available output fields"),

        make_option(

            "--filter-by",

            dest="filter_by",

            metavar="FILTERS",

            help="Filter results. Comma separated list of key `cond` val pairs"

                 " that displayed entries must satisfy. e.g."

                 " --filter-by \"deleted=False,id>=22\"."),

        make_option(

            "--list-filters",

            dest="list_filters",

            action="store_true",

            default=False,

            help="List available filters"),

        make_option(

            "--no-headers",

            dest="headers",

            action="store_false",

            default=True,

            help="Do not display headers"),

        make_option(

            "--output-format",

            dest="output_format",

            metavar="[pretty, csv, json]",

            default="pretty",

            choices=["pretty", "csv", "json"],

            help="Select the output format: pretty [the default], tabs"

                 " [tab-separated output], csv [comma-separated output]"),

    )

    def __init__(self, *args, **kwargs):

        if self.user_uuid_field:

            self.option_list += (

                make_option(

                    "-u", "--user",

                    dest="user",

                    metavar="USER",

                    help="List items only for this user."

                         " 'USER' can be either a user UUID or a display"

                         " name"),

                make_option(

                    "--display-mails",

                    dest="display_mails",

                    action="store_true",

                    default=False,

                    help="Include the user's email"),

            )

        if self.deleted_field:

            self.option_list += (

                make_option(

                    "-d", "--deleted",

                    dest="deleted",

                    action="store_true",

                    help="Display only deleted items"),

            )

        super(ListCommand, self).__init__(*args, **kwargs)

    def handle(self, *args, **options):

        if len(args) > 0:

            raise CommandError("List commands do not accept any argument")

        assert(self.object_class), "object_class variable must be declared"

        if options["list_fields"]:

            self.display_fields()

            return

        if options["list_filters"]:

            self.display_filters()

            return

        # --output option

        if options["fields"]:

            fields = options["fields"]

            fields = fields.split(",")

            self.validate_fields(fields)

            self.fields = options["fields"].split(",")

        # --filter-by option

        if options["filter_by"]:

            filters, excludes = util.parse_filters(options["filter_by"])

        else:

            filters, excludes = ({}, {})

        self.filters.update(filters)

        self.excludes.update(excludes)

        # --user option

        user = options.get("user")

        if user:

            if "@" in user:

                user = UserCache().get_uuid(user)

            self.filters[self.user_uuid_field] = user

        # --deleted option

        if self.deleted_field:

            deleted = options.get("deleted")

            if deleted:

                self.filters[self.deleted_field] = True

            else:

                self.filters[self.deleted_field] = False

        # Special handling of arguments

        self.handle_args(self, *args, **options)

        objects = self.object_class.objects

        try:

            objects = objects.filter(**self.filters)

            objects = objects.exclude(**self.excludes)

        except FieldError as e:

            raise CommandError(e)

        except Exception as e:

            raise CommandError("Can not filter results: %s" % e)

        # --display-mails option

        display_mails = options.get("display_mails")

        if display_mails:

            if 'user_mail' in self.object_class._meta.get_all_field_names():

                raise RuntimeError("%s has already a 'user_mail' attribute")

            self.fields.append("user.email")

            self.FIELDS["user.email"] =\

                ("user_email", "The email of the owner.")

            uuids = [getattr(obj, self.user_uuid_field) for obj in objects]

            ucache = UserCache()

            ucache.fetch_names(list(set(uuids)))

            for obj in objects:

                uuid = getattr(obj, self.user_uuid_field)

                obj.user_email = ucache.get_name(uuid)

        # Special handling of DB results

        self.handle_db_objects(objects)

        headers = self.fields

        columns = [self.FIELDS[key][0] for key in headers]

        table = []

        for obj in objects:

            row = []

            for attr in columns:

                if callable(attr):

                    row.append(attr(obj))

                else:

                    item = obj

                    attrs = attr.split(".")

                    for attr in attrs:

                        item = getattr(item, attr)

                    row.append(item)

            table.append(row)

        # Special handle of output

        self.handle_output(table, headers)

        # Print output

        output_format = options["output_format"]

        headers = headers if options["headers"] else None

        util.pprint_table(self.stdout, table, headers, output_format)

    def handle_args(self, *args, **kwargs):

        pass

    def handle_db_objects(self, objects):

        pass

    def handle_output(self, table, headers):

        pass

    def display_fields(self):

        headers = ["Field", "Description"]

        table = []

        for field, (_, help_msg) in self.FIELDS.items():

            table.append((field, help_msg))

        util.pprint_table(self.stdout, table, headers)

    def validate_fields(self, fields):

        for f in fields:

            if f not in self.FIELDS.keys():

                raise CommandError("Unknown field '%s'. 'Use --list-fields"

                                   " option to find out available fields."

                                   % f)

    def display_filters(self):

        headers = ["Filter", "Description", "Help"]

        table = []

        for field in self.object_class._meta.fields:

            table.append((field.name, field.verbose_name, field.help_text))

        util.pprint_table(self.stdout, table, headers)