"""
Django models related to course groups functionality.
"""

import json
import logging

from django.contrib.auth.models import User
from django.db import models
from xmodule_django.models import CourseKeyField

log = logging.getLogger(__name__)


class CourseUserGroup(models.Model):
    """
    This model represents groups of users in a course.  Groups may have different types,
    which may be treated specially.  For example, a user can be in at most one cohort per
    course, and cohorts are used to split up the forums by group.
    """
    class Meta(object):
        unique_together = (('name', 'course_id'), )

    name = models.CharField(max_length=255,
                            help_text=("What is the name of this group?  "
                                       "Must be unique within a course."))
    users = models.ManyToManyField(User, db_index=True, related_name='course_groups',
                                   help_text="Who is in this group?")

    # Note: groups associated with particular runs of a course.  E.g. Fall 2012 and Spring
    # 2013 versions of 6.00x will have separate groups.
    course_id = CourseKeyField(
        max_length=255,
        db_index=True,
        help_text="Which course is this group associated with?",
    )

    # For now, only have group type 'cohort', but adding a type field to support
    # things like 'question_discussion', 'friends', 'off-line-class', etc
    COHORT = 'cohort'
    GROUP_TYPE_CHOICES = ((COHORT, 'Cohort'),)
    group_type = models.CharField(max_length=20, choices=GROUP_TYPE_CHOICES)

    @classmethod
    def create(cls, name, course_id, group_type=COHORT):
        """
        Create a new course user group.

        Args:
            name: Name of group
            course_id: course id
            group_type: group type
        """
        return cls.objects.get_or_create(
            course_id=course_id,
            group_type=group_type,
            name=name
        )


class CourseUserGroupPartitionGroup(models.Model):
    """
    Create User Partition Info.
    """
    course_user_group = models.OneToOneField(CourseUserGroup)
    partition_id = models.IntegerField(
        help_text="contains the id of a cohorted partition in this course"
    )
    group_id = models.IntegerField(
        help_text="contains the id of a specific group within the cohorted partition"
    )
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)


class CourseCohortsSettings(models.Model):
    """
    This model represents cohort settings for courses.
    """
    is_cohorted = models.BooleanField(default=False)

    course_id = CourseKeyField(
        unique=True,
        max_length=255,
        db_index=True,
        help_text="Which course are these settings associated with?",
    )

    _cohorted_discussions = models.TextField(db_column='cohorted_discussions', null=True, blank=True)  # JSON list

    # pylint: disable=invalid-name
    always_cohort_inline_discussions = models.BooleanField(default=True)

    @property
    def cohorted_discussions(self):
        """Jsonify the cohorted_discussions"""
        return json.loads(self._cohorted_discussions)

    @cohorted_discussions.setter
    def cohorted_discussions(self, value):
        """Un-Jsonify the cohorted_discussions"""
        self._cohorted_discussions = json.dumps(value)


class CourseCohort(models.Model):
    """
    This model represents cohort related info.
    """
    course_user_group = models.OneToOneField(CourseUserGroup, unique=True, related_name='cohort')

    RANDOM = 'random'
    MANUAL = 'manual'
    ASSIGNMENT_TYPE_CHOICES = ((RANDOM, 'Random'), (MANUAL, 'Manual'),)
    assignment_type = models.CharField(max_length=20, choices=ASSIGNMENT_TYPE_CHOICES, default=MANUAL)

    @classmethod
    def create(cls, cohort_name=None, course_id=None, course_user_group=None, assignment_type=MANUAL):
        """
        Create a complete(CourseUserGroup + CourseCohort) object.

        Args:
            cohort_name: Name of the cohort to be created
            course_id: Course Id
            course_user_group: CourseUserGroup
            assignment_type: 'random' or 'manual'
        """
        if course_user_group is None:
            course_user_group, __ = CourseUserGroup.create(cohort_name, course_id)

        course_cohort, __ = cls.objects.get_or_create(
            course_user_group=course_user_group,
            defaults={'assignment_type': assignment_type}
        )

        return course_cohort
