from django.db import models
from django.utils import timezone

from django.core.files.storage import FileSystemStorage
from django.conf import settings
from django.utils.html import format_html

from django.urls import reverse

from django.utils.translation import ugettext_lazy as _

from sortedm2m.fields import SortedManyToManyField

from generic.models import ExamBase

import reversion

class Category(models.Model):
    category = models.CharField(max_length=200)

    def __str__(self):
        return self.category

class Question(models.Model):
    stem = models.TextField(
        blank=False,
        help_text="Stem of the question",
    )

    answer_help_text = "Answer text"

    BEST_ANSWER_CHOICES = (
        ('a', 'a_answer'),
        ('b', 'b_answer'),
        ('c', 'c_answer'),
        ('d', 'd_answer'),
        ('e', 'e_answer'),
    )

    # I doubt this is the best way to structure the model
    # (but it should work)
    a_answer = models.TextField(
        help_text=answer_help_text
    )
    a_feedback = models.TextField(
        blank=True,
        help_text="Feedback for answer",
    )

    b_answer = models.TextField(
        help_text=answer_help_text
    )
    b_feedback = models.TextField(
        blank=True,
        help_text="Feedback for answer",
    )

    c_answer = models.TextField(
        help_text=answer_help_text
    )
    c_feedback = models.TextField(
        blank=True,
        help_text="Feedback for answer",
    )

    d_answer = models.TextField(
        help_text=answer_help_text
    )
    d_feedback = models.TextField(
        blank=True,
        help_text="Feedback for answer",
    )

    e_answer = models.TextField(
        help_text=answer_help_text
    )
    e_feedback = models.TextField(
        blank=True,
        help_text="Feedback for answer",
    )

    feedback = models.TextField(
        blank=True,
        help_text="General question feedback",
    )

    best_answer = models.CharField(max_length=20, choices=BEST_ANSWER_CHOICES, help_text="The correct answer")

    created_date = models.DateTimeField(default=timezone.now)

    author = models.ManyToManyField(
        settings.AUTH_USER_MODEL,
        blank=True,
        help_text="Author(s) of question",
        related_name="sbas_authored_questions",
    )

    category = models.ForeignKey(
        Category, on_delete=models.SET_NULL, null=True, blank=True
    )

    def __str__(self):
        return self.stem

    def clean(self):
        if self.a_answer:
            self.a_answer = self.a_answer.strip()
        if self.b_answer:
            self.b_answer = self.b_answer.strip()
        if self.c_answer:
            self.c_answer = self.c_answer.strip()
        if self.d_answer:
            self.d_answer = self.d_answer.strip()
        if self.e_answer:
            self.e_answer = self.e_answer.strip()

    def get_absolute_url(self):
        return reverse("sbas:question_detail", kwargs={"pk": self.pk})

    def get_answers(self):
        return (self.a_answer, self.b_answer, self.c_answer, self.d_answer, self.e_answer)

    def get_correct_answer(self):
        if self.best_answer == "a": return self.a_answer
        if self.best_answer == "b": return self.b_answer
        if self.best_answer == "c": return self.c_answer
        if self.best_answer == "d": return self.d_answer
        if self.best_answer == "e": return self.e_answer

    def get_correct_answer_stripped(self):
        return self.get_correct_answer().replace("<p>","",1).replace("</p>","",1)

    def get_stem_stripped(self):
        return self.stem.replace("<p>","",1).replace("</p>","",1)


@reversion.register
class Exam(ExamBase):
    app_name = "sbas"
    
    exam_questions = SortedManyToManyField(
        Question, related_name="exams", blank="true"
    )

    time_limit = models.IntegerField(
        help_text="Exam time limit (in seconds)",
        blank=True,
        null=True,
    )

    recreate_json = None

    author = models.ManyToManyField(settings.AUTH_USER_MODEL,
                                    blank=True,
                                    help_text='Author of exam',
                                    related_name="sba_exam_author")



@reversion.register
class CidUserAnswer(models.Model):
    """User answers by candidate"""

    question = models.ForeignKey(
        Question, related_name="cid_user_answers", on_delete=models.CASCADE
    )
    answer = models.CharField(max_length=20, choices=Question.BEST_ANSWER_CHOICES, help_text="The correct answer")

    cid = models.IntegerField(blank=True, null=True)

    # Each user answer is associated with a particular exam
    exam = models.ForeignKey(
        Exam, related_name="cid_user_answers", on_delete=models.CASCADE, null=True
    )

    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

    def __str__(self):
        return "{}/{}/{}".format(self.cid, self.exam, self.question.pk)

    def get_answer(self):
        return self.answer

    def get_correct(self):
        return self.answer == self.question.best_answer

    def get_score(self):
        if self.get_correct():
            return 1
        return 0