from django.db import models
from django.urls import reverse
from django.conf import settings
from django.core.validators import FileExtensionValidator
from django.db.models.signals import pre_save

from django.db.models import Q

from app.models import Session
from .utils import *

User = settings.AUTH_USER_MODEL

YEARS = (
        (1, '1'),
        (2, '2'),
        (3, '3'),
        (4, '4'),
        (4, '5'),
        (4, '6'),
    )

# LEVEL_COURSE = "Level course"
BACHLOAR_DEGREE = "Bachloar"
MASTER_DEGREE = "Master"

LEVEL = (
    # (LEVEL_COURSE, "Level course"),
    (BACHLOAR_DEGREE, "Bachloar Degree"),
    (MASTER_DEGREE, "Master Degree"),
)

FIRST = "First"
SECOND = "Second"
THIRD = "Third"

SEMESTER = (
    (FIRST, "First"),
    (SECOND, "Second"),
    (THIRD, "Third"),
)


class ProgramManager(models.Manager):
    def search(self, query=None):
        qs = self.get_queryset()
        if query is not None:
            or_lookup = (Q(title__icontains=query) | 
                         Q(summary__icontains=query)
                        )
            qs = qs.filter(or_lookup).distinct() # distinct() is often necessary with Q lookups
        return qs


class Program(models.Model):
    title = models.CharField(max_length=150, unique=True)
    summary = models.TextField(null=True, blank=True)

    objects = ProgramManager()

    def __str__(self):
        return self.title

    def get_absolute_url(self):
        return reverse('program_detail', kwargs={'pk': self.pk})


class CourseManager(models.Manager):
    def search(self, query=None):
        qs = self.get_queryset()
        if query is not None:
            or_lookup = (Q(title__icontains=query) | 
                         Q(summary__icontains=query)| 
                         Q(code__icontains=query)| 
                         Q(slug__icontains=query)
                        )
            qs = qs.filter(or_lookup).distinct() # distinct() is often necessary with Q lookups
        return qs


class Course(models.Model):
    slug = models.SlugField(blank=True, unique=True)
    title = models.CharField(max_length=200, null=True)
    code = models.CharField(max_length=200, unique=True, null=True)
    credit = models.IntegerField(null=True, default=0)
    summary = models.TextField(max_length=200, blank=True, null=True)
    program = models.ForeignKey(Program, on_delete=models.CASCADE)
    level = models.CharField(max_length=25, choices=LEVEL, null=True)
    year = models.IntegerField(choices=YEARS, default=0)
    semester = models.CharField(choices=SEMESTER, max_length=200)
    is_elective = models.BooleanField(default=False, blank=True, null=True)

    objects = CourseManager()

    def __str__(self):
        return "{0} ({1})".format(self.title, self.code)

    def get_absolute_url(self):
        return reverse('course_detail', kwargs={'slug': self.slug})
    
    @property
    def is_current_semester(self):
        from app.models import Semester
        current_semester = Semester.objects.get(is_current_semester=True)

        if self.semester == current_semester.semester:
            return True
        else:
            return False


def course_pre_save_receiver(sender, instance, *args, **kwargs):
    if not instance.slug:
        instance.slug = unique_slug_generator(instance)

pre_save.connect(course_pre_save_receiver, sender=Course)


class CourseAllocation(models.Model):
    lecturer = models.ForeignKey(User, on_delete=models.CASCADE, related_name='allocated_lecturer')
    courses = models.ManyToManyField(Course, related_name='allocated_course')
    session = models.ForeignKey(Session, on_delete=models.CASCADE, blank=True, null=True)

    def __str__(self):
        return self.lecturer.get_full_name

    def get_absolute_url(self):
        return reverse('edit_allocated_course', kwargs={'pk': self.pk})


class Upload(models.Model):
    title = models.CharField(max_length=100)
    course = models.ForeignKey(Course, on_delete=models.CASCADE)
    file = models.FileField(upload_to='course_files/', validators=[FileExtensionValidator(['pdf', 'docx', 'doc', 'xls', 'xlsx', 'ppt', 'pptx', 'zip', 'rar', '7zip'])])
    updated_date = models.DateTimeField(auto_now=True, auto_now_add=False, null=True)
    upload_time = models.DateTimeField(auto_now=False, auto_now_add=True, null=True)

    def __str__(self):
        return str(self.file)[6:]

    def get_extension_short(self):
        ext = str(self.file).split(".")
        ext = ext[len(ext)-1]

        if ext == 'doc' or ext == 'docx':
            return 'word'
        elif ext == 'pdf':
            return 'pdf'
        elif ext == 'xls' or ext == 'xlsx':
            return 'excel'
        elif ext == 'ppt' or ext == 'pptx':
            return 'powerpoint'
        elif ext == 'zip' or ext == 'rar' or ext == '7zip':
            return 'archive'

    def delete(self, *args, **kwargs):
        self.file.delete()
        super().delete(*args, **kwargs)


class UploadVideo(models.Model):
    title = models.CharField(max_length=100)
    slug = models.SlugField(blank=True, unique=True)
    course = models.ForeignKey(Course, on_delete=models.CASCADE)
    video = models.FileField(upload_to='course_videos/', validators=[FileExtensionValidator(['mp4', 'mkv', 'wmv', '3gp', 'f4v', 'avi', 'mp3'])])
    summary = models.TextField(null=True, blank=True)
    timestamp = models.DateTimeField(auto_now=False, auto_now_add=True, null=True)

    def __str__(self):
        return str(self.title)

    def get_absolute_url(self):
        return reverse('video_single', kwargs={'slug': self.course.slug, 'video_slug': self.slug})

    def delete(self, *args, **kwargs):
        self.video.delete()
        super().delete(*args, **kwargs)


def video_pre_save_receiver(sender, instance, *args, **kwargs):
    if not instance.slug:
        instance.slug = unique_slug_generator(instance)

pre_save.connect(video_pre_save_receiver, sender=UploadVideo)