import os
from django.db import models
from django.utils.translation import gettext_lazy as _

from filer.fields.image import FilerImageField
from filer.fields.file import FilerFileField

from apps.account.models import StudentUser


def lesson_file_upload_to(instance, filename):
    return os.path.join(f"courses/{instance.course.slug}/lessons/{filename}")




class Lesson(models.Model):
    class ContentTypeChoices(models.TextChoices):
        YOUTUBE_LINK = 'youtube_link', 'Youtube Link'
        VIDEO_FILE = 'video_file', 'Video File'

    course = models.ForeignKey("course.Course", on_delete=models.CASCADE, related_name='lessons', verbose_name='Course')
    title = models.CharField(max_length=255, verbose_name='Lesson Title')
    priority = models.IntegerField(null=True, blank=True, verbose_name='Priority')
    is_active = models.BooleanField(default=True, verbose_name=_('Is Active'))
    duration = models.PositiveIntegerField(verbose_name='Duration (in minutes)')
    content_type = models.CharField(max_length=50, choices=ContentTypeChoices.choices, verbose_name='Content Type')
    content_file = models.FileField(
        null=True,
        blank=True,
        upload_to=lesson_file_upload_to,
    )
    video_link = models.CharField(max_length=500, null=True, blank=True, verbose_name='Link')

    created_at = models.DateTimeField(auto_now_add=True, verbose_name=_("Created at"))
    updated_at = models.DateTimeField(auto_now=True, verbose_name=_("Updated At"))


    def __str__(self):
        return f"{self.course.title} - {self.title}"

    def is_completed_by(self, student):
        return self.completions.filter(student=student).exists()
    
    
    def save(self, *args, **kwargs):
        print(f'---> start')
        if self.priority is None:
            # If priority is not set, set it to the next available priority
            max_priority = self.course.lessons.aggregate(max_priority=models.Max('priority'))['max_priority']
            self.priority = (max_priority or 0) + 1
        else:
            self._adjust_priorities()
        super().save(*args, **kwargs)


    def _adjust_priorities(self):
        # Adjust priorities of other lessons in the course
        lessons = self.course.lessons.exclude(pk=self.pk)
        # Shift priorities for lessons with the same or higher priority
        lessons.filter(priority__gte=self.priority).update(priority=models.F('priority') + 1)
        
        
            # # If priority is set, adjust the priorities of other lessons
            # lessons = self.course.lessons.exclude(pk=self.pk).order_by('priority')
            
            # updated_priorities = []
            # inserted = False

            # for lesson in lessons:
            #     if lesson.priority >= self.priority and not inserted:
            #         updated_priorities.append((self.priority, self))
            #         inserted = True
            #     updated_priorities.append((lesson.priority if not inserted else lesson.priority + 1, lesson))

            # if not inserted:
            #     updated_priorities.append((self.priority, self))

            # # Update priorities in bulk
            # for priority, lesson in updated_priorities:
            #     lesson.priority = priority
            #     lesson.save(update_fields=['priority'])

    

class LessonCompletion(models.Model):
    student = models.ForeignKey(
        StudentUser,
        on_delete=models.CASCADE,
        related_name='lesson_completions'
    )
    lesson = models.ForeignKey(
        Lesson,
        on_delete=models.CASCADE,
        related_name='completions'
    )
    completed_at = models.DateTimeField(auto_now_add=True)
    created_at = models.DateTimeField(auto_now_add=True, verbose_name=_("Created at"))

    class Meta:
        unique_together = ('student', 'lesson') 
        
    def __str__(self):
        return f"{self.student.fullname} - {self.lesson.title} - Completed"