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

class Instructor(models.Model):
    name = models.CharField(max_length=255)
    title = models.CharField(max_length=255, help_text="e.g. Professor of Computer Science")
    bio = models.TextField()
    expertise = models.CharField(max_length=255)
    photo_url = models.URLField(blank=True, null=True)

    def __str__(self):
        return self.name

class Course(models.Model):
    LEVEL_CHOICES = [
        ('Beginner', 'Beginner'),
        ('Intermediate', 'Intermediate'),
        ('Advanced', 'Advanced'),
    ]
    title = models.CharField(max_length=255)
    slug = models.SlugField(unique=True)
    description = models.TextField()
    instructor = models.ForeignKey(Instructor, on_delete=models.CASCADE, related_name='courses')
    price = models.DecimalField(max_digits=10, decimal_places=2)
    duration = models.CharField(max_length=100, help_text="e.g. 10 weeks")
    level = models.CharField(max_length=50, choices=LEVEL_CHOICES)
    image_url = models.URLField(blank=True, null=True)
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.title

class WishlistItem(models.Model):
    user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='wishlist')
    course = models.ForeignKey(Course, on_delete=models.CASCADE)
    added_at = models.DateTimeField(auto_now_add=True)

    class Meta:
        unique_together = ('user', 'course')

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