import uuid

from django.db import models


class Course(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    org_id = models.UUIDField(db_index=True)
    title = models.CharField(max_length=255)
    slug = models.SlugField(max_length=255, unique=True)
    description = models.TextField(blank=True)
    version = models.PositiveIntegerField(default=1)
    is_published = models.BooleanField(default=False)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["title"]

    def __str__(self):
        return self.title


class Module(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    course = models.ForeignKey(Course, on_delete=models.CASCADE, related_name="modules")
    title = models.CharField(max_length=255)
    order = models.PositiveIntegerField(default=0)
    version = models.PositiveIntegerField(default=1)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["order"]
        constraints = [
            models.UniqueConstraint(fields=["course", "order"], name="unique_course_module_order")
        ]

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


class Lesson(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    module = models.ForeignKey(Module, on_delete=models.CASCADE, related_name="lessons")
    title = models.CharField(max_length=255)
    order = models.PositiveIntegerField(default=0)
    version = models.PositiveIntegerField(default=1)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["order"]
        constraints = [
            models.UniqueConstraint(fields=["module", "order"], name="unique_module_lesson_order")
        ]

    def __str__(self):
        return f"{self.module} / {self.title}"


class Page(models.Model):
    CONTENT_TEXT = "text"
    CONTENT_VIDEO = "video"
    CONTENT_QUIZ = "quiz"
    CONTENT_EMBED = "embed"
    CONTENT_TYPE_CHOICES = [
        (CONTENT_TEXT, "Text"),
        (CONTENT_VIDEO, "Video"),
        (CONTENT_QUIZ, "Quiz"),
        (CONTENT_EMBED, "Embed"),
    ]

    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    lesson = models.ForeignKey(Lesson, on_delete=models.CASCADE, related_name="pages")
    title = models.CharField(max_length=255)
    order = models.PositiveIntegerField(default=0)
    content_type = models.CharField(
        max_length=20, choices=CONTENT_TYPE_CHOICES, default=CONTENT_TEXT
    )
    content_body = models.TextField(blank=True)
    is_required = models.BooleanField(default=True)
    # Minimum active dwell time (seconds) a learner must accumulate before advancing.
    required_seconds = models.PositiveIntegerField(default=0)
    version = models.PositiveIntegerField(default=1)
    created_at = models.DateTimeField(auto_now_add=True)
    updated_at = models.DateTimeField(auto_now=True)

    class Meta:
        ordering = ["order"]
        constraints = [
            models.UniqueConstraint(fields=["lesson", "order"], name="unique_lesson_page_order")
        ]

    def __str__(self):
        return f"{self.lesson} / {self.title}"