Add comments app with models, views, and tests; integrate comments into existing models

comments/models.py

@@ -0,0 +1,73 @@
+from django.db import models
+from django.conf import settings
+from django.contrib.contenttypes.fields import GenericForeignKey
+from django.contrib.contenttypes.models import ContentType
+
+class CommentThread(models.Model):
+    """
+    A generic comment thread that can be attached to any model instance.
+    Used for tracking discussions on various objects across the platform.
+    """
+    content_type = models.ForeignKey(
+        ContentType,
+        on_delete=models.CASCADE,
+        related_name='comment_threads'
+    )
+    object_id = models.PositiveIntegerField()
+    content_object = GenericForeignKey('content_type', 'object_id')
+
+    title = models.CharField(max_length=255, blank=True)
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+    created_by = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.SET_NULL,
+        null=True,
+        related_name='created_comment_threads'
+    )
+    is_locked = models.BooleanField(default=False)
+    is_hidden = models.BooleanField(default=False)
+
+    class Meta:
+        indexes = [
+            models.Index(fields=['content_type', 'object_id']),
+        ]
+        ordering = ['-created_at']
+
+    def __str__(self):
+        return f"Comment Thread on {self.content_object} - {self.title}"
+
+
+class Comment(models.Model):
+    """
+    Individual comment within a comment thread.
+    """
+    thread = models.ForeignKey(
+        CommentThread,
+        on_delete=models.CASCADE,
+        related_name='comments'
+    )
+    author = models.ForeignKey(
+        settings.AUTH_USER_MODEL,
+        on_delete=models.SET_NULL,
+        null=True,
+        related_name='comments'
+    )
+    content = models.TextField()
+    created_at = models.DateTimeField(auto_now_add=True)
+    updated_at = models.DateTimeField(auto_now=True)
+    is_edited = models.BooleanField(default=False)
+    is_hidden = models.BooleanField(default=False)
+    parent = models.ForeignKey(
+        'self',
+        on_delete=models.CASCADE,
+        null=True,
+        blank=True,
+        related_name='replies'
+    )
+
+    class Meta:
+        ordering = ['created_at']
+
+    def __str__(self):
+        return f"Comment by {self.author} on {self.created_at}"