from datetime import datetime

class Message:
    """Chat message in a conversation"""
    
    TABLE_NAME = "messages"
    
    def __init__(self, id, conversation_id, sender_id, content, created_at=None):
        self.id = id
        self.conversation_id = conversation_id
        self.sender_id = sender_id
        self.content = content
        self.created_at = created_at or datetime.utcnow()
    
    def to_dict(self):
        return {
            "id": self.id,
            "conversation_id": self.conversation_id,
            "sender_id": self.sender_id,
            "content": self.content,
            "created_at": self.created_at.isoformat() if self.created_at else None,
        }