from typing import Dict, Any, Optional

class SlackEvent(dict):
    @staticmethod
    def from_payload(payload: Dict[str, Any]) -> Optional["SlackEvent"]:
        try:
            event = SlackEvent(payload)
            return event
        except KeyError:
            return None
    
    @property
    def text(self) -> str:
        
        if self.get("event", {}).get("channel_type") == "im":
                blocks = self.get("event", {}).get("blocks", [])
                if not blocks:
                    return ""

                elements = blocks[0].get("elements", [])
                if not elements:
                    return "" 

                elements = elements[0].get("elements", [])
                text = ""

                for el in elements:
                    if el.get("type") == "text":
                        text += el.get("text", "")
                    elif el.get("type") == "link":
                        text += el.get("url", "")

                return text 

                
        if self.get("event",{}).get("channel_type") == 'channel': 
            message_text = ""
            for block in self.get("event", {}).get("blocks", []):
                if block.get("type") == "rich_text":
                    for element in block.get("elements", []):
                        if element.get("type") == "rich_text_section":
                            parts = []
                            for el in element.get("elements", []):
                                if el.get("type") == "text":
                                    parts.append(el["text"])
                                elif el.get("type") == "link":
                                    parts.append(el["url"])
                            message_text = "".join(parts)
                            
            return message_text


    
    @property
    def user_id(self) -> Optional[str]:
        return self.get("event", {}).get("user","")
    
    @property
    def channel_id(self) -> Optional[str]:
        return self.get("event", {}).get("channel","")
    
    @property
    def type(self) -> str:
        """ message对应私聊，app_mention对应频道at """
        return self.get("event", {}).get("channel_type", "")
    
    @property
    def message_id(self) -> str:
        return self.get("event_id","")
    
    @property
    def pic_url(self) -> str:
        """提取 Slack 事件中的图片 URL"""
        files = self.get("event", {}).get("files", [])
        if files:
            return files[0].get("url_private", "")
        return None
        
    
    @property
    def sender_name(self) -> str:
        return self.get("event", {}).get("user","")
    
    def __getattr__(self, key: str) -> Optional[Any]:
        return self.get(key)

    def __setattr__(self, key: str, value: Any) -> None:
        self[key] = value

    def __repr__(self) -> str:
        return f"<SlackEvent {super().__repr__()}>"