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__()}>'