"""
A2A (Agent-to-Agent) Protocol Implementation
基于A2A协议标准的Agent间通信协议实现

参考资料: https://a2a-protocol.org/latest/
实现完整的Agent间无缝通信和协作协议
"""

from typing import Dict, Any, List, Optional, Union, Callable, Set, Tuple
from dataclasses import dataclass, field
from enum import Enum
import asyncio
import json
import uuid
from datetime import datetime, timedelta
import logging
from abc import ABC, abstractmethod

logger = logging.getLogger(__name__)


class A2AMessageType(Enum):
    """A2A消息类型"""
    # 基础消息类型
    HANDSHAKE = "handshake"                 # 握手建立连接
    CAPABILITY_EXCHANGE = "capability_exchange"  # 能力交换
    TASK_REQUEST = "task_request"           # 任务请求
    TASK_RESPONSE = "task_response"         # 任务响应
    COLLABORATION_INVITE = "collaboration_invite"  # 协作邀请
    COLLABORATION_ACCEPT = "collaboration_accept"  # 协作接受
    COLLABORATION_REJECT = "collaboration_reject"  # 协作拒绝
    
    # 协作消息类型
    WORK_ASSIGNMENT = "work_assignment"     # 工作分配
    PROGRESS_UPDATE = "progress_update"     # 进度更新
    RESULT_SHARING = "result_sharing"       # 结果分享
    FEEDBACK = "feedback"                   # 反馈
    
    # 控制消息类型
    HEARTBEAT = "heartbeat"                 # 心跳
    STATUS_QUERY = "status_query"           # 状态查询
    STATUS_REPORT = "status_report"         # 状态报告
    ERROR_REPORT = "error_report"           # 错误报告
    DISCONNECT = "disconnect"               # 断开连接


class A2ACapabilityType(Enum):
    """A2A能力类型"""
    # 基础能力
    TEXT_PROCESSING = "text_processing"
    CODE_GENERATION = "code_generation"
    DATA_ANALYSIS = "data_analysis"
    REASONING = "reasoning"
    PLANNING = "planning"
    
    # 专业能力
    MACHINE_LEARNING = "machine_learning"
    WEB_SCRAPING = "web_scraping"
    API_INTEGRATION = "api_integration"
    DATABASE_OPERATIONS = "database_operations"
    FILE_OPERATIONS = "file_operations"
    
    # 协作能力
    TASK_COORDINATION = "task_coordination"
    WORKFLOW_MANAGEMENT = "workflow_management"
    TEAM_LEADERSHIP = "team_leadership"
    PEER_REVIEW = "peer_review"


class A2AProtocolVersion(Enum):
    """A2A协议版本"""
    V1_0 = "1.0"
    V1_1 = "1.1"
    V2_0 = "2.0"


@dataclass
class A2ACapability:
    """A2A能力描述"""
    capability_type: A2ACapabilityType
    version: str
    description: str
    input_formats: List[str]
    output_formats: List[str]
    parameters: Dict[str, Any] = field(default_factory=dict)
    constraints: Dict[str, Any] = field(default_factory=dict)
    performance_metrics: Dict[str, Any] = field(default_factory=dict)


@dataclass
class A2AAgentProfile:
    """A2A Agent配置文件"""
    agent_id: str
    agent_name: str
    agent_type: str
    version: str
    capabilities: List[A2ACapability]
    supported_protocols: List[A2AProtocolVersion]
    endpoint: str
    metadata: Dict[str, Any] = field(default_factory=dict)
    
    def to_dict(self) -> Dict[str, Any]:
        """转换为字典格式"""
        return {
            "agent_id": self.agent_id,
            "agent_name": self.agent_name,
            "agent_type": self.agent_type,
            "version": self.version,
            "capabilities": [
                {
                    "type": cap.capability_type.value,
                    "version": cap.version,
                    "description": cap.description,
                    "input_formats": cap.input_formats,
                    "output_formats": cap.output_formats,
                    "parameters": cap.parameters,
                    "constraints": cap.constraints,
                    "performance_metrics": cap.performance_metrics
                }
                for cap in self.capabilities
            ],
            "supported_protocols": [p.value for p in self.supported_protocols],
            "endpoint": self.endpoint,
            "metadata": self.metadata
        }


@dataclass
class A2AMessage:
    """A2A协议消息"""
    message_id: str
    protocol_version: A2AProtocolVersion
    message_type: A2AMessageType
    sender_id: str
    receiver_id: Optional[str]  # None表示广播
    timestamp: datetime
    payload: Dict[str, Any]
    
    # 可选字段
    correlation_id: Optional[str] = None
    reply_to: Optional[str] = None
    ttl: Optional[int] = None  # 生存时间(秒)
    priority: int = 5  # 1-10, 1最高优先级
    encryption: bool = False
    signature: Optional[str] = None
    
    def to_dict(self) -> Dict[str, Any]:
        """转换为字典格式"""
        return {
            "message_id": self.message_id,
            "protocol_version": self.protocol_version.value,
            "message_type": self.message_type.value,
            "sender_id": self.sender_id,
            "receiver_id": self.receiver_id,
            "timestamp": self.timestamp.isoformat(),
            "payload": self.payload,
            "correlation_id": self.correlation_id,
            "reply_to": self.reply_to,
            "ttl": self.ttl,
            "priority": self.priority,
            "encryption": self.encryption,
            "signature": self.signature
        }
    
    @classmethod
    def from_dict(cls, data: Dict[str, Any]) -> 'A2AMessage':
        """从字典创建消息"""
        return cls(
            message_id=data["message_id"],
            protocol_version=A2AProtocolVersion(data["protocol_version"]),
            message_type=A2AMessageType(data["message_type"]),
            sender_id=data["sender_id"],
            receiver_id=data.get("receiver_id"),
            timestamp=datetime.fromisoformat(data["timestamp"]),
            payload=data["payload"],
            correlation_id=data.get("correlation_id"),
            reply_to=data.get("reply_to"),
            ttl=data.get("ttl"),
            priority=data.get("priority", 5),
            encryption=data.get("encryption", False),
            signature=data.get("signature")
        )


class A2ATransport(ABC):
    """A2A传输层抽象接口"""
    
    @abstractmethod
    async def send_message(self, message: A2AMessage, target_endpoint: str) -> bool:
        """发送消息"""
        pass
    
    @abstractmethod
    async def receive_message(self) -> Optional[A2AMessage]:
        """接收消息"""
        pass
    
    @abstractmethod
    async def connect(self, endpoint: str) -> bool:
        """建立连接"""
        pass
    
    @abstractmethod
    async def disconnect(self) -> bool:
        """断开连接"""
        pass


class A2AHTTPTransport(A2ATransport):
    """基于HTTP的A2A传输实现"""
    
    def __init__(self):
        self.session = None
        self.connections: Dict[str, Any] = {}
    
    async def send_message(self, message: A2AMessage, target_endpoint: str) -> bool:
        """通过HTTP发送消息"""
        try:
            # 模拟HTTP发送
            logger.info(f"Sending A2A message {message.message_id} to {target_endpoint}")
            
            # 在实际实现中，这里会使用aiohttp发送HTTP请求
            # async with self.session.post(f"{target_endpoint}/a2a/message", 
            #                             json=message.to_dict()) as response:
            #     return response.status == 200
            
            # 模拟成功
            await asyncio.sleep(0.01)  # 模拟网络延迟
            return True
            
        except Exception as e:
            logger.error(f"Failed to send A2A message: {e}")
            return False
    
    async def receive_message(self) -> Optional[A2AMessage]:
        """接收HTTP消息"""
        # 在实际实现中，这里会从HTTP服务器接收消息
        # 这里返回None表示没有消息
        return None
    
    async def connect(self, endpoint: str) -> bool:
        """建立HTTP连接"""
        try:
            # 在实际实现中，这里会建立HTTP连接池
            self.connections[endpoint] = {"status": "connected", "last_ping": datetime.now()}
            logger.info(f"Connected to A2A endpoint: {endpoint}")
            return True
        except Exception as e:
            logger.error(f"Failed to connect to {endpoint}: {e}")
            return False
    
    async def disconnect(self) -> bool:
        """断开HTTP连接"""
        try:
            self.connections.clear()
            logger.info("Disconnected from all A2A endpoints")
            return True
        except Exception as e:
            logger.error(f"Failed to disconnect: {e}")
            return False


class A2AWebSocketTransport(A2ATransport):
    """基于WebSocket的A2A传输实现"""
    
    def __init__(self):
        self.websockets: Dict[str, Any] = {}
        self.message_queue: asyncio.Queue = asyncio.Queue()
    
    async def send_message(self, message: A2AMessage, target_endpoint: str) -> bool:
        """通过WebSocket发送消息"""
        try:
            logger.info(f"Sending A2A message {message.message_id} via WebSocket to {target_endpoint}")
            
            # 在实际实现中，这里会使用websockets库发送消息
            # websocket = self.websockets.get(target_endpoint)
            # if websocket:
            #     await websocket.send(json.dumps(message.to_dict()))
            #     return True
            
            # 模拟成功
            await asyncio.sleep(0.005)  # 模拟更低的网络延迟
            return True
            
        except Exception as e:
            logger.error(f"Failed to send A2A message via WebSocket: {e}")
            return False
    
    async def receive_message(self) -> Optional[A2AMessage]:
        """接收WebSocket消息"""
        try:
            # 在实际实现中，这里会从WebSocket接收消息
            # message_data = await self.message_queue.get()
            # return A2AMessage.from_dict(message_data)
            return None
        except Exception as e:
            logger.error(f"Failed to receive WebSocket message: {e}")
            return None
    
    async def connect(self, endpoint: str) -> bool:
        """建立WebSocket连接"""
        try:
            # 在实际实现中，这里会建立WebSocket连接
            self.websockets[endpoint] = {"status": "connected", "last_ping": datetime.now()}
            logger.info(f"WebSocket connected to A2A endpoint: {endpoint}")
            return True
        except Exception as e:
            logger.error(f"Failed to connect WebSocket to {endpoint}: {e}")
            return False
    
    async def disconnect(self) -> bool:
        """断开WebSocket连接"""
        try:
            # 在实际实现中，这里会关闭所有WebSocket连接
            for endpoint, ws in self.websockets.items():
                # await ws.close()
                pass
            self.websockets.clear()
            logger.info("Disconnected all WebSocket connections")
            return True
        except Exception as e:
            logger.error(f"Failed to disconnect WebSocket: {e}")
            return False


class A2AMessageHandler(ABC):
    """A2A消息处理器抽象接口"""
    
    @abstractmethod
    async def handle_message(self, message: A2AMessage) -> Optional[A2AMessage]:
        """处理消息，返回响应消息(如果需要)"""
        pass


class A2AProtocolHandler:
    """A2A协议处理器"""
    
    def __init__(self, agent_profile: A2AAgentProfile, transport: A2ATransport):
        self.agent_profile = agent_profile
        self.transport = transport
        self.message_handlers: Dict[A2AMessageType, A2AMessageHandler] = {}
        self.connected_agents: Dict[str, A2AAgentProfile] = {}
        self.active_collaborations: Dict[str, Dict[str, Any]] = {}
        self.message_history: List[A2AMessage] = []
        
    def register_message_handler(self, message_type: A2AMessageType, handler: A2AMessageHandler):
        """注册消息处理器"""
        self.message_handlers[message_type] = handler
        logger.info(f"Registered A2A message handler for {message_type.value}")
    
    async def connect_to_agent(self, target_endpoint: str) -> bool:
        """连接到其他Agent"""
        try:
            # 建立传输层连接
            if not await self.transport.connect(target_endpoint):
                return False
            
            # 发送握手消息
            handshake_message = A2AMessage(
                message_id=str(uuid.uuid4()),
                protocol_version=A2AProtocolVersion.V2_0,
                message_type=A2AMessageType.HANDSHAKE,
                sender_id=self.agent_profile.agent_id,
                receiver_id=None,  # 将在握手响应中确定
                timestamp=datetime.now(),
                payload={
                    "agent_profile": self.agent_profile.to_dict(),
                    "handshake_version": "2.0",
                    "supported_features": [
                        "capability_exchange",
                        "task_collaboration", 
                        "progress_tracking",
                        "result_sharing"
                    ]
                }
            )
            
            success = await self.transport.send_message(handshake_message, target_endpoint)
            if success:
                logger.info(f"Handshake sent to {target_endpoint}")
            
            return success
            
        except Exception as e:
            logger.error(f"Failed to connect to agent at {target_endpoint}: {e}")
            return False
    
    async def send_capability_exchange(self, target_agent_id: str, target_endpoint: str) -> bool:
        """发送能力交换消息"""
        try:
            capability_message = A2AMessage(
                message_id=str(uuid.uuid4()),
                protocol_version=A2AProtocolVersion.V2_0,
                message_type=A2AMessageType.CAPABILITY_EXCHANGE,
                sender_id=self.agent_profile.agent_id,
                receiver_id=target_agent_id,
                timestamp=datetime.now(),
                payload={
                    "capabilities": [cap.to_dict() if hasattr(cap, 'to_dict') else {
                        "type": cap.capability_type.value,
                        "version": cap.version,
                        "description": cap.description,
                        "input_formats": cap.input_formats,
                        "output_formats": cap.output_formats,
                        "parameters": cap.parameters,
                        "constraints": cap.constraints,
                        "performance_metrics": cap.performance_metrics
                    } for cap in self.agent_profile.capabilities],
                    "agent_metadata": self.agent_profile.metadata
                }
            )
            
            return await self.transport.send_message(capability_message, target_endpoint)
            
        except Exception as e:
            logger.error(f"Failed to send capability exchange: {e}")
            return False
    
    async def send_task_request(self, target_agent_id: str, target_endpoint: str, 
                              task_description: str, task_data: Dict[str, Any]) -> str:
        """发送任务请求"""
        try:
            correlation_id = str(uuid.uuid4())
            
            task_message = A2AMessage(
                message_id=str(uuid.uuid4()),
                protocol_version=A2AProtocolVersion.V2_0,
                message_type=A2AMessageType.TASK_REQUEST,
                sender_id=self.agent_profile.agent_id,
                receiver_id=target_agent_id,
                timestamp=datetime.now(),
                correlation_id=correlation_id,
                payload={
                    "task_description": task_description,
                    "task_data": task_data,
                    "expected_output_format": "json",
                    "deadline": (datetime.now() + timedelta(hours=1)).isoformat(),
                    "priority": 5
                }
            )
            
            success = await self.transport.send_message(task_message, target_endpoint)
            if success:
                # 记录发送的消息
                self.message_history.append(task_message)
                return correlation_id
            return None
            
        except Exception as e:
            logger.error(f"Failed to send task request: {e}")
            return None
    
    async def send_collaboration_invite(self, target_agents: List[str], 
                                      collaboration_type: str, collaboration_data: Dict[str, Any]) -> str:
        """发送协作邀请"""
        try:
            collaboration_id = str(uuid.uuid4())
            
            for agent_id in target_agents:
                invite_message = A2AMessage(
                    message_id=str(uuid.uuid4()),
                    protocol_version=A2AProtocolVersion.V2_0,
                    message_type=A2AMessageType.COLLABORATION_INVITE,
                    sender_id=self.agent_profile.agent_id,
                    receiver_id=agent_id,
                    timestamp=datetime.now(),
                    correlation_id=collaboration_id,
                    payload={
                        "collaboration_id": collaboration_id,
                        "collaboration_type": collaboration_type,
                        "collaboration_data": collaboration_data,
                        "participants": target_agents,
                        "role_requirements": collaboration_data.get("roles", {}),
                        "expected_duration": collaboration_data.get("duration", "1h")
                    }
                )
                
                # 在实际实现中，需要知道每个agent的endpoint
                # 这里简化处理
                await self.transport.send_message(invite_message, f"http://agent-{agent_id}")
            
            # 记录协作
            self.active_collaborations[collaboration_id] = {
                "type": collaboration_type,
                "participants": target_agents,
                "status": "invited",
                "created_at": datetime.now(),
                "data": collaboration_data
            }
            
            return collaboration_id
            
        except Exception as e:
            logger.error(f"Failed to send collaboration invite: {e}")
            return None
    
    async def process_message(self, message: A2AMessage) -> Optional[A2AMessage]:
        """处理接收到的消息"""
        try:
            # 记录消息
            self.message_history.append(message)
            
            # 检查消息是否过期
            if message.ttl:
                message_age = (datetime.now() - message.timestamp).total_seconds()
                if message_age > message.ttl:
                    logger.warning(f"Message {message.message_id} expired")
                    return None
            
            # 查找处理器
            handler = self.message_handlers.get(message.message_type)
            if handler:
                response = await handler.handle_message(message)
                if response:
                    logger.info(f"Generated response for message {message.message_id}")
                return response
            else:
                # 默认处理
                return await self._default_message_handler(message)
                
        except Exception as e:
            logger.error(f"Failed to process message {message.message_id}: {e}")
            return self._create_error_response(message, str(e))
    
    async def _default_message_handler(self, message: A2AMessage) -> Optional[A2AMessage]:
        """默认消息处理器"""
        if message.message_type == A2AMessageType.HANDSHAKE:
            return await self._handle_handshake(message)
        elif message.message_type == A2AMessageType.CAPABILITY_EXCHANGE:
            return await self._handle_capability_exchange(message)
        elif message.message_type == A2AMessageType.HEARTBEAT:
            return await self._handle_heartbeat(message)
        elif message.message_type == A2AMessageType.STATUS_QUERY:
            return await self._handle_status_query(message)
        else:
            logger.warning(f"No handler for message type {message.message_type.value}")
            return None
    
    async def _handle_handshake(self, message: A2AMessage) -> A2AMessage:
        """处理握手消息"""
        try:
            remote_profile_data = message.payload.get("agent_profile", {})
            
            # 创建响应
            response = A2AMessage(
                message_id=str(uuid.uuid4()),
                protocol_version=A2AProtocolVersion.V2_0,
                message_type=A2AMessageType.HANDSHAKE,
                sender_id=self.agent_profile.agent_id,
                receiver_id=message.sender_id,
                timestamp=datetime.now(),
                correlation_id=message.message_id,
                payload={
                    "agent_profile": self.agent_profile.to_dict(),
                    "handshake_accepted": True,
                    "supported_features": [
                        "capability_exchange",
                        "task_collaboration", 
                        "progress_tracking",
                        "result_sharing"
                    ]
                }
            )
            
            logger.info(f"Handshake completed with agent {message.sender_id}")
            return response
            
        except Exception as e:
            logger.error(f"Failed to handle handshake: {e}")
            return self._create_error_response(message, str(e))
    
    async def _handle_capability_exchange(self, message: A2AMessage) -> A2AMessage:
        """处理能力交换消息"""
        try:
            remote_capabilities = message.payload.get("capabilities", [])
            
            # 存储远程Agent能力信息
            # 这里可以进行能力匹配和兼容性检查
            
            response = A2AMessage(
                message_id=str(uuid.uuid4()),
                protocol_version=A2AProtocolVersion.V2_0,
                message_type=A2AMessageType.CAPABILITY_EXCHANGE,
                sender_id=self.agent_profile.agent_id,
                receiver_id=message.sender_id,
                timestamp=datetime.now(),
                correlation_id=message.message_id,
                payload={
                    "capabilities_received": len(remote_capabilities),
                    "compatibility_status": "compatible",
                    "suggested_collaboration_patterns": [
                        "sequential_processing",
                        "parallel_processing",
                        "peer_review"
                    ]
                }
            )
            
            logger.info(f"Capability exchange completed with agent {message.sender_id}")
            return response
            
        except Exception as e:
            logger.error(f"Failed to handle capability exchange: {e}")
            return self._create_error_response(message, str(e))
    
    async def _handle_heartbeat(self, message: A2AMessage) -> A2AMessage:
        """处理心跳消息"""
        return A2AMessage(
            message_id=str(uuid.uuid4()),
            protocol_version=A2AProtocolVersion.V2_0,
            message_type=A2AMessageType.HEARTBEAT,
            sender_id=self.agent_profile.agent_id,
            receiver_id=message.sender_id,
            timestamp=datetime.now(),
            correlation_id=message.message_id,
            payload={
                "status": "alive",
                "timestamp": datetime.now().isoformat()
            }
        )
    
    async def _handle_status_query(self, message: A2AMessage) -> A2AMessage:
        """处理状态查询消息"""
        return A2AMessage(
            message_id=str(uuid.uuid4()),
            protocol_version=A2AProtocolVersion.V2_0,
            message_type=A2AMessageType.STATUS_REPORT,
            sender_id=self.agent_profile.agent_id,
            receiver_id=message.sender_id,
            timestamp=datetime.now(),
            correlation_id=message.message_id,
            payload={
                "agent_status": "active",
                "current_load": len(self.active_collaborations),
                "available_capabilities": len(self.agent_profile.capabilities),
                "uptime": "1h 23m",
                "last_activity": datetime.now().isoformat()
            }
        )
    
    def _create_error_response(self, original_message: A2AMessage, error_message: str) -> A2AMessage:
        """创建错误响应消息"""
        return A2AMessage(
            message_id=str(uuid.uuid4()),
            protocol_version=A2AProtocolVersion.V2_0,
            message_type=A2AMessageType.ERROR_REPORT,
            sender_id=self.agent_profile.agent_id,
            receiver_id=original_message.sender_id,
            timestamp=datetime.now(),
            correlation_id=original_message.message_id,
            payload={
                "error_type": "processing_error",
                "error_message": error_message,
                "original_message_id": original_message.message_id,
                "timestamp": datetime.now().isoformat()
            }
        )
    
    def get_connection_status(self) -> Dict[str, Any]:
        """获取连接状态"""
        return {
            "agent_id": self.agent_profile.agent_id,
            "connected_agents": len(self.connected_agents),
            "active_collaborations": len(self.active_collaborations),
            "messages_processed": len(self.message_history),
            "transport_type": type(self.transport).__name__
        }


# 便利函数
def create_a2a_capability(capability_type: A2ACapabilityType, 
                         version: str = "1.0",
                         description: str = "",
                         input_formats: List[str] = None,
                         output_formats: List[str] = None) -> A2ACapability:
    """创建A2A能力描述"""
    return A2ACapability(
        capability_type=capability_type,
        version=version,
        description=description or f"{capability_type.value} capability",
        input_formats=input_formats or ["text", "json"],
        output_formats=output_formats or ["text", "json"]
    )


def create_a2a_agent_profile(agent_id: str,
                           agent_name: str,
                           agent_type: str = "general",
                           capabilities: List[A2ACapability] = None,
                           endpoint: str = None) -> A2AAgentProfile:
    """创建A2A Agent配置文件"""
    return A2AAgentProfile(
        agent_id=agent_id,
        agent_name=agent_name,
        agent_type=agent_type,
        version="1.0",
        capabilities=capabilities or [],
        supported_protocols=[A2AProtocolVersion.V2_0],
        endpoint=endpoint or f"http://localhost:8000/agents/{agent_id}"
    ) 