"""
Agent Chat Streaming Endpoint
SSE-based real-time streaming for Sales & Feedback agents
"""
from typing import AsyncGenerator
from stream_utils import format_sse, EVENT_STATUS, EVENT_TOKEN, EVENT_DONE, EVENT_ERROR, EVENT_METADATA
from datetime import datetime


async def agent_chat_stream(
    request,
    agent_service,
    conversation_service
) -> AsyncGenerator[str, None]:
    """
    Stream agent responses in real-time (SSE format)
    
    Args:
        request: ChatRequest with message, session_id, mode, user_id
        agent_service: AgentService instance
        conversation_service: ConversationService instance
    
    Yields SSE events:
        - status: Processing updates
        - token: Text chunks
        - metadata: Session info
        - done: Completion signal
        - error: Error messages
    """
    try:
        # === SESSION MANAGEMENT ===
        session_id = request.session_id
        if not session_id:
            session_id = conversation_service.create_session(
                metadata={"user_agent": "api", "created_via": "agent_stream"},
                user_id=request.user_id
            )
            yield format_sse(EVENT_METADATA, {"session_id": session_id})
        
        # Get conversation history
        history = conversation_service.get_conversation_history(session_id)
        
        # Convert to messages format
        messages = []
        for h in history:
            messages.append({"role": h["role"], "content": h["content"]})

        
        # Determine mode
        mode = getattr(request, 'mode', 'sales')  # Default to sales
        user_id = getattr(request, 'user_id', None)
        access_token = getattr(request, 'access_token', None)
        
        # Debug logging
        print(f"📋 Request Info:")
        print(f"  - Mode: {mode}")
        print(f"  - User ID: {user_id}")
        print(f"  - Access Token: {'✅ Present' if access_token else '❌ Missing'}")
        if access_token:
            print(f"  - Token preview: {access_token[:20]}...")
        
        # === STATUS UPDATE ===
        if mode == 'feedback':
            yield format_sse(EVENT_STATUS, "Đang kiểm tra lịch sử sự kiện của bạn...")
        else:
            yield format_sse(EVENT_STATUS, "Đang tư vấn...")
        
        # === CALL AGENT ===
        result = await agent_service.chat(
            user_message=request.message,
            conversation_history=messages,
            mode=mode,
            user_id=user_id,
            access_token=access_token
        )
        
        agent_response = result["message"]
        
        # === STREAM RESPONSE TOKEN BY TOKEN ===
        # Simple character-by-character streaming
        chunk_size = 5  # Characters per chunk
        for i in range(0, len(agent_response), chunk_size):
            chunk = agent_response[i:i+chunk_size]
            yield format_sse(EVENT_TOKEN, chunk)
            # Small delay for smoother streaming
            import asyncio
            await asyncio.sleep(0.02)
        
        # === SAVE HISTORY ===
        conversation_service.add_message(
            session_id=session_id,
            role="user",
            content=request.message
        )
        conversation_service.add_message(
            session_id=session_id,
            role="assistant",
            content=agent_response
        )
        
        # === DONE ===
        yield format_sse(EVENT_DONE, {
            "session_id": session_id,
            "timestamp": datetime.utcnow().isoformat(),
            "mode": mode,
            "tool_calls": len(result.get("tool_calls", []))
        })
    
    except Exception as e:
        print(f"⚠️ Agent Stream Error: {e}")
        yield format_sse(EVENT_ERROR, str(e))