"""
Proxy handler for Z.AI API requests
"""
import json
import logging
import re
import time
from typing import AsyncGenerator, Dict, Any, Optional
import httpx
from fastapi import HTTPException
from fastapi.responses import StreamingResponse

from config import settings
from cookie_manager import cookie_manager
from models import ChatCompletionRequest, ChatCompletionResponse, ChatCompletionStreamResponse

logger = logging.getLogger(__name__)

class ProxyHandler:
    def __init__(self):
        self.client = httpx.AsyncClient(timeout=60.0)
    
    async def __aenter__(self):
        return self
    
    async def __aexit__(self, exc_type, exc_val, exc_tb):
        await self.client.aclose()
    
    def transform_content(self, content: str) -> str:
        """Transform content by replacing HTML tags and optionally removing think tags"""
        if not content:
            return content

        logger.debug(f"SHOW_THINK_TAGS setting: {settings.SHOW_THINK_TAGS}")

        # Optionally remove thinking content based on configuration
        if not settings.SHOW_THINK_TAGS:
            logger.debug("Removing thinking content from response")
            original_length = len(content)

            # Remove <details> blocks (thinking content) - handle both closed and unclosed tags
            # First try to remove complete <details>...</details> blocks
            content = re.sub(r'<details[^>]*>.*?</details>', '', content, flags=re.DOTALL)

            # Then remove any remaining <details> opening tags and everything after them until we hit answer content
            # Look for pattern: <details...><summary>...</summary>...content... and remove the thinking part
            content = re.sub(r'<details[^>]*>.*?(?=\s*[A-Z]|\s*\d|\s*$)', '', content, flags=re.DOTALL)

            content = content.strip()

            logger.debug(f"Content length after removing thinking content: {original_length} -> {len(content)}")
        else:
            logger.debug("Keeping thinking content, converting to <think> tags")

            # Replace <details> with <think>
            content = re.sub(r'<details[^>]*>', '<think>', content)
            content = content.replace('</details>', '</think>')

            # Remove <summary> tags and their content
            content = re.sub(r'<summary>.*?</summary>', '', content, flags=re.DOTALL)

            # If there's no closing </think>, add it at the end of thinking content
            if '<think>' in content and '</think>' not in content:
                # Find where thinking ends and answer begins
                think_start = content.find('<think>')
                if think_start != -1:
                    # Look for the start of the actual answer (usually starts with a capital letter or number)
                    answer_match = re.search(r'\n\s*[A-Z0-9]', content[think_start:])
                    if answer_match:
                        insert_pos = think_start + answer_match.start()
                        content = content[:insert_pos] + '</think>\n' + content[insert_pos:]
                    else:
                        content += '</think>'

        return content.strip()
    
    async def proxy_request(self, request: ChatCompletionRequest) -> Dict[str, Any]:
        """Proxy request to Z.AI API"""
        cookie = await cookie_manager.get_next_cookie()
        if not cookie:
            raise HTTPException(status_code=503, detail="No available cookies")
        
        # Transform model name
        target_model = settings.UPSTREAM_MODEL if request.model == settings.MODEL_NAME else request.model
        
        # Determine if this should be a streaming response
        is_streaming = request.stream if request.stream is not None else settings.DEFAULT_STREAM

        # Validate parameter compatibility
        if is_streaming and not settings.SHOW_THINK_TAGS:
            logger.warning("SHOW_THINK_TAGS=false is ignored for streaming responses")

        # Prepare request data
        request_data = request.model_dump(exclude_none=True)
        request_data["model"] = target_model

        # Build request data based on actual Z.AI format from zai-messages.md
        import uuid

        request_data = {
            "stream": True,  # Always request streaming from Z.AI for processing
            "model": target_model,
            "messages": request_data["messages"],
            "background_tasks": {
                "title_generation": True,
                "tags_generation": True
            },
            "chat_id": str(uuid.uuid4()),
            "features": {
                "image_generation": False,
                "code_interpreter": False,
                "web_search": False,
                "auto_web_search": False
            },
            "id": str(uuid.uuid4()),
            "mcp_servers": ["deep-web-search"],
            "model_item": {
                "id": target_model,
                "name": "GLM-4.5",
                "owned_by": "openai"
            },
            "params": {},
            "tool_servers": [],
            "variables": {
                "{{USER_NAME}}": "User",
                "{{USER_LOCATION}}": "Unknown",
                "{{CURRENT_DATETIME}}": "2025-08-04 16:46:56"
            }
        }



        logger.debug(f"Sending request data: {request_data}")
        
        headers = {
            "Content-Type": "application/json",
            "Authorization": f"Bearer {cookie}",
            "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36",
            "Accept": "application/json, text/event-stream",
            "Accept-Language": "zh-CN",
            "sec-ch-ua": '"Not)A;Brand";v="8", "Chromium";v="138", "Google Chrome";v="138"',
            "sec-ch-ua-mobile": "?0",
            "sec-ch-ua-platform": '"macOS"',
            "x-fe-version": "prod-fe-1.0.53",
            "Origin": "https://chat.z.ai",
            "Referer": "https://chat.z.ai/c/069723d5-060b-404f-992c-4705f1554c4c"
        }
        
        try:
            response = await self.client.post(
                settings.UPSTREAM_URL,
                json=request_data,
                headers=headers
            )
            
            if response.status_code == 401:
                await cookie_manager.mark_cookie_failed(cookie)
                raise HTTPException(status_code=401, detail="Invalid authentication")
            
            if response.status_code != 200:
                raise HTTPException(status_code=response.status_code, detail=f"Upstream error: {response.text}")
            
            await cookie_manager.mark_cookie_success(cookie)
            return {"response": response, "cookie": cookie}
            
        except httpx.RequestError as e:
            logger.error(f"Request error: {e}")
            await cookie_manager.mark_cookie_failed(cookie)
            raise HTTPException(status_code=503, detail="Upstream service unavailable")
    
    async def process_streaming_response(self, response: httpx.Response) -> AsyncGenerator[Dict[str, Any], None]:
        """Process streaming response from Z.AI"""
        buffer = ""
        
        async for chunk in response.aiter_text():
            buffer += chunk
            lines = buffer.split('\n')
            buffer = lines[-1]  # Keep incomplete line in buffer
            
            for line in lines[:-1]:
                line = line.strip()
                if not line.startswith("data: "):
                    continue
                
                payload = line[6:].strip()
                if payload == "[DONE]":
                    return
                
                try:
                    parsed = json.loads(payload)

                    # Check for errors first
                    if parsed.get("error") or (parsed.get("data", {}).get("error")):
                        error_detail = (parsed.get("error", {}).get("detail") or
                                      parsed.get("data", {}).get("error", {}).get("detail") or
                                      "Unknown error from upstream")
                        logger.error(f"Upstream error: {error_detail}")
                        raise HTTPException(status_code=400, detail=f"Upstream error: {error_detail}")

                    # Transform the response
                    if parsed.get("data"):
                        # Remove unwanted fields
                        parsed["data"].pop("edit_index", None)
                        parsed["data"].pop("edit_content", None)

                        # Note: We don't transform delta_content here because <think> tags
                        # might span multiple chunks. We'll transform the final aggregated content.

                    yield parsed

                except json.JSONDecodeError:
                    continue  # Skip non-JSON lines
    
    async def handle_chat_completion(self, request: ChatCompletionRequest):
        """Handle chat completion request"""
        proxy_result = await self.proxy_request(request)
        response = proxy_result["response"]

        # Determine final streaming mode
        is_streaming = request.stream if request.stream is not None else settings.DEFAULT_STREAM

        if is_streaming:
            # For streaming responses, SHOW_THINK_TAGS setting is ignored
            return StreamingResponse(
                self.stream_response(response, request.model),
                media_type="text/event-stream",
                headers={
                    "Cache-Control": "no-cache",
                    "Connection": "keep-alive",
                }
            )
        else:
            # For non-streaming responses, SHOW_THINK_TAGS setting applies
            return await self.non_stream_response(response, request.model)
    
    async def stream_response(self, response: httpx.Response, model: str) -> AsyncGenerator[str, None]:
        """Generate streaming response"""
        async for parsed in self.process_streaming_response(response):
            yield f"data: {json.dumps(parsed)}\n\n"
        yield "data: [DONE]\n\n"
    
    async def non_stream_response(self, response: httpx.Response, model: str) -> ChatCompletionResponse:
        """Generate non-streaming response"""
        chunks = []
        async for parsed in self.process_streaming_response(response):
            chunks.append(parsed)
            logger.debug(f"Received chunk: {parsed}")  # Debug log

        if not chunks:
            raise HTTPException(status_code=500, detail="No response from upstream")

        logger.info(f"Total chunks received: {len(chunks)}")
        logger.debug(f"First chunk structure: {chunks[0] if chunks else 'None'}")

        # Aggregate content based on SHOW_THINK_TAGS setting
        if settings.SHOW_THINK_TAGS:
            # Include all content
            full_content = "".join(
                chunk.get("data", {}).get("delta_content", "") for chunk in chunks
            )
        else:
            # Only include answer phase content
            full_content = "".join(
                chunk.get("data", {}).get("delta_content", "")
                for chunk in chunks
                if chunk.get("data", {}).get("phase") == "answer"
            )

        logger.info(f"Aggregated content length: {len(full_content)}")
        logger.debug(f"Full aggregated content: {full_content}")  # Show full content for debugging

        # Apply content transformation (including think tag filtering)
        transformed_content = self.transform_content(full_content)

        logger.info(f"Transformed content length: {len(transformed_content)}")
        logger.debug(f"Transformed content: {transformed_content[:200]}...")

        # Create OpenAI-compatible response
        return ChatCompletionResponse(
            id=chunks[0].get("data", {}).get("id", "chatcmpl-unknown"),
            created=int(time.time()),
            model=model,
            choices=[{
                "index": 0,
                "message": {
                    "role": "assistant",
                    "content": transformed_content
                },
                "finish_reason": "stop"
            }]
        )