import json
from pathlib import Path

import httpx
from typing import Optional, AsyncIterator, Dict, Any, Iterator, List, Callable
import logging
import asyncio
from litserve import LitAPI
from pydantic import BaseModel
from .utils import extract_json


class GenerationResponse(BaseModel):
    generated_text: str

class InferenceApi(LitAPI):
    def __init__(self, config: Dict[str, Any]):
        """Initialize the Inference API with configuration."""
        super().__init__()
        self.logger = logging.getLogger(__name__)
        self.logger.info("Initializing Inference API")
        self._device = None
        self.stream = False
        self.config = config
        self.llm_config = config.get('llm_server', {})

    def setup(self, device: Optional[str] = None):
        """Synchronous setup method required by LitAPI"""
        self._device = device
        self.logger.info(f"Inference API setup completed on device: {device}")
        return self  # It's common for setup methods to return self for chaining

    async def _get_client(self):
        """Get or create HTTP client as needed"""
        host = self.llm_config.get('host', 'localhost')
        port = self.llm_config.get('port', 8002)

        # Construct base URL, omitting port for HF spaces
        if 'hf.space' in host:
            base_url = f"https://{host}"
        else:
            base_url = f"http://{host}:{port}"

        return httpx.AsyncClient(
            base_url=base_url,
            timeout=float(self.llm_config.get('timeout', 60.0))
        )

    def _get_endpoint(self, endpoint_name: str) -> str:
        """Get full endpoint path including prefix"""
        endpoints = self.llm_config.get('endpoints', {})
        api_prefix = self.llm_config.get('api_prefix', '')
        endpoint = endpoints.get(endpoint_name, '')
        return f"{api_prefix}{endpoint}"

    async def _make_request(
            self,
            method: str,
            endpoint: str,
            *,
            params: Optional[Dict[str, Any]] = None,
            json: Optional[Dict[str, Any]] = None,
            stream: bool = False
    ) -> Any:
        """Make an authenticated request to the LLM Server."""
        base_url = self.llm_config.get('base_url', 'http://localhost:8002')
        full_endpoint = f"{base_url.rstrip('/')}/{self._get_endpoint(endpoint).lstrip('/')}"

        try:
            self.logger.info(f"Making {method} request to: {full_endpoint}")
            async with await self._get_client() as client:
                if stream:
                    return await client.stream(
                        method,
                        self._get_endpoint(endpoint),
                        params=params,
                        json=json
                    )
                else:
                    response = await client.request(
                        method,
                        self._get_endpoint(endpoint),
                        params=params,
                        json=json
                    )
                    response.raise_for_status()
                    return response

        except Exception as e:
            self.logger.error(f"Error in request to {full_endpoint}: {str(e)}")
            raise

    def predict(self, x: str, **kwargs) -> Iterator[str]:
        """Non-async prediction method that yields results."""
        loop = asyncio.get_event_loop()
        async def async_gen():
            async for item in self._async_predict(x, **kwargs):
                yield item

        gen = async_gen()
        while True:
            try:
                yield loop.run_until_complete(gen.__anext__())
            except StopAsyncIteration:
                break

    async def _async_predict(self, x: str, **kwargs) -> AsyncIterator[str]:
        """Internal async prediction method."""
        if self.stream:
            async for chunk in self.generate_stream(x, **kwargs):
                yield chunk
        else:
            response = await self.generate_response(x, **kwargs)
            yield response

    async def generate_response(
            self,
            prompt: str,
            system_message: Optional[str] = None,
            max_new_tokens: Optional[int] = None
    ) -> str:
        """Generate a complete response by forwarding the request to the LLM Server."""
        self.logger.debug(f"Forwarding generation request for prompt: {prompt[:50]}...")

        try:
            response = await self._make_request(
                "POST",
                "generate",
                json={
                    "prompt": prompt,
                    "system_message": system_message,
                    "max_new_tokens": max_new_tokens
                }
            )
            data = response.json()
            return data["generated_text"]

        except Exception as e:
            self.logger.error(f"Error in generate_response: {str(e)}")
            raise

    async def structured_llm_query(
            self,
            template_name: str,
            input_text: str,
            additional_context: Optional[Dict[str, Any]] = None,
            pre_hooks: Optional[List[Callable]] = None,
            post_hooks: Optional[List[Callable]] = None
    ) -> Dict[str, Any]:
        """Execute a structured LLM query using a template."""
        template_path = Path(__file__).parent / "prompt_templates" / f"{template_name}.json"

        try:
            # Load and parse template
            with open(template_path) as f:
                template = json.load(f)

            # Apply pre-processing hooks
            processed_input = input_text
            if pre_hooks:
                for hook in pre_hooks:
                    processed_input = hook(processed_input)

            # Format the prompt with the context
            context = {"input_text": processed_input}
            if additional_context:
                context.update(additional_context)

            prompt = template["prompt_template"].format(**context)

            # Make the request to the LLM
            response = await self._make_request(
                "POST",
                "generate",
                json={
                    "prompt": prompt,
                    "system_message": template.get("system_message"),
                    "max_new_tokens": 1000
                }
            )

            # Extract JSON from response
            data = response.json()
            result = extract_json(data["generated_text"])

            # Apply any additional post-processing hooks
            if post_hooks:
                for hook in post_hooks:
                    result = hook(result)

            return result

        except FileNotFoundError:
            raise ValueError(f"Template {template_name} not found")
        except Exception as e:
            self.logger.error(f"Error in structured_llm_query: {str(e)}")
            raise

    async def expand_query(
            self,
            query: str,
            system_message: Optional[str] = None
    ) -> Dict[str, Any]:
        """Expand a query for RAG processing."""
        return await self.structured_llm_query(
            template_name="query_expansion",
            input_text=query,
            additional_context={"system_message": system_message} if system_message else None
        )

    async def rerank_chunks(
            self,
            query: str,
            chunks: List[str],
            system_message: Optional[str] = None
    ) -> Dict[str, Any]:
        """Rerank text chunks based on their relevance to the query."""
        # Format chunks as numbered list for better LLM processing
        formatted_chunks = "\n".join(f"{i+1}. {chunk}" for i, chunk in enumerate(chunks))

        return await self.structured_llm_query(
            template_name="chunk_rerank",
            input_text=query,
            additional_context={
                "chunks": formatted_chunks,
                "system_message": system_message
            }
        )


    async def generate_stream(
            self,
            prompt: str,
            system_message: Optional[str] = None,
            max_new_tokens: Optional[int] = None
    ) -> AsyncIterator[str]:
        """Generate a streaming response by forwarding the request to the LLM Server."""
        self.logger.debug(f"Forwarding streaming request for prompt: {prompt[:50]}...")

        try:
            async with await self._make_request(
                    "POST",
                    "generate_stream",
                    json={
                        "prompt": prompt,
                        "system_message": system_message,
                        "max_new_tokens": max_new_tokens
                    },
                    stream=True
            ) as response:
                async for chunk in response.aiter_text():
                    yield chunk

        except Exception as e:
            self.logger.error(f"Error in generate_stream: {str(e)}")
            raise

    async def generate_embedding(self, text: str) -> List[float]:
        """Generate embedding vector from input text."""
        self.logger.debug(f"Forwarding embedding request for text: {text[:50]}...")

        try:
            response = await self._make_request(
                "POST",
                "embedding",
                json={"text": text}
            )
            data = response.json()
            return data["embedding"]

        except Exception as e:
            self.logger.error(f"Error in generate_embedding: {str(e)}")
            raise

    async def check_system_status(self) -> Dict[str, Any]:
        """Check system status of the LLM Server."""
        self.logger.debug("Checking system status...")

        try:
            response = await self._make_request(
                "GET",
                "system_status"
            )
            return response.json()

        except Exception as e:
            self.logger.error(f"Error in check_system_status: {str(e)}")
            raise

    async def download_model(self, model_name: Optional[str] = None) -> Dict[str, str]:
        """Download model files from the LLM Server."""
        self.logger.debug(f"Forwarding model download request for: {model_name or 'default model'}")

        try:
            response = await self._make_request(
                "POST",
                "model_download",
                params={"model_name": model_name} if model_name else None
            )
            return response.json()

        except Exception as e:
            self.logger.error(f"Error in download_model: {str(e)}")
            raise

    async def validate_system(self) -> Dict[str, Any]:
        """Validate system configuration and setup."""
        self.logger.debug("Validating system configuration...")

        try:
            response = await self._make_request(
                "GET",
                "system_validate"
            )
            return response.json()

        except Exception as e:
            self.logger.error(f"Error in validate_system: {str(e)}")
            raise

    async def initialize_model(self, model_name: Optional[str] = None) -> Dict[str, Any]:
        """Initialize specified model or default model."""
        self.logger.debug(f"Initializing model: {model_name or 'default'}")

        try:
            response = await self._make_request(
                "POST",
                "model_initialize",
                params={"model_name": model_name} if model_name else None
            )
            return response.json()

        except Exception as e:
            self.logger.error(f"Error in initialize_model: {str(e)}")
            raise

    async def initialize_embedding_model(self, model_name: Optional[str] = None) -> Dict[str, Any]:
        """Initialize embedding model."""
        self.logger.debug(f"Initializing embedding model: {model_name or 'default'}")

        try:
            response = await self._make_request(
                "POST",
                "model_initialize_embedding",
                json={"model_name": model_name} if model_name else {}
            )
            return response.json()

        except Exception as e:
            self.logger.error(f"Error in initialize_embedding_model: {str(e)}")
            raise

    def decode_request(self, request: Any, **kwargs) -> str:
        """Convert the request payload to input format."""
        if isinstance(request, dict) and "prompt" in request:
            return request["prompt"]
        return request

    def encode_response(self, output: Iterator[str], **kwargs) -> Dict[str, Any]:
        """Convert the model output to a response payload."""
        if self.stream:
            return {"generated_text": output}
        try:
            result = next(output)
            return {"generated_text": result}
        except StopIteration:
            return {"generated_text": ""}

    async def cleanup(self):
        """Cleanup method - no longer needed as clients are created per-request"""
        pass