import logging
from typing import List, Dict, Any, Union, AsyncGenerator

# LangChain imports
from langchain_openai import ChatOpenAI
from langchain_anthropic import ChatAnthropic
from langchain_cohere import ChatCohere
from langchain_huggingface import ChatHuggingFace, HuggingFaceEndpoint
from langchain_core.messages import SystemMessage, HumanMessage

# Local imports
from .utils import getconfig, get_auth
from .prompts import system_prompt
from .sources import (
    _process_context,
    _build_messages,
    _parse_citations,
    _extract_sources,
    _create_sources_list,
    clean_citations
)


# Set up logger
logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------
# Configuration and Model Initialization
# ---------------------------------------------------------------------
config = getconfig("params.cfg")
PROVIDER = config.get("generator", "PROVIDER")
MODEL = config.get("generator", "MODEL")
MAX_TOKENS = int(config.get("generator", "MAX_TOKENS"))
TEMPERATURE = float(config.get("generator", "TEMPERATURE"))
INFERENCE_PROVIDER = config.get("generator", "INFERENCE_PROVIDER")
ORGANIZATION = config.get("generator", "ORGANIZATION")

# Set up authentication for the selected provider
auth_config = get_auth(PROVIDER)

def _get_chat_model():
    """Initialize the appropriate LangChain chat model based on provider"""
    common_params = {"temperature": TEMPERATURE, "max_tokens": MAX_TOKENS}
    
    providers = {
        "openai": lambda: ChatOpenAI(model=MODEL, openai_api_key=auth_config["api_key"], streaming=True, **common_params),
        "anthropic": lambda: ChatAnthropic(model=MODEL, anthropic_api_key=auth_config["api_key"], streaming=True, **common_params),
        "cohere": lambda: ChatCohere(model=MODEL, cohere_api_key=auth_config["api_key"], streaming=True, **common_params),
        "huggingface": lambda: ChatHuggingFace(llm=HuggingFaceEndpoint(
            repo_id=MODEL, 
            huggingfacehub_api_token=auth_config["api_key"], 
            task="text-generation", 
            provider=INFERENCE_PROVIDER,
            server_kwargs={"bill_to": ORGANIZATION},
            temperature=TEMPERATURE, 
            max_new_tokens=MAX_TOKENS, 
            streaming=True
        ))
    }
    
    if PROVIDER not in providers:
        raise ValueError(f"Unsupported provider: {PROVIDER}")
    
    return providers[PROVIDER]()

# Initialize chat model
chat_model = _get_chat_model()


# ---------------------------------------------------------------------
# LLM Call Functions
# ---------------------------------------------------------------------
async def _call_llm(messages: list) -> str:
    """Provider-agnostic LLM call using LangChain (non-streaming)"""
    try:
        response = await chat_model.ainvoke(messages)
        return response.content.strip()
    except Exception as e:
        logger.exception(f"LLM generation failed with provider '{PROVIDER}' and model '{MODEL}': {e}")
        raise

async def _call_llm_streaming(messages: list) -> AsyncGenerator[str, None]:
    """Provider-agnostic streaming LLM call using LangChain"""
    try:
        async for chunk in chat_model.astream(messages):
            if hasattr(chunk, 'content') and chunk.content:
                yield chunk.content
    except Exception as e:
        logger.exception(f"LLM streaming failed with provider '{PROVIDER}' and model '{MODEL}': {e}")
        yield f"Error: {str(e)}"

# ---------------------------------------------------------------------
# Main Generation Functions
# ---------------------------------------------------------------------
async def generate(query: str, context: Union[str, List[Dict[str, Any]]], chatui_format: bool = False) -> Union[str, Dict[str, Any]]:
    """Generate an answer to a query using provided context through RAG"""
    if not query.strip():
        error_msg = "Query cannot be empty"
        return {"error": error_msg} if chatui_format else f"Error: {error_msg}"
    
    try:
        formatted_context, processed_results = _process_context(context)
        messages = _build_messages(query, formatted_context)
        answer = await _call_llm(messages)
        
        # Clean citations to ensure proper format and remove unwanted sections
        answer = clean_citations(answer)
        
        if chatui_format:
            result = {"answer": answer}
            if processed_results:
                cited_numbers = _parse_citations(answer)
                cited_sources = _extract_sources(processed_results, cited_numbers)
                result["sources"] = _create_sources_list(cited_sources)
            return result
        else:
            return answer
            
    except Exception as e:
        logger.exception("Generation failed")
        error_msg = str(e)
        return {"error": error_msg} if chatui_format else f"Error: {error_msg}"

async def generate_streaming(query: str, context: Union[str, List[Dict[str, Any]]], chatui_format: bool = False) -> AsyncGenerator[Union[str, Dict[str, Any]], None]:
    """Generate a streaming answer to a query using provided context through RAG"""
    if not query.strip():
        error_msg = "Query cannot be empty"
        if chatui_format:
            yield {"event": "error", "data": {"error": error_msg}}
        else:
            yield f"Error: {error_msg}"
        return
    
    try:
        formatted_context, processed_results = _process_context(context)
        messages = _build_messages(system_prompt, query, formatted_context)
        
        # Stream the response and accumulate for citation parsing (filter out any sources that were not cited)
        accumulated_response = ""
        async for chunk in _call_llm_streaming(messages):
            accumulated_response += chunk
            if chatui_format:
                yield {"event": "data", "data": chunk}
            else:
                yield chunk
        
        # Clean citations in the complete response
        cleaned_response = clean_citations(accumulated_response)
        
        # Send sources at the end if available and in ChatUI format
        if chatui_format and processed_results:
            cited_numbers = _parse_citations(cleaned_response)
            cited_sources = _extract_sources(processed_results, cited_numbers)
            sources = _create_sources_list(cited_sources)
            yield {"event": "sources", "data": {"sources": sources}}
        
        # Send END event for ChatUI format
        if chatui_format:
            yield {"event": "end", "data": {}}
        
    except Exception as e:
        logger.exception("Streaming generation failed")
        error_msg = str(e)
        if chatui_format:
            yield {"event": "error", "data": {"error": error_msg}}
        else:
            yield f"Error: {error_msg}"