import logging
import math

from fastapi import APIRouter, Depends, HTTPException

from app.api.schemas import (
    AnswerGenerationRequest,
    AnswerGenerationResponse,
    DocumentSearchRequest,
    DocumentSearchResponse,
    RetrievedDocument,
)
from app.dependencies import get_rag_service
from app.services.rag_service import RAGService

router = APIRouter()
logger = logging.getLogger(__name__)


def sanitize_score(score: float | None) -> float | None:
    """Replace NaN and infinity values with 0.0"""
    if score is None:
        logger.debug("Score is None, returning None")
        return None

    if math.isnan(score):
        logger.warning("NaN score detected, replacing with 0.0")
        return 0.0

    if math.isinf(score):
        logger.warning(f"Infinite score detected ({score}), replacing with 0.0")
        return 0.0

    logger.debug(f"Score is valid: {score}")
    return score


def sanitize_retrieved_documents(
    documents: list[RetrievedDocument],
) -> list[RetrievedDocument]:
    """Ensure all document scores are valid JSON-serializable values"""
    logger.debug(f"Sanitizing scores for {len(documents)} documents")

    sanitized_count = 0
    for i, doc in enumerate(documents):
        if doc.score is not None:
            original_score = doc.score
            doc.score = sanitize_score(doc.score)

            if original_score != doc.score:
                logger.debug(
                    f"Document {i + 1}: sanitized score {original_score} -> {doc.score}"
                )
                sanitized_count += 1
            else:
                logger.debug(f"Document {i + 1}: score {doc.score} unchanged")

    if sanitized_count > 0:
        logger.info(f"Sanitized {sanitized_count} document scores")
    else:
        logger.debug("No score sanitization needed")

    return documents


@router.post("/search", response_model=DocumentSearchResponse)
async def search_documents(
    request: DocumentSearchRequest, rag_service: RAGService = Depends(get_rag_service)
) -> DocumentSearchResponse:
    """
    Search for relevant documents based on the query.
    Returns top K most relevant documents.
    """
    logger.info(
        f"Document search request received: query='{request.query}', top_k={request.top_k}"
    )

    try:
        logger.debug("Calling RAG service for document search")
        documents = rag_service.search_documents(
            query=request.query, top_k=request.top_k
        )
        logger.debug(f"RAG service returned {len(documents)} documents")

        logger.debug("Sanitizing document scores")
        sanitized_documents = sanitize_retrieved_documents(documents)

        response = DocumentSearchResponse(
            query=request.query,
            documents=sanitized_documents,
            total_results=len(sanitized_documents),
        )

        logger.info(
            f"Document search completed successfully: {len(sanitized_documents)} results returned"
        )
        return response

    except Exception as e:
        logger.error(
            f"Document search failed for query '{request.query}': {str(e)}",
            exc_info=True,
        )
        raise HTTPException(status_code=500, detail=str(e)) from e


@router.post("/answer", response_model=AnswerGenerationResponse)
async def generate_answer(
    request: AnswerGenerationRequest, rag_service: RAGService = Depends(get_rag_service)
) -> AnswerGenerationResponse:
    """
    Generate an answer based on the query using RAG.
    Optionally returns the source documents used.
    """
    logger.info(
        f"Answer generation request received: query='{request.query}', top_k={request.top_k}, include_sources={request.include_sources}"
    )

    try:
        logger.debug("Calling RAG service for answer generation")
        result = rag_service.generate_answer(
            query=request.query,
            top_k=request.top_k,
            include_sources=request.include_sources,
        )
        logger.debug(
            f"RAG service returned result with answer length: {len(result.get('answer', ''))}"
        )

        if "sources" in result and result["sources"]:
            logger.debug(
                f"Sanitizing scores for {len(result['sources'])} source documents"
            )
            result["sources"] = sanitize_retrieved_documents(result["sources"])
        else:
            logger.debug("No sources to sanitize")

        response = AnswerGenerationResponse(**result)

        answer_length = len(result.get("answer", ""))
        documents_used = result.get("documents_used", 0)
        retrieval_method = result.get("retrieval_method", "unknown")

        logger.info(
            f"Answer generation completed successfully: {answer_length} chars generated, {documents_used} documents used, method={retrieval_method}"
        )
        return response

    except Exception as e:
        logger.error(
            f"Answer generation failed for query '{request.query}': {str(e)}",
            exc_info=True,
        )
        raise HTTPException(status_code=500, detail=str(e)) from e


@router.get("/health")
async def health_check():
    """Check if the service is healthy and index is loaded"""
    logger.debug("Health check request received")

    try:
        response = {"status": "healthy", "index_loaded": True}
        logger.debug("Health check completed successfully")
        return response

    except Exception as e:
        logger.error(f"Health check failed: {str(e)}", exc_info=True)
        return {"status": "unhealthy", "index_loaded": False}