import asyncio
import logging
from typing import Dict, Any

from fastapi import HTTPException, UploadFile, status, Depends
from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
from config import Config

from .rag_pipeline import route_and_process_query, add_document_to_rag, check_system_health
from .document_handler import extract_text_from_file

# Configure logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

security = HTTPBearer()

# Supported file types
SUPPORTED_CONTENT_TYPES = Config.RAG_SUPPORTED_CONTENT_TYPES

MAX_FILE_SIZE = Config.RAG_MAX_FILE_SIZE
MAX_QUERY_LENGTH = Config.RAG_MAX_QUERY_LENGTH

async def verify_token(credentials: HTTPAuthorizationCredentials = Depends(security)):
    """Verify Bearer token from Authorization header."""
    token = credentials.credentials
    expected_token = Config.SECRET_TOKEN
    
    if not expected_token:
        logger.error("MY_SECRET_TOKEN not configured")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Server configuration error"
        )
    
    if token != expected_token:
        logger.warning(f"Invalid token attempt: {token[:10]}...")
        raise HTTPException(
            status_code=status.HTTP_403_FORBIDDEN,
            detail="Invalid or expired token"
        )
    return token

async def handle_rag_query(query: str) -> Dict[str, Any]:
    """Handle an incoming query by routing it and getting the appropriate answer."""
    
    # Input validation
    if not query or not query.strip():
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST, 
            detail="Query cannot be empty"
        )
    
    if len(query) > MAX_QUERY_LENGTH:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail=f"Query too long. Please limit to {MAX_QUERY_LENGTH} characters."
        )
    
    try:
        logger.info(f"Processing query: {query[:50]}...")
        
        # Process query in thread pool 
        response = await asyncio.to_thread(route_and_process_query, query)
        
        logger.info(f"Query processed successfully. Route: {response.get('route', 'Unknown')}")
        return response
        
    except Exception as e:
        logger.error(f"Error processing query: {e}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Error processing your query. Please try again."
        )

async def handle_document_upload(file: UploadFile) -> Dict[str, str]:
    """Handle uploading a document to the RAG's vector store."""
    
    # File validation
    if not file.filename:
        raise HTTPException(
            status_code=status.HTTP_400_BAD_REQUEST,
            detail="No file provided"
        )
    
    if file.content_type not in SUPPORTED_CONTENT_TYPES:
        raise HTTPException(
            status_code=status.HTTP_415_UNSUPPORTED_MEDIA_TYPE,
            detail=f"Unsupported file type: {file.content_type}. "
                   f"Supported types: {', '.join(SUPPORTED_CONTENT_TYPES)}"
        )
    
    # Check file size
    contents = await file.read()
    if len(contents) > MAX_FILE_SIZE:
        raise HTTPException(
            status_code=status.HTTP_413_REQUEST_ENTITY_TOO_LARGE,
            detail=f"File too large. Maximum size: {MAX_FILE_SIZE / (1024*1024):.1f}MB"
        )
    
    # Reset file pointer
    await file.seek(0)
    
    try:
        logger.info(f"Processing file upload: {file.filename}")
        
        # Extract text from file
        text = await extract_text_from_file(file)
        
        if not text or not text.strip():
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="The file appears to be empty or could not be read."
            )
        
        if len(text) < 50:  # Too short to be meaningful
            raise HTTPException(
                status_code=status.HTTP_400_BAD_REQUEST,
                detail="The extracted text is too short to be meaningful."
            )
        
        # Add to RAG system
        success = await asyncio.to_thread(
            add_document_to_rag, 
            text, 
            {
                "source": file.filename,
                "content_type": file.content_type,
                "size": len(contents)
            }
        )
        
        if not success:
            raise HTTPException(
                status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
                detail="Failed to add document to the knowledge base"
            )
        
        logger.info(f"Successfully processed file: {file.filename}")
        
        return {
            "message": f"Successfully uploaded and processed '{file.filename}'. "
                      f"It is now available for querying.",
            "filename": file.filename,
            "text_length": len(text),
            "content_type": file.content_type
        }

    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Error processing file {file.filename}: {e}")
        raise HTTPException(
            status_code=status.HTTP_500_INTERNAL_SERVER_ERROR,
            detail="Error processing the file. Please try again."
        )

async def handle_health_check() -> Dict[str, Any]:
    """Handle health check requests."""
    try:
        health_status = await asyncio.to_thread(check_system_health)
        
        if health_status["status"] == "unhealthy":
            raise HTTPException(
                status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
                detail="Service is currently unhealthy"
            )
        
        return health_status
        
    except HTTPException:
        raise
    except Exception as e:
        logger.error(f"Health check failed: {e}")
        raise HTTPException(
            status_code=status.HTTP_503_SERVICE_UNAVAILABLE,
            detail="Health check failed"
        )