from typing import List, Dict, Optional
from pdf_parser import extract_text_from_pdfs
from vector_store import VectorStore
from embeddings import CLIPEmbedder
from multimodal_model import Gemma3Model  # ← Changed from GemmaVisionModel
import logging

logger = logging.getLogger(__name__)

class RAGPipeline:
    def __init__(self, pdf_dir: str, chroma_dir: str = "./chroma_db", device: str = "cpu"):
        self.pdf_dir = pdf_dir
        self.device = device
        
        logger.info("→ Initializing RAG Pipeline...")
        
        try:
            # Initialize embedder
            logger.debug("Loading embedder...")
            self.embedder = CLIPEmbedder(
                model_name="openai/clip-vit-base-patch32",
                device=device
            )
            
            # Initialize vector store
            logger.debug("Initializing vector store...")
            self.vector_store = VectorStore(persist_dir=chroma_dir)
            self.vector_store.get_or_create_collection()
            
            # Initialize LLM with Gemma3Model
            logger.debug("Loading Gemma 3 1B model...")
            self.llm = Gemma3Model(model_name="unsloth/gemma-3-1b-pt", device=device)  # ← Use Gemma3Model
            
            logger.info("✓ RAG Pipeline initialized successfully")
        
        except Exception as e:
            logger.error(f"Failed to initialize pipeline: {str(e)}", exc_info=True)
            raise
    
    def index_pdfs(self):
        """Index PDFs with error logging"""
        logger.info("→ Starting PDF indexing...")
        
        try:
            documents, metadatas = extract_text_from_pdfs(self.pdf_dir)
            
            if not documents:
                logger.warning("No documents extracted")
                return
            
            logger.debug(f"Extracted {len(documents)} document chunks")
            
            ids = [f"doc_{i}" for i in range(len(documents))]
            self.vector_store.add_documents(documents, metadatas, ids)
            
            logger.info(f"✓ Indexed {len(documents)} document chunks")
        
        except Exception as e:
            logger.error(f"Error during indexing: {str(e)}", exc_info=True)
            raise
    
    def retrieve_documents(self, query: str, n_results: int = 5) -> List[Dict]:
        """Retrieve documents with error handling"""
        try:
            logger.debug(f"Searching for: {query[:50]}...")
            results = self.vector_store.search(query, n_results=n_results)
            
            retrieved_docs = []
            for doc, metadata in zip(results["documents"][0], results["metadatas"][0]):
                retrieved_docs.append({
                    "content": doc,
                    "source": f"{metadata.get('filename', 'Unknown')} (p{metadata.get('page', '?')})"
                })
            
            logger.debug(f"Retrieved {len(retrieved_docs)} documents")
            return retrieved_docs
        
        except Exception as e:
            logger.error(f"Error retrieving documents: {str(e)}", exc_info=True)
            return []
    
    def answer_question(self, question: str, n_context_docs: int = 3) -> Dict:
        """Answer question using RAG with comprehensive error handling"""
        
        logger.info(f"Processing question: {question[:50]}...")
        
        try:
            # Retrieve relevant documents
            logger.debug(f"Retrieving {n_context_docs} documents...")
            retrieved_docs = self.retrieve_documents(question, n_results=n_context_docs)
            
            if not retrieved_docs:
                logger.warning("No documents retrieved")
                return {
                    "answer": "No relevant documents found.",
                    "sources": [],
                    "context_used": 0
                }
            
            logger.debug(f"Retrieved {len(retrieved_docs)} documents")
            
            # Combine context (limit to prevent memory issues)
            context = "\n\n".join([
                f"[{doc['source']}]\n{doc['content'][:500]}"
                for doc in retrieved_docs
            ])[:2000]
            
            logger.debug("Generating answer with Gemma 3...")
            
            try:
                # Use greedy decoding for faster inference with Gemma 3
                answer = self.llm.answer_question(question, context)
            except Exception as e:
                logger.warning(f"Answer generation failed ({e}), using greedy fallback...")
                # Fallback to greedy
                answer = self.llm.generate_response_greedy(
                    f"Q: {question}\nA:"
                )
            
            # Extract answer
            if "Answer:" in answer:
                answer = answer.split("Answer:")[-1].strip()
            
            logger.info("✓ Answer generated successfully")
            
            return {
                "answer": answer[:1000],  # Limit output length
                "sources": [doc["source"] for doc in retrieved_docs],
                "context_used": len(retrieved_docs)
            }
        
        except Exception as e:
            logger.error(f"Error in answer_question: {str(e)}", exc_info=True)
            return {
                "answer": f"Error generating answer: {str(e)}",
                "sources": [],
                "context_used": 0
            }
    
    def summarize_documents(self) -> str:
        """Summarize all indexed documents"""
        collection_info = self.vector_store.get_collection_info()
        doc_count = collection_info.get("document_count", 0)
        
        if doc_count == 0:
            return "No documents to summarize"
        
        # Sample documents
        results = self.vector_store.search("main topic summary", n_results=5)
        sampled_content = " ".join([doc for docs in results["documents"] for doc in docs[:200]])
        
        summary = self.llm.summarize_text(sampled_content)
        return summary
    
    def get_collection_info(self) -> Dict:
        """Get collection statistics"""
        return self.vector_store.get_collection_info()