"""
Document Loader
Scans PDF folder, processes PDFs, and stores in database + Qdrant
"""

import sys
from pathlib import Path

# Add project root to path
project_root = Path(__file__).parent.parent.parent
sys.path.insert(0, str(project_root))

from typing import Dict
from datetime import datetime
from src.cdms.pdf_processor import PDFProcessor
from src.cdms.schema import DatabaseManager, Document, DocumentChunk
from src.rag.embeddings import OpenAIEmbeddingService
from src.rag.vector_store import QdrantVectorStore, get_shared_vector_store
from src.config.credentials import CredentialsManager
from src.config.paths import PDF_DIR
from src.cdms.product_catalog import normalize_filename


class DocumentLoader:
    """
    Loads and indexes PDF documents for RAG
    
    Usage:
        loader = DocumentLoader()
        loader.load_all_pdfs()  # Process all PDFs in data/pdfs/
    """
    
    def __init__(self, pdf_folder: str = None, vector_store=None):
        """
        Initialize document loader

        Args:
            pdf_folder: Folder containing PDF files (defaults to the CDMS PDF dir
                        PDF_DIR = <root>/data/pdfs/cdms, where the labels live)
            vector_store: Optional shared QdrantVectorStore. The embedded (on-disk)
                        Qdrant allows only ONE client per path per process, so in
                        online mode the loader MUST reuse the RAG searcher's store
                        instead of opening a second one (which would lock-fail and
                        silently drop the freshly fetched label's chunks).
        """
        self.pdf_folder = Path(pdf_folder) if pdf_folder is not None else PDF_DIR
        self.pdf_folder.mkdir(parents=True, exist_ok=True)
        
        # Initialize components
        self.pdf_processor = PDFProcessor()
        self.db_manager = DatabaseManager()
        
        # Initialize embedding service (will load OpenAI key)
        try:
            creds = CredentialsManager()
            openai_key = creds.get_api_key("openai")
            self.embedding_service = OpenAIEmbeddingService(api_key=openai_key)
        except Exception as e:
            print(f"⚠️  Warning: Could not initialize OpenAI embeddings: {e}")
            self.embedding_service = None
        
        # Reuse the provided store, else the process-wide singleton (never open a
        # second client to the embedded store — see get_shared_vector_store).
        if vector_store is not None:
            self.vector_store = vector_store
        else:
            try:
                self.vector_store = get_shared_vector_store()
            except Exception as e:
                print(f"⚠️  Warning: Could not initialize Qdrant: {e}")
                self.vector_store = None
    
    def load_pdf(self, pdf_path: str, force_reprocess: bool = False, pdf_url: str = None) -> Dict:
        """
        Load a single PDF file
        
        Args:
            pdf_path: Path to PDF file
            force_reprocess: If True, reprocess even if already indexed
            pdf_url: Optional original PDF URL (for CDMS labels from Tavily)
        
        Returns:
            Dict with processing result
        """
        pdf_path = Path(pdf_path)
        
        if not pdf_path.exists():
            return {
                "success": False,
                "error": f"File not found: {pdf_path}"
            }
        
        # Check if already processed
        session = self.db_manager.get_session()
        try:
            doc_id = Document.generate_id(str(pdf_path))
            existing_doc = session.query(Document).filter_by(id=doc_id).first()
            
            if existing_doc and existing_doc.processed == 1 and not force_reprocess:
                return {
                    "success": True,
                    "message": f"PDF already processed: {pdf_path.name}",
                    "document_id": doc_id,
                    "skipped": True
                }
            
            # If force reprocess, delete old chunks and document
            if force_reprocess and existing_doc:
                # Delete old chunks
                session.query(DocumentChunk).filter_by(document_id=doc_id).delete()
                # Delete old document
                session.delete(existing_doc)
                session.commit()
                print(f"🔄 Re-processing: {pdf_path.name}")
        
            # Process PDF
            print(f"📄 Processing: {pdf_path.name}")
            result = self.pdf_processor.process_pdf(str(pdf_path))
            
            if not result["success"]:
                return result
            
            # Store in database. Persist the source URL in doc_metadata so
            # citations survive even if Qdrant is rebuilt from SQLite alone.
            doc = Document(
                id=doc_id,
                filename=pdf_path.name,
                filepath=str(pdf_path),
                file_size=pdf_path.stat().st_size,
                num_pages=result["num_pages"],
                num_chunks=result["num_chunks"],
                processed=1,
                last_processed=datetime.utcnow(),
                doc_metadata={"pdf_url": pdf_url} if pdf_url else None
            )

            session.merge(doc)
            
            # Store chunks with accurate page numbers
            chunks = result.get("chunks", [])
            page_numbers = result.get("page_numbers", [])

            # PHASE 2 FIX: Validate page numbers with warnings
            if not page_numbers:
                print(f"⚠️  Warning: No page numbers provided for {pdf_path.name}, estimating...")
                page_numbers = [(idx // 3) + 1 for idx in range(len(chunks))]
            elif len(page_numbers) != len(chunks):
                print(f"⚠️  Warning: Page numbers count ({len(page_numbers)}) doesn't match chunks count ({len(chunks)}) for {pdf_path.name}")
                # Fix by padding or truncating to match
                if len(page_numbers) < len(chunks):
                    last_page = page_numbers[-1] if page_numbers else 1
                    page_numbers.extend([last_page] * (len(chunks) - len(page_numbers)))
                else:
                    page_numbers = page_numbers[:len(chunks)]

            # URL hash for reliable matching (computed once per PDF).
            url_hash = ""
            if pdf_url:
                import hashlib
                url_hash = hashlib.md5(pdf_url.encode()).hexdigest()[:12]

            # Normalized product name (e.g. "roundup_bdc94bbee383.pdf" -> "roundup")
            # stored in the payload so retrieval can filter by product AT the vector
            # level, instead of post-filtering a global (Roundup-dominated) top-k.
            product = normalize_filename(pdf_path.name)

            # Pass 1: write SQLite chunk rows and collect texts for BATCH embedding.
            # (Previously embeddings were generated one OpenAI call per chunk; batching
            # collapses ~N calls per PDF into a single request -- ~2100 calls -> ~53.)
            chunk_ids = []
            chunk_texts = []
            chunk_pages = []
            chunk_indices = []
            for idx, (chunk_text, page_num) in enumerate(zip(chunks, page_numbers)):
                # PHASE 2 FIX: Validate page number is positive
                if page_num <= 0:
                    page_num = (idx // 3) + 1
                    page_numbers[idx] = page_num
                chunk_id = DocumentChunk.generate_id(doc_id, idx)

                # Calculate token count (rough estimate: 1 token ≈ 4 chars)
                token_count = len(chunk_text) // 4

                chunk = DocumentChunk(
                    id=chunk_id,
                    document_id=doc_id,
                    chunk_index=idx,
                    content=chunk_text,
                    page_number=page_num,  # ENHANCED: Accurate page number from PDF processor
                    char_count=len(chunk_text),
                    token_count=token_count
                )
                session.merge(chunk)

                chunk_ids.append(chunk_id)
                chunk_texts.append(chunk_text)
                chunk_pages.append(page_num)
                chunk_indices.append(idx)

            chunks_stored = len(chunk_ids)
            embeddings_generated = 0

            # Pass 2: one batched embedding request per PDF, then upsert to Qdrant.
            if self.embedding_service and self.vector_store and chunk_texts:
                try:
                    embeddings = self.embedding_service.generate_embeddings_batch(chunk_texts)
                    for chunk_id, embedding, chunk_text, page_num, idx in zip(
                        chunk_ids, embeddings, chunk_texts, chunk_pages, chunk_indices
                    ):
                        metadata = {
                            "document_id": doc_id,
                            "document_name": pdf_path.name,
                            "chunk_index": idx,
                            "content": chunk_text,  # Store full content for search
                            "page_number": page_num,  # ENHANCED: Accurate page number
                            "source_file": pdf_path.name,
                            "product": product,  # normalized product for Qdrant-level filtering
                            "pdf_url": pdf_url if pdf_url else "",  # PHASE 1 FIX: Store PDF URL in metadata
                            "url_hash": url_hash  # PHASE 1 FIX: Store URL hash for reliable matching
                        }
                        self.vector_store.add_document_chunk(
                            chunk_id=chunk_id,
                            embedding=embedding,
                            metadata=metadata
                        )
                        embeddings_generated += 1
                except Exception as e:
                    print(f"⚠️  Warning: Could not generate embeddings for {pdf_path.name}: {e}")

            session.commit()
            
            return {
                "success": True,
                "document_id": doc_id,
                "filename": pdf_path.name,
                "chunks_stored": chunks_stored,
                "embeddings_generated": embeddings_generated,
                "num_pages": result["num_pages"]
            }
        
        finally:
            session.close()
    
    def load_all_pdfs(self, force_reprocess: bool = False) -> Dict:
        """
        Load all PDFs from the pdf_folder
        
        Returns:
            Dict with summary of processing
        """
        if not self.pdf_folder.exists():
            return {
                "success": False,
                "error": f"PDF folder not found: {self.pdf_folder}"
            }
        
        pdf_files = list(self.pdf_folder.glob("*.pdf"))
        
        if not pdf_files:
            return {
                "success": False,
                "error": f"No PDF files found in {self.pdf_folder}"
            }
        
        print(f"📚 Found {len(pdf_files)} PDF file(s)")
        print("-" * 70)
        
        results = []
        for pdf_file in pdf_files:
            result = self.load_pdf(str(pdf_file), force_reprocess=force_reprocess)
            results.append(result)
            if result.get("success") and not result.get("skipped"):
                print(f"✅ {pdf_file.name}: {result.get('chunks_stored', 0)} chunks, {result.get('embeddings_generated', 0)} embeddings")
            elif result.get("skipped"):
                print(f"⏭️  {pdf_file.name}: Already processed (skipped)")
            print()
        
        # Summary
        successful = sum(1 for r in results if r.get("success"))
        total_chunks = sum(r.get("chunks_stored", 0) for r in results)
        total_embeddings = sum(r.get("embeddings_generated", 0) for r in results)
        
        return {
            "success": True,
            "total_files": len(pdf_files),
            "successful": successful,
            "total_chunks": total_chunks,
            "total_embeddings": total_embeddings,
            "results": results
        }


# Test function
if __name__ == "__main__":
    print("Testing Document Loader...")
    print("=" * 70)
    
    loader = DocumentLoader()
    
    # Load all PDFs
    result = loader.load_all_pdfs()
    
    if result.get("success"):
        print("\n" + "=" * 70)
        print("✅ Processing Complete!")
        print(f"   Files processed: {result['successful']}/{result['total_files']}")
        print(f"   Total chunks: {result['total_chunks']}")
        print(f"   Embeddings generated: {result['total_embeddings']}")
    else:
        print(f"\n❌ Error: {result.get('error')}")
        print("\n💡 To use:")
        print("   1. Create data/pdfs/ folder")
        print("   2. Add PDF files")
        print("   3. Make sure OPENAI_API_KEY is in .env")
        print("   4. Make sure Qdrant is running (Docker)")