"""ChromaDB integration for vector storage and retrieval."""
from typing import List, Dict, Optional, Tuple
import chromadb
from chromadb.config import Settings
import uuid
import os
from embedding_models import EmbeddingFactory, EmbeddingModel
from chunking_strategies import ChunkingFactory
import json


class ChromaDBManager:
    """Manager for ChromaDB operations."""
    
    def __init__(self, persist_directory: str = "./chroma_db"):
        """Initialize ChromaDB manager.
        
        Args:
            persist_directory: Directory to persist ChromaDB data
        """
        self.persist_directory = persist_directory
        os.makedirs(persist_directory, exist_ok=True)
        
        # Initialize ChromaDB client with is_persistent=True to use persistent storage
        try:
            self.client = chromadb.PersistentClient(
                path=persist_directory,
                settings=Settings(
                    anonymized_telemetry=False,
                    allow_reset=True  # Allow reset if needed
                )
            )
        except Exception as e:
            print(f"Warning: Could not create persistent client: {e}")
            print("Falling back to regular client...")
            self.client = chromadb.Client(Settings(
                persist_directory=persist_directory,
                anonymized_telemetry=False,
                allow_reset=True
            ))
        
        self.embedding_model = None
        self.current_collection = None
    
    def reconnect(self):
        """Reconnect to ChromaDB in case of connection loss."""
        try:
            self.client = chromadb.PersistentClient(
                path=self.persist_directory,
                settings=Settings(
                    anonymized_telemetry=False,
                    allow_reset=True
                )
            )
            print("✅ Reconnected to ChromaDB")
        except Exception as e:
            print(f"Error reconnecting: {e}")
    
    def create_collection(
        self,
        collection_name: str,
        embedding_model_name: str,
        metadata: Optional[Dict] = None
    ) -> chromadb.Collection:
        """Create a new collection.
        
        Args:
            collection_name: Name of the collection
            embedding_model_name: Name of the embedding model
            metadata: Additional metadata for the collection
            
        Returns:
            ChromaDB collection
        """
        # Delete if exists
        try:
            self.client.delete_collection(collection_name)
        except:
            pass
        
        # Create embedding model
        self.embedding_model = EmbeddingFactory.create_embedding_model(embedding_model_name)
        self.embedding_model.load_model()
        
        # Create collection with metadata
        collection_metadata = {
            "embedding_model": embedding_model_name,
            "hnsw:space": "cosine"
        }
        if metadata:
            collection_metadata.update(metadata)
        
        self.current_collection = self.client.create_collection(
            name=collection_name,
            metadata=collection_metadata
        )
        
        print(f"Created collection: {collection_name}")
        return self.current_collection
    
    def get_collection(self, collection_name: str) -> chromadb.Collection:
        """Get an existing collection.
        
        Args:
            collection_name: Name of the collection
            
        Returns:
            ChromaDB collection
        """
        self.current_collection = self.client.get_collection(collection_name)
        
        # Load embedding model from metadata
        metadata = self.current_collection.metadata
        if "embedding_model" in metadata:
            self.embedding_model = EmbeddingFactory.create_embedding_model(
                metadata["embedding_model"]
            )
            self.embedding_model.load_model()
        
        return self.current_collection
    
    def list_collections(self) -> List[str]:
        """List all collections.
        
        Returns:
            List of collection names
        """
        collections = self.client.list_collections()
        return [col.name for col in collections]
    
    def clear_all_collections(self) -> int:
        """Delete all collections from the database.
        
        Returns:
            Number of collections deleted
        """
        collections = self.list_collections()
        count = 0
        
        for collection_name in collections:
            try:
                self.client.delete_collection(collection_name)
                print(f"Deleted collection: {collection_name}")
                count += 1
            except Exception as e:
                print(f"Error deleting collection {collection_name}: {e}")
        
        self.current_collection = None
        self.embedding_model = None
        print(f"✅ Cleared {count} collections")
        return count
    
    def delete_collection(self, collection_name: str) -> bool:
        """Delete a specific collection.
        
        Args:
            collection_name: Name of the collection to delete
            
        Returns:
            True if deleted successfully, False otherwise
        """
        try:
            self.client.delete_collection(collection_name)
            if self.current_collection and self.current_collection.name == collection_name:
                self.current_collection = None
                self.embedding_model = None
            print(f"✅ Deleted collection: {collection_name}")
            return True
        except Exception as e:
            print(f"❌ Error deleting collection: {e}")
            return False
    
    def add_documents(
        self,
        documents: List[str],
        metadatas: Optional[List[Dict]] = None,
        ids: Optional[List[str]] = None,
        batch_size: int = 100
    ):
        """Add documents to the current collection.
        
        Args:
            documents: List of document texts
            metadatas: List of metadata dictionaries
            ids: List of document IDs
            batch_size: Batch size for processing
        """
        if not self.current_collection:
            raise ValueError("No collection selected. Create or get a collection first.")
        
        if not self.embedding_model:
            raise ValueError("No embedding model loaded.")
        
        # Generate IDs if not provided
        if ids is None:
            ids = [str(uuid.uuid4()) for _ in documents]
        
        # Generate default metadata if not provided
        if metadatas is None:
            metadatas = [{"index": i} for i in range(len(documents))]
        
        # Process in batches
        total_docs = len(documents)
        print(f"Adding {total_docs} documents to collection...")
        
        for i in range(0, total_docs, batch_size):
            batch_docs = documents[i:i + batch_size]
            batch_ids = ids[i:i + batch_size]
            batch_metadatas = metadatas[i:i + batch_size]
            
            # Generate embeddings
            embeddings = self.embedding_model.embed_documents(batch_docs)
            
            # Add to collection
            self.current_collection.add(
                documents=batch_docs,
                embeddings=embeddings.tolist(),
                metadatas=batch_metadatas,
                ids=batch_ids
            )
            
            print(f"Added batch {i//batch_size + 1}/{(total_docs-1)//batch_size + 1}")
        
        print(f"Successfully added {total_docs} documents")
    
    def load_dataset_into_collection(
        self,
        collection_name: str,
        embedding_model_name: str,
        chunking_strategy: str,
        dataset_data: List[Dict],
        chunk_size: int = 512,
        overlap: int = 50
    ):
        """Load a dataset into a new collection with chunking.
        
        Args:
            collection_name: Name for the new collection
            embedding_model_name: Embedding model to use
            chunking_strategy: Chunking strategy to use
            dataset_data: List of dataset samples
            chunk_size: Size of chunks
            overlap: Overlap between chunks
        """
        # Create collection
        self.create_collection(
            collection_name,
            embedding_model_name,
            metadata={
                "chunking_strategy": chunking_strategy,
                "chunk_size": chunk_size,
                "overlap": overlap
            }
        )
        
        # Get chunker
        chunker = ChunkingFactory.create_chunker(chunking_strategy)
        
        # Process documents
        all_chunks = []
        all_metadatas = []
        
        print(f"Processing {len(dataset_data)} documents with {chunking_strategy} chunking...")
        
        for idx, sample in enumerate(dataset_data):
            # Use 'documents' list if available, otherwise fall back to 'context'
            documents = sample.get("documents", [])
            
            # If documents is empty, use context as fallback
            if not documents:
                context = sample.get("context", "")
                if context:
                    documents = [context]
            
            if not documents:
                continue
            
            # Process each document separately for better granularity
            for doc_idx, document in enumerate(documents):
                if not document or not str(document).strip():
                    continue
                
                # Chunk each document
                chunks = chunker.chunk_text(str(document), chunk_size, overlap)
                
                # Create metadata for each chunk
                for chunk_idx, chunk in enumerate(chunks):
                    all_chunks.append(chunk)
                    all_metadatas.append({
                        "doc_id": idx,
                        "doc_idx": doc_idx,  # Track which document within the sample
                        "chunk_id": chunk_idx,
                        "question": sample.get("question", ""),
                        "answer": sample.get("answer", ""),
                        "dataset": sample.get("dataset", ""),
                        "total_docs": len(documents)
                    })
        
        # Add all chunks to collection
        self.add_documents(all_chunks, all_metadatas)
        
        print(f"Loaded {len(all_chunks)} chunks from {len(dataset_data)} samples")
    
    def query(
        self,
        query_text: str,
        n_results: int = 5,
        filter_metadata: Optional[Dict] = None
    ) -> Dict:
        """Query the collection.
        
        Args:
            query_text: Query text
            n_results: Number of results to return
            filter_metadata: Metadata filter
            
        Returns:
            Query results
        """
        if not self.current_collection:
            raise ValueError("No collection selected.")
        
        if not self.embedding_model:
            raise ValueError("No embedding model loaded.")
        
        # Generate query embedding
        query_embedding = self.embedding_model.embed_query(query_text)
        
        # Query collection with retry logic
        try:
            results = self.current_collection.query(
                query_embeddings=[query_embedding.tolist()],
                n_results=n_results,
                where=filter_metadata
            )
        except Exception as e:
            if "default_tenant" in str(e):
                print("Warning: Lost connection to ChromaDB, reconnecting...")
                self.reconnect()
                # Try again after reconnecting
                results = self.current_collection.query(
                    query_embeddings=[query_embedding.tolist()],
                    n_results=n_results,
                    where=filter_metadata
                )
            else:
                raise
        
        return results
    
    def get_retrieved_documents(
        self,
        query_text: str,
        n_results: int = 5
    ) -> List[Dict]:
        """Get retrieved documents with metadata.
        
        Args:
            query_text: Query text
            n_results: Number of results
            
        Returns:
            List of retrieved documents with metadata
        """
        results = self.query(query_text, n_results)
        
        retrieved_docs = []
        for i in range(len(results['documents'][0])):
            retrieved_docs.append({
                "document": results['documents'][0][i],
                "metadata": results['metadatas'][0][i],
                "distance": results['distances'][0][i] if 'distances' in results else None
            })
        
        return retrieved_docs
    
    def delete_collection(self, collection_name: str):
        """Delete a collection.
        
        Args:
            collection_name: Name of collection to delete
        """
        try:
            self.client.delete_collection(collection_name)
            print(f"Deleted collection: {collection_name}")
        except Exception as e:
            print(f"Error deleting collection: {str(e)}")
    
    def get_collection_stats(self, collection_name: Optional[str] = None) -> Dict:
        """Get statistics for a collection.
        
        Args:
            collection_name: Name of collection (uses current if None)
            
        Returns:
            Dictionary with collection statistics
        """
        if collection_name:
            collection = self.client.get_collection(collection_name)
        elif self.current_collection:
            collection = self.current_collection
        else:
            raise ValueError("No collection specified or selected")
        
        count = collection.count()
        metadata = collection.metadata
        
        return {
            "name": collection.name,
            "count": count,
            "metadata": metadata
        }