"""
    Secure version of RAG with Memory for customer support agent.    
"""

import os
import sys
from typing import Dict
from loguru import logger
from langchain_community.chat_message_histories import ChatMessageHistory
from langchain_core.chat_history import BaseChatMessageHistory
from langchain_core.runnables.history import RunnableWithMessageHistory
from langchain_core.prompts import ChatPromptTemplate, MessagesPlaceholder
from langchain_classic.chains.history_aware_retriever import create_history_aware_retriever
from langchain_classic.chains.combine_documents import create_stuff_documents_chain
from langchain_classic.chains.retrieval import create_retrieval_chain
from langchain_huggingface import HuggingFaceEndpoint, ChatHuggingFace
from langchain_community.vectorstores import Chroma
from langchain_huggingface.embeddings import HuggingFaceEmbeddings
from langchain_community.document_loaders import DirectoryLoader
from langchain_text_splitters import RecursiveCharacterTextSplitter
from dotenv import load_dotenv
from langchain_community.document_loaders import TextLoader
load_dotenv()
__import__('pysqlite3')
import sys
sys.modules['sqlite3'] = sys.modules.pop('pysqlite3')

# Setup production logging
logger.remove()
logger.add(sys.stdout, format="<green>{time:HH:mm:ss}</green> | <level>{level}</level> | {message}", level="INFO")

class MemoryRAG:
    def __init__(self, docs_path: str, model: str = "meta-llama/Llama-3.1-8B-Instruct"):
        self.docs_path = docs_path
        self.store: Dict[str, BaseChatMessageHistory] = {}
        
        try:
            logger.info(f"Initializing RAG with knowledge base: {docs_path}")
            
            # 1. Load and chunk documents
            loader = DirectoryLoader(docs_path, glob="**/*.md",
                                     loader_cls=TextLoader, silent_errors=False)
            docs = loader.load()
            logger.info(f"RAG DATABASE STATUS: Loaded {len(docs)} documents from {docs_path}")
            if not docs:
                logger.warning(f"No documents found in {docs_path}. RAG will be empty.")

            splitter = RecursiveCharacterTextSplitter(chunk_size=600, chunk_overlap=100)
            chunks = splitter.split_documents(docs)

            # 2. Vector DB - Persistent storage
            embeddings = HuggingFaceEmbeddings(model_name="all-MiniLM-L6-v2")
            self.db = Chroma.from_documents(
                chunks, 
                embeddings, 
                persist_directory="./chroma_db"
            )

            # 3. LLM Setup
            hf_token = os.getenv("HF_API_TOKEN")
            if not hf_token:
                logger.critical("HF_API_TOKEN is missing from environment variables!")
                raise RuntimeError("HF_API_TOKEN not set")

            self.raw_llm = HuggingFaceEndpoint(
                repo_id=model,
                huggingfacehub_api_token=hf_token,
                temperature=0.1,
                max_new_tokens=200,
                return_full_text=False, 
                task="conversational"
            )
            self.llm = ChatHuggingFace(llm=self.raw_llm)

            # 4. Chains Setup
            self.retriever = self.db.as_retriever(search_kwargs={"k": 6})
            
            contextualize_q_system_prompt = (
            "Given a chat history and the latest user question "
            "which might reference context in the chat history, "
            "formulate a standalone question which can be understood "
            "without the chat history. Do NOT answer the question, "
            "just reformulate it if needed and otherwise return it as is."
        )
            context_prompt = ChatPromptTemplate.from_messages([
            ("system", contextualize_q_system_prompt),
            MessagesPlaceholder(variable_name="chat_history"),
            ("human", "{input}"),
        ])

            history_aware_retriever = create_history_aware_retriever(self.llm, self.retriever, context_prompt)

            qa_prompt = ChatPromptTemplate.from_messages([
                ("system", (
                    "You are the SmartCoffee Support AI. Use the provided context to answer the user's question. "
                    "\n\n"
                    "### FORMATTING RULES:\n"
                    "- Use **Markdown** for all responses.\n"
                    "- If the answer involves a process or multiple steps, use a **numbered list** (1, 2, 3).\n"
                    "- If the answer contains several facts, use **bullet points** (•).\n"
                    "- Use **bold text** for button names or important terms (e.g., 'Press the **Brew** button').\n"
                    "- Keep the response concise and avoid long paragraphs."
                    "- If the answer is not in the context, say: 'I'm sorry, I don't have that specific policy in my records.'\n"
                    "- DO NOT use your internal knowledge to invent support tiers, response times, or phone numbers.\n"
                    "\n\n"
                    "Context: {context}"
                )),
                MessagesPlaceholder(variable_name="chat_history"),
                ("human", "{input}"),
                    ])
            question_answer_chain = create_stuff_documents_chain(self.llm, qa_prompt)
            self.rag_chain = create_retrieval_chain(history_aware_retriever, question_answer_chain)
            
            logger.success("MemoryRAG system initialized successfully.")

        except Exception as e:
            logger.exception("Failed to initialize MemoryRAG components")
            raise e

    def get_session_history(self, session_id: str) -> BaseChatMessageHistory:
        if session_id not in self.store:
            self.store[session_id] = ChatMessageHistory()
        return self.store[session_id]

    def query(self, question: str, session_id: str = "default_session") -> dict:
        # Create a logger tied to this session
        session_logger = logger.bind(session_id=session_id)
        
        conversational_rag_chain = RunnableWithMessageHistory(
            self.rag_chain,
            self.get_session_history,
            input_messages_key="input",
            history_messages_key="chat_history",
            output_messages_key="answer",
        )

        try:
            session_logger.info(f"RAG Query received: {question[:50]}...")
            
            result = conversational_rag_chain.invoke(
                {"input": question},
                config={"configurable": {"session_id": session_id}},
            )

            # Extract sources directly from the result
            sources = list(set([doc.metadata.get("source", "unknown") for doc in result.get("context", [])]))

            session_logger.success("RAG Query completed.")
            return {
                "answer": result["answer"].strip(),
                "sources": sources
            }

        except Exception as e:
            session_logger.error(f"RAG Query Error: {e}")
            return {
                "answer": "I'm sorry, I encountered an error accessing my knowledge base.",
                "sources": []
            }


if __name__ == "__main__":
    import os
    import glob

    # 1. Define the same safe paths you used in tools.py
    possible_paths = [
        "/app/data/knowledge_base",
        "./data/knowledge_base",
        "./backend/data/knowledge_base"
    ]

    KNOWLEDGE_BASE_PATH = None
    for p in possible_paths:
        # Check if the folder exists and actually has .md files inside
        if os.path.exists(p) and glob.glob(os.path.join(p, "*.md")):
            KNOWLEDGE_BASE_PATH = p
            break

    if not KNOWLEDGE_BASE_PATH:
        print("CRITICAL ERROR: No knowledge base found in any of the possible paths!")
        # Fallback to a default to prevent crash, but it will be empty
        KNOWLEDGE_BASE_PATH = "./data/knowledge_base" 

    # 2. Use the detected path
    rag = MemoryRAG(KNOWLEDGE_BASE_PATH, model="meta-llama/Llama-3.1-8B-Instruct")