from langchain.chains import RetrievalQA
from langchain.embeddings import HuggingFaceEmbeddings
from langchain.callbacks.streaming_stdout import StreamingStdOutCallbackHandler
from langchain.vectorstores import Chroma
from langchain.llms import Ollama
import chromadb
import os
import argparse
import time

model = os.environ.get("MODEL", "mistral")
# For embeddings model, the example uses a sentence-transformers model
# https://www.sbert.net/docs/pretrained_models.html 
# "The all-mpnet-base-v2 model provides the best quality, while all-MiniLM-L6-v2 is 5 times faster and still offers good quality."
embeddings_model_name = os.environ.get("EMBEDDINGS_MODEL_NAME", "all-MiniLM-L6-v2")
persist_directory = os.environ.get("PERSIST_DIRECTORY", "db")
target_source_chunks = int(os.environ.get('TARGET_SOURCE_CHUNKS',4))

from constants import CHROMA_SETTINGS

def main():
    # Parse the command line arguments
    args = parse_arguments()
    embeddings = HuggingFaceEmbeddings(model_name=embeddings_model_name)

    db = Chroma(persist_directory=persist_directory, embedding_function=embeddings)

    retriever = db.as_retriever(search_kwargs={"k": target_source_chunks})
    # activate/deactivate the streaming StdOut callback for LLMs
    callbacks = [] if args.mute_stream else [StreamingStdOutCallbackHandler()]

    llm = Ollama(model=model, callbacks=callbacks)

    qa = RetrievalQA.from_chain_type(llm=llm, chain_type="stuff", retriever=retriever, return_source_documents= not args.hide_source)
    # Interactive questions and answers
    while True:
        query = input("\nEnter a query: ")
        if query == "exit":
            break
        if query.strip() == "":
            continue

        # Get the answer from the chain
        start = time.time()
        res = qa(query)
        answer, docs = res['result'], [] if args.hide_source else res['source_documents']
        end = time.time()

        # Print the result
        print("\n\n> Question:")
        print(query)
        print(answer)

        # Print the relevant sources used for the answer
        for document in docs:
            print("\n> " + document.metadata["source"] + ":")
            print(document.page_content)

def parse_arguments():
    parser = argparse.ArgumentParser(description='privateGPT: Ask questions to your documents without an internet connection, '
                                                 'using the power of LLMs.')
    parser.add_argument("--hide-source", "-S", action='store_true',
                        help='Use this flag to disable printing of source documents used for answers.')

    parser.add_argument("--mute-stream", "-M",
                        action='store_true',
                        help='Use this flag to disable the streaming StdOut callback for LLMs.')

    return parser.parse_args()


if __name__ == "__main__":
    main()
