"""
ingest.py — Load FAQ JSON, create LangChain Documents, and store
embeddings in a local ChromaDB collection.

Run directly to (re)build the vector store:
    python -m src.ingest
"""

from __future__ import annotations

import json
import os
from pathlib import Path

from langchain_core.documents import Document
from langchain_chroma import Chroma
from langchain_ollama import OllamaEmbeddings

# Paths: keep knowledge data and vector store under rag/
_HERE = Path(__file__).parent
_RAG_DIR = _HERE.parent / "data"
FAQ_PATH = _RAG_DIR / "faq.json"
CHROMA_DIR = _RAG_DIR / "chroma_db"

EMBED_MODEL = os.getenv("EMBED_MODEL", "embeddinggemma:latest")
OLLAMA_BASE_URL = os.getenv("OLLAMA_BASE_URL", "http://localhost:11434")
OLLAMA_AUTH_TOKEN = os.getenv("OLLAMA_AUTH_TOKEN") or os.getenv("HUGGINGFACE_HUB_TOKEN") or os.getenv("HF_TOKEN")
COLLECTION_NAME = "naijalingo_faq"


def _ollama_client_kwargs() -> dict:
    if not OLLAMA_AUTH_TOKEN:
        return {}
    return {"headers": {"Authorization": f"Bearer {OLLAMA_AUTH_TOKEN}"}}


def load_faq_documents(faq_path: Path = FAQ_PATH) -> list[Document]:
    with open(faq_path, encoding="utf-8") as f:
        items = json.load(f)

    docs: list[Document] = []
    for i, item in enumerate(items):
        question = item.get("question", "").strip()
        answer = item.get("answer", "").strip()
        content = f"Question: {question}\nAnswer: {answer}"
        docs.append(
            Document(
                page_content=content,
                metadata={"source": "faq.json", "index": i, "question": question},
            )
        )
    return docs


def build_vectorstore(
    faq_path: Path = FAQ_PATH,
    chroma_dir: Path = CHROMA_DIR,
    embed_model: str = EMBED_MODEL,
) -> Chroma:
    docs = load_faq_documents(faq_path)
    embeddings = OllamaEmbeddings(
        model=embed_model,
        base_url=OLLAMA_BASE_URL,
        client_kwargs=_ollama_client_kwargs(),
    )

    chroma_dir.mkdir(parents=True, exist_ok=True)
    vectorstore = Chroma.from_documents(
        documents=docs,
        embedding=embeddings,
        collection_name=COLLECTION_NAME,
        persist_directory=str(chroma_dir),
    )
    print(f"[ingest] Indexed {len(docs)} FAQ entries -> {chroma_dir}")
    return vectorstore


def load_vectorstore(
    chroma_dir: Path = CHROMA_DIR,
    embed_model: str = EMBED_MODEL,
) -> Chroma:
    embeddings = OllamaEmbeddings(
        model=embed_model,
        base_url=OLLAMA_BASE_URL,
        client_kwargs=_ollama_client_kwargs(),
    )
    return Chroma(
        collection_name=COLLECTION_NAME,
        embedding_function=embeddings,
        persist_directory=str(chroma_dir),
    )


def get_or_build_vectorstore() -> Chroma:
    if CHROMA_DIR.exists() and any(CHROMA_DIR.iterdir()):
        print("[ingest] Loading existing vector store from disk...")
        return load_vectorstore()
    print("[ingest] Building vector store for the first time...")
    return build_vectorstore()


if __name__ == "__main__":
    build_vectorstore()