import sys
import subprocess
from typing import Any

import streamlit as st

from src.vectorstore import get_retriever
from src.qa_chain import make_conversational_chain
import os
import json
from typing import Dict, List, Tuple, cast

# Unconditionally import KG modules; let import errors propagate so failures are visible
from src.kg.store import KGStore
from src.kg.retriever import KGRetriever


def run_ingest_cli(data_dir: str, persist_dir: str) -> str:
    """Run the ingestion module to rebuild the vectorstore.

    Runs the ingest CLI as a subprocess and returns stdout on success.
    On failure raises subprocess.CalledProcessError with captured stdout/stderr so callers
    (for example the Streamlit UI) can display a helpful error message.
    """
    cmd = [
        sys.executable,
        "-m",
        "src.ingest",
        "--data-dir",
        data_dir,
        "--persist-dir",
        persist_dir,
    ]
    try:
        # Add a timeout to avoid indefinite hanging; 600s (10 minutes) is generous for large ingests
        completed = subprocess.run(cmd, capture_output=True, text=True, timeout=600)
    except subprocess.TimeoutExpired as te:
        # Provide helpful error including partial output
        raise subprocess.CalledProcessError(
            returncode=124,
            cmd=cmd,
            output=getattr(te, 'output', '') or '',
            stderr=f"Ingest process timed out after {te.timeout} seconds",
        )

    # Check return code and raise with captured output on failure
    if completed.returncode != 0:
        # Raise with captured output to make it easy to present to the user
        raise subprocess.CalledProcessError(
            returncode=completed.returncode,
            cmd=cmd,
            output=completed.stdout,
            stderr=completed.stderr,
        )
    return completed.stdout


def _load_chunks_index(persist_dir: str) -> Dict[str, Dict]:
    idx_path = os.path.join(persist_dir, "chunks_index.json")
    if not os.path.exists(idx_path):
        return {}
    try:
        with open(idx_path, "r", encoding="utf-8") as fh:
            return json.load(fh)
    except Exception:
        return {}


def answer_with_kg(
        chain,
        question: str,
        chat_history: List[Tuple[str, str]],
        persist_dir: str,
        kg_hops: int = 1,
        kg_context_max_chars: int = 1000,
    ) -> Any:
    """Augment question with KG context (if available) and run the chain.

    This is a low-risk integration: we build a short textual summary from the KG
    (node labels and short chunk snippets from chunks_index.json) and prepend it to
    the question. The chain's retriever still runs; KG context is additional grounding.
    """
    kg_text_parts: List[str] = []
    # Load chunks index mapping
    chunks_index = _load_chunks_index(persist_dir)

    # Load KG unconditionally; let import or parse errors raise so callers can see them.
    kg_path = os.path.join(persist_dir, "kg_store.ttl")
    try:
        kg = KGStore(path=kg_path)
        retr = KGRetriever(kg)
        chunk_ids, summaries = retr.get_context_for_question(question, hops=kg_hops)
        if summaries:
            kg_text_parts.append("KG entities: " + ", ".join(summaries))
        # add chunk snippets
        for cid in chunk_ids:
            info = chunks_index.get(cid)
            if info:
                txt = info.get("text", "")
                if txt:
                    snippet = txt.strip().replace("\n", " ")[:min(len(txt), kg_context_max_chars)]
                    kg_text_parts.append(f"[KG chunk {cid}]: {snippet}")
    except Exception:
        # If KG load or query fails, skip KG augmentation (allow the exception to surface in logs)
        kg_text_parts = []

    kg_context = "\n\n".join(kg_text_parts) if kg_text_parts else ""
    if kg_context:
        augmented_question = f"KG CONTEXT:\n{kg_context}\n\nUser Question:\n{question}"
    else:
        augmented_question = question

    return chain({"question": augmented_question, "chat_history": chat_history})


@st.cache_resource(show_spinner=False)
def build_or_load_retriever_cached(
        data_dir: str,
        persist_dir: str,
        top_k: int,
        retrieval_mode: str,
) -> Any:
    """Load a retriever from the persisted vectorstore or build a new one.

    If loading fails—usually because the vectorstore doesn't exist—this
    function triggers ingestion and retries loading.

    Args:
        data_dir: Directory containing input documents.
        persist_dir: Directory where the Chroma vectorstore is stored.
        top_k: Number of chunks to retrieve.
        retrieval_mode: Retrieval strategy (mmr, similarity, hybrid).

    Returns:
        An initialized retriever instance.
    """
    try:
        # Cast retrieval_mode to the expected literal type to satisfy type checkers
        from typing import Literal
        RetrievalMode = Literal["mmr", "similarity", "hybrid"]
        mode = cast(RetrievalMode, retrieval_mode)
        return get_retriever(
            persist_dir=persist_dir,
            top_k=top_k,
            retrieval_mode=mode,
        )
    except Exception:
        run_ingest_cli(data_dir=data_dir, persist_dir=persist_dir)
        from typing import Literal
        RetrievalMode = Literal["mmr", "similarity", "hybrid"]
        mode = cast(RetrievalMode, retrieval_mode)
        return get_retriever(
            persist_dir=persist_dir,
            top_k=top_k,
            retrieval_mode=mode,
        )


@st.cache_resource(show_spinner=False)
def get_chain_cached(
        model_name: str,
        top_k: int,
        retrieval_mode: str,
        data_dir: str,
        persist_dir: str,
) -> Any:
    """Create or load a cached conversational QA chain.

    Args:
        model_name: The OpenAI model to use (gpt-3.5-turbo, gpt-4).
        top_k: Number of chunks to retrieve.
        retrieval_mode: Retrieval mode for the retriever.
        data_dir: Path to data directory.
        persist_dir: Path to vectorstore directory.

    Returns:
        A fully configured conversational QA chain.
    """
    retriever = build_or_load_retriever_cached(
        data_dir=data_dir,
        persist_dir=persist_dir,
        top_k=top_k,
        retrieval_mode=retrieval_mode,
    )
    return make_conversational_chain(retriever, model_name=model_name)