"""
EpiRAG -- server.py
------------------
Flask server. Detects environment and chooses ChromaDB mode:

  LOCAL (EPIRAG_ENV != "cloud"):
    Reads from persistent ./chroma_db/ - fast restarts, no re-embedding.

  CLOUD (EPIRAG_ENV=cloud, e.g. HF Spaces):
    Builds in-memory ChromaDB from ./papers/ at startup.
    Takes ~2-3 min cold start. No disk writes needed.
"""

import os
import time
import chromadb
from flask import Flask, jsonify, request, send_from_directory
from flask_cors import CORS
from query import rag_query, set_components

app = Flask(__name__, static_folder="static")
CORS(app)

COLLECTION_NAME = "epirag"
IS_CLOUD        = os.environ.get("EPIRAG_ENV", "").lower() == "cloud"

# Startup: build or load corpus ----------------------------------
_collection = None
_embedder   = None
CORPUS_STATS = {}

def init_corpus():
    global _collection, _embedder, CORPUS_STATS

    if IS_CLOUD:
        print("Cloud mode — building in-memory corpus from ./papers/", flush=True)
        from ingest import build_collection_in_memory
        _collection, _embedder = build_collection_in_memory()
    else:
        print("Local mode — loading from ./chroma_db/", flush=True)
        from sentence_transformers import SentenceTransformer
        client      = chromadb.PersistentClient(path="./chroma_db")
        _collection = client.get_collection(COLLECTION_NAME)
        _embedder   = SentenceTransformer("all-MiniLM-L6-v2")

    # Injecting into query.py
    set_components(_embedder, _collection)

    # Build stats
    count   = _collection.count()
    results = _collection.get(limit=count, include=["metadatas"])
    papers  = sorted(set(
        m.get("paper_name", m.get("source", "Unknown"))
        for m in results["metadatas"]
    ))
    CORPUS_STATS.update({
        "chunks":    count,
        "papers":    len(papers),
        "paperList": papers,
        "status":    "online",
        "mode":      "cloud (in-memory)" if IS_CLOUD else "local (persistent)"
    })
    print(f"Corpus ready: {count} chunks / {len(papers)} papers", flush=True)


init_corpus()


# ROUTES ----------------------------------------------------------------
@app.route("/")
def index():
    return send_from_directory("static", "index.html")


@app.route("/api/stats")
def stats():
    return jsonify(CORPUS_STATS)


@app.route("/api/query", methods=["POST"])
def query():
    data     = request.json or {}
    question = (data.get("question") or "").strip()
    if not question:
        return jsonify({"error": "No question provided"}), 400

    groq_key   = os.environ.get("GROQ_API_KEY")
    tavily_key = os.environ.get("TAVILY_API_KEY")
    if not groq_key:
        return jsonify({"error": "GROQ_API_KEY not set on server"}), 500

    start      = time.time()
    result     = rag_query(question, groq_key, tavily_key)
    elapsed_ms = int((time.time() - start) * 1000)

    return jsonify({
        "answer":     result["answer"],
        "sources":    result["sources"],
        "mode":       result["mode"],
        "avg_sim":    result["avg_sim"],
        "latency_ms": elapsed_ms,
        "tokens":     len(result["answer"]) // 4,
        "question":   question
    })


@app.route("/api/health")
def health():
    return jsonify({"status": "ok", "corpus": CORPUS_STATS.get("status", "unknown")})


if __name__ == "__main__":
    port = int(os.environ.get("PORT", 7860))   # 7860 is HF Spaces default
    app.run(debug=False, host="0.0.0.0", port=port)