# rag.py  (v2 – with filters + fallbacks)
from __future__ import annotations
import os, uuid, tempfile, requests, shutil, re
from pathlib import Path
from functools import lru_cache
from typing import List, Tuple
from datasets import load_dataset
from langchain_text_splitters import RecursiveCharacterTextSplitter
from langchain_community.vectorstores import FAISS
from langchain_huggingface import HuggingFaceEmbeddings
from langchain_core.prompts import PromptTemplate
from langchain.chains import RetrievalQA
from langchain_huggingface import HuggingFaceEndpoint
from supabase import create_client

# ---------- config ----------
HF_DS = "NimrodDev/LD_Events2"
EMBED_MODEL = "sentence-transformers/all-MiniLM-L6-v2"
LLM_MODEL = "microsoft/DialoGPT-medium"
FAISS_PATH = Path("faiss_db")
SUPABASE_URL = os.getenv("SUPABASE_URL")
SUPABASE_KEY = os.getenv("SUPABASE_KEY")
HF_TOKEN = os.getenv("HF_TOKEN")

supabase = create_client(SUPABASE_URL, SUPABASE_KEY)

# ---------- keyword filters ----------
GREETING_RE = re.compile(r"\b(hi|hello|hey|good morning|good afternoon|good evening)\b", re.I)
THANKS_RE = re.compile(r"\b(thank|thanks|appreciate)\b", re.I)
BYE_RE = re.compile(r"\b(bye|goodbye|see you|later)\b", re.I)
MONEY_RE = re.compile(r"\b(price|cost|budget|cheap|expensive|money|usd|ksh|payment|deposit)\b", re.I)
COMPLAIN_RE = re.compile(r"\b(complain|bad|terrible|awful|disappointed|angry|slow|rude)\b", re.I)

# ---------- company-specific fallbacks ----------
FALLBACKS = {
    "LD Events": {
        "greeting": "Hello! 👋 Welcome to LD Events – your trusted partner for weddings, graduations and corporate events.",
        "money": "Our pricing depends on venue, guest count and package. Please share a few details so we can give you a tailored quote.",
        "complain": "We’re sorry to hear this. A senior agent will contact you within 30 minutes to resolve the issue.",
        "thanks": "You’re welcome! If you need anything else, just text back.",
        "bye": "Thanks for chatting with LD Events. Have a lovely day!",
        "default": "I’m not sure about that, but a human agent will follow up shortly."
    },
    "Lamaki Designs": {
        "greeting": "Karibu! 🏗️ Lamaki Designs here – quality construction, architectural plans and project management.",
        "money": "Cost varies by project size and materials. Kindly share your plot size / plan so we can estimate for you.",
        "complain": "We apologise for the inconvenience. Our site manager will call you within 30 minutes to sort it out.",
        "thanks": "Asante! Feel free to text any time.",
        "bye": "Good-bye and stay safe!",
        "default": "Let me get back to you on that."
    }
}

# ---------- helpers ----------
def _company_from_text(text: str) -> str:
    t = text.lower()
    if any(k in t for k in ("ld events", "event", "wedding", "venue", "graduation")):
        return "LD Events"
    if any(k in t for k in ("lamaki", "construction", "build", "site", "bungalow", "architect")):
        return "Lamaki Designs"
    return "LD Events"  # default

def _detect_intent(text: str) -> str:
    if GREETING_RE.search(text):
        return "greeting"
    if THANKS_RE.search(text):
        return "thanks"
    if BYE_RE.search(text):
        return "bye"
    if MONEY_RE.search(text):
        return "money"
    if COMPLAIN_RE.search(text):
        return "complain"
    return "normal"

def _fallback_answer(company: str, intent: str) -> str:
    return FALLBACKS[company].get(intent, FALLBACKS[company]["default"])

# ---------- pdf loader ----------
def download_pdfs() -> List[Path]:
    data_dir = Path("data")
    data_dir.mkdir(exist_ok=True)
    ds = load_dataset(HF_DS, split="train", streaming=True)
    paths = []
    for row in ds:
        url = row["pdf_url"]
        name = row.get("name", uuid.uuid4().hex) + ".pdf"
        dest = data_dir / name
        if not dest.exists():
            r = requests.get(url, stream=True, timeout=30)
            r.raise_for_status()
            with open(dest, "wb") as f:
                shutil.copyfileobj(r.raw, f)
        paths.append(dest)
    return paths

# ---------- vector store ----------
@lru_cache(maxsize=1)
def get_vectorstore() -> FAISS:
    if FAISS_PATH.exists():
        return FAISS.load_local(str(FAISS_PATH), HuggingFaceEmbeddings(model_name=EMBED_MODEL),
                                allow_dangerous_deserialization=True)
    docs = []
    splitter = RecursiveCharacterTextSplitter(chunk_size=600, chunk_overlap=50)
    for pdf in download_pdfs():
        text = Path(pdf).read_text(encoding="utf-8", errors="ignore")
        docs.extend(splitter.create_documents([text], metadatas=[{"source": pdf.name}]))
    vs = FAISS.from_documents(docs, HuggingFaceEmbeddings(model_name=EMBED_MODEL))
    vs.save_local(str(FAISS_PATH))
    return vs

# ---------- llm ----------
@lru_cache(maxsize=1)
def get_llm():
    return HuggingFaceEndpoint(
        repo_id=LLM_MODEL,
        temperature=0.1,
        max_new_tokens=150,
        huggingfacehub_api_token=HF_TOKEN
    )

PROMPT = PromptTemplate.from_template("""You are Amina, assistant for {company}.
Use only the context below. If unsure, say: “A human agent will follow up.”
Context: {context}
Question: {question}
Answer:""")

# ---------- main entry ----------
def ask_question(phone: str, question: str) -> Tuple[str, List]:
    intent = _detect_intent(question)
    company = _company_from_text(question)

    # short-circuit greetings/thanks/bye – no LLM, no context needed
    if intent in ("greeting", "thanks", "bye"):
        answer = _fallback_answer(company, intent)
        _save_chat(phone, question, answer)
        return answer, []

    # money or complaints: fallback if no docs
    vs = get_vectorstore()
    docs = vs.similarity_search(question, k=3)
    if not docs:
        answer = _fallback_answer(company, intent if intent in ("money", "complain") else "default")
        _save_chat(phone, question, answer)
        return answer, []

    # normal RAG
    qa = RetrievalQA.from_chain_type(
        llm=get_llm(),
        retriever=vs.as_retriever(search_kwargs={"k": 3}),
        return_source_documents=True,
        chain_type_kwargs={"prompt": PROMPT}
    )
    result = qa({"query": question, "company": company})
    answer = result["result"].strip()
    _save_chat(phone, question, answer)
    return answer, result.get("source_documents", [])

def _save_chat(phone: str, q: str, a: str) -> None:
    supabase.table("chat_memory").insert({"user_phone": phone, "role": "user", "message": q}).execute()
    supabase.table("chat_memory").insert({"user_phone": phone, "role": "assistant", "message": a}).execute()