import os
import re
import requests
from fastapi import FastAPI
from pydantic import BaseModel
from typing import List, Optional
from fastapi.middleware.cors import CORSMiddleware
from huggingface_hub import InferenceClient

app = FastAPI(title="Yuyu - LibraryLuxe AI")

app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)

# ================== CONFIG ==================
HF_TOKEN = os.getenv("HF_TOKEN")
client = InferenceClient(api_key=HF_TOKEN)

# Better model (try these in order)
MODEL = "Qwen/Qwen2.5-7B-Instruct"          # Best quality
# MODEL = "mistralai/Mistral-7B-Instruct-v0.3"
# MODEL = "microsoft/Phi-3.5-mini-instruct"

# ===========================================

class ChatHistoryItem(BaseModel):
    role: str
    content: str

class ChatRequest(BaseModel):
    message: str
    history: List[ChatHistoryItem] = []

class BookEnrichment(BaseModel):
    title: Optional[str] = None
    author: Optional[str] = None
    cover_url: Optional[str] = None
    description: Optional[str] = None
    isbn: Optional[str] = None

class ChatResponse(BaseModel):
    response: str
    book_data: Optional[BookEnrichment] = None

# ================== MASTER LIBRARIAN KNOWLEDGE BASE ==================
SYSTEM_PROMPT = """
You are Yuyu, the Master Librarian at LibraryLuxe.
### CORE RULES:
- ALL prices and balances must be mentioned in MMK (Myanmar Kyat).
- Use the 'Actual Library Plans' and 'User Context' provided in the message for precision.
### 1. MEMBERSHIP & SUBSCRIPTIONS
- We have different plans (Basic, Premium, Basic yearly, Premium yearly.) with different book limits and prices.
(Basic: maxed books=3, Borrow days=14 days, Premium: maxed books=5, Borrow days=21days)
- Users can subscribe using their Wallet or other payment methods.
- IMPORTANT: When a user subscribes, it might stay "Pending" until an Admin approves it.
- To Renew/Upgrade: Go to the 'Membership' page and click 'Renew' or 'Upgrade'.
### 2. WALLET & PAYMENTS
- Users have a digital Wallet. They can 'Top Up' money into it.
- Wallet balance can be used to buy subscriptions instantly.
- To Top Up: Go to the 'Wallet' section in the profile menu.
### 3. LOYALTY & REWARDS
- Users earn 'Loyalty Points' for borrowing books and buying membership plans.
- Points can be redeemed for 'Rewards' in 'Rewards' page.
- To check points: Visit the 'Rewards' page.
### 4. BORROWING & RETURNS
- Each plan has a 'Max Books' limit and 'Borrowing Days' limit.
- To Return: Users must 'Request Return' from their 'My Books' page OR go to the library and return it. A librarian will then verify the physical return.
- Overdue books might prevent new borrowings.
### 5. PERSONALITY & TONE
- Be warm, helpful, and professional.
- Use the user's name if provided.
- ALWAYS use the 'Actual Library Plans' and 'User Context' provided in the message for precision.
- If you don't know a specific detail about their account, ask them to check their 'Dashboard' or email aiyurina1610@gmail.com.
Keep responses helpful but concise (max 2 paragraphs).
"""



def get_book_details(isbn: str) -> Optional[BookEnrichment]:
    try:
        url = f"https://openlibrary.org/api/books?bibkeys=ISBN:{isbn}&format=json&jscmd=data"
        resp = requests.get(url, timeout=6)
        data = resp.json()
        key = f"ISBN:{isbn}"
        if key in data:
            b = data[key]
            return BookEnrichment(
                title=b.get("title"),
                author=", ".join([a.get("name", "") for a in b.get("authors", [])]),
                cover_url=b.get("cover", {}).get("large"),
                description=b.get("notes") or b.get("description"),
                isbn=isbn
            )
    except:
        pass
    return None

@app.get("/")
def home():
    return {"status": "online", "message": "Yuyu is ready!"}

@app.post("/chat", response_model=ChatResponse)
async def chat(request: ChatRequest):
    # Extract ISBN
    isbn_match = re.search(r"\b(?:97[89])?\d{9}[\dX]\b", request.message)
    book_data = get_book_details(isbn_match.group(0)) if isbn_match else None

    # Build messages
    messages = [{"role": "system", "content": SYSTEM_PROMPT}]
    
    # Add recent history
    for item in request.history[-6:]:
        messages.append({"role": item.role, "content": item.content})
    
    messages.append({"role": "user", "content": request.message})

    try:
        response = client.chat.completions.create(
            model=MODEL,
            messages=messages,
            max_tokens=450,
            temperature=0.75,
            top_p=0.9,
        )
        ai_reply = response.choices[0].message.content.strip()
        
    except Exception as e:
        ai_reply = "I'm a bit overloaded right now... Please try again in a few seconds."

    return ChatResponse(response=ai_reply, book_data=book_data)