import uvicorn
from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from typing import List, Optional
from graph import app_graph

app = FastAPI(title="Clause.ai Backend")

origins = [
    "https://clause-ai-nbu8.vercel.app", 
    "http://localhost:3000"              
]

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

# --- API MODELS ---
class DraftRequest(BaseModel):
    query: str

class AgentResponse(BaseModel):
    status: str
    phase: str
    message: str
    missing_info: List[str] = []
    draft: Optional[str] = None
    reference: Optional[str] = None

@app.get("/")
def home():
    return {"status": "Clause.ai Brain is Online"}

@app.post("/draft", response_model=AgentResponse)
async def generate_clause(request: DraftRequest):
    try:
        # Initialize the state
        initial_state = {
            "query": request.query,
            "messages": [],
            "context": "",
            "reference_clause": "",
            "final_draft": "",
            "phase": "",
            "missing_info": [],
            "clarification_question": ""
        }
        
        # Run the LangGraph Agent
        result = app_graph.invoke(initial_state)
        
        phase = result.get("phase", "")
        
        # --- SCENARIO 1: Guardrail stopped (general question/greeting/injection) ---
        if phase == "stopped":
            return {
                "status": "general_response",
                "phase": "stopped",
                "message": result.get("final_draft", ""),
                "missing_info": [],
                "draft": None,
                "reference": None
            }
        
        # --- SCENARIO 2: Triage needs clarification ---
        if phase == "planning":
            return {
                "status": "needs_info",
                "phase": "planning",
                "message": result.get("clarification_question", "Please provide more details."),
                "missing_info": result.get("missing_info", []),
                "draft": None,
                "reference": None
            }
        
        # --- SCENARIO 3: Draft completed successfully ---
        if phase == "drafting" or result.get("final_draft"):
            return {
                "status": "success",
                "phase": "drafting",
                "message": "Draft generated successfully.",
                "missing_info": [],
                "draft": result.get("final_draft", ""),
                "reference": result.get("reference_clause", "")
            }
        
        # --- FALLBACK: Unknown state ---
        return {
            "status": "error",
            "phase": "unknown",
            "message": "Unable to process your request. Please try again.",
            "missing_info": [],
            "draft": None,
            "reference": None
        }

    except Exception as e:
        print(f"❌ Error: {e}")
        raise HTTPException(status_code=500, detail=str(e))

if __name__ == "__main__":
    uvicorn.run(app, host="0.0.0.0", port=8000)