import shutil
import os
from pydantic import BaseModel
from typing import List, Dict
from src.ingest import ingest_file
from src.chain import get_rag_chain
from src import config
from contextlib import asynccontextmanager
from fastapi import FastAPI, UploadFile, File, HTTPException

rag_chain = None

@asynccontextmanager
async def lifespan(app: FastAPI):
    global rag_chain
    print("Initializing RAG chain at startup...")
    try:
        rag_chain = get_rag_chain()
        print("RAG chain ready.")
    except Exception as e:
        print(f"RAG chain not initialized (no collection yet): {e}")
        rag_chain = None
    yield

app = FastAPI(title="GeneSeek V2 API", lifespan=lifespan)

@app.get("/")
async def root():
    return {"message": "GeneSeek"}

@app.get("/health")
async def health_check():
    return {"status": "ok", "service": "GeneSeek V2 API"}

class ChatRequest(BaseModel):
    question: str

class ChatResponse(BaseModel):
    answer: str
    contexts: List[Dict]

@app.post("/upload")
async def upload_document(file: UploadFile = File(...)):
    global rag_chain
    
    allowed = {".txt", ".pdf"}
    ext = os.path.splitext(file.filename)[1].lower()
    if ext not in allowed:
        raise HTTPException(400, f"Invalid file. Allowed: {allowed}")

    file_path = config.RAW_DATA_DIR / file.filename
    try:
        with open(file_path, "wb") as buffer:
            shutil.copyfileobj(file.file, buffer)
    except Exception as e:
        raise HTTPException(500, f"Save failed: {e}")

    try:
        result = ingest_file(str(file_path))
    except Exception as e:
        raise HTTPException(500, f"Ingestion failed: {e}")

    if result is False:
        return {"message": "File already ingested. Skipping.", "status": "skipped"}

    rag_chain = get_rag_chain()
    return {"message": f"Successfully indexed {file.filename}", "status": "success"}


@app.post("/chat", response_model=ChatResponse)
async def chat_endpoint(request: ChatRequest):
    global rag_chain
    if rag_chain is None:
        raise HTTPException(503, "No documents ingested yet. Please upload a file first.")
    try:
        result = rag_chain(request.question)
        return ChatResponse(answer=result["answer"], contexts=result["contexts"])
    except Exception as e:
        raise HTTPException(500, detail=str(e))

if __name__ == "__main__":
    import uvicorn
    uvicorn.run("main:app", host="127.0.0.1", port=8000, reload=False)