app.py

from fastapi import FastAPI, HTTPException, Depends
from fastapi.security import APIKeyHeader
from pydantic import BaseModel
from transformers import pipeline
import os
from typing import List, Optional

app = FastAPI()

# API Key security – read from environment secret
API_KEY = os.getenv("INTERNAL_API_KEY")
if not API_KEY:
    raise RuntimeError("INTERNAL_API_KEY environment variable not set")
API_KEY_NAME = "X-Internal-API-Key"

api_key_header = APIKeyHeader(name=API_KEY_NAME, auto_error=False)

async def verify_api_key(api_key: str = Depends(api_key_header)):
    if not api_key or api_key != API_KEY:
        raise HTTPException(status_code=403, detail="Invalid API Key")
    return api_key

model = pipeline("zero-shot-classification", model="vicgalle/xlm-roberta-large-xnli-anli")

DEFAULT_TOPICS = [
    "Health", "Education", "Water Supply", "Electricity", "Housing", "Transport",
    "Roads", "Bridges", "Railways", "Airports", "Digital Infrastructure",
    "Agriculture", "Irrigation", "Livestock", "Forestry", "Environment", "Climate Change",
    "Economy", "Employment", "Small Business", "Industry", "Trade", "Tourism",
    "Social Protection", "Pension", "Disability Support", "Food Security", "Poverty Reduction",
    "Governance", "Justice", "Police", "Defense", "Public Safety",
    "Urban Planning", "Rural Development", "Land Administration", "Migration",
    "Sports", "Culture", "Youth", "Women Affairs", "Diaspora"
]

class TopicRequest(BaseModel):
    text: str
    candidate_topics: Optional[List[str]] = None

class TopicResponse(BaseModel):
    topics: List[dict]

@app.post("/suggest-topics", response_model=TopicResponse)
async def suggest_topics(request: TopicRequest, _ = Depends(verify_api_key)):
    if not request.text.strip():
        raise HTTPException(status_code=400, detail="Empty text")
    candidate = request.candidate_topics or DEFAULT_TOPICS
    result = model(request.text, candidate)
    top = [{"topic": result["labels"][i], "confidence": result["scores"][i]} for i in range(min(3, len(result["labels"])))]
    return {"topics": top}

@app.get("/health")
async def health():
    return {"status": "ok"}