"""
oO ML Serving — Phase 0 stub.

Returns a placeholder response that matches the interface the real scorer will implement.
The recommender service calls this via RemotePolicy (not yet wired in Phase 0).

Contract:
  POST /score
  Body: { user_id: str, candidates: [{ id: str, content: str, source: str, source_id?: str }] }
  Response: { tip_id: str, score: float }
"""

from fastapi import FastAPI, HTTPException
from pydantic import BaseModel
import random

app = FastAPI(title="oO ML Serving", version="0.0.0")


class Candidate(BaseModel):
    id: str
    content: str
    source: str
    source_id: str | None = None


class ScoreRequest(BaseModel):
    user_id: str
    candidates: list[Candidate]


class ScoreResponse(BaseModel):
    tip_id: str
    score: float
    policy: str


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


@app.post("/score", response_model=ScoreResponse)
def score(req: ScoreRequest):
    if not req.candidates:
        raise HTTPException(status_code=422, detail="No candidates")
    # Stub: random uniform scoring — real model slots in here
    chosen = random.choice(req.candidates)
    return ScoreResponse(tip_id=chosen.id, score=1.0, policy="stub-random")