// File d'attente de questions par room. Préchargée au lancement de la partie
// depuis la DB (si dispo), sinon depuis la banque en dur. Le QuizRound y pioche.

import { hasDb } from "../../../db"
import { loadQuizPool } from "../../../db/quiz-repo"
import type { ServerRoom } from "../../../rooms"
import { QUIZ_QUESTIONS, type QuizQuestion } from "./questions"

interface RoomPool {
  queue: QuizQuestion[]
  /** true si les questions viennent de la DB (→ marquer jouées). */
  fromDb: boolean
}

const poolByRoom = new WeakMap<ServerRoom, RoomPool>()

function shuffle<T>(items: T[]): T[] {
  const arr = [...items]
  for (let i = arr.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1))
    ;[arr[i], arr[j]] = [arr[j], arr[i]]
  }
  return arr
}

/** Précharge les questions de la partie. À appeler avant de lancer le moteur. */
export async function prepareQuizForRoom(room: ServerRoom): Promise<void> {
  const needed = room.settings.rounds.filter((r) => r.type === "quiz").length
  let queue: QuizQuestion[] = []
  let fromDb = false

  if (hasDb) {
    try {
      queue = await loadQuizPool(room.code, Math.max(needed, 1))
      fromDb = queue.length > 0
    } catch (err) {
      console.error("[quiz] chargement DB échoué, fallback banque en dur", err)
    }
  }

  if (queue.length === 0) {
    queue = shuffle(QUIZ_QUESTIONS)
    fromDb = false
  }

  poolByRoom.set(room, { queue, fromDb })
}

/** Pioche la prochaine question. Fallback aléatoire si la file est vide. */
export function takeQuestion(room: ServerRoom): {
  question: QuizQuestion
  fromDb: boolean
} {
  const pool = poolByRoom.get(room)
  if (pool && pool.queue.length > 0) {
    return { question: pool.queue.shift()!, fromDb: pool.fromDb }
  }
  const question =
    QUIZ_QUESTIONS[Math.floor(Math.random() * QUIZ_QUESTIONS.length)]
  return { question, fromDb: false }
}