import { readFileSync } from "node:fs";
import { fileURLToPath } from "node:url";

const source = JSON.parse(readFileSync(fileURLToPath(new URL("../shared/arena-stages.json", import.meta.url)), "utf8"));

function normalizeStage(stage) {
  return Object.freeze({
    ...stage,
    assets: Object.freeze([
      { id: "visual", url: `${stage.assetBaseUrl}/visual.glb` },
      { id: "collision", url: `${stage.assetBaseUrl}/collision.glb` },
      { id: "navigation", url: `${stage.assetBaseUrl}/navigation.glb` },
    ]),
  });
}

export const ARENA_STAGES = Object.freeze(source.stages.map(normalizeStage));
export const VALIDATED_ARENA_STAGES = Object.freeze(ARENA_STAGES.filter((stage) => (
  stage.validation.traversal
  && stage.validation.collision
  && stage.validation.spawnSafety
  && stage.validation.lineOfSight
  && stage.validation.performance
)));

export function arenaStageById(stageId) {
  return ARENA_STAGES.find((stage) => stage.id === stageId) ?? null;
}

export function chooseArenaStage({ random = Math.random, previousStageId = null, allowUnvalidated = false } = {}) {
  const pool = allowUnvalidated ? ARENA_STAGES : VALIDATED_ARENA_STAGES;
  if (!pool.length) throw new Error("No validated arena stages are available.");
  const alternatives = pool.length > 1 ? pool.filter((stage) => stage.id !== previousStageId) : pool;
  return alternatives[Math.floor(random() * alternatives.length)];
}