// 回响星核 / Echo Nexus — 云排行榜 mini-service
// P2/#4：把信标本机排行榜升级为云排行榜。
// 端口固定 3030；Caddy 通过 ?XTransformPort=3030 转发。
// 内存存储（重启清空），Hono + Bun 原生。
//
// API：
//   GET  /api/leaderboard        → { entries: BeaconScoreEntry[], total }
//   POST /api/leaderboard        body { entry } → { entries, total, rank }
//   GET  /api/leaderboard/stats  → { totalSubmissions, uniquePlayers, topScore }
//   GET  /                        → 健康检查
//
// 所有响应自动 CORS 开放（hono/cors），OPTIONS 预检 hono 自动处理。

import { Hono } from "hono";
import { cors } from "hono/cors";

// ---------------------------------------------------------------------------
// 类型（与前端 BeaconScoreEntry 一致，但这里宽松化以接受历史数据）
// ---------------------------------------------------------------------------
interface BeaconScoreEntry {
  timestamp: number;
  dateKey: string;
  challenge: string;
  difficulty: string;
  progress: number;
  score: number;
  durationSec: number;
  isWeekly?: boolean;
  isTimed?: boolean;
}

// ---------------------------------------------------------------------------
// 内存存储
// ---------------------------------------------------------------------------
const entries: BeaconScoreEntry[] = [];
const MAX_ENTRIES = 1000;
const TOP_N = 100;

// 简单防刷：同 dateKey+challenge 10 秒内只接受 1 次提交
const lastSubmitAt = new Map<string, number>();
const RATE_LIMIT_MS = 10_000;

function sortEntries() {
  entries.sort((a, b) => {
    if (b.score !== a.score) return b.score - a.score;
    // 同分情况下，用时短者靠前
    if (a.durationSec !== b.durationSec) return a.durationSec - b.durationSec;
    // 仍相同，按时间戳升序（先提交靠前）
    return a.timestamp - b.timestamp;
  });
  while (entries.length > MAX_ENTRIES) entries.pop();
}

function findRank(entry: BeaconScoreEntry): number {
  const idx = entries.findIndex(
    (e) =>
      e.timestamp === entry.timestamp &&
      e.dateKey === entry.dateKey &&
      e.score === entry.score
  );
  return idx >= 0 ? idx + 1 : -1;
}

// ---------------------------------------------------------------------------
// Hono 实例
// ---------------------------------------------------------------------------
const app = new Hono();

// 全局 CORS 开放（前端跨端口访问）
app.use(
  "*",
  cors({
    origin: "*",
    allowMethods: ["GET", "POST", "OPTIONS"],
    allowHeaders: ["Content-Type", "X-Requested-With"],
    exposeHeaders: ["Content-Length"],
    maxAge: 600,
  })
);

// 健康检查
app.get("/", (c) =>
  c.json({
    service: "echo-nexus-leaderboard",
    version: "v0.8.2",
    ok: true,
    uptime: Math.floor(process.uptime?.() ?? 0),
  })
);

// GET /api/leaderboard — 返回 Top100
app.get("/api/leaderboard", (c) => {
  sortEntries();
  const top = entries.slice(0, TOP_N);
  return c.json({ entries: top, total: entries.length });
});

// POST /api/leaderboard — 插入一条记录，返回新榜 + 排名
app.post("/api/leaderboard", async (c) => {
  let body: { entry?: unknown };
  try {
    body = await c.req.json();
  } catch {
    return c.json({ error: "Invalid JSON body" }, 400);
  }
  if (!body || !body.entry || typeof body.entry !== "object") {
    return c.json({ error: "Missing entry in body" }, 400);
  }
  const e = body.entry as Partial<BeaconScoreEntry>;
  if (
    typeof e.timestamp !== "number" ||
    typeof e.dateKey !== "string" ||
    typeof e.challenge !== "string" ||
    typeof e.difficulty !== "string" ||
    typeof e.score !== "number"
  ) {
    return c.json({ error: "Entry schema mismatch" }, 400);
  }

  // 防刷：同 dateKey+challenge 10 秒内只接受 1 次
  const key = `${e.dateKey}|${e.challenge}`;
  const now = Date.now();
  const last = lastSubmitAt.get(key) ?? 0;
  if (now - last < RATE_LIMIT_MS) {
    return c.json(
      {
        error: "Rate limited",
        retryAfterMs: RATE_LIMIT_MS - (now - last),
        rank: -1,
      },
      429
    );
  }
  lastSubmitAt.set(key, now);

  // 规范化 entry（去多余字段，补默认值）
  const entry: BeaconScoreEntry = {
    timestamp: e.timestamp,
    dateKey: e.dateKey,
    challenge: e.challenge,
    difficulty: e.difficulty,
    progress: typeof e.progress === "number" ? e.progress : 0,
    score: Math.max(0, Math.floor(e.score)),
    durationSec: typeof e.durationSec === "number" ? e.durationSec : 0,
    isWeekly: e.isWeekly === true,
    isTimed: e.isTimed === true,
  };

  entries.push(entry);
  sortEntries();
  const rank = findRank(entry);

  return c.json({
    entries: entries.slice(0, TOP_N),
    total: entries.length,
    rank,
  });
});

// GET /api/leaderboard/stats — 全局统计
app.get("/api/leaderboard/stats", (c) => {
  sortEntries();
  const uniqueDateKeys = new Set(entries.map((e) => e.dateKey));
  return c.json({
    totalSubmissions: entries.length,
    uniquePlayers: uniqueDateKeys.size,
    topScore: entries.length > 0 ? entries[0].score : 0,
  });
});

// ---------------------------------------------------------------------------
// 启动
// ---------------------------------------------------------------------------
const PORT = 3030;
console.log(`[leaderboard-service] listening on :${PORT}`);

const server = {
  port: PORT,
  fetch: app.fetch,
};

export default server;