/* 贪蛇出动 - 通用工具函数 */
(function () {
  'use strict';
  window.GS = window.GS || {};

  const U = {};
  GS.U = U;

  U.rand = (a, b) => a + Math.random() * (b - a);
  U.randInt = (a, b) => Math.floor(U.rand(a, b + 1));
  U.pick = arr => arr[Math.floor(Math.random() * arr.length)];
  U.clamp = (v, a, b) => Math.max(a, Math.min(b, v));
  U.dist2 = (x1, y1, x2, y2) => { const dx = x2 - x1, dy = y2 - y1; return dx * dx + dy * dy; };
  U.dist = (x1, y1, x2, y2) => Math.sqrt(U.dist2(x1, y1, x2, y2));

  // 角度归一化到 [-PI, PI]
  U.normAngle = a => {
    while (a > Math.PI) a -= Math.PI * 2;
    while (a < -Math.PI) a += Math.PI * 2;
    return a;
  };

  // 数字格式化：>=1e6 显示为 "1,194k"，否则千分位
  U.fmt = n => {
    n = Math.floor(n);
    if (n >= 1e6) return Math.floor(n / 1000).toLocaleString('en-US') + 'k';
    return n.toLocaleString('en-US');
  };

  // 北京时间日期串 YYYY-MM-DD（今日最佳用）
  U.todayBJ = () => {
    const d = new Date(Date.now() + (8 * 60 + new Date().getTimezoneOffset()) * 60000);
    const m = String(d.getMonth() + 1).padStart(2, '0');
    const day = String(d.getDate()).padStart(2, '0');
    return d.getFullYear() + '-' + m + '-' + day;
  };

  U.nowStr = () => {
    const d = new Date();
    const p = x => String(x).padStart(2, '0');
    return d.getFullYear() + '-' + p(d.getMonth() + 1) + '-' + p(d.getDate()) + ' ' +
      p(d.getHours()) + ':' + p(d.getMinutes()) + ':' + p(d.getSeconds());
  };

  // 简单空间哈希网格（金币拾取/碰撞加速）
  class Grid {
    constructor(cell) { this.cell = cell; this.m = new Map(); }
    clear() { this.m.clear(); }
    _key(cx, cy) { return cx + ',' + cy; }
    insert(obj) {
      const cx = Math.floor(obj.x / this.cell), cy = Math.floor(obj.y / this.cell);
      const k = this._key(cx, cy);
      let arr = this.m.get(k);
      if (!arr) { arr = []; this.m.set(k, arr); }
      arr.push(obj);
    }
    query(x, y, r) {
      const out = [];
      const c0 = Math.floor((x - r) / this.cell), c1 = Math.floor((x + r) / this.cell);
      const r0 = Math.floor((y - r) / this.cell), r1 = Math.floor((y + r) / this.cell);
      for (let cx = c0; cx <= c1; cx++) for (let cy = r0; cy <= r1; cy++) {
        const arr = this.m.get(this._key(cx, cy));
        if (arr) for (const o of arr) out.push(o);
      }
      return out;
    }
  }
  U.Grid = Grid;
})();