/* 贪蛇出动 - 世界：金币生成/拾取/磁铁/边界/相机/死亡掉币 */
(function () {
  'use strict';
  window.GS = window.GS || {};
  const U = GS.U;

  class World {
    constructor() {
      this.size = GS.CFG.worldSize;
      this.coins = [];          // {x,y,r,value,kind:0普通 1星 2大, phase}
      this.grid = new U.Grid(220);
      this.cam = { x: this.size / 2, y: this.size / 2, scale: 1 };
      this.seed();
    }

    seed() {
      this.coins.length = 0;
      for (let i = 0; i < GS.CFG.coinCount; i++) this.coins.push(this._makeCoin());
      this._rebuild();
    }

    _makeCoin(x, y, kind) {
      const k = kind != null ? kind : (Math.random() < 0.08 ? 1 : 0);
      const base = {
        0: { r: 7, value: 2 },
        1: { r: 12, value: 10 },   // 星币：+幸运星
        2: { r: 14, value: 20 }    // 大金币：尸体掉落
      }[k];
      return {
        x: x != null ? x : U.rand(60, this.size - 60),
        y: y != null ? y : U.rand(60, this.size - 60),
        r: base.r, value: base.value, kind: k,
        phase: U.rand(0, Math.PI * 2),
        vx: 0, vy: 0
      };
    }

    _rebuild() {
      this.grid.clear();
      for (const c of this.coins) this.grid.insert(c);
    }

    // 尸体掉币：沿身体间隔掉落
    dropFromSegments(segs) {
      for (let i = 0; i < segs.length; i += 2) {
        const s = segs[i];
        this.coins.push(this._makeCoin(
          U.clamp(s.x + U.rand(-14, 14), 40, this.size - 40),
          U.clamp(s.y + U.rand(-14, 14), 40, this.size - 40), 2));
      }
      this._rebuild();
    }

    // 外部新增单枚金币（加速掉落等），并重建网格索引
    addCoin(x, y, kind) {
      const c = this._makeCoin(
        U.clamp(x, 40, this.size - 40),
        U.clamp(y, 40, this.size - 40), kind || 0);
      c.r = kind === 2 ? 14 : (kind === 1 ? 12 : 5);
      c.value = kind === 2 ? 20 : (kind === 1 ? 10 : 1);
      this.coins.push(c);
      this.grid.insert(c);
      return c;
    }

    // 宝藏屋奖励：玩家附近撒一大簇金币
    treasureBurst(x, y) {
      for (let i = 0; i < 70; i++) {
        const a = U.rand(0, Math.PI * 2), d = U.rand(30, 320);
        this.coins.push(this._makeCoin(
          U.clamp(x + Math.cos(a) * d, 40, this.size - 40),
          U.clamp(y + Math.sin(a) * d, 40, this.size - 40),
          Math.random() < 0.25 ? 1 : (Math.random() < 0.4 ? 2 : 0)));
      }
      this._rebuild();
    }

    update(dt, snakes, now) {
      let moved = false;
      for (const s of snakes) {
        if (s.dead) continue;
        const h = s.head;
        const magnet = now < s.magnetUntil;
        const eatR = s.radius + 16;
        const pullR = magnet ? 260 : eatR;
        const near = this.grid.query(h.x, h.y, Math.max(pullR, 60));
        for (const c of near) {
          if (c._eaten) continue;
          const d2 = U.dist2(h.x, h.y, c.x, c.y);
          if (magnet && d2 < pullR * pullR) {
            const d = Math.sqrt(d2) || 1;
            const pull = 420 * dt;
            c.x += (h.x - c.x) / d * pull;
            c.y += (h.y - c.y) / d * pull;
            moved = true;
          }
          if (d2 < (eatR + c.r) * (eatR + c.r)) {
            c._eaten = true;
            s.grow(c.value);
            s.coins += c.value;
            if (c.kind === 1) s.lucky += 1;
          }
        }
      }
      if (this.coins.some(c => c._eaten)) {
        this.coins = this.coins.filter(c => !c._eaten);
        // 补充普通金币保持总量
        while (this.coins.length < GS.CFG.coinCount) this.coins.push(this._makeCoin());
        moved = true;
      }
      if (moved) this._rebuild();
    }

    // 相机跟随
    updateCam(target, viewW, viewH, dt) {
      const k = 1 - Math.pow(0.001, dt); // 平滑跟随
      this.cam.x += (target.x - this.cam.x) * k;
      this.cam.y += (target.y - this.cam.y) * k;
      const base = Math.min(viewW, viewH) / 720;
      this.cam.scale = U.clamp(base, 0.7, 1.6);
    }

    inBounds(x, y, margin) {
      return x > margin && y > margin && x < this.size - margin && y < this.size - margin;
    }

    // 碰撞判定：返回 {type:'body', snake} 或 {type:'wall'} 或 null
    collide(s, snakes) {
      const h = s.head;
      if (!this.inBounds(h.x, h.y, s.radius * 0.5)) return { type: 'wall' };
      for (const o of snakes) {
        if (o === s || o.dead) continue;
        const segs = o.segments();
        const rr = (s.radius * 0.8 + o.radius * 0.9);
        // 跳过对方头部附近（允许并排）
        for (let i = 2; i < segs.length; i++) {
          const g = segs[i];
          if (U.dist2(h.x, h.y, g.x, g.y) < rr * rr) return { type: 'body', snake: o };
        }
      }
      return null;
    }
  }

  GS.World = World;
})();