// 摄像机：跟随 / 锁定 / 缩放（坑向关的"摄像头"道具靠它搞事）
import { clamp, lerp } from './util.js';

export class Camera {
  constructor(w = 800, h = 608) {
    this.w = w; this.h = h;
    this.x = 0; this.y = 0;
    this.zoom = 1;
    this.tz = 1;
    this.mode = 'follow';
    this.lockX = 0; this.lockY = 0;
    this.shakeX = 0; this.shakeY = 0;
    this.snapped = false;
  }

  reset(level, player) {
    this.zoom = 1; this.tz = 1; this.mode = 'follow';
    this.snapTo(player, level);
  }

  viewW() { return this.w / this.zoom; }
  viewH() { return this.h / this.zoom; }

  snapTo(player, level) {
    this.x = clamp(player.cx - this.viewW() / 2, 0, Math.max(0, level.pxW - this.viewW()));
    this.y = clamp(player.cy - this.viewH() / 2, 0, Math.max(0, level.pxH - this.viewH()));
    this.mode = 'follow';
    this.zoom = 1; this.tz = 1;
  }

  update(level, player, dt) {
    const zone = level.camZone;
    let tx, ty, tz = 1, speed = 0.16;

    if (zone) {
      if (zone.mode === 'lock') {
        this.mode = 'lock';
        tx = zone.lx !== null ? zone.lx : zone.x;
        ty = zone.ly !== null ? zone.ly : zone.y;
        tz = zone.zoom || 1;
        speed = 0.05;   // 缓慢移动，制造迷失感
      } else if (zone.mode === 'zoom') {
        this.mode = 'zoom';
        tz = zone.zoom || 1;
        tx = player.cx - this.w / tz / 2;
        ty = player.cy - this.h / tz / 2;
        speed = 0.14;
      } else if (zone.mode === 'off') {
        this.mode = 'off';
        tx = this.x; ty = this.y; tz = zone.zoom || this.zoom; speed = 0;
      }
    } else {
      this.mode = 'follow';
      tx = player.cx - this.w / this.zoom / 2;
      ty = player.cy - this.h / this.zoom / 2;
      tz = 1;
      speed = 0.16;
    }

    this.tz = lerp(this.tz, tz, 0.06);
    if (Math.abs(this.tz - this.zoom) > 0.002) this.zoom = this.tz;

    if (speed > 0) {
      this.x = lerp(this.x, tx, speed);
      this.y = lerp(this.y, ty, speed);
    }
    this.clampToLevel(level);

    // 抖动
    const sh = level.shake || 0;
    if (sh > 0.2) {
      this.shakeX = (Math.random() - 0.5) * sh;
      this.shakeY = (Math.random() - 0.5) * sh;
    } else { this.shakeX = 0; this.shakeY = 0; }
  }

  clampToLevel(level) {
    const vw = this.viewW(), vh = this.viewH();
    if (level.pxW <= vw) { this.x = (level.pxW - vw) / 2; }
    else this.x = clamp(this.x, 0, level.pxW - vw);
    if (level.pxH <= vh) { this.y = (level.pxH - vh) / 2; }
    else this.y = clamp(this.y, 0, level.pxH - vh);
  }

  apply(ctx) {
    ctx.translate(this.shakeX, this.shakeY);
    if (this.zoom !== 1) ctx.scale(this.zoom, this.zoom);
    ctx.translate(-this.x, -this.y);
  }
}