import { _decorator, Component, Node, Vec3, Camera, view } from 'cc';
const { ccclass, property } = _decorator;

@ccclass('CameraFollow')
export class CameraFollow extends Component {

    @property(Node)
    target: Node | null = null;  // 要跟随的目标（玩家）

    @property({ range: [0.1, 10] })
    followSpeed: number = 5.0;  // 跟随速度

    @property(Vec3)
    offset: Vec3 = new Vec3(0, 0, 10);  // 相机相对目标的偏移

    @property({ range: [0, 1] })
    smoothness: number = 0.1;  // 平滑度，0为瞬间跟随，1为最慢跟随

    @property
    mapWidth: number = 1080;  // 地图宽度

    @property
    mapHeight: number = 2560;  // 地图高度

    private camera: Camera | null = null;

    onLoad() {
        // 获取相机组件
        this.camera = this.getComponent(Camera);
        if (!this.camera) {
            console.error('CameraFollow: 未找到Camera组件');
        }
    }

    start() {
        if (this.target) {
            // 初始化相机位置
            const initialPos = this.target.position.clone();
            initialPos.add(this.offset);
            this.node.position = initialPos;
        }
    }

    update(deltaTime: number) {
        if (!this.target) return;

        // 计算目标位置
        const targetPosition = this.target.position.clone();
        targetPosition.add(this.offset);

        // 应用地图边界限制
        const clampedPosition = this.clampCameraPosition(targetPosition);

        // 使用插值实现平滑跟随
        const currentPosition = this.node.position;
        const newPosition = new Vec3();

        // 根据平滑度设置插值速度
        const lerpFactor = Math.min(1.0, this.followSpeed * deltaTime * (1 - this.smoothness + 0.1));

        Vec3.lerp(newPosition, currentPosition, clampedPosition, lerpFactor);
        this.node.position = newPosition;
    }

    // 限制相机位置在地图边界内
    private clampCameraPosition(position: Vec3): Vec3 {
        if (!this.camera) return position;

        // 获取屏幕可见区域大小
        const visibleSize = view.getVisibleSize();

        // 计算相机能看到的世界区域的一半
        const halfCameraWidth = visibleSize.width * 0.5;
        const halfCameraHeight = visibleSize.height * 0.5;

        // 计算地图边界（地图锚点为0.5,0.5，所以范围是-mapWidth/2到+mapWidth/2）
        const mapHalfWidth = this.mapWidth * 0.5;
        const mapHalfHeight = this.mapHeight * 0.5;

        // 计算相机位置的边界（确保相机边缘不超出地图边界）
        const minX = -mapHalfWidth + halfCameraWidth;
        const maxX = mapHalfWidth - halfCameraWidth;
        const minY = -mapHalfHeight + halfCameraHeight;
        const maxY = mapHalfHeight - halfCameraHeight;

        // 限制相机位置
        const clampedPosition = position.clone();
        clampedPosition.x = Math.max(minX, Math.min(maxX, position.x));
        clampedPosition.y = Math.max(minY, Math.min(maxY, position.y));

        return clampedPosition;
    }

    // 设置跟随目标
    setTarget(target: Node) {
        this.target = target;
        if (target) {
            const initialPos = target.position.clone();
            initialPos.add(this.offset);
            this.node.position = initialPos;
        }
    }

    // 设置偏移量
    setOffset(offset: Vec3) {
        this.offset = offset;
    }

    // 瞬间移动到目标位置
    snapToTarget() {
        if (!this.target) return;

        const targetPosition = this.target.position.clone();
        targetPosition.add(this.offset);
        const clampedPosition = this.clampCameraPosition(targetPosition);
        this.node.position = clampedPosition;
    }
}