import { _decorator, Component, director, Director, math, Node, Size, Sprite, UITransform } from 'cc';

const { ccclass, property, requireComponent, executeInEditMode } = _decorator;

@ccclass('PreserveAspectRatioSprite')
@requireComponent(Sprite)
@executeInEditMode
export class PreserveAspectRatioSprite extends Component {
    private _sprite: Sprite;
    private _uiTransform: UITransform;

    protected onLoad(): void {}

    protected onEnable() {
        this._sprite = this.getComponent(Sprite);
        this._uiTransform = this.getComponent(UITransform);
        this.addEventListeners();
        this.resize();
    }

    protected onDisable() {
        this.removeEventListeners();
    }

    protected addEventListeners() {
        director.on(Director.EVENT_AFTER_UPDATE, this.resize, this);
        this.node.off(Node.EventType.ANCHOR_CHANGED, this.resize, this);
        this.node.off(Node.EventType.SIZE_CHANGED, this.resize, this);
    }

    protected removeEventListeners() {
        director.off(Director.EVENT_AFTER_UPDATE, this.resize, this);
        this.node.off(Node.EventType.SIZE_CHANGED, this.resize, this);
        this.node.off(Node.EventType.ANCHOR_CHANGED, this.resize, this);
    }

    protected resize() {
        if (!this._sprite.spriteFrame) {
            return;
        }

        const spriteSize = this._sprite.spriteFrame.originalSize;
        const rectSize = this._uiTransform.contentSize.clone();

        const spriteRatio = spriteSize.x / spriteSize.y;
        const rectRatio = rectSize.width / rectSize.height;

        if (spriteRatio > rectRatio) {
            const oldHeight = rectSize.height;
            rectSize.height = rectSize.width * (1 / spriteRatio);
            rectSize.y += (oldHeight - rectSize.height) * this._uiTransform.anchorY;
        } else {
            const oldWidth = rectSize.width;
            rectSize.width = rectSize.height * spriteRatio;
            rectSize.x += (oldWidth - rectSize.width) * this._uiTransform.anchorX;
        }

        this._uiTransform.contentSize = rectSize;
    }
}