import {
    SMouseButton,
    SMouseEvent,
    SNetUtil,
    SObject,
    STouchState
} from "@saga-web/base/lib/";
import { SSvgPaintEngine } from "./engines/SSvgPaintEngine";
import { SPoint } from "./types/SPoint";
import { SPainter } from "./SPainter";

/**
 * Canvas视图基类
 *
 * @author  庞利祥(sybotan@126.com)
 */
export class SCanvasView extends SObject {
    private _needDraw = true;
    /** canvas视图 */
    protected readonly canvasView: HTMLCanvasElement;
    get canvas(): CanvasRenderingContext2D | null {
        return this.canvasView.getContext("2d") as CanvasRenderingContext2D;
    } // Get canvas

    /** 宽度 */
    get width(): number {
        return this.canvasView.width;
    } // Get width()

    /** 高度 */
    get height(): number {
        return this.canvasView.height;
    } // Get height()

    /** 原点坐标 */
    private _origin = new SPoint();
    get origin(): SPoint {
        return this._origin;
    } // Get origin
    set origin(v: SPoint) {
        if (!this.moveable) {
            return;
        }
        this._origin.x = v.x;
        this._origin.y = v.y;
        this._needDraw = true;
    } // Set origin

    /** 可否进行平移操作 */
    moveable = true;
    /** 缩放比例 */
    private _scale: number = 1;
    get scale(): number {
        return this._scale;
    } // Get scale
    set scale(v: number) {
        if (!this.scalable) {
            return;
        }
        this._scale = v;
        this._needDraw = true;
    } // Set scale

    /** 可否执行绽放操作 */
    scalable = true;
    /** 鼠标滚轮缩放速度 */
    wheelZoom = 1.05;
    /** 最小缩放比例 */
    minScale = 0.000001;
    /** 最大缩放比例 */
    maxScale = 1000000;

    /** 最后一次更新时间 */
    private _lastFrameTime = 0;

    /** 鼠标中键按下时位置 */
    private _midKeyPos = new SPoint();

    /** 手执状态 */
    private _touchState = STouchState.None;
    /** 手指拖动点 */
    private _touchPoint = new SPoint();
    /** 未缩放时二指间距离 */
    private _beforeLength = 0;
    /** 缩放后二指间距离 */
    private _afterLength = 0;

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    //
    /**
     * 构造函数
     *
     * @param   id      画布对象ID
     */
    constructor(id: string) {
        super();
        this.canvasView = document.getElementById(id) as HTMLCanvasElement;
        this.bindEvent(this.canvasView);

        this.requestAnimationFrame(this.loop.bind(this));
    } // Constructor

    /**
     * 更新视图
     */
    update(): void {
        this._needDraw = true;
    } // Function update()

    /**
     * 保存图像
     *
     * @param   name    名称
     * @param   type    图像类型
     */
    saveImage(name: string, type: string): void {
        let url = this.canvasView.toDataURL(`image/${type}`);
        SNetUtil.downLoad(name, url);
    } // Function saveImage()

    /**
     * 图像的URL
     *
     * @param   type    图像类型
     */
    imageUrl(type: string): string {
        return this.canvasView.toDataURL(`image/${type}`);
    } // Function imageUrl()

    /**
     * 视图内容保存为SVG文件
     *
     * @param   name    文件名
     */
    saveSvg(name: string): void {
        let url = URL.createObjectURL(
            new Blob([this.svgData()], { type: "text/xml,charset=UTF-8" })
        );
        SNetUtil.downLoad(name, url);
    } // Function saveSvg()

    /**
     * 视图SVG图形的数据
     *
     * @return  URL地址
     */
    svgData(): string {
        let engine = new SSvgPaintEngine(this.width, this.height);
        let painter = new SPainter(engine);
        this.onDraw(painter);
        return engine.toSvg();
    } // Function saveSvg()

    /**
     * 缩放视图时计算视图的位置与缩放比例
     *
     * @param   zoom        缩放比例
     * @param   x0          缩放计算的中心点X坐标
     * @param   y0          缩放计算的中心点Y坐标
     */
    scaleByPoint(zoom: number, x0: number, y0: number): void {
        if (!this.scalable) {
            return;
        }

        let z = zoom;
        /**
         * 缩放比例在最小比例和最大比例范围内
         */
        if (this.scale * zoom >= this.maxScale) {
            z = this.maxScale / this.scale;
            this.scale = this.maxScale;
        } else if (this.scale * zoom <= this.minScale) {
            z = this.minScale / this.scale;
            this.scale = this.minScale;
        } else {
            this.scale *= zoom;
        }

        this.origin.x = x0 - (x0 - this.origin.x) * z;
        this.origin.y = y0 - (y0 - this.origin.y) * z;
    } // Function scaleByPoint()

    ////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    //
    /**
     * 循环
     */
    protected loop(): void {
        /** painter对象 */
        let ctx = this.canvas;
        if (null != ctx && this._needDraw) {
            this._needDraw = false;
            let painter = new SPainter(this);
            this.onDraw(painter);
        }
        this.requestAnimationFrame(this.loop.bind(this));
    } // Function loop()

    /**
     * 绘制视图
     *
     * @param   painter     painter对象
     */
    protected onDraw(painter: SPainter): void {} // Function onDraw()

    /**
     * 鼠标单击事件
     *
     * @param   event       事件参数
     */
    protected onClick(event: MouseEvent): void {} // Function onClick()

    /**
     * 鼠标双击事件
     *
     * @param   event       事件参数
     */
    protected onDoubleClick(event: MouseEvent): void {} // Function onDoubleClick()

    /**
     * 鼠标按下事件
     *
     * @param   event       事件参数
     */
    protected onMouseDown(event: MouseEvent): void {
        let se = new SMouseEvent(event);
        if (se.buttons & SMouseButton.MidButton) {
            this._midKeyPos.x = se.x;
            this._midKeyPos.y = se.y;
        }
    } // Function onMouseDown()

    /**
     * 鼠标移动事件
     *
     * @param   event       事件参数
     */
    protected onMouseMove(event: MouseEvent): void {
        // 如果可以移动
        if (this.moveable) {
            // 按中键移动
            let se = new SMouseEvent(event);
            if (se.buttons & SMouseButton.MidButton) {
                this.origin.x += se.x - this._midKeyPos.x;
                this.origin.y += se.y - this._midKeyPos.y;
                this._midKeyPos.x = se.x;
                this._midKeyPos.y = se.y;
                this.update();
                return;
            }
        }
    } // Function onMouseMove()

    /**
     * 鼠标松开事件
     *
     * @param   event       事件参数
     */
    protected onMouseUp(event: MouseEvent): void {} // Function onMouseUp()

    /**
     * 上下文菜单事件
     *
     * @param   event       事件参数
     */
    protected onContextMenu(event: MouseEvent): void {} // Function onContextMenu()

    /**
     * 鼠标滚轮事件
     *
     * @param   event       事件参数
     */
    protected onMouseWheel(event: WheelEvent): void {
        if (event.deltaY < 0) {
            this.scaleByPoint(this.wheelZoom, event.offsetX, event.offsetY);
        } else {
            this.scaleByPoint(1 / this.wheelZoom, event.offsetX, event.offsetY);
        }
    } // Function onMouseWheel()

    /**
     * 按键按下事件
     *
     * @param   event       事件参数
     */
    protected onKeyDown(event: KeyboardEvent): void {} // Function onKeydown()

    /**
     * 按键press事件
     *
     * @param   event       事件参数
     */
    protected onKeyPress(event: KeyboardEvent): void {} // Function onKeypress()

    /**
     * 按键松开事件
     *
     * @param   event       事件参数
     */
    protected onKeyUp(event: KeyboardEvent): void {} // Function onKeyup()

    /**
     * 开始触摸事件
     *
     * @param   event       事件参数
     */
    protected onTouchStart(event: TouchEvent): void {
        let touches = event.touches;
        if (touches.length == 1) {
            this._touchPoint.x = event.touches[0].clientX;
            this._touchPoint.y = event.touches[0].clientY;
        }
        if (touches.length == 2) {
            this._touchState = STouchState.Zoom;
            this._beforeLength = this.getDistance(event);
        }
    } // Function onTouchStart()

    /**
     * 触摸移动事件
     *
     * @param   event       事件参数
     */
    protected onTouchMove(event: TouchEvent): void {
        let touches = event.touches;
        if (touches.length == 1) {
            this.origin.x += event.touches[0].clientX - this._touchPoint.x;
            this.origin.y += event.touches[0].clientY - this._touchPoint.y;
            this._touchPoint.x = event.touches[0].clientX;
            this._touchPoint.y = event.touches[0].clientY;
        }
        if (touches.length == 2) {
            this.viewZoom(event);
        }
    } // Function onTouchMove()

    /**
     * 结束触摸事件
     *
     * @param   event       事件参数
     */
    protected onTouchEnd(event: TouchEvent): void {
        this._touchState = STouchState.None;
    } // Function onTouchEnd()

    /**
     * View大小变更事件
     *
     * @param   event       事件参数
     */
    protected onResize(event: UIEvent): void {} // Function onClick()

    /**
     * 绑定事件
     *
     * @param   element     要绑定事件的元素
     */
    private bindEvent(element: HTMLElement): void {
        // 绑定鼠标事件
        element.onclick = this.onClick.bind(this);
        element.ondblclick = this.onDoubleClick.bind(this);
        element.onmousedown = this.onMouseDown.bind(this);
        element.onmousemove = this.onMouseMove.bind(this);
        element.onmouseup = this.onMouseUp.bind(this);
        element.oncontextmenu = this.onContextMenu.bind(this);
        element.onwheel = this.onMouseWheel.bind(this);

        // 绑定按键事件
        element.onkeydown = this.onKeyDown.bind(this);
        element.onkeypress = this.onKeyPress.bind(this);
        element.onkeyup = this.onKeyUp.bind(this);

        // 触摸事件
        element.ontouchstart = this.onTouchStart.bind(this);
        element.ontouchmove = this.onTouchMove.bind(this);
        element.ontouchend = this.onTouchEnd.bind(this);

        // 绑定窗口事件
        element.onresize = this.onResize.bind(this);
    } // Function bindEvent()

    /**
     * 启动动画帧（即指定时间执行回调函数）
     *
     * @param   callback        回调函数
     */
    private requestAnimationFrame(callback: FrameRequestCallback): number {
        let currTime = new Date().getTime();
        let timeToCall = Math.max(0, 16 - (currTime - this._lastFrameTime));
        let id = setTimeout(function(): void {
            callback(currTime + timeToCall);
        }, timeToCall);
        this._lastFrameTime = currTime + timeToCall;
        return id;
    } // Function requestAnimationFrame()

    /**
     * 缩放视图
     *
     * @param   event       触摸事件
     */
    private viewZoom(event: TouchEvent): boolean {
        if (this._touchState == STouchState.Zoom) {
            // 获取两点的距离
            this._afterLength = this.getDistance(event);
            // 变化的长度;
            let gapLenght = this._afterLength - this._beforeLength;
            if (Math.abs(gapLenght) > 5 && this._beforeLength != 0.0) {
                // 求的缩放的比例
                let tempScale = this._afterLength / this._beforeLength;
                let p = this.getMiddlePoint(event);
                // 重设置
                this.scaleByPoint(tempScale, p.x, p.y);
                this._beforeLength = this._afterLength;
            }
        }
        return true;
    } // Function onTouchMove()

    /**
     * 获取两手指之间的距离
     *
     * @param   event       触摸事件
     * @return 两手指之间的距离
     */
    private getDistance(event: TouchEvent): number {
        if (event.touches.length < 2) {
            return 0;
        }

        let dx = event.touches[0].clientX - event.touches[1].clientX;
        let dy = event.touches[0].clientY - event.touches[1].clientY;
        return Math.sqrt(dx * dx + dy * dy);
    } // Function getDistance()

    /**
     * 获得两个手指触摸点的中点坐标
     *
     * @param   event
     * @return  得到视图的x坐标中点
     */
    private getMiddlePoint(event: TouchEvent): SPoint {
        return new SPoint(
            (event.touches[0].clientX + event.touches[1].clientX) / 2,
            (event.touches[0].clientY + event.touches[1].clientY) / 2
        );
    } // Function getMiddlePoint()
} // Class SCanvasView