import {Component, Mixins, Ref} from "vue-property-decorator";
import {emitNames} from '../enum/emit';
import ScrollApi from '../api/scroll';
import ScrollStatus from './status';
import {
    Config,
    EventTypes,
    ListenerEventTarget,
    ScrollConfig,
    ScrollXConfig,
    ScrollYConfig
} from "../types/on";

@Component({

    created(this:ScrollViewConfig){
        this._config = {};
        this._scrollConfig = {
            look:false,
            stipitate:undefined,
            x:{
                x:0,
                width:0,
                actualWidth:0,
                maxScroll:0
            },
            y:{
                y:0,
                height:0,
                actualHeight:0,
                maxScroll:0
            }
        };
    },

    mounted(this:ScrollViewConfig){
        // 执行安装
        return this.installScroll();
    },

    // 释放组件的时候触发
    beforeDestroy(this:ScrollViewConfig){
        this._scrollApi && this._scrollApi.destroy();
        this._scrollConfig.stipitate&&clearTimeout(this._scrollConfig.stipitate);
        this._scrollApi = undefined;
        this.scrollEl && this._config.scrollUnique && this.removeEventListener(this.scrollEl,'scroll',this._config.scrollUnique);
    }

})
export default class ScrollViewConfig extends  Mixins(ScrollStatus) {

    // 滚动标签实例
    @Ref('scroll') scrollEl:HTMLElement | undefined;
    // 滚动包容标签实例
    @Ref('scrollTake') scrollTakeEl:HTMLElement | undefined;

    // 运行时的 scrollApi
    _scrollApi:ScrollApi | undefined;
    // 运行时参数
    _config:Config={};
    // 滚动系列参数配置
    _scrollConfig:ScrollConfig={
        look:false,
        stipitate:undefined,
        x:{
            x:0,
            width:0,
            actualWidth:0,
            maxScroll:0
        },
        y:{
            y:0,
            height:0,
            actualHeight:0,
            maxScroll:0
        }
    };
    // 配置滚动系列参数
    setScrollConfig(){
        if (this._scrollConfig.look) return;
        // 设置锁
        this._scrollConfig.look = true;
        // 配置 x 轴
        this.scrollX && this.setScrollAxisConfig('x');
        // 配置 y 轴
        this.scrollY && this.setScrollAxisConfig('y');
        // 帧频率不允许重复
        this._scrollConfig.stipitate = setTimeout(()=>{
            this._scrollConfig.stipitate = undefined;
            this._scrollConfig.look = false;
        },16.66);
    };
    // 配置单独轴系列参数
    setScrollAxisConfig(axis:'x' | 'y'){

        if (this.scrollEl === undefined || this.scrollTakeEl === undefined) return;

        let sizeKey: 'width' | 'height' = axis === 'x' ? 'width':'height';
        let actualKey : 'actualWidth' | 'actualHeight' = axis === 'x' ? 'actualWidth' :'actualHeight';
        let scrollAxis: 'scrollLeft' | 'scrollTop' = axis === 'x'? 'scrollLeft' :'scrollTop';
        let elSizeKey:'offsetWidth' | 'offsetHeight' = axis === 'x' ? 'offsetWidth' :'offsetHeight';

        // 设置配置文件
        // @ts-ignore
        this._scrollConfig[axis] = {
            [sizeKey]: this.scrollEl[elSizeKey] || 0,
            [axis]: this.scrollEl[scrollAxis] || 0,
            [actualKey]: this.scrollTakeEl[elSizeKey] || 0,
            maxScroll:0
        };
        //
        // // 设置最大滚动
        // @ts-ignore
        (this._scrollConfig[axis] as ScrollYConfig | ScrollXConfig).maxScroll = Math.max(0,this._scrollConfig[axis][actualKey] - this._scrollConfig[axis][sizeKey]);

    };
    // 安装
    installScroll(){

        // 设置当前的配置文件
        this.setScrollConfig();

        // 创建滚动Api
        if (this.scrollEl !== undefined) {
            this._scrollApi = new ScrollApi(this._scrollConfig,this.scrollEl);
        }

        // 如果存在此三种的任何一种 事件开启监听
        if (
            (this.$listeners[emitNames.onScroll]
            ||
            this.$listeners[emitNames.onScrollLower]
            ||
            this.$listeners[emitNames.onScrollUpper]) && this.scrollEl !== undefined
        ) {

            // 获取存储的唯一标识
            this._config.scrollUnique = this.addEventListener(this.scrollEl,'scroll',()=> this.onScroll());
        }

    }
    // 滚动时触发
    onScroll(){
        if (this.scrollEl) {
            // 设置配置
            this.setScrollConfig();

            if (this.$listeners[emitNames.onScrollUpper] || this.$listeners[emitNames.onScrollLower]) {

                if (this.scrollY) {
                    if ( this.$listeners[emitNames.onScrollLower] && this.testScrollDistance('y','lowerThreshold','_lowerThresholdYStatus')) {
                        this.emitScrollLower('y');
                    } else if (this.$listeners[emitNames.onScrollUpper] && this.testScrollDistance('y','upperThreshold','_upperThresholdYStatus')) {
                        this.emitScrollUpper('y');
                    }
                }

                if (this.scrollX) {
                    if ( this.$listeners[emitNames.onScrollLower] && this.testScrollDistance('x','lowerThreshold','_lowerThresholdXStatus')) {
                        this.emitScrollLower('x');
                    } else if (this.$listeners[emitNames.onScrollUpper] && this.testScrollDistance('x','upperThreshold','_upperThresholdXStatus')) {
                        this.emitScrollUpper('x');
                    }
                }

            }

            if(this.$listeners[emitNames.onScroll]) {
                return this.emitScroll(this._scrollConfig);
            }

        }
    }

    // 校验是否满足条件
    testScrollDistance(axis:'x' | 'y',key:'lowerThreshold' | 'upperThreshold',testKey:'_lowerThresholdXStatus'|'_lowerThresholdYStatus'|'_upperThresholdXStatus'|'_upperThresholdYStatus'){

        if (
        this[key] !== undefined
        &&
        // @ts-ignore
        key === 'upperThreshold' ? this._scrollConfig[axis][axis] <= this[key] : this._scrollConfig[axis].maxScroll - this._scrollConfig[axis][axis] <= this[key]
        ) {

            if (!this[testKey]) {
                this[testKey] = true;

                return true;
            }

        } else {
            this[testKey] = false;
        }
        return false;

    }

    // 监听器对象
    _listeners: { [key:string]:ListenerEventTarget } | undefined = undefined;

    // 添加监听
    addEventListener<T extends EventTypes>(el:HTMLElement,event:T,target:ListenerEventTarget){
        // 如果没有监听器对象创建
        if (this._listeners === undefined) {
            this._listeners = {};
        }

        let unique:string = this.getUnique(event);

        this._listeners[unique] = target;

        if (window.addEventListener !== undefined) {
            el.addEventListener(event,target,{
                passive:true
            });
        } else {
            // @ts-ignore 兼容策略
            el.attachEvent('on'+event,target,{
                passive:true
            });
        }

        return unique;
    }

    // 移除兼容
    removeEventListener<K extends EventTypes>(el:HTMLElement,event:K,unique:string){
        if (this._listeners !== undefined && this._listeners[unique] !== undefined) {
            if (window.removeEventListener !== undefined) {
                el.removeEventListener(event, this._listeners[unique]);
            } else {
                // @ts-ignore 兼容策略
                el.detachEvent('on' + event, this._listeners[unique]);
            }
            return  true;
        } else {
            return false;
        }



    }

    // 获取唯一值
    getUnique(value:string=''):string{
        return  new Date().getTime() + value  + Math.floor(Math.random() * 10000) ;
    }

}