// 拖拽的指令
const drag = {
    beforeMount(el: any, binding: any) {
        // 自定义属性，判断是否可拖拽
        if (!binding.value) return
        const dragDom = el.querySelector('.drag_content')
        const dialogHeaderEl = el.querySelector('.drag_header')
        dialogHeaderEl.style.cssText += ';cursor:move;'

        // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
        const sty = (function () {
            if ((document.body as any).currentStyle) {
                // 在ie下兼容写法
                return (dom: any, attr: any) => dom.currentStyle[attr]
            }
            return (dom: any, attr: any) => getComputedStyle(dom, null)[attr]
        })()

        dialogHeaderEl.onmousedown = (e: any) => {
            // 鼠标按下，计算当前元素距离可视区的距离
            const disX = e.clientX - dialogHeaderEl.offsetLeft
            const disY = e.clientY - dialogHeaderEl.offsetTop
            const screenWidth = document.body.clientWidth // body当前宽度
            const screenHeight = document.documentElement.clientHeight // 可见区域高度(应为body高度，可某些环境下无法获取)

            const dragDomWidth = dragDom.offsetWidth // 移动内容宽度 - 必须设置
            const dragDomheight = dragDom.offsetHeight // 移动内容高度 - 必须设置

            const minDragDomLeft = dragDom.offsetLeft // 离左侧最小距离
            const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth // 离左侧最大距离

            const minDragDomTop = dragDom.offsetTop // 离顶部最小距离
            const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight // 离顶部最大距离

            // 获取到的值带px 正则匹配替换
            let styL = sty(dragDom, 'left')
            // 为兼容ie
            if (styL === 'auto') styL = '0px'
            let styT = sty(dragDom, 'top')

            // console.log(styL)
            // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
            if (styL.includes('%')) {
                styL = +document.body.clientWidth * (+styL.replace(/%/g, '') / 100)
                styT = +document.body.clientHeight * (+styT.replace(/%/g, '') / 100)
            } else {
                styL = +styL.replace(/px/g, '')
                styT = +styT.replace(/px/g, '')
            }

            document.onmousemove = function (e) {
                // 通过事件委托，计算移动的距离
                let left = e.clientX - disX
                let top = e.clientY - disY
                // 边界处理
                if (-(left) > minDragDomLeft) {
                    left = -(minDragDomLeft)
                } else if (left > maxDragDomLeft) {
                    left = maxDragDomLeft
                }

                if (-(top) > minDragDomTop) {
                    top = -(minDragDomTop)
                } else if (top > maxDragDomTop) {
                    top = maxDragDomTop
                }

                // 移动当前元素
                dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`
            }

            document.onmouseup = function (e: any) {
                document.onmousemove = null
                document.onmouseup = null
            }
            return false
        }
    }
}
// 挂载，注册
const directives = {
    install: function (app: any) {
        app.directive('dialogDrag', drag)
    }
};
export default directives;