// +----------------------------------------------------------------------
// | Description: v-drag 弹窗拖拽
// +----------------------------------------------------------------------

export default {
    bind (el, binding, vnode, oldVnode) {
        const value = binding.value
        if (value == false) return
        // 获取拖拽内容头部
        const dialogHeaderEl = el.querySelector('.el-dialog__header');
        const dragDom = el.querySelector('.el-dialog');
        dialogHeaderEl.style.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 = dragDom.currentStyle || window.getComputedStyle(dragDom, null);
        dragDom.style.position = 'absolute';
        dragDom.style.marginTop = 0;
        let width = dragDom.style.width;
        if (width.includes('%')) {
            width = +document.body.clientWidth * (+width.replace(/\%/g, '') / 100);
        } else {
            width = +width.replace(/\px/g, '');
        }
        dragDom.style.left = `${(document.body.clientWidth - width) / 2}px`;
        // 鼠标按下事件
        dialogHeaderEl.onmousedown = (e) => {
            // 鼠标按下，计算当前元素距离可视区的距离 (鼠标点击位置距离可视窗口的距离)
            const disX = e.clientX - dialogHeaderEl.offsetLeft;
            const disY = e.clientY - dialogHeaderEl.offsetTop;

            // 获取到的值带px 正则匹配替换
            let styL, styT;

            // 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 (sty.left.includes('%')) {
                styL = +document.body.clientWidth * (+sty.left.replace(/\%/g, '') / 100);
                styT = +document.body.clientHeight * (+sty.top.replace(/\%/g, '') / 100);
            } else {
                styL = +sty.left.replace(/\px/g, '');
                styT = +sty.top.replace(/\px/g, '');
            };

            // 鼠标拖拽事件
            document.onmousemove = function (e) {
                // 通过事件委托，计算移动的距离 （开始拖拽至结束拖拽的距离）
                const l = e.clientX - disX;
                const t = e.clientY - disY;

                let finallyL = l + styL
                let finallyT = t + styT

                // 移动当前元素
                dragDom.style.left = `${finallyL}px`;
                dragDom.style.top = `${finallyT}px`;

            };

            document.onmouseup = function (e) {
                document.onmousemove = null;
                document.onmouseup = null;
            };
        }
    }
};
