import React, { useRef, useEffect, useState } from 'react';
import { v4 } from 'uuid';
import './index.less';

const createUUID = () => {
    return v4();
};

// 单条参考线组件
const GuidesLine = (props) => {
    const { id, top, removeCb, updateCb } = props;
    const dragRef = useRef(null);

    useEffect(() => {
        const drag = dragRef.current;
        drag.onmousedown = (ev) => {
            ev.preventDefault();
            const diffY = ev.clientY - drag.offsetTop;
            document.onmousemove = (ev) => {
                ev.preventDefault();
                ev.stopPropagation();
                let moveY = ev.clientY - diffY;
                drag.style.top = moveY + 'px';
            };
            document.onmouseup = (ev) => {
                document.onmousemove = null;
                document.onmouseup = null;
                // 如果小于等于20则去除参考线
                if (ev.clientY <= 20) {
                    removeCb(id);
                } else {
                    updateCb(id, ev.clientY);
                }
            };
        };

        return () => {
            drag.onmousedown = null;
        };
    }, [props]);

    return (
        <div
            ref={dragRef}
            className="guides-line guides-line__h"
            data-id={id}
            style={{ top: `${top}px` }}
            onDoubleClick={() => {
                // 双击删除
                removeCb(id);
            }}
        ></div>
    );
};

// 坐标尺
const Ruler = () => {
    const rulerRef = useRef(null);
    const [guidesLineList, setGuidesLineList] = useState([]); //参考线列表
    const [virtualGuidesTop, setVirtualGuidesTop] = useState(0); //虚拟参考线距离顶部高度

    useEffect(() => {
        const el = rulerRef.current;
        el.onmousedown = (ev) => {
            setVirtualGuidesTop(ev.clientY);
            document.onmousemove = (ev) => {
                ev.preventDefault();
                setVirtualGuidesTop(ev.clientY);
            };
            document.onmouseup = (ev) => {
                document.onmousemove = null;
                document.onmouseup = null;
                setVirtualGuidesTop(0);
                if (ev.clientY > 20) {
                    // 添加新的参考线
                    const list = [
                        ...guidesLineList,
                        {
                            id: createUUID(),
                            top: ev.clientY,
                        },
                    ];
                    console.log(list);
                    setGuidesLineList(list);
                }
            };
        };

        return () => {
            el.onmousedown = null;
        };
    }, [guidesLineList]);

    return (
        <>
            <div className="ruler" ref={rulerRef}>
                {virtualGuidesTop !== 0 && virtualGuidesTop > 20 && <div className="virtual-guides-line guides-line-h" style={{ top: `${virtualGuidesTop}px` }}></div>}
            </div>

            {/* 渲染参考线列表 */}
            {guidesLineList.map((item) => {
                return (
                    <GuidesLine
                        key={item.id}
                        id={item.id}
                        top={item.top}
                        removeCb={(id) => {
                            setGuidesLineList(guidesLineList.filter((item) => item.id !== id));
                        }}
                        updateCb={(id, top) => {
                            console.log(id);
                            setGuidesLineList(
                                guidesLineList.map((item) => {
                                    if (item.id === id) {
                                        item.top = top;
                                    }
                                    return item;
                                })
                            );
                        }}
                    />
                );
            })}
        </>
    );
};

export default Ruler;

* {
    padding: 0;
    margin: 0;
}
// 标尺样式
.ruler {
    width: 100%;
    height: 20px;
    background-color: #ccc;
    border-bottom: 1px solid #000;
    position: absolute;
    z-index: 1;
    .virtual-guides-line {
        height: 1px;
        width: 100%;
        background-color: #aaa;
        position: absolute;
        left: 0;
        top: 0;
    }
}

// 参考线样式
.guides-line {
    position: absolute;
    &.guides-line__h {
        left: 0;
        top: 0;
        height: 5px;
        width: 100%;
        &:hover {
            cursor: n-resize;
        }
        &::before {
            content: ' ';
            display: block;
            background-color: aqua;
            height: 1px;
            width: 100%;
        }
    }
}