import { v4 } from 'uuid';
type Arr = Record<string, any>[]
export const flatten = (source: Arr) => {
    const arr: Arr = []
    const recursion = (source: Arr, pid: string | null) => {
        source.forEach(item => {
            const { children, ...rest } = item
            const id = v4()
            arr.push({
                ...rest,
                pid,
                id
            })
            if (children && children.length) {
                recursion(children, id)
            }
        });
    }
    recursion(source, null)
    return arr
}

export const unflatten = (source: Arr) => {
    const arr: Arr = []
    const obj: Record<string, any> = {}
    source.forEach(item => {
        const { pid } = item
        if (!pid) {
            arr.push(item)
        } else {
            if (!obj[pid]) {
                obj[pid] = []
            }
            obj[pid].push(item)
        }
    })
    source.forEach(item => {
        const { id } = item
        const childs = obj[id]
        if (childs) {
            item.children = childs
        }
    })
    return arr
}