import { isPlainObject } from "../../is"

/**
 * 展平对象为一层的对象
 * 深度的属性名用 . 连接，如 { a: { b: 1 } } => { 'a.b': 1 }
 * @param ob 要展平的对象
 * @param options.ignorePrefix 要忽略的前缀，如 `$`，会让 { inf: { parentId: {$in:[]} } } 变成 { 'inf.parentId': {$in:[]} }
 */
export function flattenObject(ob: any, options?: { ignorePrefix?: string }) {
    let result: { [path: string]: number | null } = {}
    each(ob)
    return result

    function each(obj: any, prefix: string = ""): void {
        for (const key in obj) {
            let shouldFlatten = isPlainObject(obj[key])

            if (options?.ignorePrefix) {
                if (shouldFlatten) {
                    let hasIgnoreKey = Object.keys(obj[key]).some((k) => k.startsWith(options.ignorePrefix!))
                    if (hasIgnoreKey) shouldFlatten = false
                }
            }

            if (shouldFlatten) {
                each(obj[key], `${prefix}${key}.`)
            } else {
                result[`${prefix}${key}`] = obj[key]
            }
        }
    }
}

/**
 * 把 MongoDB 的对象展平
 * 会忽略拥有以 `$` 开头的属性的对象
 */
export function flattenMongo(ob: any, options?: { ignorePrefix?: string }) {
    let rootOb: any = {}
    let readyOb: any = {}
    for (const key in ob) {
        if (key.startsWith("$")) {
            rootOb[key] = flattenObject(ob[key], { ignorePrefix: "$" })
        } else {
            readyOb[key] = ob[key]
        }
    }
    return Object.assign(flattenObject(readyOb, { ignorePrefix: "$" }), rootOb)
}