// @ts-ignore
import common from "common-prefix"

export interface IUrlPack {
    __p: string
    [name: string]: string
}

export interface IUrlMap {
    [name: string]: string
}

export const urlsPacker = {
    /**
     * 把多个 url 组成的表，序列化为特殊格式的 JSON 文本
     * 这个文本会复用多个 url 的共同前缀，节省空间
     *
     * @example
     *  { "32":"32-56c4fb498d439255a209d5b0d26d06d7.png",
     *   "72":"72-22dc147ceb29dfdd990fb031fec4ee64.png",
     *   "144":"144-39fff0a4372bc98c2d501a43179b01c1.png",
     *   "__p":"https://file-cn.moonvy.com/t/38cedb9e-f2f0-40d5-8964-2108d7dbc549/c/icons/icon-@"
     *   }
     * @param urlMap
     */
    pack(urlMap: { [name: string]: string }): string {
        let urlPack: any = {}

        let prefix
        let prefixReg

        let urls: string[] = Object.values(urlMap).map((x) => x)
        let lcp = common(urls)
        if (lcp && lcp.length > 0) {
            prefix = lcp
            urlPack.__p = lcp
            prefixReg = RegExp("^" + prefix)
        }
        // console.log("lcp", lcp)
        for (let name in urlMap) {
            let url = urlMap[name]
            if (prefixReg) url = url.replace(prefixReg, "")
            urlPack[name] = url
        }

        return JSON.stringify(urlPack)
    },
    /**
     * 把特殊格式的 Url JSON 文本还原成对象
     * @param urlpack
     */
    unpack(urlpack: string): { [name: string]: string } {
        let data: IUrlPack = JSON.parse(urlpack)
        let prefix = data.__p
        delete (<any>data).__p

        if (prefix) {
            for (let key in data) {
                data[key] = prefix + data[key]
            }
        }
        return data
    },
}