import md5 from 'md5'
import { BILI_NAV } from "../constants/tools.js";

const mixinKeyEncTab = [
    46, 47, 18, 2, 53, 8, 23, 32, 15, 50, 10, 31, 58, 3, 45, 35, 27, 43, 5, 49,
    33, 9, 42, 19, 29, 28, 14, 39, 12, 38, 41, 13, 37, 48, 7, 16, 24, 55, 40,
    61, 26, 17, 0, 1, 60, 51, 30, 4, 22, 25, 54, 21, 56, 59, 6, 63, 57, 62, 11,
    36, 20, 34, 44, 52
]

// 对 imgKey 和 subKey 进行字符顺序打乱编码
const getMixinKey = (orig) => mixinKeyEncTab.map(n => orig[n]).join('').slice(0, 32)

// 为请求参数进行 wbi 签名
function encWbi(params, img_key, sub_key) {
    const mixin_key = getMixinKey(img_key + sub_key),
        curr_time = Math.round(Date.now() / 1000),
        chr_filter = /[!'()*]/g

    Object.assign(params, { wts: curr_time }) // 添加 wts 字段
    // 按照 key 重排参数
    const query = Object
        .keys(params)
        .sort()
        .map(key => {
            // 过滤 value 中的 "!'()*" 字符
            const value = params[key].toString().replace(chr_filter, '')
            return `${encodeURIComponent(key)}=${encodeURIComponent(value)}`
        })
        .join('&')

    const wbi_sign = md5(query + mixin_key) // 计算 w_rid

    return query + '&w_rid=' + wbi_sign
}

// 获取最新的 img_key 和 sub_key
async function getWbiKeys(SESSDATA) {
    const res = await fetch(BILI_NAV, {
        headers: {
            // SESSDATA 字段
            Cookie: `SESSDATA=${SESSDATA}`
        }
    })
    const { data: { wbi_img: { img_url, sub_url } } } = await res.json()

    return {
        img_key: img_url.slice(
            img_url.lastIndexOf('/') + 1,
            img_url.lastIndexOf('.')
        ),
        sub_key: sub_url.slice(
            sub_url.lastIndexOf('/') + 1,
            sub_url.lastIndexOf('.')
        )
    }
}

/**
 * 算法来自：https://github.com/SocialSisterYi/bilibili-API-collect/blob/master/docs/misc/sign/wbi.md
 * 参考了算法来源：https://github.com/SocialSisterYi/bilibili-API-collect/issues/631
 * @return {Promise<string>}
 */
export async function getWbi(videoData, SESSDATA) {
    const web_keys = await getWbiKeys(SESSDATA)
    const params = { ...videoData },
        img_key_res = web_keys.img_key,
        sub_key_res = web_keys.sub_key
    // eg. bar=514&baz=1919810&foo=114&wts=1684805578&w_rid=bb97e15f28edf445a0e4420d36f0157e
    return encWbi(params, img_key_res, sub_key_res);
}