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| 1 | +import { createHash } from "node:crypto"; |
| 2 | + |
| 3 | +/** |
| 4 | + * Last.fm 底层签名 HTTP 客户端 |
| 5 | + * API 文档: https://www.last.fm/api |
| 6 | + */ |
| 7 | + |
| 8 | +const API_URL = "https://ws.audioscrobbler.com/2.0/"; |
| 9 | + |
| 10 | +// 应用级凭证 |
| 11 | +const LASTFM_API_KEY = "79fa364d995b13c2b21bdd65b7e7054f"; |
| 12 | +const LASTFM_API_SECRET = "6d2ecc338d0a0802669e529f14b8034f"; |
| 13 | + |
| 14 | +/** Last.fm JSON 响应中我们关心的字段 */ |
| 15 | +interface LastfmResponse { |
| 16 | + error?: number; |
| 17 | + message?: string; |
| 18 | + token?: string; |
| 19 | + session?: { name: string; key: string }; |
| 20 | +} |
| 21 | + |
| 22 | +/** |
| 23 | + * 生成浏览器授权地址 |
| 24 | + * @param token - auth.getToken 拿到的临时令牌 |
| 25 | + * @returns 授权页 URL |
| 26 | + */ |
| 27 | +export const getAuthUrl = (token: string): string => |
| 28 | + `https://www.last.fm/api/auth/?api_key=${LASTFM_API_KEY}&token=${token}`; |
| 29 | + |
| 30 | +/** |
| 31 | + * 生成 api_sig：除 format 外按字母序拼 key+value，末尾接 secret 后取 md5 |
| 32 | + * 注意：MD5 是 Last.fm 签名协议的强制要求（服务端同样以 md5 校验），并非用于 |
| 33 | + * 加密/防篡改的安全用途，无法替换为更强算法，否则所有请求会被 Last.fm 拒绝。 |
| 34 | + * @param params - 待签名参数（不含 api_sig / format） |
| 35 | + * @returns 32 位十六进制签名 |
| 36 | + */ |
| 37 | +const sign = (params: Record<string, string>): string => { |
| 38 | + const base = Object.keys(params) |
| 39 | + .filter((key) => key !== "format") |
| 40 | + .sort() |
| 41 | + .map((key) => `${key}${params[key]}`) |
| 42 | + .join(""); |
| 43 | + return createHash("md5") |
| 44 | + .update(base + LASTFM_API_SECRET, "utf-8") |
| 45 | + .digest("hex"); |
| 46 | +}; |
| 47 | + |
| 48 | +/** |
| 49 | + * 组装请求参数：补 method/api_key，按需签名，最后补 format |
| 50 | + * @param method - API 方法名 |
| 51 | + * @param params - 业务参数 |
| 52 | + * @param signed - 是否需要签名 |
| 53 | + * @returns URLSearchParams |
| 54 | + */ |
| 55 | +const buildParams = ( |
| 56 | + method: string, |
| 57 | + params: Record<string, string>, |
| 58 | + signed: boolean, |
| 59 | +): URLSearchParams => { |
| 60 | + const base: Record<string, string> = { method, api_key: LASTFM_API_KEY, ...params }; |
| 61 | + if (signed) base.api_sig = sign(base); |
| 62 | + base.format = "json"; |
| 63 | + return new URLSearchParams(base); |
| 64 | +}; |
| 65 | + |
| 66 | +/** GET 请求（读操作） */ |
| 67 | +const get = async ( |
| 68 | + method: string, |
| 69 | + params: Record<string, string> = {}, |
| 70 | + signed = false, |
| 71 | +): Promise<LastfmResponse> => { |
| 72 | + const qs = buildParams(method, params, signed); |
| 73 | + const res = await fetch(`${API_URL}?${qs.toString()}`); |
| 74 | + const data = (await res.json()) as LastfmResponse; |
| 75 | + if (data.error) throw new Error(`Last.fm ${data.error}: ${data.message ?? "未知错误"}`); |
| 76 | + return data; |
| 77 | +}; |
| 78 | + |
| 79 | +/** POST 请求（写操作，必签名） */ |
| 80 | +const post = async ( |
| 81 | + method: string, |
| 82 | + params: Record<string, string> = {}, |
| 83 | +): Promise<LastfmResponse> => { |
| 84 | + const body = buildParams(method, params, true); |
| 85 | + const res = await fetch(API_URL, { |
| 86 | + method: "POST", |
| 87 | + headers: { "Content-Type": "application/x-www-form-urlencoded" }, |
| 88 | + body: body.toString(), |
| 89 | + }); |
| 90 | + const data = (await res.json()) as LastfmResponse; |
| 91 | + if (data.error) throw new Error(`Last.fm ${data.error}: ${data.message ?? "未知错误"}`); |
| 92 | + return data; |
| 93 | +}; |
| 94 | + |
| 95 | +/** 已授权会话 */ |
| 96 | +export interface LastfmSession { |
| 97 | + /** 用户名 */ |
| 98 | + name: string; |
| 99 | + /** 会话密钥（不过期） */ |
| 100 | + key: string; |
| 101 | +} |
| 102 | + |
| 103 | +/** |
| 104 | + * 获取临时授权令牌 |
| 105 | + * @returns token 字符串 |
| 106 | + */ |
| 107 | +export const getToken = async (): Promise<string> => { |
| 108 | + const data = await get("auth.getToken", {}, true); |
| 109 | + if (!data.token) throw new Error("无法获取 Last.fm token"); |
| 110 | + return data.token; |
| 111 | +}; |
| 112 | + |
| 113 | +/** |
| 114 | + * 用授权令牌换取会话（用户在浏览器授权后才会成功） |
| 115 | + * @param token - getToken 拿到的令牌 |
| 116 | + * @returns 会话信息 |
| 117 | + */ |
| 118 | +export const getSession = async (token: string): Promise<LastfmSession> => { |
| 119 | + const data = await get("auth.getSession", { token }, true); |
| 120 | + if (!data.session?.key) throw new Error("尚未授权"); |
| 121 | + return { name: data.session.name, key: data.session.key }; |
| 122 | +}; |
| 123 | + |
| 124 | +/** |
| 125 | + * 上报「正在播放」 |
| 126 | + * @param sessionKey - 会话密钥 |
| 127 | + * @param track - 歌曲名 |
| 128 | + * @param artist - 主艺人名 |
| 129 | + * @param album - 专辑名 |
| 130 | + * @param durationSec - 时长（秒） |
| 131 | + */ |
| 132 | +export const updateNowPlaying = async ( |
| 133 | + sessionKey: string, |
| 134 | + track: string, |
| 135 | + artist: string, |
| 136 | + album?: string, |
| 137 | + durationSec?: number, |
| 138 | +): Promise<void> => { |
| 139 | + const params: Record<string, string> = { sk: sessionKey, track, artist }; |
| 140 | + if (album) params.album = album; |
| 141 | + if (durationSec) params.duration = String(durationSec); |
| 142 | + await post("track.updateNowPlaying", params); |
| 143 | +}; |
| 144 | + |
| 145 | +/** |
| 146 | + * 记录播放（scrobble） |
| 147 | + * @param sessionKey - 会话密钥 |
| 148 | + * @param track - 歌曲名 |
| 149 | + * @param artist - 主艺人名 |
| 150 | + * @param timestamp - 开始播放的 Unix 时间戳（秒） |
| 151 | + * @param album - 专辑名 |
| 152 | + * @param durationSec - 时长（秒） |
| 153 | + */ |
| 154 | +export const scrobble = async ( |
| 155 | + sessionKey: string, |
| 156 | + track: string, |
| 157 | + artist: string, |
| 158 | + timestamp: number, |
| 159 | + album?: string, |
| 160 | + durationSec?: number, |
| 161 | +): Promise<void> => { |
| 162 | + const params: Record<string, string> = { |
| 163 | + sk: sessionKey, |
| 164 | + track, |
| 165 | + artist, |
| 166 | + timestamp: String(timestamp), |
| 167 | + }; |
| 168 | + if (album) params.album = album; |
| 169 | + if (durationSec) params.duration = String(durationSec); |
| 170 | + await post("track.scrobble", params); |
| 171 | +}; |
| 172 | + |
| 173 | +/** |
| 174 | + * 喜欢 / 取消喜欢 |
| 175 | + * @param sessionKey - 会话密钥 |
| 176 | + * @param track - 歌曲名 |
| 177 | + * @param artist - 主艺人名 |
| 178 | + * @param loved - true 为 Love，false 为 Unlove |
| 179 | + */ |
| 180 | +export const love = async ( |
| 181 | + sessionKey: string, |
| 182 | + track: string, |
| 183 | + artist: string, |
| 184 | + loved: boolean, |
| 185 | +): Promise<void> => { |
| 186 | + await post(loved ? "track.love" : "track.unlove", { sk: sessionKey, track, artist }); |
| 187 | +}; |
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