feat: 下载沿用曲库已有的歌手 / 专辑文件夹写法

歌手或专辑文件夹名与曲库已有文件夹只差空格、大小写、全半角时（如
「G.E.M.邓紫棋」与「G.E.M. 邓紫棋」），放进已有文件夹，并把歌手、
专辑歌手标签统一成该写法，避免同一歌手被拆成两个目录 / 两个艺人。

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

server/src/core/layout.ts

@@ -1,6 +1,8 @@
 // 输出目录与文件名规则
 //   album: {音乐目录}/{第一位专辑艺人}/{专辑}/{NN}. {歌名}.ext   —— 与 NAS 现有曲库结构一致
 //   flat : {音乐目录}/{歌手} - {歌名}.ext                        —— 旧版单曲下载格式
+// 曲库里已有只差空格 / 大小写 / 全半角的歌手或专辑文件夹时，沿用已有文件夹名，避免同一歌手拆成两个目录
+import fs from 'node:fs';
 import path from 'node:path';
 import type { Layout } from '../config.ts';
 import { sanitize, sanitizePathSegment } from './util.ts';
@@ -18,6 +20,26 @@ export interface Target {
   dir: string;
   baseName: string; // 不含扩展名
   isAlbumDir: boolean;
+  /** 歌手名被替换为曲库已有写法时：{ from: 平台写法, to: 曲库写法 } */
+  artistAlias?: { from: string; to: string };
+}
+
+/** 判断两个文件夹名是否「同一个」：忽略空白、大小写、全半角 */
+export function folderKey(name: string): string {
+  return name.normalize('NFKC').toLowerCase().replace(/\s+/g, '');
+}
+
+/** 在 parent 下找与 name 等价的已有文件夹，找到返回已有的名字 */
+function existingFolder(parent: string, name: string): string {
+  let entries: fs.Dirent[];
+  try {
+    entries = fs.readdirSync(parent, { withFileTypes: true });
+  } catch {
+    return name;
+  }
+  if (entries.some((e) => e.isDirectory() && e.name === name)) return name;
+  const key = folderKey(name);
+  return entries.find((e) => e.isDirectory() && folderKey(e.name) === key)?.name ?? name;
 }
 
 export function resolveTarget(musicDir: string, layout: Layout, input: LayoutInput): Target {
@@ -25,13 +47,29 @@ export function resolveTarget(musicDir: string, layout: Layout, input: LayoutInp
   if (layout === 'flat') {
     return { dir: musicDir, baseName: sanitize(`${input.artists} - ${title}`), isAlbumDir: false };
   }
-  const firstArtist = input.artists.split(' / ')[0];
+  const primary = input.albumArtistPrimary || input.artists.split(' / ')[0] || '';
-  const artistDir = sanitizePathSegment(input.albumArtistPrimary || firstArtist, '未知歌手');
+  const wantArtistDir = sanitizePathSegment(primary, '未知歌手');
-  const albumDir = sanitizePathSegment(input.album, '未知专辑');
+  const artistDir = existingFolder(musicDir, wantArtistDir);
+  const albumDir = existingFolder(path.join(musicDir, artistDir), sanitizePathSegment(input.album, '未知专辑'));
   let baseName = title;
   if (input.trackNo) {
     const width = Math.max(2, String(input.trackTotal || 0).length);
     baseName = `${String(input.trackNo).padStart(width, '0')}. ${title}`;
   }
-  return { dir: path.join(musicDir, artistDir, albumDir), baseName: sanitize(baseName), isAlbumDir: true };
+  return {
+    dir: path.join(musicDir, artistDir, albumDir),
+    baseName: sanitize(baseName),
+    isAlbumDir: true,
+    // 只有原名本身就是合法文件夹名时才回写标签（含 / 等被替换过的名字不处理）
+    artistAlias: artistDir !== wantArtistDir && primary === wantArtistDir ? { from: primary, to: artistDir } : undefined,
+  };
+}
+
+/** 把 "A / B" 形式的歌手串中等于 from 的那一位替换为 to */
+export function applyArtistAlias(artists: string | undefined, alias: Target['artistAlias']): string | undefined {
+  if (!artists || !alias) return artists;
+  return artists
+    .split(' / ')
+    .map((a) => (a === alias.from ? alias.to : a))
+    .join(' / ');
 }

server/src/core/pipeline.ts

@@ -3,7 +3,7 @@
 import fs from 'node:fs';
 import path from 'node:path';
 import type { Layout } from '../config.ts';
-import { resolveTarget } from './layout.ts';
+import { applyArtistAlias, resolveTarget } from './layout.ts';
 import { mergeLrc, parseCredits } from './lyrics.ts';
 import { downloadToFile, fetchBuffer, type Progress } from './net/http.ts';
 import type { QualityKey } from './quality.ts';
@@ -100,7 +100,7 @@ async function downloadOnce(provider: MusicProvider, id: string, opts: DownloadO
   reporter?.stage?.('metadata', '获取元数据');
   const meta = await provider.getTrackMeta(id).catch(() => null);
   const name = audio.name || meta?.name || id;
-  const artists = audio.artists || meta?.artists || '未知歌手';
+  let artists = audio.artists || meta?.artists || '未知歌手';
   const album = audio.album || meta?.album || '';
 
   const target = resolveTarget(ctx.musicDir, opts.layout, {
@@ -111,6 +111,15 @@ async function downloadOnce(provider: MusicProvider, id: string, opts: DownloadO
     trackNo: meta?.trackNo,
     trackTotal: meta?.trackTotal,
   });
+  // 沿用了曲库已有的歌手文件夹名（如「G.E.M. 邓紫棋」）时，标签里的歌手名也统一成该写法
+  if (target.artistAlias) {
+    artists = applyArtistAlias(artists, target.artistAlias)!;
+    if (meta) {
+      meta.albumArtist = applyArtistAlias(meta.albumArtist, target.artistAlias);
+      meta.albumArtistPrimary = target.artistAlias.to;
+    }
+    reporter?.log?.('info', `歌手名统一为曲库已有写法：${target.artistAlias.to}`);
+  }
   await fs.promises.mkdir(target.dir, { recursive: true });
   const dest = path.join(target.dir, `${target.baseName}.${audio.ext}`);