feat: add yt-dlp argument builder

src/lib/ytdlp.ts

@@ -0,0 +1,39 @@
+import path from 'path'
+import { config } from '../../config/app.config'
+
+export type YtdlpParams = {
+  url: string
+  uuid: string
+  format: string
+  quality: string
+  subtitles: boolean
+  extraArgs: string | null
+}
+
+export function buildYtdlpArgs(params: YtdlpParams): string[] {
+  const { url, uuid, format, quality, subtitles, extraArgs } = params
+  const outputTemplate = path.join(config.STORAGE_PATH, `${uuid}.%(ext)s`)
+
+  const args: string[] = ['--no-playlist', '-o', outputTemplate]
+
+  if (quality !== 'best') {
+    const height = quality.replace('p', '')
+    args.push('-f', `${format}[height<=?${height}]+bestaudio/best[height<=?${height}]`)
+  }
+
+  if (subtitles) {
+    args.push('--write-sub', '--sub-lang', 'fr,en')
+  }
+
+  if (extraArgs) {
+    try {
+      const extra = JSON.parse(extraArgs) as string[]
+      args.push(...extra)
+    } catch {
+      // malformed extraArgs — skip silently
+    }
+  }
+
+  args.push(url)
+  return args
+}