api: use zod for request schema validation

api/src/processing/schema.js

@@ -0,0 +1,42 @@
+import { z } from "zod";
+
+import { normalizeURL } from "./url.js";
+import { verifyLanguageCode } from "../misc/utils.js";
+
+export const apiSchema = z.object({
+    url: z.string()
+          .min(1)
+          .transform((url) => normalizeURL(decodeURIComponent(url))),
+
+    audioFormat: z.enum(
+        ["best", "mp3", "ogg", "wav", "opus"]
+    ).default("mp3"),
+
+    downloadMode: z.enum(
+        ["auto", "audio", "mute"]
+    ).default("auto"),
+
+    filenameStyle: z.enum(
+        ["classic", "pretty", "basic", "nerdy"]
+    ).default("classic"),
+
+    youtubeVideoCodec: z.enum(
+        ["h264", "av1", "vp9"]
+    ).default("h264"),
+
+    videoQuality: z.enum([
+        "max", "4320", "2160", "1440", "1080", "720", "480", "360", "240", "144"
+    ]).default("720"),
+
+    youtubeDubLang: z.string()
+                     .length(2)
+                     .transform(verifyLanguageCode)
+                     .optional(),
+
+    disableMetadata: z.boolean().default(false),
+    tiktokFullAudio: z.boolean().default(false),
+    tiktokH265: z.boolean().default(false),
+    twitterGif: z.boolean().default(false),
+    youtubeDubBrowserLang: z.boolean().default(false),
+})
+.strict();