SnapOtter/apps/api/src/routes/tools/trim-audio.ts

import { extname } from "node:path";
import type { FastifyInstance } from "fastify";
import { z } from "zod";
import { audioContentType, runMediaTool } from "../../lib/media-tool.js";
import { createToolRoute } from "../tool-factory.js";

const settingsSchema = z
  .object({
    startS: z.number().min(0).default(0),
    endS: z.number().positive(),
  })
  .refine((s) => s.endS > s.startS, { message: "End must be after start" });

export function registerTrimAudio(app: FastifyInstance) {
  createToolRoute(app, {
    toolId: "trim-audio",
    settingsSchema,
    process: async () => {
      throw new Error("trim-audio is v2-only");
    },
    processV2: async (ctx) => {
      const settings = settingsSchema.parse(ctx.settings);
      const origExt = extname(ctx.inputs[0].filename) || ".mp3";
      const base = ctx.inputs[0].filename.replace(/\.[^.]+$/, "");
      const outName = `${base}_trimmed${origExt}`;
      const contentType = audioContentType(origExt);

      const { outPath } = await runMediaTool(ctx, outName, (inPath, out) => {
        // Fast seek with stream-copy for audio
        return [
          "-ss",
          String(settings.startS),
          "-to",
          String(settings.endS),
          "-i",
          inPath,
          "-c",
          "copy",
          out,
        ];
      });
      return { scratchPath: outPath, filename: outName, contentType };
    },
  });
}