import { writeFile, rm, mkdtemp } from "node:fs/promises"
import { join } from "node:path"
import { tmpdir } from "node:os"
import { execFile } from "node:child_process"
import { promisify } from "node:util"

const execFileAsync = promisify(execFile)

export interface TranscribeConfig {
  ffmpeg?: string
  whisperCli?: string
  model?: string
  threads?: number
}

export function createTranscribeHandler(config?: TranscribeConfig) {
  const ffmpeg = config?.ffmpeg ?? "/opt/homebrew/bin/ffmpeg"
  const whisperCli = config?.whisperCli ?? "/opt/homebrew/bin/whisper-cli"
  const model =
    config?.model ??
    "/opt/homebrew/share/whisper-cpp/models/ggml-base.en.bin"
  const threads = config?.threads ?? 4

  return async (request: Request): Promise<Response> => {
    const headers = { "Content-Type": "application/json" }
    let tmpDir = ""

    try {
      const formData = await request.formData()
      const file = formData.get("audio") as File | null
      if (!file) {
        return new Response(
          JSON.stringify({ error: "audio file required" }),
          { status: 400, headers },
        )
      }

      tmpDir = await mkdtemp(join(tmpdir(), "whisper-"))
      const inputPath = join(tmpDir, "input.webm")
      const wavPath = join(tmpDir, "input.wav")
      const buf = Buffer.from(await file.arrayBuffer())
      await writeFile(inputPath, buf)

      await execFileAsync(
        ffmpeg,
        ["-i", inputPath, "-ar", "16000", "-ac", "1", "-f", "wav", wavPath],
        { timeout: 15000 },
      )

      const { stdout } = await execFileAsync(
        whisperCli,
        ["-m", model, "-f", wavPath, "--no-timestamps", "--no-prints", "-t", String(threads)],
        { timeout: 30000 },
      )

      return new Response(JSON.stringify({ text: stdout.trim() }), { headers })
    } catch (err: any) {
      const is4xx = err.message?.includes("Content-Type") || err.message?.includes("audio file");
      return new Response(
        JSON.stringify({ error: err.message }),
        { status: is4xx ? 400 : 500, headers },
      )
    } finally {
      if (tmpDir) {
        try { await rm(tmpDir, { recursive: true }) } catch {}
      }
    }
  }
}