import type { SpeechRecognitionResult } from "./types.js"

export class SpeechRecognitionTask {
  isRecording = false
  isProcessing = false

  private recorder: MediaRecorder | null = null
  private stream: MediaStream | null = null
  private chunks: Blob[] = []
  private cancelled = false
  private endpoint: string
  private ready: Promise<void>
  private onComplete: () => void

  constructor(endpoint: string, onComplete: () => void) {
    this.endpoint = endpoint
    this.onComplete = onComplete
    this.ready = this.begin()
  }

  private async begin(): Promise<void> {
    this.stream = await navigator.mediaDevices.getUserMedia({ audio: true })
    this.recorder = new MediaRecorder(this.stream, { mimeType: "audio/webm;codecs=opus" })
    this.chunks = []
    this.recorder.ondataavailable = (e) => {
      if (e.data.size > 0) this.chunks.push(e.data)
    }
    this.recorder.start()
    this.isRecording = true
  }

  async finish(): Promise<SpeechRecognitionResult> {
    await this.ready
    if (!this.recorder || this.cancelled) {
      this.onComplete()
      return { text: "", isFinal: true }
    }

    const blob = await new Promise<Blob>((resolve) => {
      this.recorder!.onstop = () => {
        resolve(new Blob(this.chunks, { type: "audio/webm" }))
      }
      this.recorder!.stop()
    })

    this.teardown()
    this.isRecording = false
    this.isProcessing = true

    try {
      const fd = new FormData()
      fd.append("audio", blob, "recording.webm")
      const r = await fetch(this.endpoint, {
        method: "POST",
        body: fd,
        signal: AbortSignal.timeout(30000),
      })
      if (!r.ok) throw new Error("HTTP " + r.status)
      const data = await r.json()
      this.isProcessing = false
      this.onComplete()
      return { text: (data.text || "").trim(), isFinal: true }
    } catch (err) {
      this.isProcessing = false
      this.onComplete()
      throw err
    }
  }

  cancel(): void {
    this.cancelled = true
    if (this.recorder?.state === "recording") this.recorder.stop()
    this.teardown()
    this.isRecording = false
    this.isProcessing = false
    this.onComplete()
  }

  private teardown(): void {
    this.stream?.getTracks().forEach((t) => t.stop())
    this.recorder = null
    this.stream = null
    this.chunks = []
  }
}