export const MIN_AUDIO_PLAYBACK_RATE = 0.1;
export const MAX_AUDIO_PLAYBACK_RATE = 4;
export const AUDIO_PLAYBACK_RATE_STEP = 0.1;

export type AudioToolRequest =
  | { kind: "trim"; startSeconds: number; endSeconds: number }
  | { kind: "speed"; playbackRate: number };

export function normalizeAudioPlaybackRate(value: unknown, fallback = 1) {
  const parsed = Number.parseFloat(String(value ?? "").replace(/x$/i, ""));
  const safe = Number.isFinite(parsed) ? parsed : fallback;
  return Math.round(
    Math.min(MAX_AUDIO_PLAYBACK_RATE, Math.max(MIN_AUDIO_PLAYBACK_RATE, safe)) * 100,
  ) / 100;
}

export function stepAudioPlaybackRate(value: unknown, direction: 1 | -1) {
  return normalizeAudioPlaybackRate(
    normalizeAudioPlaybackRate(value) + direction * AUDIO_PLAYBACK_RATE_STEP,
  );
}

export function formatAudioPlaybackRate(value: unknown) {
  return `${normalizeAudioPlaybackRate(value).toFixed(2)}x`;
}

export function formatAudioPlaybackRateSuffix(value: unknown) {
  const rate = normalizeAudioPlaybackRate(value);
  return Number.isInteger(rate) ? `${rate}x` : `${rate.toFixed(2).replace(/0+$/, "")}x`;
}

export function getDefaultAudioTrimRange(durationSeconds: unknown) {
  const duration = Math.max(0.1, Number(durationSeconds) || 0.1);
  return {
    startSeconds: 0,
    endSeconds: Math.min(duration, Math.max(0.1, duration / 3)),
  };
}

export function normalizeAudioTrimRange(
  durationSeconds: unknown,
  startSeconds: unknown,
  endSeconds: unknown,
) {
  const duration = Math.max(0.1, Number(durationSeconds) || 0.1);
  const start = Math.min(duration - 0.05, Math.max(0, Number(startSeconds) || 0));
  const end = Math.min(duration, Math.max(start + 0.05, Number(endSeconds) || duration));
  return { startSeconds: start, endSeconds: end };
}

export function getProcessedAudioTitle(sourceTitle: string, request: AudioToolRequest) {
  const base = String(sourceTitle || "音频").trim() || "音频";
  return request.kind === "trim"
    ? `${base}_截取`
    : `${base}_${formatAudioPlaybackRateSuffix(request.playbackRate)}`;
}

export function getAudioDownloadExtension(source: unknown) {
  const pathname = String(source || "").split(/[?#]/, 1)[0];
  return pathname.match(/\.(wav|mp3|m4a|aac|ogg|webm)$/i)?.[1]?.toLowerCase() || "mp3";
}