import type { VoiceInfo } from "@rakazo/contracts";

/** Friendly German presets when Kokoro exposes df_/dm_ voices. */
export const GERMAN_VOICE_PRESETS: VoiceInfo[] = [
  { id: "df_eva", label: "Eva", description: "warm" },
  { id: "dm_bernd", label: "Bernd", description: "klar" },
  { id: "df_victoria", label: "Victoria", description: "freundlich" },
  { id: "dm_martin", label: "Martin", description: "ruhig" },
];

/**
 * Kokoro encodes a voice's language in the first letter of its id (`df_eva` is German,
 * `af_heart` American English, `bf_emma` British English).
 */
const KOKORO_LANGUAGE_PREFIXES: Record<string, string> = {
  de: "d",
  en: "ab",
  es: "e",
  fr: "f",
  hi: "h",
  it: "i",
  ja: "j",
  pt: "p",
  zh: "z",
};

function voiceLanguagePrefixes(locale: string): string | undefined {
  const language = locale.toLowerCase().split("-")[0] ?? "";
  return KOKORO_LANGUAGE_PREFIXES[language];
}

const PRESET_BY_ID = new Map(GERMAN_VOICE_PRESETS.map((voice) => [voice.id, voice]));

/** Strip engine prefix (df_eva → Eva) for display when no preset exists. */
export function formatVoiceLabel(id: string): string {
  const preset = PRESET_BY_ID.get(id);
  if (preset) return preset.label;
  const suffix = id.replace(/^[a-z]{2}_/, "");
  if (!suffix) return id;
  return suffix.charAt(0).toUpperCase() + suffix.slice(1).replace(/_/g, " ");
}

export function voiceDescription(id: string, fallback?: string): string | undefined {
  return PRESET_BY_ID.get(id)?.description ?? fallback;
}

/**
 * Only the voices that speak the UI language. Ids without a Kokoro language prefix are kept,
 * and every voice is kept when none speaks the language, so the picker never ends up empty.
 */
export function voicesForLocale(voices: VoiceInfo[], locale: string): VoiceInfo[] {
  const prefixes = voiceLanguagePrefixes(locale);
  if (!prefixes) return voices;
  const matching = voices.filter((voice) => {
    const prefix = /^([a-z])[fm]_/.exec(voice.id)?.[1];
    return !prefix || prefixes.includes(prefix);
  });
  return matching.length > 0 ? matching : voices;
}

export function defaultVoiceForLocale(voices: VoiceInfo[], locale: string): VoiceInfo | undefined {
  const listed = voicesForLocale(voices, locale);
  return listed.find((voice) => voice.id === "df_eva") ?? listed[0];
}

/** The voice to keep using for this UI language: the current one when it fits, else the default. */
export function voiceIdForLocale(
  voices: VoiceInfo[],
  locale: string,
  currentId: string,
): string | undefined {
  const listed = voicesForLocale(voices, locale);
  if (listed.some((voice) => voice.id === currentId)) return currentId;
  return defaultVoiceForLocale(voices, locale)?.id;
}

/** Match a user-provided name (Eva, bernd, df_eva) against available voices. */
export function matchVoiceByName(voices: VoiceInfo[], query: string): VoiceInfo | undefined {
  const needle = query.trim().toLowerCase();
  if (!needle) return undefined;
  const byId = voices.find((voice) => voice.id.toLowerCase() === needle);
  if (byId) return byId;
  const byLabel = voices.find((voice) => voice.label.toLowerCase() === needle);
  if (byLabel) return byLabel;
  const suffix = needle.replace(/^[a-z]{2}_/, "");
  return voices.find((voice) => {
    const label = voice.label.toLowerCase();
    const idSuffix = voice.id.replace(/^[a-z]{2}_/, "").toLowerCase();
    return label.includes(suffix) || idSuffix.includes(suffix) || suffix.includes(idSuffix);
  });
}