export function cn(...parts: Array<string | false | null | undefined>): string {
  return parts.filter(Boolean).join(" ");
}

export function uid(prefix = "id"): string {
  const rand =
    typeof crypto !== "undefined" && "randomUUID" in crypto
      ? crypto.randomUUID().slice(0, 8)
      : Math.random().toString(36).slice(2, 10);
  return `${prefix}_${Date.now().toString(36)}_${rand}`;
}

/** Deterministic-ish shuffle (Fisher-Yates). Returns a new array. */
export function shuffle<T>(input: readonly T[]): T[] {
  const out = [...input];
  for (let i = out.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [out[i], out[j]] = [out[j], out[i]];
  }
  return out;
}

export function formatDate(timestamp: number): string {
  try {
    return new Intl.DateTimeFormat(undefined, {
      day: "numeric",
      month: "short",
      year: "numeric",
    }).format(new Date(timestamp));
  } catch {
    return "";
  }
}

/** Remove ```json fences and stray prose around a JSON object. */
export function stripFences(text: string): string {
  let value = text.trim();
  const fence = value.match(/```(?:json)?\s*([\s\S]*?)```/i);
  if (fence) value = fence[1].trim();
  if (value.startsWith("{") || value.startsWith("[")) return value;
  const start = value.indexOf("{");
  const end = value.lastIndexOf("}");
  if (start !== -1 && end > start) return value.slice(start, end + 1);
  return value;
}

export function parseJsonLoose(text: string): unknown {
  const cleaned = stripFences(text);
  try {
    return JSON.parse(cleaned);
  } catch {
    // Last resort: tolerate trailing commas from chatty models.
    return JSON.parse(cleaned.replace(/,\s*([}\]])/g, "$1"));
  }
}

export function truncate(value: string, max: number): string {
  return value.length > max ? `${value.slice(0, max - 1)}…` : value;
}

/**
 * A friendlier label for a model name: "gemma4:31b-cloud" → "Gemma 4 31B",
 * "gpt-oss:120b" → "GPT OSS 120B". Chips show this; the raw name lives in a
 * tooltip (and the picker keeps the technical names).
 */
export function prettyModelName(name: string): string {
  const base = name.replace(/:cloud$/i, "").replace(/-cloud$/i, "");
  const [family, ...tagParts] = base.split(":");
  const words = family
    .replace(/[-_.]+/g, " ")
    .replace(/([a-z])(\d)/gi, "$1 $2")
    .trim()
    .split(/\s+/)
    .filter(Boolean);
  const prettyFamily = words
    .map((word) =>
      /^[a-z]{1,3}$/i.test(word) && word === word.toLowerCase()
        ? word.toUpperCase()
        : word.charAt(0).toUpperCase() + word.slice(1),
    )
    .join(" ");
  const tag = tagParts
    .join(" ")
    .replace(/^(\d+)([a-z])$/i, (_match, size: string, unit: string) => `${size}${unit.toUpperCase()}`);
  return [prettyFamily, tag].filter(Boolean).join(" ");
}