import { clsx } from 'clsx';
import { twMerge } from 'tailwind-merge';

export function cn(...inputs) {
  return twMerge(clsx(inputs));
}

export function fmt(amount) {
  const n = Number(amount) || 0;
  const sign = n < 0 ? '-' : '';
  return sign + '$' + Math.abs(n).toFixed(2).replace(/\B(?=(\d{3})+(?!\d))/g, ',');
}

export function fmtDate(dateStr) {
  if (!dateStr) return '—';
  const [y, m, d] = dateStr.split('-');
  return `${parseInt(m)}/${parseInt(d)}/${y}`;
}

export function localDateString(date = new Date()) {
  const year = date.getFullYear();
  const month = String(date.getMonth() + 1).padStart(2, '0');
  const day = String(date.getDate()).padStart(2, '0');
  return `${year}-${month}-${day}`;
}

export function todayStr() {
  return localDateString();
}

export function fmtUptime(seconds) {
  const d = Math.floor(seconds / 86400);
  const h = Math.floor((seconds % 86400) / 3600);
  const m = Math.floor((seconds % 3600) / 60);
  const s = seconds % 60;
  if (d > 0) return `${d}d ${h}h ${m}m`;
  if (h > 0) return `${h}h ${m}m ${s}s`;
  if (m > 0) return `${m}m ${s}s`;
  return `${s}s`;
}

export function fmtBytes(bytes) {
  if (!bytes) return '0 B';
  if (bytes < 1024)    return `${bytes} B`;
  if (bytes < 1048576) return `${(bytes / 1024).toFixed(1)} KB`;
  return `${(bytes / 1048576).toFixed(2)} MB`;
}

const CATEGORY_COLOR_TONES = [
  { border: 'border-emerald-300/50', bg: 'bg-emerald-400/15', text: 'text-emerald-700 dark:text-emerald-200', bar: 'bg-emerald-500' },
  { border: 'border-sky-300/50',     bg: 'bg-sky-400/15',     text: 'text-sky-700 dark:text-sky-200',     bar: 'bg-sky-500' },
  { border: 'border-amber-300/50',   bg: 'bg-amber-400/15',   text: 'text-amber-700 dark:text-amber-200',   bar: 'bg-amber-500' },
  { border: 'border-rose-300/50',    bg: 'bg-rose-400/15',    text: 'text-rose-700 dark:text-rose-200',    bar: 'bg-rose-500' },
  { border: 'border-indigo-300/50',  bg: 'bg-indigo-400/15',  text: 'text-indigo-700 dark:text-indigo-200',  bar: 'bg-indigo-500' },
  { border: 'border-violet-300/50',  bg: 'bg-violet-400/15',  text: 'text-violet-700 dark:text-violet-200',  bar: 'bg-violet-500' },
  { border: 'border-teal-300/50',    bg: 'bg-teal-400/15',    text: 'text-teal-700 dark:text-teal-200',    bar: 'bg-teal-500' },
  { border: 'border-orange-300/50',  bg: 'bg-orange-400/15',  text: 'text-orange-700 dark:text-orange-200',  bar: 'bg-orange-500' },
];

// Deterministic color tone for a category (or merchant) name, used for
// badges and avatars so the same name always renders the same color.
export function categoryColor(name) {
  const key = String(name || 'Uncategorized');
  let hash = 0;
  for (let i = 0; i < key.length; i++) {
    hash = (hash * 31 + key.charCodeAt(i)) | 0;
  }
  const index = Math.abs(hash) % CATEGORY_COLOR_TONES.length;
  return CATEGORY_COLOR_TONES[index];
}