/** Formatting and utility helpers */

export function formatNumber(n) {
  if (n == null) return '—';
  if (n >= 1_000_000) return (n / 1_000_000).toFixed(1) + 'M';
  if (n >= 1_000) return (n / 1_000).toFixed(1) + 'K';
  return String(n);
}

export function formatBytes(bytes) {
  if (!bytes) return '0 B';
  const k = 1024;
  const sizes = ['B', 'KB', 'MB', 'GB', 'TB'];
  const i = Math.floor(Math.log(bytes) / Math.log(k));
  return parseFloat((bytes / Math.pow(k, i)).toFixed(1)) + ' ' + sizes[i];
}

export function formatDate(ts) {
  if (!ts) return '—';
  return new Date(ts).toLocaleString();
}

export function formatRelative(ts) {
  if (!ts) return '—';
  const diff = Date.now() - new Date(ts).getTime();
  const s = Math.floor(diff / 1000);
  if (s < 60) return 'just now';
  const m = Math.floor(s / 60);
  if (m < 60) return `${m}m ago`;
  const h = Math.floor(m / 60);
  if (h < 24) return `${h}h ago`;
  const d = Math.floor(h / 24);
  return `${d}d ago`;
}

export function roleColor(role) {
  return { admin: 'red', faculty: 'yellow', student: 'blue' }[role] ?? 'gray';
}

export function tierColor(tier) {
  return {
    GPU_NVIDIA: 'green',
    GPU_AMD: 'yellow',
    CPU_ONLY: 'gray',
  }[tier] ?? 'gray';
}

export function modelTagColor(tag) {
  return {
    RECOMMENDED: 'green',
    POSSIBLE: 'yellow',
    NOT_RECOMMENDED: 'red',
    CPU_ONLY: 'gray',
  }[tag] ?? 'gray';
}

/** Debounce a function */
export function debounce(fn, ms = 300) {
  let timer;
  return (...args) => {
    clearTimeout(timer);
    timer = setTimeout(() => fn(...args), ms);
  };
}

/** Copy text to clipboard and return a promise */
export async function copyToClipboard(text) {
  await navigator.clipboard.writeText(text);
}

/** Simple markdown-to-HTML for chat messages (code blocks, bold, italic, lists) */
export function renderMarkdown(text) {
  if (!text) return '';
  let html = text
    // Code blocks
    .replace(/```(\w*)\n?([\s\S]*?)```/g, (_, lang, code) =>
      `<pre><code class="language-${lang || 'text'}">${escapeHtml(code.trim())}</code></pre>`)
    // Inline code
    .replace(/`([^`]+)`/g, (_, c) => `<code class="inline-code">${escapeHtml(c)}</code>`)
    // Bold
    .replace(/\*\*(.*?)\*\*/g, '<strong>$1</strong>')
    // Italic
    .replace(/\*(.*?)\*/g, '<em>$1</em>')
    // Headers
    .replace(/^### (.+)$/gm, '<h3 class="text-lg font-semibold mt-3 mb-1">$1</h3>')
    .replace(/^## (.+)$/gm, '<h2 class="text-xl font-semibold mt-4 mb-2">$1</h2>')
    .replace(/^# (.+)$/gm, '<h1 class="text-2xl font-bold mt-4 mb-2">$1</h1>')
    // Unordered list
    .replace(/^- (.+)$/gm, '<li class="ml-4 list-disc">$1</li>')
    .replace(/(<li.*<\/li>\n?)+/g, m => `<ul class="my-2 space-y-1">${m}</ul>`)
    // Numbered list
    .replace(/^\d+\. (.+)$/gm, '<li class="ml-4 list-decimal">$1</li>')
    // Paragraphs (double newlines)
    .replace(/\n\n/g, '</p><p class="mb-2">')
    // Single newlines
    .replace(/\n/g, '<br>');

  return `<p class="mb-2">${html}</p>`;
}

function escapeHtml(str) {
  return str
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;');
}

/** Generate a heatmap grid for 26 weeks of activity data */
export function buildHeatmap(dailyData) {
  // dailyData: [{date: "2026-01-01", count: 5}, ...]
  const map = {};
  dailyData.forEach(d => { map[d.date] = d.count; });

  const today = new Date();
  const cells = [];
  for (let i = 181; i >= 0; i--) {
    const d = new Date(today);
    d.setDate(d.getDate() - i);
    const key = d.toISOString().slice(0, 10);
    cells.push({ date: key, count: map[key] ?? 0 });
  }
  return cells;
}

export function heatmapColor(count) {
  if (!count) return 'var(--surface3)';
  if (count < 3)  return 'rgba(217,116,73,0.25)';
  if (count < 8)  return 'rgba(217,116,73,0.50)';
  if (count < 20) return 'rgba(217,116,73,0.75)';
  return 'var(--accent)';
}