export function downloadUrl(item) {
  return new URL(item.url, window.location.origin).href;
}

export function forcedDownloadUrl(item) {
  const url = new URL(downloadUrl(item));
  url.searchParams.set('dl', '1');
  return url.href;
}

export function displayName(item) {
  return item.downloadName || item.originalName || 'file';
}

export function fileExtension(item) {
  const name = displayName(item);
  const dot = name.lastIndexOf('.');
  if (dot > 0 && dot < name.length - 1) return name.slice(dot + 1).toUpperCase();
  return '';
}

export function linkLabel(item) {
  return item.originalName || item.downloadName || 'file';
}

export function buildLinkFormats(item) {
  const url = downloadUrl(item);
  const name = linkLabel(item);
  const mime = item.mimeType || '';
  const isImage = mime.startsWith('image/') && mime !== 'image/svg+xml';

  let html;
  let bbcode;
  let markdown;
  if (isImage) {
    html = `<img src="${url}" alt="${name}">`;
    bbcode = `[img]${url}[/img]`;
    markdown = `![${name}](${url})`;
  } else {
    html = `<a href="${url}" target="_blank" rel="noopener">${name}</a>`;
    bbcode = `[url=${url}]${name}[/url]`;
    markdown = `[${name}](${url})`;
  }

  return [
    { label: 'Direct', value: url },
    { label: 'HTML', value: html },
    { label: 'BBCode', value: bbcode },
    { label: 'Markdown', value: markdown }
  ];
}

export function formatBytes(bytes) {
  if (!Number.isFinite(bytes) || bytes < 0) return '-';
  if (bytes < 1024) return `${bytes} B`;
  const units = ['KB', 'MB', 'GB', 'TB'];
  let value = bytes;
  let i = -1;
  do {
    value /= 1024;
    i += 1;
  } while (value >= 1024 && i < units.length - 1);
  return `${value.toFixed(value >= 100 ? 0 : 1)} ${units[i]}`;
}

export function formatDate(iso) {
  try {
    return new Date(iso).toLocaleString();
  } catch {
    return '';
  }
}

export async function copyText(text) {
  const fallback = () => {
    const ta = document.createElement('textarea');
    ta.value = text;
    ta.style.position = 'fixed';
    ta.style.opacity = '0';
    document.body.appendChild(ta);
    ta.select();
    let ok = false;
    try {
      ok = document.execCommand('copy');
    } catch {
      ok = false;
    }
    ta.remove();
    return ok;
  };

  if (navigator.clipboard && window.isSecureContext) {
    try {
      await navigator.clipboard.writeText(text);
      return true;
    } catch {
      return fallback();
    }
  }
  return fallback();
}