const BLOG_DIR = 'blog/';
const ATTACHMENT_DIR = BLOG_DIR + 'files/';
const MANIFEST = BLOG_DIR + 'manifest.json';
const TXT_EXT = /\.(txt|text)$/i;
const ATTACHMENT_RE = /\[\[(?:file|attachment):\s*([^\]]+)\]\]/gi;
const BLOG_COLLAPSE_THRESHOLD = 300; // characters before collapsing
const BLOG_PREVIEW_LINES = 3; // number of lines shown in preview

function escapeHtml(value) {
  return value
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

function parseIndexHtmlList(text) {
  const hrefs = [];
  const re = /href="([^"]+)"/g;
  let m;
  while ((m = re.exec(text)) !== null) {
    const name = m[1];
    if (TXT_EXT.test(name)) hrefs.push(name);
  }
  return hrefs;
}

async function loadBlogFiles() {
  try {
    const response = await fetch(MANIFEST, { cache: 'no-cache' });
    if (response.ok) {
      return await response.json();
    }
  } catch (e) {
    // manifest missing or unreadable
  }

  try {
    const response = await fetch(BLOG_DIR, { cache: 'no-cache' });
    if (response.ok) {
      const text = await response.text();
      return parseIndexHtmlList(text);
    }
  } catch (e) {
    console.warn('Could not read blog directory listing', e);
  }

  return [];
}

function parseDateLine(rawDate) {
  if (!rawDate) return null;
  let value = rawDate.trim();
  if (value.toLowerCase().startsWith('date:')) {
    value = value.slice(5).trim();
  }
  if (!value) return null;
  const normalized = value.replace(' ', 'T');
  const date = new Date(normalized);
  return Number.isNaN(date.getTime()) ? null : date;
}

function extractAttachments(body) {
  const attachments = new Set();
  body.replace(ATTACHMENT_RE, (_, filename) => {
    const safeName = filename.trim();
    if (safeName) attachments.add(safeName);
    return '';
  });
  return Array.from(attachments);
}

function parseBlogText(text, filename) {
  const lines = text.replace(/\r/g, '').split('\n');
  let index = 0;
  while (index < lines.length && !lines[index].trim()) index += 1;

  const rawDate = index < lines.length ? lines[index].trim() : '';
  if (rawDate.toLowerCase().startsWith('date:')) {
    index += 1;
  } else {
    index += 1;
  }

  while (index < lines.length && !lines[index].trim()) index += 1;
  const title = index < lines.length ? lines[index].trim() : 'Untitled';
  index += 1;

  while (index < lines.length && !lines[index].trim()) index += 1;
  const body = lines.slice(index).join('\n').trim();

  return {
    filename,
    title: title || 'Untitled',
    date: parseDateLine(rawDate) || null,
    dateLabel: rawDate || '',
    body: body || '',
    attachments: extractAttachments(body),
  };
}

function formatDate(date) {
  if (!date) return 'Unknown date';
  return new Intl.DateTimeFormat('en-US', {
    year: 'numeric', month: 'short', day: 'numeric', hour: 'numeric', minute: '2-digit'
  }).format(date);
}

function createParagraphs(body) {
  return body
    .split(/\n{2,}/)
    .filter(Boolean)
    .map((paragraph) => {
      const p = document.createElement('p');
      const text = escapeHtml(paragraph).replace(ATTACHMENT_RE, (match, filename) => {
        const safeName = filename.trim();
        const url = ATTACHMENT_DIR + encodeURI(safeName);
        return `<a href="${url}" target="_blank" rel="noopener noreferrer">${escapeHtml(safeName)}</a>`;
      });
      const lines = text.split('\n');
      p.innerHTML = lines.join('<br>');
      return p;
    });
}

function renderBlogEntries(entries) {
  const container = document.querySelector('.blog-feed');
  container.innerHTML = '';

  if (!entries.length) {
    container.textContent = 'No posts found. Add .txt files to the blog/ folder and enable blog manifest or directory listing.';
    return;
  }

  entries.forEach((entry) => {
    const article = document.createElement('article');
    article.className = 'blog-post';

    const title = document.createElement('h3');
    title.className = 'blog-title';
    title.textContent = entry.title;

    const meta = document.createElement('div');
    meta.className = 'blog-meta';
    meta.textContent = entry.date
      ? formatDate(entry.date)
      : entry.dateLabel || 'Date not provided';


    const body = document.createElement('div');
    body.className = 'blog-body';

    const paragraphs = createParagraphs(entry.body);

    if (!paragraphs.length) {
      const empty = document.createElement('p');
      empty.textContent = 'No content yet.';
      body.appendChild(empty);
    } else {
      paragraphs.forEach((p) => body.appendChild(p));
    }


    let content = body;

    // Collapse long posts
    if (entry.body.length > BLOG_COLLAPSE_THRESHOLD) {
      const wrapper = document.createElement('div');
      wrapper.className = 'blog-collapse';

      const preview = document.createElement('p');
      preview.className = 'blog-preview';

      preview.textContent = entry.body
        .split('\n')
        .filter(line => line.trim())
        .slice(0, BLOG_PREVIEW_LINES)
        .join('\n');


      const button = document.createElement('button');
      button.className = 'blog-expand-button';
      button.textContent = 'Read more';


      body.style.display = 'none';

      button.addEventListener('click', () => {
        const expanded = body.style.display !== 'none';

        body.style.display = expanded ? 'none' : 'block';
        preview.style.display = expanded ? 'block' : 'none';
        button.textContent = expanded ? 'Read more' : 'Show less';
      });


      wrapper.appendChild(preview);
      wrapper.appendChild(button);
      wrapper.appendChild(body);

      content = wrapper;
    }


    if (entry.attachments && entry.attachments.length) {
      const attachTitle = document.createElement('div');
      attachTitle.className = 'blog-meta';
      attachTitle.textContent = 'Attachments:';

      const list = document.createElement('ul');
      list.className = 'blog-attachment-list';

      entry.attachments.forEach((attachment) => {
        const item = document.createElement('li');
        const link = document.createElement('a');

        link.href = ATTACHMENT_DIR + encodeURI(attachment);
        link.target = '_blank';
        link.rel = 'noopener noreferrer';
        link.textContent = attachment;

        item.appendChild(link);
        list.appendChild(item);
      });

      article.appendChild(attachTitle);
      article.appendChild(list);
    }


    article.appendChild(title);
    article.appendChild(meta);
    article.appendChild(content);

    container.appendChild(article);
  });
}