// blog.js – with collapsible posts
const BLOG_DIR = 'blog/';
const MANIFEST = BLOG_DIR + 'manifest.json';

// ---------- helpers ----------
function parseIndexHtmlList(text) {
  const hrefs = [];
  const re = /href="([^"]+)"/g;
  let m;
  while ((m = re.exec(text)) !== null) {
    const name = m[1];
    if (name.match(/\.(txt)$/i)) hrefs.push(name);
  }
  return hrefs;
}

// fetch a list of post filenames
async function loadPostList() {
  try {
    const r = await fetch(MANIFEST, { cache: 'no-cache' });
    if (r.ok) return await r.json();
  } catch (_) { /* fall through */ }

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

// parse a single post file: first line = date/time, second = title, rest = content
async function fetchPost(filename) {
  const resp = await fetch(BLOG_DIR + filename);
  if (!resp.ok) throw new Error('Failed to fetch ' + filename);
  const text = await resp.text();
  const lines = text.split(/\r?\n/);
  const dateTime = lines[0]?.trim() || '';
  const title = lines[1]?.trim() || 'Untitled';
  const content = lines.slice(2).join('\n').trim();
  return { dateTime, title, content, filename };
}

// ---------- rendering with collapse ----------
function createPostElement(post) {
  const article = document.createElement('article');
  article.className = 'blog-post';

  // header: date & title
  const header = document.createElement('header');
  const dateP = document.createElement('p');
  dateP.className = 'post-date';
  dateP.textContent = post.dateTime || 'No date';
  const titleH = document.createElement('h3');
  titleH.textContent = post.title;
  header.appendChild(dateP);
  header.appendChild(titleH);
  article.appendChild(header);

  // content container
  const contentDiv = document.createElement('div');
  contentDiv.className = 'post-content';

  // full content (preserve line breaks)
  const fullContent = document.createElement('div');
  fullContent.className = 'post-full';
  fullContent.style.whiteSpace = 'pre-wrap';
  fullContent.textContent = post.content;

  // preview content (only if needed)
  const previewContent = document.createElement('div');
  previewContent.className = 'post-preview';
  previewContent.style.whiteSpace = 'pre-wrap';

  const fullText = post.content;
  const needsCollapse = fullText.length > 300;

  if (needsCollapse) {
    // Build preview: take up to 3 lines, but keep total length < 300
    const lines = fullText.split(/\r?\n/);
    let previewLines = [];
    let previewLength = 0;
    // take at least 3 lines if available, but stop if adding next line exceeds 300
    for (let i = 0; i < Math.min(lines.length, 3); i++) {
      const line = lines[i];
      if (previewLength + line.length + (i > 0 ? 1 : 0) < 300) {
        previewLines.push(line);
        previewLength += line.length + (i > 0 ? 1 : 0);
      } else {
        // if we haven't taken any line yet, take part of this line
        if (i === 0) {
          previewLines.push(line.slice(0, 300));
          previewLength = 300;
        }
        break;
      }
    }
    // if we still have less than 3 lines but we have more lines, force include them up to 300 chars
    while (previewLines.length < 3 && previewLines.length < lines.length) {
      const nextLine = lines[previewLines.length];
      if (previewLength + nextLine.length + (previewLines.length > 0 ? 1 : 0) < 300) {
        previewLines.push(nextLine);
        previewLength += nextLine.length + (previewLines.length > 0 ? 1 : 0);
      } else {
        // truncate the next line to fit within 300
        const remaining = 300 - previewLength - (previewLines.length > 0 ? 1 : 0);
        if (remaining > 0) {
          previewLines.push(nextLine.slice(0, remaining));
        }
        break;
      }
    }
    previewContent.textContent = previewLines.join('\n');
    // if preview is empty, fallback to first 300 chars
    if (!previewContent.textContent) {
      previewContent.textContent = fullText.slice(0, 300);
    }

    // toggle button
    const toggleBtn = document.createElement('button');
    toggleBtn.className = 'read-more-btn';
    toggleBtn.textContent = 'Read more';
    toggleBtn.setAttribute('aria-expanded', 'false');

    // Initially, full content is hidden, preview is visible
    fullContent.style.display = 'none';
    previewContent.style.display = 'block';

    toggleBtn.addEventListener('click', () => {
      const expanded = toggleBtn.getAttribute('aria-expanded') === 'true';
      if (expanded) {
        fullContent.style.display = 'none';
        previewContent.style.display = 'block';
        toggleBtn.textContent = 'Read more';
        toggleBtn.setAttribute('aria-expanded', 'false');
      } else {
        fullContent.style.display = 'block';
        previewContent.style.display = 'none';
        toggleBtn.textContent = 'Show less';
        toggleBtn.setAttribute('aria-expanded', 'true');
      }
    });

    contentDiv.appendChild(previewContent);
    contentDiv.appendChild(fullContent);
    contentDiv.appendChild(toggleBtn);
  } else {
    // short post – show full content only
    fullContent.style.display = 'block';
    contentDiv.appendChild(fullContent);
  }

  article.appendChild(contentDiv);
  return article;
}

// ---------- main init ----------
async function initBlog() {
  const list = await loadPostList();
  const feed = document.querySelector('.blog-feed');
  feed.innerHTML = '';

  if (!list.length) {
    feed.textContent = 'No blog posts found. Create blog/manifest.json or enable directory listing.';
    return;
  }

  // fetch and sort posts (newest first based on filename or date? we'll sort by filename descending)
  const posts = await Promise.all(list.map(f => fetchPost(f).catch(err => {
    console.warn('Skipping', f, err);
    return null;
  })));
  const validPosts = posts.filter(p => p !== null);
  // sort by dateTime (if possible) or filename – we'll sort by dateTime descending
  validPosts.sort((a, b) => {
    // try to parse as ISO date, else compare as strings
    const dA = new Date(a.dateTime);
    const dB = new Date(b.dateTime);
    if (!isNaN(dA) && !isNaN(dB)) return dB - dA;
    return b.dateTime.localeCompare(a.dateTime);
  });

  validPosts.forEach(post => {
    const el = createPostElement(post);
    feed.appendChild(el);
  });
}

document.addEventListener('DOMContentLoaded', initBlog);