import { escapeHtml } from '../utils.js';

function buildTree(relPaths, sep) {
  const tree = { _files: [], _dirs: {} };
  relPaths.forEach((rel) => {
    const parts = rel.split(sep);
    let node = tree;
    for (let i = 0; i < parts.length - 1; i++) {
      const dir = parts[i];
      if (!node._dirs[dir]) node._dirs[dir] = { _files: [], _dirs: {} };
      node = node._dirs[dir];
    }
    node._files.push(rel);
  });
  return tree;
}

function renderTree(node, prefix, sep, currentRel, depth) {
  let html = '';
  const depthClass = depth > 0 ? ` class="nav-depth-${Math.min(depth, 3)}"` : '';

  node._files.slice().sort().forEach((rel) => {
    const label = rel.split(sep).pop().replace(/\.md$/i, '').replace(/-/g, ' ');
    const abs = prefix + rel;
    const cls = rel === currentRel ? ' active' : '';
    if (depth === 0) {
      html += `\n<li><a href="#" class="nav-root-link${cls}" data-path="${escapeHtml(abs)}">${escapeHtml(label)}</a></li>`;
    } else {
      html += `\n<li${depthClass}><a href="#" class="nav-file-link${cls}" data-path="${escapeHtml(abs)}">${escapeHtml(label)}</a></li>`;
    }
  });

  Object.keys(node._dirs).sort().forEach((dirName) => {
    const child = node._dirs[dirName];
    const isOpen = currentRel && currentRel.split(sep).includes(dirName);
    const openAttr = isOpen ? ' open' : '';

    const homeFile = child._files.find((f) => /^home\.md$/i.test(f.split(sep).pop()));
    let folderLabel;
    if (homeFile) {
      const abs = prefix + homeFile;
      const cls = homeFile === currentRel ? ' active' : '';
      folderLabel = `<a href="#" class="nav-folder-link${cls}" data-path="${escapeHtml(abs)}" onclick="event.stopPropagation()">${escapeHtml(dirName)}</a>`;
    } else {
      folderLabel = `<span class="nav-folder-name">${escapeHtml(dirName)}</span>`;
    }

    const arrow = `<span class="nav-arrow" onclick="event.preventDefault();event.stopPropagation();var d=this.closest('details');d.open=!d.open">▶</span>`;

    const childNode = {
      _files: homeFile ? child._files.filter((f) => f !== homeFile) : child._files,
      _dirs: child._dirs,
    };

    html += `\n<li${depthClass}><details class="nav-folder"${openAttr}>`;
    html += `\n  <summary>${arrow}${folderLabel}</summary>`;
    html += `\n  <ul class="nav-tree">`;
    html += renderTree(childNode, prefix, sep, currentRel, depth + 1);
    html += `\n  </ul>\n</details></li>`;
  });

  return html;
}

function buildSidebar(baseDir, files, currentFile) {
  const sep = baseDir.includes('\\') ? '\\' : '/';
  const dirName = baseDir.split(sep).pop();
  const prefix = baseDir.endsWith(sep) ? baseDir : baseDir + sep;
  const toRel = abs => abs.startsWith(prefix) ? abs.slice(prefix.length) : abs;
  const currentRel = currentFile ? toRel(currentFile) : null;
  const relPaths = files.map(toRel);
  const tree = buildTree(relPaths, sep);

  let html = `<div class="sidebar__title-block">
    <h1 class="sidebar__title-block__title">${escapeHtml(dirName)}</h1>
  </div>
  <ul class="sidebar__menu nav-tree">`;
  html += renderTree(tree, prefix, sep, currentRel, 0);
  html += `\n  </ul>`;
  return html;
}

export function renderSidebar(baseDir, files, currentFile, onNavigate) {
  const sidebarEl = document.querySelector('#sidebar');
  sidebarEl.innerHTML = buildSidebar(baseDir, files, currentFile);
  sidebarEl.querySelectorAll('a[data-path]').forEach(a => {
    a.addEventListener('click', e => {
      e.preventDefault();
      onNavigate(a.dataset.path);
    });
  });
}