/**
 * notebooks v1
 */
const pagination = require('hexo-pagination')

function paginationWithEmpty(base, posts, options={}) {
  const { layout, data = {} } = options
  if (posts.length === 0) {
    base = `${base}/`
    return [{
      path: base,
      layout: layout,
      data: {
        ...data,
        base: base,
        total: 1,
        current: 1,
        current_url: base,
        posts: posts,
        prev: 0,
        prev_link: '',
        next: 0,
        next_link: '',
      }
    }]
  } else {
    return pagination(base, posts, options)
  }
}

hexo.extend.generator.register('notebooks', function (locals) {
  const { site_tree, notebooks } = hexo.theme.config
  if (notebooks.tree.length === undefined) {
    return []
  }

  const routes = []

  // The index page of all notebooks.
  routes.push({
    path: site_tree.notebooks.base_dir + '/index.html',
    layout: ['notebooks'],
    data: {
      layout: 'notebooks',
      menu_id: site_tree.notebooks.menu_id,
    }
  })

  for (const notebook of Object.values(notebooks.tree)) {
    const pages = locals.pages.filter(p => notebook.noteMap.has(p._id)).sort(notebook.order_by)
    pages.data.sort((a, b) => notebook.noteMap.get(b._id).pin - notebook.noteMap.get(a._id).pin)

    // Note list pages (for every tag) of current notebook.
    for (const [_, tag] of notebook.tagTree) {
      const notes = pages.filter(p => tag.noteSet.has(p._id))
      const slices = paginationWithEmpty(tag.path, notes, {
        perPage: notebook.per_page,
        layout: ['notes'],
        data: {
          layout: 'notes',
          menu_id: notebook.menu_id,
          notebook: notebook.id,
          activeTag: tag.id,
        }
      })
      routes.push(...slices)
    }
  }

  return routes
})