overleaf/services/web/frontend/js/features/file-tree/util/count-in-tree.js

export function countFiles(fileTreeData) {
  if (!fileTreeData) {
    return 0
  }

  const value = _countElements(fileTreeData)

  const limit = window.ExposedSettings.maxEntitiesPerProject
  const status = fileCountStatus(value, limit, Math.ceil(limit / 20))

  return { value, status, limit }
}

function fileCountStatus(value, limit, range) {
  if (value >= limit) {
    return 'error'
  }

  if (value >= limit - range) {
    return 'warning'
  }

  return 'success'
}

// Copied and adapted from ProjectEntityMongoUpdateHandler
function _countElements(rootFolder) {
  function countFolder(folder) {
    if (folder == null) {
      return 0
    }

    let total = 0
    if (folder.folders) {
      total += folder.folders.length
      for (const subfolder of folder.folders) {
        total += countFolder(subfolder)
      }
    }
    if (folder.docs) {
      total += folder.docs.length
    }
    if (folder.fileRefs) {
      total += folder.fileRefs.length
    }
    return total
  }

  return countFolder(rootFolder)
}