function listIncludesUserId(list, userId) {
  if (!userId || !list?.length) return false
  return list.some((id) => String(id) === String(userId))
}

/** Viewer has blocked the profile owner */
function viewerBlockedUser(user, viewerId) {
  if (!user || !viewerId) return false
  return listIncludesUserId(user.blocked_by, viewerId)
}

/** Profile owner has blocked the viewer */
function userBlockedViewer(user, viewerId) {
  if (!user || !viewerId) return false
  return listIncludesUserId(user.blocked_users, viewerId)
}

/** Viewer (blocked person) cannot see profile/posts of user who blocked them */
function viewerIsBlockedBy(user, viewerId) {
  return userBlockedViewer(user, viewerId)
}

function blockedProfilePayload(user) {
  return {
    _id: user._id,
    user_name: user.user_name,
    blocked_you: true,
    is_self: false,
    user_type: user.user_type,
    postsCount: 0,
    allProjectsCount: 0,
    successfulProjectsCount: 0,
  }
}

/** User IDs who have blocked the viewer */
async function getBlockerUserIds(UserModel, viewerId) {
  if (!viewerId) return []
  return UserModel.find({ blocked_users: viewerId }).distinct('_id')
}

module.exports = {
  listIncludesUserId,
  viewerBlockedUser,
  userBlockedViewer,
  viewerIsBlockedBy,
  blockedProfilePayload,
  getBlockerUserIds,
}