const UserFollowModel = require('../models/UserFollowModel')
const { isHiddenFromPublic } = require('./accountLifecycle')

async function viewerCanSeeUserContent (viewerId, profileUser) {
  if (!profileUser) return false
  if (isHiddenFromPublic(profileUser)) return false
  if (!profileUser.is_private) return true
  if (!viewerId) return false
  if (String(viewerId) === String(profileUser._id)) return true
  return !!(await UserFollowModel.exists({
    followerId: viewerId,
    followingId: profileUser._id,
  }))
}

async function filterPostsHiddenByPrivateProfile (posts, viewerId) {
  if (!posts?.length) return posts

  const authorIds = [...new Set(posts.map((p) => String(p.user_id)))]
  const UserModel = require('../models/UserModel')
  const authors = await UserModel.find({ _id: { $in: authorIds } })
    .select('_id is_private account_status')
    .lean()

  const authorsById = Object.fromEntries(authors.map((u) => [String(u._id), u]))
  const privateAuthorIds = authors
    .filter((u) => u.is_private && !isHiddenFromPublic(u))
    .map((u) => String(u._id))

  let visiblePrivateIds = new Set()
  if (privateAuthorIds.length && viewerId) {
    if (privateAuthorIds.includes(String(viewerId))) {
      visiblePrivateIds.add(String(viewerId))
    }
    const follows = await UserFollowModel.find({
      followerId: viewerId,
      followingId: { $in: privateAuthorIds },
    })
      .select('followingId')
      .lean()
    follows.forEach((f) => visiblePrivateIds.add(String(f.followingId)))
  }

  return posts.filter((post) => {
    const author = authorsById[String(post.user_id)]
    if (!author || isHiddenFromPublic(author)) return false
    if (!author.is_private) return true
    if (!viewerId) return false
    if (String(viewerId) === String(author._id)) return true
    return visiblePrivateIds.has(String(author._id))
  })
}

async function filterStoryUserIdsByPrivateProfile (userIds, viewerId) {
  if (!userIds?.length) return []

  const UserModel = require('../models/UserModel')
  const users = await UserModel.find({ _id: { $in: userIds } })
    .select('_id is_private account_status')
    .lean()

  const visible = []
  for (const user of users) {
    // eslint-disable-next-line no-await-in-loop
    if (await viewerCanSeeUserContent(viewerId, user)) {
      visible.push(String(user._id))
    }
  }
  return visible
}

module.exports = {
  viewerCanSeeUserContent,
  filterPostsHiddenByPrivateProfile,
  filterStoryUserIdsByPrivateProfile,
}