Sets

app/controllers/application_controller.rb

@@ -85,6 +85,10 @@ class ApplicationController < ActionController::Base
       puts "---"
     end
 
+    if Rails.env.development?
+      Rails.logger.error("<<< \n #{exception.class} exception thrown: #{exception.message}\n#{exception.backtrace.join("\n")}\n<<<")
+    end
+
     if exception.is_a?(::ActiveRecord::StatementInvalid) && exception.to_s =~ /statement timeout/
       if Rails.env.production?
         NewRelic::Agent.notice_error(exception, :uri => request.original_url, :referer => request.referer, :request_params => params, :custom_params => {:user_id => CurrentUser.user.id, :user_ip_addr => CurrentUser.ip_addr})

app/controllers/post_set_maintainers_controller.rb

@@ -0,0 +1,94 @@
+class PostSetMaintainersController < ApplicationController
+  respond_to :html
+  respond_to :js, except: [:index]
+  before_action :member_only
+
+
+  def index
+    @invites = PostSetMaintainer.where(user_id: CurrentUser.id).includes(:post_set)
+  end
+
+  def create
+    @set = PostSet.find(params[:post_set_id])
+    @user = User.find_by_name(params[:username])
+    check_edit_access(@set)
+    @invite = PostSetMaintainer.new(post_set_id: @set.id, user_id: @user.id, status: 'pending')
+    @invite.validate
+
+    if @invite.invalid?
+      flash[:notice] = @invite.errors.full_messages.join('; ')
+      redirect_to maintainers_post_set_path(@set)
+      return
+    end
+
+    if RateLimiter.check_limit("set.invite.#{CurrentUser.id}", 5, 1.hours)
+      flash[:notice] = "You must wait an hour before inviting more set maintainers."
+
+    end
+
+    PostSetMaintainer.where(user_id: @user.id, post_set_id: @set.id).destroy_all
+    @invite.save
+
+    if @invite.valid?
+      RateLimiter.hit("set.invite.#{CurrentUser.id}", 1.hours)
+      flash[:notice] = "#{@user.pretty_name} invited to be a maintainer"
+    else
+      flash[:notice] = @invite.errors.full_messages.join('; ')
+    end
+    redirect_to maintainers_post_set_path(@set)
+  end
+
+  def destroy
+    @maintainer = PostSetMaintainer.find(params[:id] || params[:post_set_maintainer][:id])
+    @set = @maintainer.post_set
+    check_edit_access(@set)
+    check_cancel_access(@maintainer)
+
+    @maintainer.cancel!
+  end
+
+  def approve
+    @maintainer = PostSetMaintainer.find(params[:id])
+    check_approve_access(@maintainer)
+
+    @maintainer.approve!
+  end
+
+  def deny
+    @maintainer = PostSetMaintainer.find(params[:id])
+    raise User::PrivilegeError unless @maintainer.user_id == CurrentUser.id
+
+    @maintainer.deny!
+  end
+
+  def block
+    @maintainer = PostSetMaintainer.find(params[:id])
+    check_block_access(@maintainer)
+
+    @maintainer.block!
+  end
+
+  private
+
+  def check_approve_access(maintainer)
+    raise User::PrivilegeError unless maintainer.user_id == CurrentUser.id
+    raise User::PrivilegeError if ['blocked', 'approved'].include?(maintainer.status)
+  end
+
+  def check_cancel_access(maintainer)
+    raise User::PrivilegeError if maintainer.status == 'blocked'
+    raise User::PrivilegeError if maintainer.status == 'cooldown' && @maintainer.created_at > 24.hours.ago
+  end
+
+  def check_block_access(maintainer)
+    raise User::PrivilegeError unless maintainer.user_id == CurrentUser.id
+    raise User::PrivilegeError if maintainer.status == 'blocked'
+  end
+
+  def check_edit_access(set)
+    unless set.is_owner?(CurrentUser) || CurrentUser.is_admin?
+      raise User::PrivilegeError
+    end
+  end
+
+end

app/controllers/post_sets_controller.rb

@@ -0,0 +1,166 @@
+class PostSetsController < ApplicationController
+  respond_to :html, :json, :xml
+  before_action :member_only, only: [:new, :create, :update, :destroy,
+                                     :edit, :maintainers, :update_posts,
+                                     :add_post, :remove_post]
+
+  def index
+    if !params[:post_id].blank?
+      if CurrentUser.is_admin?
+        @sets = PostSet.paginate(include: :set_entries, conditions: ["set_entries.post_id = ?", params[:post_id]], page: 1, per_page: 50)
+      else
+        @sets = PostSet.paginate(include: :set_entries, conditions: ["(post_sets.public = TRUE OR post_sets.user_id = ?) AND set_entries.post_id = ?", CurrentUser.id || 0, params[:post_id]], page: 1, per_page: 50)
+      end
+    elsif !params[:maintainer_id].blank?
+      if CurrentUser.is_admin?
+        @sets = PostSet.paginate(include: :set_maintainers, conditions: ["(set_maintainers.user_id = ? AND set_maintainers.status = 'approved')", params[:maintainer_id]], page: 1, per_page: 50)
+      else
+        @sets = PostSet.paginate(include: :set_maintainers, conditions: ["(post_sets.public = TRUE OR post_sets.user_id = ?) AND (set_maintainers.user_id = ? AND set_maintainers.status = 'approved')", CurrentUser.id || 0, params[:maintainer_id]], page: 1, per_page: 50)
+      end
+    else
+      @sets = PostSet.search(search_params).paginate(params[:page], limit: params[:limit])
+    end
+
+    respond_with(@sets)
+  end
+
+  def atom
+    begin
+      @sets = PostSet.visible.order(id: :desc).limit(32)
+      headers["Content-Type"] = "application/atom+xml"
+    rescue RuntimeError => e
+      @set = []
+    end
+
+    render layout: false
+  end
+
+  def new
+    @set = PostSet.new
+  end
+
+  def create
+    @set = PostSet.create(set_params)
+    flash[:notice] = @set.valid? ? 'Set created' : @set.errors.full_messages.join('; ')
+    respond_with(@set)
+  end
+
+  def show
+    @set = PostSet.find(params[:id])
+    check_view_access(@set)
+
+    respond_with(@set)
+  end
+
+  def edit
+    @set = PostSet.find(params[:id])
+    check_edit_access(@set)
+    @can_edit = @set.is_owner?(CurrentUser) || CurrentUser.is_admin?
+    respond_with(@set)
+  end
+
+  def update
+    @set = PostSet.find(params[:id])
+    check_edit_access(@set)
+    @set.update(set_params)
+    flash[:notice] = @set.valid? ? 'Set updated.' : @set.errors.full_messages.join('; ')
+
+    if CurrentUser.is_admin? && !@set.is_owner?(CurrentUser.user)
+      if @set.saved_change_to_is_public?
+        ModAction.log("User ##{CurrentUser.id} marked set ##{@set.id} as private", :set_mark_private)
+      end
+
+      if @set.saved_change_to_watched_attribute?
+        ModAction.log("Admin ##{CurrentUser.id} edited set ##{@set.id}", :set_edit)
+      end
+    end
+
+    respond_with(@set)
+  end
+
+  def maintainers
+    @set = PostSet.find(params[:id])
+  end
+
+  def post_list
+    @set = PostSet.find(params[:id])
+    check_edit_access(@set)
+    respond_with(@set)
+  end
+
+  def update_posts
+    @set = PostSet.find(params[:id])
+    check_edit_access(@set)
+    @set.update(update_posts_params)
+    @set.synchronize!
+    flash[:notice] = @set.valid? ? 'Set posts updated.' : @set.errors.full_messages.join('; ')
+
+    redirect_back(fallback_location: post_list_post_set_path(@set))
+  end
+
+  def destroy
+    @set = PostSet.find(params[:id])
+    unless @set.is_owner?(CurrentUser.user) || CurrentUser.is_admin?
+      raise User::PrivilegeError
+    end
+    @set.destroy
+    respond_with(@set)
+  end
+
+  def select
+    @sets_owned = PostSet.all(order: "lower(name) ASC", conditions: ["user_id = ?", CurrentUser.id])
+    @sets_maintained = SetMaintainer.all(joins: :post_set, select: "set_maintainers.*, post_sets.*", conditions: ["set_maintainers.user_id = ? AND post_sets.public = TRUE", CurrentUser.id])
+
+    @grouped_options = {
+        "Owned" => @sets_owned.map {|x| [truncate(x.name.tr("_", " "), length: 35), x.id]},
+        "Maintained" => @sets_maintained.map {|x| [truncate(x.name.tr("_", " "), length: 35), x.id]}
+    }
+
+    render layout: false
+  end
+
+  def add_posts
+    @set = PostSet.find(params[:set_id])
+    check_edit_access(@set)
+    @set.add(params[:post_ids])
+    @set.save
+    respond_with(@set)
+  end
+
+  def remove_post
+    @set = PostSet.find(params[:set_id])
+    check_edit_access(@set)
+    @set.remove(params[:post_ids])
+    @set.save
+    respond_with(@set)
+  end
+
+  private
+
+  def check_edit_access(set)
+    unless set.is_owner?(CurrentUser.user) || set.is_maintainer?(CurrentUser.user)
+      raise User::PrivilegeError
+    end
+    if !set.is_public && !set.is_owner?(CurrentUser.user)
+      raise User::PrivilegeError
+    end
+  end
+
+  def check_view_access(set)
+    unless set.is_public || set.is_owner?(CurrentUser.user) || CurrentUser.is_admin?
+      raise User::PrivilegeError
+    end
+  end
+
+  def set_params
+    params.require(:post_set).permit(%i[name shortname description is_public transfer_on_delete])
+  end
+
+  def update_posts_params
+    params.require(:post_set).permit([:post_ids_string])
+  end
+
+  def search_params
+    params.fetch(:search, {}).permit!
+  end
+end

app/controllers/posts_controller.rb

@@ -105,7 +105,7 @@ private
           @error_message = post.errors.full_messages.join("; ")
           render :template => "static/error", :status => 500
         else
-          response_params = {:q => params[:tags_query], :pool_id => params[:pool_id], :favgroup_id => params[:favgroup_id]}
+          response_params = {:q => params[:tags_query], :pool_id => params[:pool_id], post_set_id: params[:post_set_id], favgroup_id => params[:favgroup_id]}
           response_params.reject!{|key, value| value.blank?}
           redirect_to post_path(post, response_params)
         end

app/helpers/posts_helper.rb

@@ -23,7 +23,7 @@ module PostsHelper
 
   def missed_post_search_count_js
     return nil unless post_search_counts_enabled?
-    
+
     if params[:ms] == "1" && @post_set.post_count == 0 && @post_set.is_single_tag?
       session_id = session.id
       verifier = ActiveSupport::MessageVerifier.new(Danbooru.config.reportbooru_key, serializer: JSON, digest: "SHA256")
@@ -34,7 +34,7 @@ module PostsHelper
 
   def post_search_count_js
     return nil unless post_search_counts_enabled?
-    
+
     if action_name == "index" && params[:page].nil?
       tags = Tag.scan_query(params[:tags]).sort.join(" ")
 
@@ -143,10 +143,17 @@ module PostsHelper
   def is_pool_selected?(pool)
     return false if params.has_key?(:q)
     return false if params.has_key?(:favgroup_id)
-    return false if !params.has_key?(:pool_id)
+    return false unless params.has_key?(:pool_id)
     return params[:pool_id].to_i == pool.id
   end
 
+  def is_post_set_selected?(post_set)
+    return false if params.has_key?(:q)
+    return false if params.has_key?(:pool_id)
+    return false unless params.has_key?(:post_set_id)
+    return params[:post_set_id].to_i == post_set.id
+  end
+
   def show_tag_change_notice?
     Tag.scan_query(params[:tags]).size == 1 && TagChangeNoticeService.get_forum_topic_id(params[:tags])
   end

app/logical/post_sets/post.rb

@@ -70,6 +70,18 @@ module PostSets
       ::Pool.find_by_name(pool_name)
     end
 
+    def post_set_name
+      @post_set_name ||= Tag.has_metatag?(tag_array, :set)
+    end
+
+    def has_post_set?
+      is_single_tag? && post_set_name && post_set
+    end
+
+    def post_set
+      ::PostSet.find_by_shortname(post_set_name)
+    end
+
     def favgroup_name
       @favgroup_name ||= Tag.has_metatag?(tag_array, :favgroup)
     end

app/logical/rate_limiter.rb

@@ -0,0 +1,22 @@
+class RateLimiter
+  def self.check_limit(key, max_attempts, lockout_time = 1.minute)
+    return true if Cache.get("#{key}:lockout")
+
+    attempts = Cache.get(key) || 0
+    if attempts >= max_attempts
+      Cache.put("#{key}:lockout", true, lockout_time)
+      reset_limit(key)
+    end
+  end
+
+  def self.hit(key, time_period = 1.minute)
+    value = Cache.get(key) || 0
+    Cache.put(key, value.to_i + 1, time_period)
+    return value.to_i + 1
+  end
+
+  def self.reset_limit(key)
+    Cache.delete(key)
+  end
+
+end

app/models/application_record.rb

@@ -35,6 +35,13 @@ class ApplicationRecord < ActiveRecord::Base
         where.not("#{qualified_column_for(attr)} ~ ?", "(?e)" + value)
       end
 
+      def attribute_exact_matches(attribute, value, **options)
+        return all unless value.present?
+
+        column = qualified_column_for_attribute(attribute)
+        where("#{column} = ?", value)
+      end
+
       def attribute_matches(attribute, value, **options)
         return all if value.nil?
 

app/models/post.rb

@@ -1061,6 +1061,32 @@ class Post < ApplicationRecord
     end
   end
 
+  module SetMethods
+    def post_sets
+      @post_sets ||= begin
+        return PostSet.none if pool_string.blank?
+        post_set_ids = pool_string.scan(/\d+/)
+        PostSet.where(id: post_set_ids)
+      end
+    end
+
+    def add_set!(set, force = false)
+      with_lock do
+        self.pool_string = "#{pool_string} set:#{set.id}".strip
+        update_column(:pool_string, pool_string) unless new_record?
+      end
+      # TODO: Add some indexing step here to trigger an index update when elasticsearch is merged
+    end
+
+    def remove_set!(set)
+      with_lock do
+        self.pool_string = pool_string.gsub(/(?:\A| )set:#{set.id}(?:\Z| )/, " ").strip
+        update_column(:pool_string, pool_string) unless new_record?
+      end
+      # TODO: Add some indexing step here to trigger an index update when elasticsearch is merged
+    end
+  end
+
   module PoolMethods
     def pools
       @pools ||= begin
@@ -1886,6 +1912,7 @@ class Post < ApplicationRecord
   include FavoriteMethods
   include UploaderMethods
   include PoolMethods
+  include SetMethods
   include VoteMethods
   extend CountMethods
   include ParentMethods

app/models/post_set.rb

@@ -0,0 +1,310 @@
+# -*- encoding : utf-8 -*-
+class PostSet < ApplicationRecord
+  array_attribute :post_ids, parse: /\d+/, cast: :to_i
+
+  has_many :post_set_maintainers, dependent: :destroy do
+    def in_cooldown(user)
+      where(creator_id: user.id, status: 'cooldown').where('created_at < ?', 24.hours.ago)
+    end
+    def active
+      where(status: 'approved')
+    end
+    def pending
+      where(status: 'pending')
+    end
+    def banned
+      where(status: 'banned')
+    end
+  end
+  has_many :maintainers, class_name: "User", through: :post_set_maintainers
+  belongs_to_creator counter_cache: 'set_count'
+
+  validates_length_of :name, :shortname, in: 3..100, message: "must be between three and one hundred characters long"
+  validates_uniqueness_of :name, :shortname, case_sensitive: false, message: "is already taken"
+  validates_length_of :shortname, in: 1..50, message: 'must be between one and fifty characters long'
+  validates_format_of :shortname, with: /\A[\w]+\z/, message: "must only contain numbers, letters, and underscores"
+  validates_format_of :shortname, with: /\A\d*[a-z_][\w]*\z/, message: "must contain at least one letter or underscore"
+  validates_length_of :description, maximum: 10000
+  validate :validate_number_of_posts
+  validate :can_make_public
+  validate :set_per_hour_limit, on: :create
+  validate :can_create_new_set_limit, on: :create
+
+  after_update :send_maintainer_public_dmails
+  before_destroy :send_maintainer_destroy_dmails
+  before_save :update_post_count
+
+  def self.name_to_id(name)
+    if name =~ /^\d+$/
+      name.to_i
+    else
+      select_value_sql("SELECT id FROM post_sets WHERE lower(shortname) = ?", name.downcase.tr(" ", "_")).to_i
+    end
+  end
+
+  def self.name_to_id_visible(name)
+
+  end
+
+  def self.visible(user = CurrentUser)
+    return all() if user.is_admin?
+    where('is_public = true OR creator_id = ?', user.id)
+  end
+
+  def saved_change_to_watched_attributes?
+    saved_change_to_name? || saved_change_to_shortname? || saved_change_to_description?
+  end
+
+  module ValidationMethods
+    def send_maintainer_public_dmails
+      if RateLimiter.check_limit("set.public.#{id}", 1, 24.hours)
+        return
+      end
+      if is_public_changed? && !is_public # If set was made private
+        RateLimiter.hit("set.public.#{id}", 24.hours)
+        PostSetMaintainer.active.where(post_set_id: id).each do |maintainer|
+          Dmail.create_automated(to_id: maintainer.user_id, title: "A set you maintain was made private",
+                                 body: "The set \"#{name}\":#{post_set_path(self)} by \"#{creator.name}\":#{user_path(creator)} that you maintain was set to private. You will not be able to view, add posts, or remove posts from the set until the owner makes it public again.")
+        end
+
+        PostSetMaintainer.pending.where(post_set_id: id).delete
+      elsif is_public_changed? && is_public # If set was made public
+        RateLimiter.hit("set.public.#{id}", 24.hours)
+        PostSetMaintainer.active.where(post_set_id: id).each do |maintainer|
+          Dmail.create_automated(to_id: maintainer.user_id, titlet: "A private set you had maintained was made public again",
+                                 body: "The set \"#{name}\":#{post_set_path(self)} by \"#{creaator.name}\":#{user_path(creator)} that you previously maintained was made public again. You are now able to view the set and add/remove posts.")
+        end
+      end
+    end
+
+    def send_maintainer_destroy_dmails
+      PostSetMaintainer.active.where(post_set_id: id).each do |maintainer|
+        Dmail.create_automated(to_id: maintainer.user_id,
+                               title: "A set you maintain was deleted",
+                               body: "The set #{name} by \"#{creator.name}\":#{user_path(creator)} that you maintain was deleted.")
+      end
+    end
+
+    def can_make_public
+      if is_public && creator.created_at > 3.days.ago && !creator.is_builder?
+        errors.add(:base, "Can't make a set public until your account is at least three days old")
+        false
+      else
+        true
+      end
+    end
+
+    def can_create_new_set_limit
+      if PostSet.where(creator_id: creator.id).count() >= 75
+        errors.add(:base, "You can only create 75 sets.")
+        return false
+      end
+      true
+    end
+
+    def set_per_hour_limit
+      if where("created_at > ? AND creator_id = ?", 1.hour.ago, creator.id).count() > 6 && !creator.is_builder?
+        first = where("created_at > ? AND creator_id = ?", 1.hour.ago, creator.id).order(:created_at).first()
+        errors.add(:base, "You have already created 6 sets in the last hour. You can make a new set in #{time_ago_in_words(first.created_at)}")
+        false
+      else
+        true
+      end
+    end
+
+    def validate_number_of_posts
+      if post_ids.size > 10_000
+        errors.add(:base, "Sets can have up to 10,000 posts each")
+        false
+      else
+        true
+      end
+    end
+  end
+
+  module AccessMethods
+    def can_view?(user)
+      is_public || user_id == user.id || user.is_admin?
+    end
+
+    def can_edit?(user)
+      is_owner?(user) || is_maintainer?(user)
+    end
+
+    def is_maintainer?(user)
+      return false if user.is_blocked?
+      post_set_maintainers.where(user_id: user.id, status: 'approved').count() > 0
+    end
+
+    def is_invited?(user)
+      post_set_maintainers.where(user_id: user.id, status: 'pending').count() > 0
+    end
+
+    def is_blocked?(user)
+      post_set_maintainers.where(user_id: user.id, status: 'blocked').count() > 0
+    end
+
+    def is_owner?(user)
+      return false if user.is_blocked?
+      creator_id == user.id || user.is_admin?
+    end
+  end
+
+  module PostMethods
+    def contains?(post_id)
+      post_ids.include?(post_id)
+    end
+
+    def page_number(post_id)
+      post_ids.find_index(post_id).to_i + 1
+    end
+
+    def add(ids)
+      real_ids = Post.select(:id).where(id: ids)
+      real_ids.each do |post|
+        next if contains?(post.id)
+        self.post_ids = post_ids + [post.id]
+      end
+    end
+
+    def add!(post)
+      return if contains?(post.id)
+
+      with_lock do
+        update(post_ids: post_ids + [post.id])
+        post.add_set!(self, true)
+      end
+    end
+
+    def remove(ids)
+      ids.each do |id|
+        next if contains?(id)
+        self.post_ids = post_ids - [id]
+      end
+    end
+
+    def remove!(post)
+      return unless contains?(post.id)
+
+      with_lock do
+        update(post_ids: post_ids - [post.id])
+        post.remove_set!(self)
+      end
+    end
+
+    def posts(options = {})
+      offset = options[:offset] || 0
+      limit = options[:limit] || Danbooru.config.posts_per_page
+      slice = post_ids.slice(offset, limit)
+      if slice && slice.any?
+        Post.where(id: slice).sort_by {|record| slice.index {|id| id == record.id}}
+      else
+        []
+      end
+    end
+
+    def post_count
+      post_ids.size
+    end
+
+    def first_post?(post_id)
+      post_id == post_ids.first
+    end
+
+    def last_post?(post_id)
+      post_id == post_ids.last
+    end
+
+    def previous_post_id(post_id)
+      return nil if first_post?(post_id) || !contains?(post_id)
+
+      n = post_ids.index(post_id) - 1
+      post_ids[n]
+    end
+
+    def next_post_id(post_id)
+      return nil if last_post?(post_id) || !contains?(post_id)
+
+      n = post_ids.index(post_id) + 1
+      post_ids[n]
+    end
+
+    def synchronize
+      post_ids_before = post_ids_before_last_save || post_ids_was
+      added = post_ids - post_ids_before
+      removed = post_ids_before - post_ids
+
+      added_posts = Post.where(id: added)
+      added_posts.each do |post|
+        post.add_set!(self, true)
+      end
+
+      removed_posts = Post.where(id: removed)
+      removed_posts.each do |post|
+        post.remove_set!(self)
+      end
+
+      normalize_post_ids
+    end
+
+    def synchronize!
+      synchronize
+      save if will_save_change_to_post_ids?
+    end
+
+    def normalize_post_ids
+      self.post_ids = post_ids.uniq
+    end
+
+    def update_post_count
+      normalize_post_ids
+      self.post_count = post_ids.size
+    end
+  end
+
+  module SearchMethods
+    def selected_first(current_set_id)
+      return where("true") if current_set_id.blank?
+      current_set_id = current_set_id.to_i
+      reorder(Arel.sql("(case post_sets.id when #{current_set_id} then 0 else 1 end), post_sets.name"))
+    end
+
+    def self.search(prams)
+      q = super
+
+      q = q.where('is_public = true')
+      q = q.or(where('(is_public = false AND creator_id = ?', creator_id)) if creator_id
+
+      if params[:creator_name].present?
+        user = User.find_by_name(params[:username])
+        q = q.where(creator_id: user)
+      end
+
+      q = q.attribute_exact_matches(:creator_id, params[:creator_id])
+      q = q.search_text_attribute(:name, params)
+      q = q.attribute_exact_matches(:shortname, params[:shortname])
+
+      case params[:order]
+      when 'name'
+        q = q.order(:name, id: :desc)
+      when 'shortname'
+        q = q.order(:shortname, id: :desc)
+      when 'postcount'
+        q = q.order(post_count: :desc, id: :desc)
+      when 'created_at'
+        q = q.order(:id)
+      when 'update'
+        q = q.order(updated_at: :desc)
+      else
+        q = q.order(id: :desc)
+      end
+
+      q
+    end
+  end
+
+  extend SearchMethods
+  include ValidationMethods
+  include AccessMethods
+  include PostMethods
+end

app/models/post_set_maintainer.rb

@@ -0,0 +1,149 @@
+class PostSetMaintainer < ApplicationRecord
+  belongs_to :user
+  belongs_to :post_set
+
+  validate :ensure_not_set_owner, on: :create
+  validate :ensure_set_public, on: :create
+  validate :ensure_maintainer_count, on: :create
+  validate :ensure_not_duplicate, on: :create
+
+  after_create :notify_maintainer
+
+  def notify_maintainer
+    body = "\"#{post_set.creator.name}\":/users/#{post_set.creator_id} invited you to be a maintainer of the \"#{post_set.name}\":/post_sets/#{post_set_id} set. This would allow you to add and remove posts from it.
+
+\"Click here\":/post_set_maintainers/approve/#{id} to approve the request and become a maintainer.
+
+\"Click here\":/post_set_maintainers/deny/#{id} to deny the request.
+
+\"Click here\":/post_set_maintainers/block/#{id} to deny the request and prevent yourself from being invited to this set again in the future."
+    Dmail.create_automated(
+        to_id: user_id,
+        title: "You were invite to be a maintainer of #{post_set.name}",
+        body: body
+    )
+  end
+
+  def notify_destroy
+
+  end
+
+  def cancel!
+    if status == 'pending'
+      self.status = 'cooldown'
+      save
+      return
+    end
+
+    if status == 'approved'
+      body = "\"#{post_set.creator.name}\":/users/#{post_set.creator_id} removed you as a maintainer of the \"#{post_set.name}\":/post_sets/#{post_set.id} set."
+      Dmail.create_automated(
+          to_id: user_id,
+          title: "You were removed as a set maintainer of #{post_set.name}",
+          body: body
+      )
+    end
+    destroy
+  end
+
+  def approve!
+    self.status = 'approved'
+    save
+    Dmail.create_automated(
+        to_id: post_set.creator_id,
+        title: "#{user.name} approved your invite to maintain #{post_set.name}",
+        body: "\"#{user.name}\":/users/#{user_id} approved your invite to maintain \"#{post_set.name}\":/post_sets/#{post_set.id}."
+    )
+  end
+
+  def deny!
+    if status == "pending"
+      Dmail.create_automated(
+          to_id: post_set.creator_id,
+          title: "#{user.name} denied your invite to maintain #{post_set.name}",
+          body: "\"#{user.name}\":/users/#{user.id} denied your invite to maintain \"#{post_set.name}\":/post_sets/#{post_set.id}."
+      )
+    elsif status == "approved"
+      Dmail.create_automated(
+          to_id: post_set.creator_id,
+          title: "#{user.name} removed themselves as a maintainer of #{post_set.name}",
+          body: "\"#{user.name}\":/users/#{user.id} removed themselves as a maintainer of \"#{post_set.name}\":/post_sets/#{post_set.id}."
+      )
+    end
+    destroy
+  end
+
+  def block!
+    if status == "approved"
+      Dmail.create_automated(
+          to_id: post_set.creator_id,
+          title: "#{user.name} removed themselves as a maintainer of #{post_set.name}",
+          body: "\"#{user.name}\":/users/#{user.id} removed themselves as a maintainer of \"#{post_set.name}\":/post_sets/#{post_set.id} and blocked all future invites."
+      )
+    elsif status == "pending"
+      Dmail.create_automated(
+          to_id: post_set.creator_id,
+          title: "#{user.name} denied your invite to maintain #{post_set.name}",
+          body: "\"#{user.name}\":/users/#{user.id} denied your invite to maintain \"#{post_set.name}\":/post_sets/#{post_set.id} and blocked all future invites."
+      )
+    end
+    self.status = 'blocked'
+    save
+  end
+
+  module ValidaitonMethods
+    def ensure_not_set_owner
+      if post_set.creator_id == user_id
+        errors.add(:user, "owns this set and can't be added as a maintainer")
+        false
+      end
+    end
+
+    def ensure_maintainer_count
+      if PostSetMaintainer.where(post_set_id: post_set_id).count >= 75
+        errors.add(:post_set, "current have too many maintainers")
+        false
+      end
+    end
+
+    def ensure_not_duplicate
+      existing = PostSetMaintainer.where(post_set_id: post_set_id, user_id: user_id).first
+      if existing.nil?
+        return
+      end
+      if ['approved', 'pending'].include?(existing.status)
+        errors.add(:base, "Already a maintainer of this set")
+        return false
+      end
+      if existing.status == 'blocked'
+        errors.add(:base, 'User has blocked you from inviting them to maintain this set')
+        return false
+      end
+      if existing.status == 'cooldown' && existing.created_at > 24.hours.ago
+        errors.add(:base, "User has been invited to maintain this set too recently")
+        return false
+      end
+    end
+
+    def ensure_set_public
+      unless post_set.is_public
+        errors.add(:post_set, 'must be public')
+        false
+      end
+    end
+  end
+
+  def maintained(user)
+    where(user_id: user.id, status: 'approved').joins(:post_set).where('post_set.is_public = true')
+  end
+
+  def self.active
+    where(status: 'approved')
+  end
+
+  def self.pending
+    where(status: 'pending')
+  end
+
+  include ValidaitonMethods
+end

app/models/tag.rb

@@ -18,7 +18,7 @@ class Tag < ApplicationRecord
     -locked locked width height mpixels ratio score favcount filesize source
     -source id -id date age order limit -status status tagcount parent -parent
     child pixiv_id pixiv search upvote downvote filetype -filetype flagger
-    -flagger appealer -appealer disapproval -disapproval
+    -flagger appealer -appealer disapproval -disapproval set -set
   ] + TagCategory.short_name_list.map {|x| "#{x}tags"} + COUNT_METATAGS + COUNT_METATAG_SYNONYMS
 
   SUBQUERY_METATAGS = %w[commenter comm noter noteupdater artcomm flagger -flagger appealer -appealer]
@@ -657,6 +657,25 @@ class Tag < ApplicationRecord
             q[:tags][:related] << "pool:#{pool_id}"
             q[:ordpool] = pool_id
 
+          when "set"
+            post_set_id = PostSet.name_to_id(g2)
+            post_set = PostSet.find(post_set_id)
+
+            unless post_set.can_view?(CurrentUser.user)
+              raise User::PrivilegeError
+            end
+
+            q[:tags][:related] << "set:#{post_set_id}"
+
+          when "-set"
+            post_set_id = PostSet.name_to_id(g2)
+            post_set = PostSet.find(post_set_id)
+
+            unless post_set.can_view?(CurrentUser.user)
+              raise User::PrivilegeError
+            end
+            q[:tags][:exclude] << "set:#{post_set_id}"
+
           when "-favgroup"
             favgroup_id = FavoriteGroup.name_to_id(g2)
             favgroup = FavoriteGroup.find(favgroup_id)

app/presenters/post_presenter.rb

@@ -36,8 +36,8 @@ class PostPresenter < Presenter
     if options[:pool_id]
       locals[:link_params]["pool_id"] = options[:pool_id]
     end
-    if options[:favgroup_id]
-      locals[:link_params]["favgroup_id"] = options[:favgroup_id]
+    if options[:post_set_id]
+      locals[:link_params]["post_set_id"] = options[:post_set_id]
     end
 
     locals[:tooltip] = "#{post.tag_string} rating:#{post.rating} score:#{post.score}"
@@ -160,12 +160,12 @@ class PostPresenter < Presenter
   end
 
   def has_nav_links?(template)
-    has_sequential_navigation?(template.params) || @post.pools.undeleted.any? || @post.favorite_groups(active_id=template.params[:favgroup_id]).any?
+    has_sequential_navigation?(template.params) || @post.pools.undeleted.any? || @post.post_sets.visible.any?
   end
 
   def has_sequential_navigation?(params)
     return false if Tag.has_metatag?(params[:q], :order, :ordfav, :ordpool)
-    return false if params[:pool_id].present? || params[:favgroup_id].present?
+    return false if params[:pool_id].present? || params[:post_set_id].present?
     return CurrentUser.user.enable_sequential_post_navigation 
   end
 end

app/presenters/post_set_presenters/base.rb

@@ -8,7 +8,7 @@ module PostSetPresenters
       html = ""
 
       if posts.empty?
-        return template.render("post_sets/blank")
+        return template.render("posts/blank")
       end
 
       posts.each do |post|

app/presenters/post_set_presenters/favorite_group.rb

@@ -4,7 +4,7 @@ module PostSetPresenters
       html = ""
 
       if posts.empty?
-        return template.render("post_sets/blank")
+        return template.render("posts/blank")
       end
 
       posts.each do |post|

app/presenters/post_set_presenters/pool.rb

@@ -16,7 +16,7 @@ module PostSetPresenters
       html = ""
 
       if posts.empty?
-        return template.render("post_sets/blank")
+        return template.render("posts/blank")
       end
 
       posts.each do |post|

app/presenters/post_set_presenters/pool_gallery.rb

@@ -11,7 +11,7 @@ module PostSetPresenters
       html = ""
 
       if pools.empty?
-        return template.render("post_sets/blank")
+        return template.render("posts/blank")
       end
 
       pools.each do |pool|

app/views/post_set_maintainers/approve.js.erb

@@ -0,0 +1 @@
+location.reload();

app/views/post_set_maintainers/block.js.erb

@@ -0,0 +1 @@
+location.reload();

app/views/post_set_maintainers/deny.js.erb

@@ -0,0 +1 @@
+location.reload();

app/views/post_set_maintainers/index.html.erb

@@ -0,0 +1,74 @@
+<div id="c-set-maintainer">
+  <div id="a-index">
+    <h2>Pending Invites</h2>
+    <table class="rounded nomargin" width="600px" style="margin-bottom:30px;">
+      <thead>
+      <th width="55%"><%= link_to "Set", action: "index", order: "set" %></th>
+      <th width="20%"><%= link_to "Status", action: "index", order: "status" %></th>
+      <th width="25%"></th>
+      </thead>
+      <tbody>
+      <% @invites.where(status: 'pending').each do |m| %>
+        <% if m.post_set.is_public %>
+          <tr>
+            <td><%= link_to m.post_set.name, post_set_path(m.post_set) %></td>
+            <td><%= m.status.capitalize %></td>
+            <td>
+              <%= link_to "Accept", approve_post_set_maintainer_path(m), remote: true, method: :post, 'data-confirm': 'Are you sure you want to accept this invite?' %>
+              <%= link_to "Ignore", deny_post_set_maintainer_path(m), remote: true, method: :post, 'data-confirm': 'Are you sure you want to ignore this invite?' %>
+              <%= link_to "Block", block_post_set_maintainer_path(m), remote: true, method: :post, 'data-confirm': 'Aer you sure you want to ignore and block future invites for this set?' %>
+            </td>
+          </tr>
+        <% end %>
+      <% end %>
+      </tbody>
+    </table>
+
+    <h2>Approved Invites</h2>
+    <table class="rounded nomargin" width="600px" style="margin-bottom:30px;">
+      <thead>
+      <th width="55%"><%= link_to "Set", action: "index", order: "set" %></th>
+      <th width="20%"><%= link_to "Status", action: "index", order: "status" %></th>
+      <th width="25%"></th>
+      </thead>
+      <tbody>
+      <% @invites.where(status: 'approved').each do |m| %>
+        <% if m.post_set.is_public %>
+          <tr>
+            <td><%= link_to m.post_set.name, post_set_path(m.post_set) %></td>
+            <td><%= m.status.capitalize %></td>
+            <td>
+              <%= link_to "Remove", deny_post_set_maintainer_path(m), remote: true, method: :post, 'data-confirm': 'Are you sure you want to remove yourself as maintainer of this set?' %>
+              <%= link_to "Block", block_post_set_maintainer_path(m), remote: true, method: :post, 'data-confirm': 'Aer you sure you want to remove yourself and block future invites for this set?' %>
+            </td>
+          </tr>
+        <% end %>
+      <% end %>
+      </tbody>
+    </table>
+
+    <h2>Blocked Invites</h2>
+    <table class="rounded nomargin" width="600px">
+      <thead>
+      <th width="55%"><%= link_to "Set", action: "index", order: "set" %></th>
+      <th width="20%"><%= link_to "Status", action: "index", order: "status" %></th>
+      <th width="25%"></th>
+      </thead>
+      <tbody>
+      <% @invites.where(status: 'blocked').each do |m| %>
+        <% if m.post_set.is_public %>
+          <tr>
+            <td><%= link_to m.post_set.name, post_set_path(m.post_set) %></td>
+            <td><%= m.status.capitalize %></td>
+            <td>
+              <%= link_to "Unblock", deny_post_set_maintainer_path(m), remote: true, method: :post, 'data-confirm': 'Are you sure you want to unblock invites for this set?' %>
+            </td>
+          </tr>
+        <% end %>
+      <% end %>
+      </tbody>
+    </table>
+  </div>
+</div>
+
+<%= render partial: "post_sets/secondary_links" %>

app/views/post_sets/_search.html.erb

@@ -0,0 +1,29 @@
+<% unless params[:show] %><div id='searchform_hide'><%= link_to_function "Show Search Options", "$j('#searchform').fadeIn('fast'); $('searchform_hide').hide();" %></div><% end %>
+<div class='section' id='searchform' style='width:400px;<% unless params[:show] %>display:none;<% end %>'>
+  <% unless params[:show] %><%= link_to_function "Hide Search Options", "$j('#searchform').fadeOut('fast'); $('searchform_hide').show();" %><% end %>
+  <% form_tag({action: "index"}, method: :get) do %>
+    <table class='nomargin'>
+      <tr><td><label for="name">Name</label></td>	<td><%= text_field_tag "name", params[:name], style: "width:195px"%></td></tr>
+      <tr><td><label for="name">Short Name</label></td>	<td><%= text_field_tag "shortname", params[:shortname], style: "width:195px"%></td></tr>
+      <tr><td><label for="name">Username</label></td>	<td><%= text_field_tag "username", params[:username], style: "width:195px"%></td></tr>
+
+      <tr><td><label for="type">Order</label></td>	<td>
+        <%= select_tag "order", options_for_select([
+                                                       ["Name", "name"],
+                                                       ["Short Name", "shortname"],
+                                                       ["Creator", "creator"],
+                                                       ["Post Count", "postcount"],
+                                                       ["Created", "created"],
+                                                       ["Updated", "updated"]
+                                                   ], params[:order]), style: "width:200px;" %>
+      </td></tr>
+      <tr><td colspan="2"><%= submit_tag "Search", name: nil %></td></tr>
+    </table>
+    <% if params[:show] %>
+      <input type='hidden' name='show' value='1'/>
+    <% end %>
+  <% end %>
+</div>
+<% if params[:name] || params[:type] || params[:status] %>
+  <script type='text/javascript'>$('searchform_hide').hide(); $('searchform').show();</script>
+<% end %>

app/views/post_sets/_secondary_links.html.erb

@@ -0,0 +1,29 @@
+<% content_for(:secondary_links) do %>
+  <menu>
+    <%= subnav_link_to "List", post_sets_path %>
+    <%= subnav_link_to "New", new_post_set_path %>
+    <%= subnav_link_to "Help", wiki_pages_path(title: 'help:sets') %>
+    <% if CurrentUser.is_member? %>
+      <%= subnav_link_to "Mine", post_sets_path(search: {creator_id: CurrentUser.id}) %>
+      <%= subnav_link_to "Invites", post_set_maintainers_path %>
+    <% end %>
+    <% if @set %>
+      <li>|</li>
+      <%= subnav_link_to "Posts", posts_path(tags: "set:#{@set.shortname}") %>
+      <%= subnav_link_to "Maintainers", action: "maintainers", id: params[:id] %>
+
+      <% if @set.is_owner?(CurrentUser.user) || CurrentUser.is_admin? %>
+        <%= subnav_link_to "Edit", edit_post_set_path(@set) %>
+      <% end %>
+
+      <% if @set.is_owner?(CurrentUser.user) || @set.is_maintainer?(CurrentUser.user) %>
+        <%= subnav_link_to "Edit Posts", post_list_post_set_path(@set) %>
+      <% end %>
+
+      <% if @set.is_owner?(CurrentUser.user) || CurrentUser.is_admin? %>
+        <%= subnav_link_to "Delete", post_set_path(@set), method: 'delete', data: {confirm: 'Are you sure you want to delete this set?'} %>
+      <% end %>
+      <%= subnav_link_to "Report", new_ticket_path(type: 'set', disp_id: @set.id) %>
+    <% end %>
+  </menu>
+<% end %>

app/views/post_sets/atom.html.erb

@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<feed xmlns="http://www.w3.org/2005/Atom">
+	<title><%=  Danbooru.config.app_name %> - Sets</title>
+	<link href="<%= atom_post_sets_url() %>" rel="self"/>
+  <link href="<%= post_sets_url() %>>" rel="alternate"/>
+  <id><%= atom_post_sets_url() %></id>
+  <% if @sets.any? %>
+    <updated><%= @sets[0].created_at.gmtime.xmlschema %></updated>
+  <% end %>
+  <author><name><%= Danbooru.config.app_name %></name></author>
+
+  <% @sets.each do |set| %>
+    <entry>
+      <title><%= set.name %></title>
+      <link href="<%= post_set_url(set) %>" rel="alternate"/>
+      <id><%= post_set_url(set) %></id>
+      <updated><%= set.created_at.gmtime.xmlschema %></updated>
+      <summary><%= Nokogiri::HTML(format_text set.description).text %></summary>
+      <content type="xhtml">
+        <div xmlns="http://www.w3.org/1999/xhtml">
+          <%= format_text set.description %>
+        </div>
+      </content>
+      <author>
+        <name><%= set.creator.pretty_name %></name>
+      </author>
+    </entry>
+  <% end %>
+</feed>

app/views/post_sets/destroy.html.erb

@@ -0,0 +1,10 @@
+<h3>Delete Set</h3>
+
+<div class='section' style='width:500px;'>
+	<% form_tag(action: "destroy") do %>
+		<p>Are you sure you wish to delete "<%= h(@set.name) %>"?</p>
+		<%= submit_tag "Yes" %> <%= button_to_function "No", "history.back()" %>
+	<% end %>
+</div>
+
+<%= render partial: "footer" %>

app/views/post_sets/edit.html.erb

@@ -0,0 +1,38 @@
+<div id="a-set">
+  <div id="c-edit">
+    <h2>Editing <span class="set-name"><%= @set.name %></span></h2>
+
+    <% if @can_edit %>
+      <div class='section'>
+        <%= simple_form_for(@set) do |f| %>
+          <%= f.input :name, as: :string, input_html: {onkeyup: 'fillShortName()'} %>
+
+          <%= f.input :shortname, label: 'Short Name', as: :string, input_html: {onchange: 'shortNameChanged()'},
+                      hint: "The short name is used for the set's metatag name. Can only contain letters, numbers, and underscores
+                and must contain at least one letter or underscore. <a href=\"/post?tags=set%3Aexample\">set:example</a>".html_safe %>
+          <%= dtext_field "post_set", "description", :classes => "autocomplete-mentions", :input_id => "set_description", :preview_id => "dtext-preview" %>
+
+          <%= f.input :is_public, label: 'Public', hint: "Private sets are only visible to you. Public sets are visible to anyone, but only you and users you
+                  assign as maintainers can edit the set. Only accounts three days or older can make public sets." %>
+
+          <%= f.input :transfer_on_delete, label: 'Transfer on Deletion', hint: 'If "Transfer on Delete" is enabled, when a post is deleted from the site, its parent (if any) will be
+                  added to this set in its place. Disable if you want posts to simply be removed from this set with no
+                  replacement.' %>
+          <%= f.button :submit, "Update" %>
+          <%= dtext_preview_button :post_set, :body, :input_id => "set_description", :preview_id => "dtext-preview" %>
+        <% end %>
+      </div>
+    <% end %>
+
+    <% if @set.is_owner?(CurrentUser) %>
+      <%= link_to "&raquo; Click here to edit maintainers.".html_safe, maintainers_post_set_path(@set) %><br/>
+    <% end %>
+
+    <% if @set.is_owner?(CurrentUser) || @set.is_maintainer?(CurrentUser) %>
+      <%= link_to "&raquo; Click here to add/remove posts.".html_safe, post_list_post_set_path(@set) %><br/>
+    <% end %>
+  </div>
+</div>
+
+
+<%= render partial: "secondary_links" %>

app/views/post_sets/index.html.erb

@@ -0,0 +1,60 @@
+<div id="c-sets">
+  <div id="a-index">
+    <%= render partial: 'search' %>
+
+    <h2>Sets</h2>
+
+    <div id="set-index">
+      <table width="100%" class="rounded">
+        <thead>
+        <tr>
+          <th width="30%"><%= link_to "Name", action: "index", order: "username" %></th>
+          <th width="20%"><%= link_to "Short Name", action: "index", order: "shortname" %></th>
+          <th width="15%">Creator</th>
+          <th width="5%"><%= link_to "Posts", action: "index", order: "postcount" %></th>
+          <th width="10%"><%= link_to "Created", action: "index", order: "created" %></th>
+          <th width="10%"><%= link_to "Updated", action: "index", order: "updated" %></th>
+          <th width="10%">Status</th>
+        </tr>
+        </thead>
+
+        <tbody>
+        <% @sets.each do |s| %>
+          <tr>
+            <td><%= link_to s.name, post_set_path(s) %></td>
+            <td><%= link_to s.shortname, posts_path(tags: "set:#{s.shortname}") %></td>
+            <td><%= link_to_user s.creator %></td>
+            <td><%= s.post_count %></td>
+            <td><span class="date" title="<%= s.created_at.strftime("%b %d, %Y %I:%M %p") %>"><%= time_ago_in_words(s.created_at) + " ago" %></span></td>
+            <td><span class="date" title="<%= s.updated_at.strftime("%b %d, %Y %I:%M %p") %>"><%= time_ago_in_words(s.updated_at) + " ago" %></span></td>
+            <td>
+              <% if s.is_public %>
+                <div class='set-status set-status-public' title='This set is public'>Public</div>
+              <% else %>
+                <div class='set-status set-status-private' title='This set is private and only visible to you'>Private</div>
+              <% end %>
+
+              <% if s.is_owner?(CurrentUser.user) %>
+                <div class='set-status set-status-owner' title='You own this set'>Owner</div>
+              <% elsif s.is_maintainer?(CurrentUser.user) %>
+                <div class='set-status set-status-maintainer' title='You are a maintainer of this set and can add and remove posts. Click to view invites'><%= link_to "Maint.", controller: "post_set_maintainers", action: "index" %></div>
+              <% elsif s.is_invited?(CurrentUser.user) %>
+                <div class='set-status set-status-invited' title='You have been invited to maintain this set. Click to view invites'><%= link_to "Invited", controller: "post_set_maintainers", action: "index" %></div>
+              <% elsif s.is_blocked?(CurrentUser.user) %>
+                <div class='set-status set-status-blocked' title='You have blocked the owner of this set from inviting you to maintain it. Click to view invites'><%= link_to "Blocked", controller: "post_set_maintainers", action: "index" %></div>
+              <% end %>
+            </td>
+          </tr>
+        <% end %>
+        </tbody>
+      </table>
+    </div>
+
+    <div id="paginator">
+      <%= numbered_paginator(@sets) %>
+    </div>
+  </div>
+</div>
+
+
+<%= render partial: "secondary_links" %>

app/views/post_sets/maintainers.html.erb

@@ -0,0 +1,74 @@
+<div id="c-sets">
+  <div id="a-maintainers">
+    <% @maintainers = @set.post_set_maintainers %>
+    <h2>Maintainers for set <span class="set-name"><%= @set.name %></span></h2>
+    <p>Maintainers are users who are assigned to a set and have the ability to add or remove posts from it. They cannot
+      edit any other details of the set.</p>
+    <h3>Approved</h3>
+    <table class="rounded nomargin" width="400px" style="margin-bottom:30px;">
+      <thead>
+      <tr>
+        <th width="55%"><%= link_to "Username", action: "maintainers", id: @set.id, order: "username" %></th>
+        <th width="30%"><%= link_to "Status", action: "maintainers", id: @set.id, order: "status" %></th>
+        <th width="15%"></th>
+      </tr>
+      </thead>
+      <tbody>
+      <% @maintainers.active.each do |m| %>
+        <tr>
+          <td><%= link_to_user m.user %></td>
+          <td><%= m.status.capitalize %></td>
+
+          <td>
+            <% if @set.is_owner?(CurrentUser) %>
+              <%= form_tag({controller: "set_maintainer", action: "destroy"}) do %>
+                <%= hidden_field_tag "id", m.id %>
+                <%= submit_tag "Remove" %>
+              <% end %>
+            <% end %>
+          </td>
+        </tr>
+      <% end %>
+      </tbody>
+    </table>
+
+    <h3>Pending</h3>
+    <table class="rounded nomargin" width="400px">
+      <thead>
+      <tr>
+        <th width="55%"><%= link_to "Username", action: "maintainers", id: @set.id, order: "username" %></th>
+        <th width="30%"><%= link_to "Status", action: "maintainers", id: @set.id, order: "status" %></th>
+        <th width="15%"></th>
+      </tr>
+      </thead>
+      <tbody>
+      <% @maintainers.pending.each do |m| %>
+        <tr>
+          <td><%= link_to_user m.user %></td>
+          <td><%= m.status.capitalize %></td>
+
+          <td>
+            <% if @set.is_owner?(CurrentUser) %>
+              <%= link_to "Remove", post_set_maintainer_path(m), method: :delete, remote: true, data: {confirm: "Are you sure you want to remove this pending invite?"} %>
+            <% end %>
+          </td>
+        </tr>
+      <% end %>
+      </tbody>
+    </table>
+
+    <% if @set.is_owner?(CurrentUser) && @set.is_public %>
+      <h3 style="margin-top:15px;">Add new Maintainer</h3>
+      <div class='section' style="width:380px;">
+        <%= form_tag(post_set_maintainers_path) do %>
+          <label for="set_maintainer_name">Username</label><br/>
+          <%= hidden_field_tag "post_set_id", @set.id %>
+          <%= text_field_tag "username" %>
+          <%= submit_tag "Create" %>
+        <% end %>
+      </div>
+    <% end %>
+  </div>
+</div>
+
+<%= render partial: "secondary_links" %>

app/views/post_sets/new.html.erb

@@ -0,0 +1,31 @@
+<div id="c-sets">
+  <div id="a-new">
+    <h2>New Set</h2>
+
+    <div>
+      <%= simple_form_for(@set) do |f| %>
+        <%= error_messages_for :post_set %>
+        <%= f.input :name, as: :string, input_html: {onkeyup: 'fillShortName()'} %>
+
+        <%= f.input :shortname, label: 'Short Name', as: :string, input_html: {onchange: 'shortNameChanged()'},
+                    hint: "The short name is used for the set's metatag name. Can only contain letters, numbers, and underscores
+                and must contain at least one letter or underscore. <a href=\"/post?tags=set%3Aexample\">set:example</a>".html_safe %>
+        <%= dtext_field "post_set", "description", :classes => "autocomplete-mentions", :input_id => "set_description", :preview_id => "dtext-preview" %>
+
+        <%= f.input :is_public, label: 'Public', hint: "Private sets are only visible to you. Public sets are visible to anyone, but only you and users you
+                  assign as maintainers can edit the set. Only accounts three days or older can make public sets." %>
+
+        <%= f.input :transfer_on_delete, label: 'Transfer on Deletion', hint: 'If "Transfer on Delete" is enabled, when a post is deleted from the site, its parent (if any) will be
+                  added to this set in its place. Disable if you want posts to simply be removed from this set with no
+                  replacement.' %>
+
+        <p>You can add posts to the set and assign maintainers on the next page.</p>
+
+        <%= f.button :submit, "Create" %>
+        <%= dtext_preview_button :post_set, :body, :input_id => "set_description", :preview_id => "dtext-preview" %>
+      <% end %>
+    </div>
+  </div>
+</div>
+
+<%= render partial: "secondary_links" %>

app/views/post_sets/post_list.erb

@@ -0,0 +1,12 @@
+<div id="c-sets">
+  <div id="a-posts">
+    <h2>Post list for set <span class="set-name"><%= @set.name %></span></h2>
+
+    <%= simple_form_for(@set, url: update_posts_post_set_path(@set), method: :post) do |f| %>
+      <%= f.input :post_ids_string, as: :text, label: 'Post IDs' %>
+      <%= f.button :submit, "Update" %>
+    <% end %>
+  </div>
+</div>
+
+<%= render partial: "secondary_links" %>

app/views/post_sets/select.html.erb

@@ -0,0 +1,7 @@
+<% form_tag(action: "add_post") do %>
+	<%= hidden_field_tag "post_id", params[:post_id] %>
+	<%= select_tag "set_id", unsorted_grouped_options_for_select(@grouped_options, session[:last_set_id]) %>
+	<% if !params[:mode] %>
+		<%= button_to_function "Add", "PostSet.add_post(#{params[:post_id]}, jQuery('#set_id').val())" %>
+	<% end %>
+<% end %>

app/views/post_sets/show.html.erb

@@ -0,0 +1,79 @@
+<div id="c-sets">
+  <div id="a-show">
+    <div class="set-header"><span class="set-name"><%= @set.name %></span> by
+      <span class="set-creator"><%= link_to_user @set.creator %></span>
+      <% if @set.is_public %>
+        <div class='set-status set-status-public' title='This set is public'>Public</div>
+      <% else %>
+        <div class='set-status set-status-private' title='This set is private and only visible to you'>Private</div>
+      <% end %>
+
+      <% if @set.is_owner?(CurrentUser.user) %>
+        <div class='set-status set-status-owner' title='You own this set'>Owner</div>
+      <% elsif @set.is_maintainer?(CurrentUser.user) %>
+        <div class='set-status set-status-maintainer' title='You are a maintainer of this set and can add and remove posts'>Maint.</div>
+      <% end %>
+    </div>
+    <div class="set-shortname">Short
+      Name: <%= link_to @set.shortname, posts_path(tags: "set:#{@set.shortname}") %></div>
+    Created:
+    <span class="date" title="<%= @set.created_at.strftime("%b %d, %Y %I:%M %p") %>"><%= time_ago_in_words(@set.created_at) + " ago" %></span>
+    |
+    Updated:
+    <span class="date" title="<%= @set.updated_at.strftime("%b %d, %Y %I:%M %p") %>"><%= time_ago_in_words(@set.updated_at) + " ago" %></span><br/>
+
+    <% if @set.description.blank? %>
+      <div class='set-description'>No description.</div>
+    <% else %>
+      <div class='set-description'><%= format_text @set.description %></div>
+    <% end %>
+    <div class='set-description-bottom'></div>
+
+    <span class="set-viewposts"><%= link_to "&raquo; View Posts (#{@set.post_count.to_s})".html_safe, posts_path(tags: "set:#{@set.shortname}") %></span><br/>
+    <%#= link_to "&raquo; Maintainers (" + PostSetMaintainer.count(conditions: ["post_set_id = ?", @set.id]).to_s + ")", action: "maintainers", id: @set.id %>
+    <br/>
+
+    <% if @set.post_count == 0 %>
+      <div class="set-empty section">
+        <p>This set has no posts in it.</p>
+
+        <% if @set.is_owner?(CurrentUser.user) || @set.is_maintainer?(CurrentUser.user) %>
+          To start adding posts to this set:
+          <ul>
+            <li>On a post's page, click <strong>Add to Set</strong> under <strong>Options</strong> in the sidebar,
+              select a set, and click <strong>Add</strong></li>
+            <li>When viewing the <%= link_to "post index", posts_path %>, select
+              <strong>Add to set...</strong> from the mode dropdown under the search bar, select a set from the new
+              dropdown, and click a post thumbnail to add it to the set.
+            </li>
+          </ul>
+        <% end %>
+      </div>
+    <% elsif @set.is_owner?(CurrentUser.user) || @set.is_maintainer?(CurrentUser.user) %>
+      <div class="section">
+        To add posts to this set:
+        <ul>
+          <li>On a post's page, click <strong>Add to Set</strong> under <strong>Options</strong> in the sidebar, select
+            a set, and click <strong>Add</strong></li>
+          <li>When viewing the <%= link_to "post index", posts_path %>, select
+            <strong>Add to set...</strong> from the mode dropdown under the search bar, select a set from the new
+            dropdown, and click a post thumbnail to add it to the set.
+          </li>
+        </ul>
+        To remove posts from this set:
+        <ul>
+          <li>When viewing the <%= link_to "post index", posts_path %>, select
+            <strong>Remove from set...</strong> from the mode dropdown under the search bar, select a set from the new
+            dropdown, and click a post thumbnail to remove it to the set.
+          </li>
+        </ul>
+      </div>
+    <% end %>
+  </div>
+</div>
+
+<% content_for(:secondary_links) do %>
+
+<% end %>
+
+<%= render partial: "secondary_links" %>

app/views/post_versions/index.html.erb

@@ -5,7 +5,7 @@
     <p>Recent updates may not have been processed yet. The most recently processed version was <%= time_ago_in_words_tagged(PostArchive.maximum(:updated_at)) %>.</p>
 
     <% if @post_versions.length == 0 %>
-      <%= render "post_sets/blank" %>
+      <%= render "posts/blank" %>
     <% else %>
       <% if params.dig(:search, :post_id).present? %>
         <%= render "revert_listing" %>

app/views/posts/partials/show/_nav_links.html.erb

@@ -5,10 +5,14 @@
     <% end %>
 
     <% if post.pools.undeleted.any? %>
-      <%= render "posts/partials/show/pool_list", post: post, pools: post.pools.undeleted.selected_first(params[:pool_id]) %>
+      <%= render "posts/partials/show/pool_list", post: post, pools: post.pools.undeleted.selected_first(params[:pool_id]).limit(5) %>
     <% end %>
 
-    <% if post.favorite_groups(active_id=params[:favgroup_id]).any? %>
+    <% if post.post_sets.visible.any? %>
+      <%= render "posts/partials/show/post_set_list", post: post, post_sets: post.post_sets.visible.selected_first(params[:post_set_id]).limit(5) %>
+    <% end %>
+
+    <% if post.favorite_groups(active_id = params[:favgroup_id]).any? %>
       <%= render "posts/partials/show/favorite_groups", :post => post %>
     <% end %>
   </div>

app/views/posts/partials/show/_post_set_list.html.erb

@@ -0,0 +1,7 @@
+<div id="set-nav">
+  <ul>
+    <% post_sets.each do |set| %>
+      <%= render "posts/partials/show/post_set_list_item", post_set: set, post: post, selected: is_post_set_selected?(set) %>
+    <% end %>
+  </ul>
+</div>

app/views/posts/partials/show/_post_set_list_item.html.erb

@@ -0,0 +1,33 @@
+<%= content_tag :li, id: "nav-link-for-set-#{post_set.id}", class: "set-selected-#{selected}" do -%>
+  <% if !post_set.first_post?(post.id) && post_set.post_ids.first -%>
+    <%= link_to("&laquo;".html_safe, post_path(post_set.post_ids.first, post_set_id: post_set.id), class: "first", title: "to first") %>
+  <% else -%>
+    <span class="first">&laquo;</span>
+  <% end -%>
+
+  <% post_set.previous_post_id(post.id).tap do |previous_post_id| -%>
+    <% if previous_post_id %>
+      <%= link_to "&lsaquo;&thinsp;prev".html_safe, post_path(previous_post_id, post_set_id: post_set.id), rel: selected ? "prev" : nil, class: "prev", title: "to page #{post_set.page_number(previous_post_id)}" -%>
+    <% else -%>
+      <span class="prev">&lsaquo;&thinsp;prev</span>
+    <% end %>
+  <% end -%>
+
+  <span class="set-name">
+    <%= link_to("Set: #{post_set.name}", post_set_path(post_set), title: "page #{post_set.page_number(post.id)}/#{post_set.post_count}") -%>
+  </span>
+
+  <% post_set.next_post_id(post.id).tap do |next_post_id| -%>
+    <% if next_post_id %>
+      <%= link_to("next&thinsp;&rsaquo;".html_safe, post_path(next_post_id, post_set_id: post_set.id), rel: selected ? "next" : nil, class: "next", title: "to page #{post_set.page_number(next_post_id)}") -%>
+    <% else -%>
+      <span class="next">next&thinsp;&rsaquo;</span>
+    <% end -%>
+  <% end -%>
+
+  <% if !post_set.last_post?(post.id) && post_set.post_ids.last -%>
+    <%= link_to("&raquo;".html_safe, post_path(post_set.post_ids.last, post_set_id: post_set.id), class: "last", title: "to page #{post_set.post_count}") -%>
+  <% else -%>
+    <span class="last">&raquo;</span>
+  <% end -%>
+<% end -%>

config/routes.rb

@@ -360,6 +360,25 @@ Rails.application.routes.draw do
     end
   end
   resources :post_report_reasons
+  resources :post_sets do
+    collection do
+      get :atom
+    end
+    member do
+      get :maintainers
+      get :post_list
+      post :update_posts
+      post :add_posts
+      post :remove_posts
+    end
+  end
+  resources :post_set_maintainers do
+    member do
+      post :approve
+      post :block
+      post :deny
+    end
+  end
 
   # aliases
   resources :wpages, :controller => "wiki_pages"

db/migrate/20190317024446_create_post_sets.rb

@@ -0,0 +1,25 @@
+class CreatePostSets < ActiveRecord::Migration[5.2]
+  def change
+    create_table :post_sets do |t|
+      t.string :name, null: false
+      t.string :shortname, null: false
+      t.text :description, default: ''
+      t.boolean :is_public, null: false, default: false
+      t.boolean :transfer_on_delete, null: false, default: false
+      t.integer :creator_id, null: false
+      t.column :creator_ip_addr, 'inet', null: true
+      t.column :post_ids, 'integer[]', null: false, default: '{}'
+      t.integer :post_count, null: false, default: 0
+      t.timestamps
+    end
+
+    create_table :post_set_maintainers do |t|
+      t.integer :post_set_id, null: false
+      t.integer :user_id, null: false
+      t.string :status, null: false, default: 'pending'
+      t.timestamps
+    end
+
+    add_column :users, :set_count, :integer, null: false, default: 0
+  end
+end

db/structure.sql

@@ -1528,6 +1528,78 @@ CREATE SEQUENCE public.post_report_reasons_id_seq
 ALTER SEQUENCE public.post_report_reasons_id_seq OWNED BY public.post_report_reasons.id;
 
 
+--
+-- Name: post_set_maintainers; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE TABLE public.post_set_maintainers (
+    id bigint NOT NULL,
+    post_set_id integer NOT NULL,
+    user_id integer NOT NULL,
+    status character varying DEFAULT 'pending'::character varying NOT NULL,
+    created_at timestamp without time zone NOT NULL,
+    updated_at timestamp without time zone NOT NULL
+);
+
+
+--
+-- Name: post_set_maintainers_id_seq; Type: SEQUENCE; Schema: public; Owner: -
+--
+
+CREATE SEQUENCE public.post_set_maintainers_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+
+--
+-- Name: post_set_maintainers_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: -
+--
+
+ALTER SEQUENCE public.post_set_maintainers_id_seq OWNED BY public.post_set_maintainers.id;
+
+
+--
+-- Name: post_sets; Type: TABLE; Schema: public; Owner: -
+--
+
+CREATE TABLE public.post_sets (
+    id bigint NOT NULL,
+    name character varying NOT NULL,
+    shortname character varying NOT NULL,
+    description text DEFAULT ''::text,
+    is_public boolean DEFAULT false NOT NULL,
+    transfer_on_delete boolean DEFAULT false NOT NULL,
+    creator_id integer NOT NULL,
+    creator_ip_addr inet,
+    post_ids integer[] DEFAULT '{}'::integer[] NOT NULL,
+    post_count integer DEFAULT 0 NOT NULL,
+    created_at timestamp without time zone NOT NULL,
+    updated_at timestamp without time zone NOT NULL
+);
+
+
+--
+-- Name: post_sets_id_seq; Type: SEQUENCE; Schema: public; Owner: -
+--
+
+CREATE SEQUENCE public.post_sets_id_seq
+    START WITH 1
+    INCREMENT BY 1
+    NO MINVALUE
+    NO MAXVALUE
+    CACHE 1;
+
+
+--
+-- Name: post_sets_id_seq; Type: SEQUENCE OWNED BY; Schema: public; Owner: -
+--
+
+ALTER SEQUENCE public.post_sets_id_seq OWNED BY public.post_sets.id;
+
+
 --
 -- Name: post_updates; Type: TABLE; Schema: public; Owner: -
 --
@@ -2208,7 +2280,8 @@ furry -rating:s'::text,
     custom_style text,
     bit_prefs bigint DEFAULT 0 NOT NULL,
     last_ip_addr inet,
-    unread_dmail_count integer DEFAULT 0 NOT NULL
+    unread_dmail_count integer DEFAULT 0 NOT NULL,
+    set_count integer DEFAULT 0 NOT NULL
 );
 
 
@@ -2583,6 +2656,20 @@ ALTER TABLE ONLY public.post_replacements ALTER COLUMN id SET DEFAULT nextval('p
 ALTER TABLE ONLY public.post_report_reasons ALTER COLUMN id SET DEFAULT nextval('public.post_report_reasons_id_seq'::regclass);
 
 
+--
+-- Name: post_set_maintainers id; Type: DEFAULT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.post_set_maintainers ALTER COLUMN id SET DEFAULT nextval('public.post_set_maintainers_id_seq'::regclass);
+
+
+--
+-- Name: post_sets id; Type: DEFAULT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.post_sets ALTER COLUMN id SET DEFAULT nextval('public.post_sets_id_seq'::regclass);
+
+
 --
 -- Name: post_votes id; Type: DEFAULT; Schema: public; Owner: -
 --
@@ -3029,6 +3116,22 @@ ALTER TABLE ONLY public.post_report_reasons
     ADD CONSTRAINT post_report_reasons_pkey PRIMARY KEY (id);
 
 
+--
+-- Name: post_set_maintainers post_set_maintainers_pkey; Type: CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.post_set_maintainers
+    ADD CONSTRAINT post_set_maintainers_pkey PRIMARY KEY (id);
+
+
+--
+-- Name: post_sets post_sets_pkey; Type: CONSTRAINT; Schema: public; Owner: -
+--
+
+ALTER TABLE ONLY public.post_sets
+    ADD CONSTRAINT post_sets_pkey PRIMARY KEY (id);
+
+
 --
 -- Name: post_votes post_votes_pkey; Type: CONSTRAINT; Schema: public; Owner: -
 --
@@ -4485,6 +4588,7 @@ INSERT INTO "schema_migrations" (version) VALUES
 ('20190222082952'),
 ('20190228144206'),
 ('20190305165101'),
-('20190313221440');
+('20190313221440'),
+('20190317024446');