#84

backend/app/controllers/posts_controller.rb

@@ -1,7 +1,3 @@
-require 'open-uri'
-require 'nokogiri'
-
-
 class PostsController < ApplicationController
   # GET /posts
   def index
@@ -77,7 +73,7 @@ class PostsController < ApplicationController
     post.thumbnail.attach(thumbnail)
     if post.save
       post.resized_thumbnail!
-      post.tags = Tag.normalise_tags(tag_names)
+      sync_post_tags!(post, Tag.normalise_tags(tag_names))
       render json: post.as_json(include: { tags: { only: [:id, :name, :category, :post_count] } }),
              status: :created
     else
@@ -110,8 +106,10 @@ class PostsController < ApplicationController
     original_created_before = params[:original_created_before]
 
     post = Post.find(params[:id].to_i)
-    tags = post.tags.where(category: 'nico').to_a + Tag.normalise_tags(tag_names)
-    if post.update(title:, tags:, original_created_from:, original_created_before:)
+    if post.update(title:, original_created_from:, original_created_before:)
+      sync_post_tags!(post,
+                      (post.tags.where(category: 'nico').to_a +
+                       Tag.normalise_tags(tag_names)))
       render json: post.as_json(include: { tags: { only: [:id, :name, :category, :post_count] } }),
              status: :ok
     else
@@ -128,7 +126,11 @@ class PostsController < ApplicationController
   def filtered_posts
     tag_names = params[:tags]&.split(' ')
     match_type = params[:match]
-    tag_names.present? ? filter_posts_by_tags(tag_names, match_type) : Post.all
+    if tag_names.present?
+      filter_posts_by_tags(tag_names, match_type)
+    else
+      Post.all
+    end
   end
 
   def filter_posts_by_tags tag_names, match_type
@@ -142,4 +144,28 @@ class PostsController < ApplicationController
     end
     posts.distinct
   end
+
+  def sync_post_tags! post, desired_tags
+    desired_tags.each do |t|
+      t.save! if t.new_record?
+    end
+
+    desired_ids = desired_tags.map(&:id).to_set
+    current_ids = post.tags.pluck(:id).to_set
+
+    to_add = desired_ids - current_ids
+    to_remove = current_ids - desired_ids
+
+    Tag.where(id: to_add).find_each do |tag|
+      begin
+        PostTag.create!(post:, tag:, created_user: current_user)
+      rescue ActiveRecord::RecordNotUnique
+        ;
+      end
+    end
+
+    PostTag.where(post_id: post.id, tag_id: to_remove.to_a).kept.find_each do |pt|
+      pt.discard_by!(current_user)
+    end
+  end
 end

backend/app/models/post.rb

@@ -1,11 +1,13 @@
-require 'mini_magick'
-
-
 class Post < ApplicationRecord
+  require 'mini_magick'
+
   belongs_to :parent, class_name: 'Post', optional: true, foreign_key: 'parent_id'
   belongs_to :uploaded_user, class_name: 'User', optional: true
-  has_many :post_tags, dependent: :destroy
-  has_many :tags, through: :post_tags
+
+  has_many :post_tags, dependent: :delete_all, inverse_of: :post
+  has_many :active_post_tags, -> { kept }, class_name: 'PostTag', inverse_of: :post
+  has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
+  has_many :tags, through: :active_post_tags
   has_many :user_post_views, dependent: :destroy
   has_many :post_similarities_as_post,
            class_name: 'PostSimilarity',

backend/app/models/post_tag.rb

@@ -1,7 +1,25 @@
 class PostTag < ApplicationRecord
+  include Discard::Model
+
   belongs_to :post
   belongs_to :tag, counter_cache: :post_count
+  belongs_to :created_user, class_name: 'User', optional: true
+  belongs_to :deleted_user, class_name: 'User', optional: true
 
   validates :post_id, presence: true
   validates :tag_id, presence: true
+  validates :post_id, uniqueness: {
+      scope: :tag_id,
+      conditions: -> { where(discarded_at: nil) } }
+
+  def discard_by! deleted_user
+    return self if discarded?
+
+    transaction do
+      update!(discarded_at: Time.current, deleted_user:)
+      Tag.where(id: tag_id).update_all('post_count = GREATEST(post_count - 1, 0)')
+    end
+
+    self
+  end
 end

backend/app/models/tag.rb

@@ -1,6 +1,8 @@
 class Tag < ApplicationRecord
-  has_many :post_tags, dependent: :destroy
-  has_many :posts, through: :post_tags
+  has_many :post_tags, dependent: :delete_all, inverse_of: :tag
+  has_many :active_post_tags, -> { kept }, class_name: 'PostTag', :inverse_of: :tag
+  has_many :post_tags_with_discarded, -> { with_discarded }, class_name: 'PostTag'
+  has_many :posts, through: :active_post_tags
   has_many :tag_aliases, dependent: :destroy
 
   has_many :nico_tag_relations, foreign_key: :nico_tag_id, dependent: :destroy
@@ -35,13 +37,13 @@ class Tag < ApplicationRecord
       'meta:' => 'meta' }.freeze
 
   def self.tagme
-    @tagme ||= Tag.find_or_initialize_by(name: 'タグ希望') do |tag|
+    @tagme ||= Tag.find_or_create_by!(name: 'タグ希望') do |tag|
       tag.category = 'meta'
     end
   end
 
   def self.bot
-    @bot ||= Tag.find_or_initialize_by(name: 'bot操作') do |tag|
+    @bot ||= Tag.find_or_create_by!(name: 'bot操作') do |tag|
       tag.category = 'meta'
     end
   end