DEV: Move discourse-chat to the core repo. (#18776)

As part of this move, we are also renaming `discourse-chat` to `chat`.

plugins/chat/lib/chat_message_updater.rb

@@ -0,0 +1,91 @@
+# frozen_string_literal: true
+class Chat::ChatMessageUpdater
+  attr_reader :error
+
+  def self.update(opts)
+    instance = new(**opts)
+    instance.update
+    instance
+  end
+
+  def initialize(chat_message:, new_content:, upload_ids: nil)
+    @chat_message = chat_message
+    @old_message_content = chat_message.message
+    @chat_channel = @chat_message.chat_channel
+    @user = @chat_message.user
+    @guardian = Guardian.new(@user)
+    @new_content = new_content
+    @upload_ids = upload_ids
+    @error = nil
+  end
+
+  def update
+    begin
+      validate_channel_status!
+      @chat_message.message = @new_content
+      upload_info = get_upload_info
+      validate_message!(has_uploads: upload_info[:uploads].any?)
+      @chat_message.cook
+      @chat_message.save!
+      update_uploads(upload_info)
+      revision = save_revision!
+      ChatPublisher.publish_edit!(@chat_channel, @chat_message)
+      Jobs.enqueue(:process_chat_message, { chat_message_id: @chat_message.id })
+      Chat::ChatNotifier.notify_edit(chat_message: @chat_message, timestamp: revision.created_at)
+    rescue => error
+      @error = error
+    end
+  end
+
+  def failed?
+    @error.present?
+  end
+
+  private
+
+  def validate_channel_status!
+    return if @guardian.can_modify_channel_message?(@chat_channel)
+    raise StandardError.new(
+            I18n.t(
+              "chat.errors.channel_modify_message_disallowed",
+              status: @chat_channel.status_name,
+            ),
+          )
+  end
+
+  def validate_message!(has_uploads:)
+    @chat_message.validate_message(has_uploads: has_uploads)
+    if @chat_message.errors.present?
+      raise StandardError.new(@chat_message.errors.map(&:full_message).join(", "))
+    end
+  end
+
+  def get_upload_info
+    return { uploads: [] } if @upload_ids.nil? || !SiteSetting.chat_allow_uploads
+
+    uploads = Upload.where(id: @upload_ids, user_id: @user.id)
+    if uploads.count != @upload_ids.count
+      # User is passing upload_ids for uploads that they don't own. Don't change anything.
+      return { uploads: @chat_message.uploads, changed: false }
+    end
+
+    new_upload_ids = uploads.map(&:id)
+    existing_upload_ids = @chat_message.upload_ids
+    difference = (existing_upload_ids + new_upload_ids) - (existing_upload_ids & new_upload_ids)
+    { uploads: uploads, changed: difference.any? }
+  end
+
+  def update_uploads(upload_info)
+    return unless upload_info[:changed]
+
+    ChatUpload.where(chat_message: @chat_message).destroy_all
+    @chat_message.attach_uploads(upload_info[:uploads])
+  end
+
+  def save_revision!
+    @chat_message.revisions.create!(
+      old_message: @old_message_content,
+      new_message: @chat_message.message,
+    )
+  end
+end