FEATURE: Add 'Create topic' automation script (#26552)

This commit adds a new automation script for creating topics. It's very similar to the existing 'create a post' automation, except that it posts new topics in a specific category and with optional tags.

Internal topic: t/125829.

plugins/automation/lib/discourse_automation/scripts/topic.rb

@@ -0,0 +1,76 @@
+# frozen_string_literal: true
+
+DiscourseAutomation::Scriptable.add(DiscourseAutomation::Scripts::TOPIC) do
+  version 1
+
+  field :creator, component: :user
+  field :creator, component: :user, triggerable: :user_updated, accepted_contexts: [:updated_user]
+
+  field :body, component: :post, required: true, accepts_placeholders: true
+  field :title, component: :text, required: true, accepts_placeholders: true
+  field :category, component: :category, required: true
+  field :tags, component: :tags
+
+  placeholder :creator_username
+  placeholder :updated_user_username, triggerable: :user_updated
+  placeholder :updated_user_name, triggerable: :user_updated
+
+  triggerables %i[recurring point_in_time user_updated]
+
+  script do |context, fields, automation|
+    creator_username = fields.dig("creator", "value")
+    creator_username = context["user"]&.username if creator_username == "updated_user"
+    creator_username ||= Discourse.system_user.username
+
+    placeholders = { creator_username: creator_username }.merge(context["placeholders"] || {})
+
+    if context["kind"] == DiscourseAutomation::Triggers::USER_UPDATED
+      user = context["user"]
+      user_data = context["user_data"]
+      user_profile_data = user_data[:profile_data] || {}
+      user_custom_fields = {}
+      user_data[:custom_fields]&.each do |k, v|
+        user_custom_fields[k.gsub(/\s+/, "_").underscore] = v
+      end
+      user = User.find(context["user"].id)
+      placeholders["username"] = user.username
+      placeholders["name"] = user.name
+      placeholders["updated_user_username"] = user.username
+      placeholders["updated_user_name"] = user.name
+      placeholders = placeholders.merge(user_profile_data, user_custom_fields)
+    end
+
+    topic_raw = fields.dig("body", "value")
+    topic_raw = utils.apply_placeholders(topic_raw, placeholders)
+
+    title = fields.dig("title", "value")
+    title = utils.apply_placeholders(title, placeholders)
+
+    creator = User.find_by(username: creator_username)
+    if !creator
+      Rails.logger.warn "[discourse-automation] creator with username: `#{creator_username}` was not found"
+      next
+    end
+
+    category_id = fields.dig("category", "value")
+    category = Category.find_by(id: category_id)
+    if !category
+      Rails.logger.warn "[discourse-automation] category of id: `#{category_id}` was not found"
+      next
+    end
+
+    tags = fields.dig("tags", "value") || []
+    new_post =
+      PostCreator.new(
+        creator,
+        raw: topic_raw,
+        title: title,
+        category: category.id,
+        tags: tags,
+      ).create!
+
+    if context["kind"] == DiscourseAutomation::Triggers::USER_UPDATED && new_post.persisted?
+      user.user_custom_fields.create(name: automation.name, value: "true")
+    end
+  end
+end