4 files changed, 112 insertions, 0 deletions
diff --git a/app/lib/command_tag/commands.rb b/app/lib/command_tag/commands.rb
new file mode 100644
index 000000000..0248e6e99
--- /dev/null
+++ b/app/lib/command_tag/commands.rb
@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+module CommandTag::Commands
+  def self.included(base)
+    CommandTag::Commands.constants.map(&CommandTag::Commands.method(:const_get)).grep(Module) do |mod|
+      base.include(mod)
+    end
+  end
+end
diff --git a/app/lib/command_tag/commands/hello_world.rb b/app/lib/command_tag/commands/hello_world.rb
new file mode 100644
index 000000000..4cf17685e
--- /dev/null
+++ b/app/lib/command_tag/commands/hello_world.rb
@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module CommandTag::Commands::HelloWorld
+  def handle_hello_world_at_start
+    @text << "\nHello, world!"
+  end
+end
diff --git a/app/lib/command_tag/commands/status_tools.rb b/app/lib/command_tag/commands/status_tools.rb
new file mode 100644
index 000000000..3c6d7137e
--- /dev/null
+++ b/app/lib/command_tag/commands/status_tools.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module CommandTag::Commands::StatusTools
+  def handle_publish_once_at_end
+    return unless author_of_parent? && !@parent.published?
+
+    PublishStatusService.new.call(@parent)
+  end
+
+  def handle_edit_once_before_save
+    return unless author_of_parent?
+
+    params = @parent.slice(*UpdateStatusService::ALLOWED_ATTRIBUTES).with_indifferent_access.compact
+    params[:text] = @text
+    UpdateStatusService.new.call(@parent, params)
+    destroy_status!
+  end
+end
diff --git a/app/lib/command_tag/processor.rb b/app/lib/command_tag/processor.rb
new file mode 100644
index 000000000..b122b9e8d
--- /dev/null
+++ b/app/lib/command_tag/processor.rb
@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+class CommandTag::Processor
+  include CommandTag::Commands
+
+  STATEMENT_RE = /^\s*#!\s*([^\n]+ (?:start|begin|do)$.*)\n\s*#!\s*(?:end|stop|done)\s*$|^\s*#!\s*(.*?)\s*$/im.freeze
+  STATEMENT_STRIP_RE = /^\s*#!\s*(?:[^\n]+ (?:start|begin|do)$.*)\n\s*#!\s*(?:end|stop|done)\s*$\n?|^\s*#!\s*(?:.*?)\s*$\n?/im.freeze
+
+  def initialize(account, status)
+    @account      = account
+    @status       = status
+    @parent       = status.thread
+    @run_once     = Set[]
+    @vars         = {}
+    @text         = status.text.gsub("\r\n", "\n").gsub("\n\r", "\n").gsub("\r", "\n")
+
+    return unless @account.present? && @account.local? && @status.present?
+  end
+
+  def process!
+    @statements = parse_statements
+    @text = @text.gsub(STATEMENT_STRIP_RE, '').split("\n")
+
+    %w(at_start once_at_start).each { |suffix| execute_statements(suffix) }
+    @text = @text.join("\n").rstrip
+    %w(before_save once_before_save).each { |suffix| execute_statements(suffix) }
+
+    if @text.blank?
+      %w(when_blank once_when_blank).each { |suffix| execute_statements(suffix) }
+
+      unless (@status.published? && !@status.edited.zero?) || @text.present?
+        %w(before_destroy once_before_destroy).each { |suffix| execute_statements(suffix) }
+        @status.destroy
+        %w(after_destroy once_after_destroy).each { |suffix| execute_statements(suffix) }
+      end
+    elsif @status.destroyed?
+      %w(after_destroy once_after_destroy).each { |suffix| execute_statements(suffix) }
+    elsif @status.update(text: @text)
+      %w(after_save once_after_save).each { |suffix| execute_statements(suffix) }
+    else
+      %w(after_save_fail once_after_save_fail).each { |suffix| execute_statements(suffix) }
+    end
+
+    %w(at_end once_at_end).each { |suffix| execute_statements(suffix) }
+  end
+
+  private
+
+  def parse_statements
+    @text.scan(STATEMENT_RE).flatten.map do |statement|
+      next if statement.blank? || statement[0]&.strip.blank?
+
+      statement = statement.scan(/^(.*) (?:start|begin|do)$(.*)|'([^']*)'|"([^"]*)"|(\S+)/im).flatten.compact
+      statement[0] = statement[0].strip.tr('- ', '_').downcase
+      statement
+    end.compact
+  end
+
+  def execute_statements(suffix)
+    @statements.each do |statement|
+      name = "handle_#{statement[0]}_#{suffix}"
+      is_run_once = suffix.start_with?('once_')
+      public_send(name, *statement[1..-1]) if respond_to?(name) && !(is_run_once && @run_once.include?(name))
+      @run_once << name if is_run_once
+    end
+  end
+
+  def author_of_status?
+    @account.id == @status.account_id
+  end
+
+  def author_of_parent?
+    @account.id == @parent&.account_id
+  end
+
+  def destroy_status!
+    @status.destroy unless @status.destroyed?
+  end
+end