Add hacky tool to convert smartdown flow to smart answer flow

This has *many* limitations and has only been tested on the
`landlord-immigration-check` flow.

script/convert-smartdown-flow-to-smart-answer-flow.rb

@@ -0,0 +1,121 @@
+unless flow_name = ARGV.shift
+  puts "Usage: #{__FILE__} <flow-name>"
+  exit 1
+end
+
+registry = SmartdownAdapter::Registry.instance
+coversheet_path = registry.send(:coversheet_path, flow_name)
+input = Smartdown::Parser::DirectoryInput.new(coversheet_path)
+flow = registry.find(flow_name)
+
+smart_answer_root = SmartAnswer::FlowRegistry.instance.load_path
+flow_path = smart_answer_root.join("#{flow_name}.rb")
+locale_path = smart_answer_root.join('locales', 'en', "#{flow_name}.yml")
+
+coversheet = Hash.new { |h, k| h[k] = {} }
+coversheet['title'] = flow.title.strip
+coversheet['body'] = flow.coversheet.body.strip
+coversheet['meta']['description'] = flow.meta_description
+start_node = flow.coversheet.elements.detect { |e| Smartdown::Model::Element::StartButton === e }.start_node
+
+question_pages_vs_questions = flow.question_pages.inject({}) do |hash, question_page|
+  if question_page.questions.length > 1
+    raise "QuestionPage '#{question_page.name}' has multiple questions which is not yet supported by this conversion tool"
+  end
+  hash[question_page.name] = question_page.questions.first.name
+  hash
+end
+
+questions = []
+content_for_questions = Hash.new { |h, k| h[k] = {} }
+flow.question_pages.each do |question_page|
+  question = question_page.questions.first
+  key = question.name
+  content_for_questions[key]['title'] = question.title.strip
+  content_for_questions[key]['body'] = question.body.strip if question.body.strip.present?
+  raise "Question '#{question.name}' has post-body '#{question.post_body}' which is not supported in SmartAnswers" if question.post_body.present?
+
+  next_node_rules = {}
+  question_page.next_nodes.each do |next_node|
+    if next_node.rules.all? { |r| (Smartdown::Model::Predicate::Equality === r.predicate) && r.predicate.varname == question.name }
+      next_node_rules[:case_statement] = next_node.rules.inject({}) do |hash, rule|
+        next_node = question_pages_vs_questions[rule.outcome] || rule.outcome
+        hash[rule.predicate.expected_value] = next_node.to_sym; hash
+      end
+    else
+      next_node_rules[:comments] = next_node.rules.inject([]) do |array, rule|
+        next_node = question_pages_vs_questions[rule.outcome] || rule.outcome
+        array << "#{rule.predicate.humanize} -> #{next_node}"; array
+      end
+    end
+  end
+
+  q = { name: question.name.to_sym, next_node_rules: next_node_rules }
+  case question
+  when Smartdown::Api::MultipleChoice
+    content_for_questions[key]['options'] = question.options.inject({}) { |h,o| h[o.value] = o.label; h }
+    q[:type] = :multiple_choice
+    q[:options] = question.options.map(&:value)
+  when Smartdown::Api::PostcodeQuestion
+    q[:type] = :postcode_question
+    q[:options] = []
+  else
+    raise "Question '#{question.name}' is of type '#{question.class}' which is not yet supported by this conversion tool"
+  end
+
+  if question_page.name == start_node
+    questions.unshift(q)
+  else
+    questions.push(q)
+  end
+end
+
+outcomes = flow.outcomes.inject([]) { |a,o| a << { name: o.name } }
+
+flow_class = "#{flow_name.underscore.classify}Flow"
+erb = File.read(Rails.root.join('script', 'templates', 'smart_answer_flow.erb'))
+template = Erubis::Eruby.new(erb)
+File.open(flow_path, 'w') do |file|
+  file.write(template.result(binding))
+end
+
+i18n = {
+  'en-GB' => {
+    'flow' => {
+      flow_name => coversheet.merge(content_for_questions)
+    }
+  }
+}
+
+File.open(locale_path, 'w') do |file|
+  file.write(i18n.to_yaml)
+end
+
+templates_root = smart_answer_root.join(flow_name)
+FileUtils.remove_dir(templates_root, force = true)
+FileUtils.makedirs(templates_root)
+
+input.outcomes.each do |outcome|
+  template_path = templates_root.join("#{outcome.name.underscore}.govspeak.erb")
+  body = outcome.read
+  # regular expression copied from Smartdown::Parser::SnippetPreParser#parse_content
+  body.gsub!(/\{\{snippet:\W?(.*)\}\}/i) do
+    "<%= render partial: '#{$1.underscore}.govspeak.erb' -%>"
+  end
+  # regular expression copied from Smartdown::Engine::Interpolator#interpolate
+  body.gsub!(/%{([^}]+)}/) do
+    raise "Outcome '#{outcome.name.underscore}' includes interpolated value '#{$1}' which is not yet supported by this conversion tool"
+  end
+  File.open(template_path, 'w') do |file|
+    file.puts '<% content_for :body do %>'
+    file.puts body.indent(2)
+    file.puts '<% end %>'
+  end
+end
+
+input.snippets.each do |snippet|
+  template_path = templates_root.join("_#{snippet.name.underscore}.govspeak.erb")
+  File.open(template_path, 'w') do |file|
+    file.puts snippet.read
+  end
+end

script/templates/smart_answer_flow.erb

@@ -0,0 +1,36 @@
+module SmartAnswer
+  class <%= flow_class %> < Flow
+    def define
+      name <%= flow_name.inspect %>
+      status <%= flow.status.to_sym.inspect %>
+      satisfies_need <%= flow.need_id.inspect %>
+
+      <% questions.each do |question| %>
+      <%= question[:type] %> <%= question[:name].inspect %> do
+        <% question[:options].each do |option| %>
+        option <%= option.inspect %>
+        <% end %>
+
+        next_node do |response|
+        <% if case_statement = question[:next_node_rules][:case_statement] %>
+          case response
+          <% case_statement.each do |value, outcome| %>
+          when <%= value.inspect %>
+            <%= outcome.to_sym.inspect %>
+          <% end %>
+          end
+        <% elsif comments = question[:next_node_rules][:comments] %>
+          <% comments.each do |comment| %>
+          # TODO: <%= comment %>
+          <% end %>
+        <% end %>
+        end
+      end
+
+      <% end %>
+      <% outcomes.each do |outcome| %>
+      outcome :<%= outcome[:name] %>
+      <% end %>
+    end
+  end
+end