Rake task for mustache syntax checking an application's surveyor surveys

mustache_check.rake

task :mustache_check => :environment do
  require 'mustache/parser'

  mustache_error = Struct.new(:record_type, :reference_identifier, :error_message)

  text_error = lambda do |text|
    begin
      Mustache::Parser.new.compile(text)
      nil
    rescue Mustache::Parser::SyntaxError => e
      e.to_s
    end
  end

  produce_error = lambda do |text_having_object|
    error = text_error[text_having_object.text] if text_having_object.text
    if error
      mustache_error.new(text_having_object.class, text_having_object.reference_identifier, error)
    end
  end

  surveys = Survey.includes(:sections => { :questions => [ :answers ] })

  latest_versions = surveys.inject({}) { |h, s|
    h[s.title] = [h[s.title], s.survey_version].compact.max; h
  }

  surveys.select { |survey| survey.survey_version == latest_versions[survey.title] }.each do |survey|
    if Rake.application.options.trace
      $stderr.puts "Analyzing #{survey.title} / testbed survey_version #{survey.survey_version} / testbed id #{survey.id}"
    end

    questions = survey.sections.collect { |sect| sect.questions }.flatten

    errors = questions.collect { |q|
      ([q] + q.answers).collect { |i| produce_error[i] }
    }.flatten.compact

    unless errors.empty?
      $stderr.puts "#{survey.title} / testbed survey_version #{survey.survey_version} / testbed id #{survey.id}" unless Rake.application.options.trace
      errors.each do |error|
        $stderr.puts "* Error on #{error.record_type.to_s.downcase} #{error.reference_identifier}"
        $stderr.puts error.error_message.split("\n").map { |line| "  #{line}" }.join("\n")
      end
    end
  end
end