module Daengine
  class DigitalAssetProcessor

    @@last_read_time = 2.days.ago

    def self.trap_signals
      sigtrap = proc {
        puts "DigitalAssetProcessor: caught trapped signal, shutting down"
        @@run = false
      }
      signals = ["SIGTERM", "SIGINT"]
      signals.push("SIGHUP") unless is_windows?
      signals.each do |signal|
        trap signal, sigtrap
      end
    end

    def self.is_windows?
      processor, platform, *rest = RUBY_PLATFORM.split("-")
      platform =~ /mswin/ || platform =~ /mingw/
    end

    def self.execute
      @@run = true
      trap_signals
      @@wthread = Thread.new { worker() }
      return @@wthread
    end

    def self.worker
      puts "DigitalAssetProcessor: start processing digital assets!"
      while @@run
        begin
          self.process_tuple_directory
          process_tuple_directory
        rescue => e
          puts e.message
          puts e.backtrace
        end
        sleep(5)
      end
      @@wthread.exit
    end

    def self.process_tuple_directory
      path = Daengine.config[:assets_path]
      raise "ERROR: DigitalAssetProcessor: Invalid assets_path provided. Unable to read from #{path}" unless File::directory?(path)
      # read the given directory, process each file in date order starting 2 days ago if last_read_time is nil
      time = self.read_last_process_time
      if not time.blank?
        @@last_read_time = time
      end
      Daengine.log("DigitalAssetProcessor: Last process time was #{@@last_read_time}", "info")
      deploy_files= []

      deploy_files = Dir.entries(path).select {
          |f| File.file?("#{path}/#{f}") and File.mtime("#{path}/#{f}") > @@last_read_time
      }.sort_by { |f| File.mtime("#{path}/#{f}") }

      if deploy_files.empty?
        Daengine.log("DigitalAssetProcessor: No digital asset deployment files found to process under #{path}", "warn")
      else
        Daengine.log("DigitalAssetProcessor: Reading digital asset deployment files from #{path}", "info")
        deploy_files.each do |filename|
          #parse the file and add metadata content to database.
          file = File.expand_path(filename, path)
          Daengine.log("DigitalAssetProcessor: Processing file #{filename} --- #{File.mtime(file)}", "info")
          open_file = File.open(file, 'rb')
          Daengine::TeamsiteMetadataParser.parse_tuple_file(open_file)
          Daengine.log("DigitalAssetProcessor: Finished processing #{filename}", "info")
          @@last_read_time = File.mtime(file)
          self.save_last_read_time
          Daengine.log("DigitalAssetProcessor: Last process time set to #{@@last_read_time}", "info")
        end
      end
    end

    def self.save_last_read_time
      begin
        target = Daengine.config[:daengine_yml_file]
        content = "last_read_time: #{@@last_read_time}"
        File.open(target, "w+") do |f|
          f.write(content)
        end
      rescue Exception => e
        Daengine.log("DigitalAssetProcessor: Failed to write to #{target}.", "warn")
      end
    end

    def self.read_last_process_time
      time = ""
      begin
        target = Daengine.config[:daengine_yml_file]
        property = YAML.load_file(target)
        time = property['last_read_time']
      rescue Exception => e
        Daengine.log("DigitalAssetProcessor: Failed to read from #{target}", "warn")
      end
      time
    end

  end
end