module Daengine
  class DigitalAssetProcessor

    @@last_read_time = 2.days.ago

    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)
      # ensure only one instance running at a time
      lockfile_name = Daengine.config[:daengine_yml_file] + '.lck'
      begin
        lockfile = File.new(lockfile_name, File::CREAT|File::EXCL)

        # 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
        last_run_time = 10.years.ago
        if not time.blank?
          @@last_read_time = time
          last_run_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|
            begin
              #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, last_run_time)
              Daengine.log("DigitalAssetProcessor: Finished processing #{filename}", "info")
              @@last_read_time = File.mtime(file) + 1.second
              self.save_last_read_time
              Daengine.log("DigitalAssetProcessor: Last process time set to #{@@last_read_time}", "info")
            rescue
              Daengine.log("Unable to process file #{filename}, #{$!.message}", "error")            
            end
          end
        end

      rescue Errno::EEXIST
        Daengine.log("DigitalAssetProcessor: Already in progress. Lockfile exists at #{lockfile_name}. Aborting!", "error")
      ensure
        unless lockfile.nil?
          lockfile.close()
          File.delete(lockfile_name)
        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("ERROR: DigitalAssetProcessor: Failed to write to #{target}.", "error")
      end
    end

    def self.read_last_process_time
      time = 2.days.ago
      begin
        target = Daengine.config[:daengine_yml_file]
        property = YAML.load_file(target)
        time = property['last_read_time']
      rescue Exception => e
        Daengine.log("ERROR: DigitalAssetProcessor: Failed to read from #{target} - #{e.message}", "error")
      end
      time
    end

  end
end