require 'rubygems/package'
require 'zlib'
require 'picsolve_docker_builder/base'
require 'picsolve_docker_builder/builder/file'

module PicsolveDockerBuilder
  module Builder
    # This Builder supports the building process of an docker image
    class Builder
      include PicsolveDockerBuilder::Base
      def initialize(opts = {})
        @opts = opts
      end

      def maintainer
        @opts[:maintainer]
      end

      def base_image
        @opts[:base_image]
      end

      def ports
        return if @opts[:ports].nil?
        ports = @opts[:ports]
        ports = [ports] unless ports.is_a?(Array)
        ports.map do |port|
          "EXPOSE #{port}"
        end.join('\n')
      end

      def adds
        files = @opts[:files].select(&:add_to_image?)
        files.map! do |f|
          "ADD #{f.path} #{f.destination}"
        end
        files.join("\n")
      end

      def command
        return '' if @opts[:command].nil?
        "CMD [\"#{@opts[:command].join('", "')}\"]"
      end

      def hook(name)
        v = @opts[:hooks][name]
        v = [v] unless v.is_a?(Array)
        v.join("\n") + "\n"
      end

      def required_attrs
        [
          :base_image,
          :maintainer,
          :ports,
          :command,
          :files
        ]
      end

      def build_tar
        tarfile = StringIO.new('')
        Gem::Package::TarWriter.new(tarfile) do |tar|
          # add Dockerfile to tar
          dockerfile.each_line do |line|
            log.debug "docker_build Dockerfile: #{line.strip}"
          end
          tar.add_file 'Dockerfile', 0644 do |tf|
            tf.write dockerfile
          end

          # add other files to tar
          @opts[:files].each do |f|
            f.add_to_tar tar
          end
        end
        StringIO.new(tarfile.string)
      end

      # Overwrite docker_build and filter build assets
      def build
        log.info 'docker build starting...'
        Docker::Image.build_from_tar(build_tar) do |stream|
          s = JSON.parse(stream)['stream']
          log.debug s.strip unless s.nil?
        end
      rescue NoMethodError => e
        log.fatal "docker build failed: #{e}"
        exit 1
      end

      def dockerfile
        <<EOS
FROM #{base_image}
MAINTAINER #{maintainer}

#{hook(:early)}

#{hook(:before_adds)}

#{adds}

#{hook(:after_adds)}

#{ports}

# call run script
#{command}

#{hook(:late)}
EOS
      end
    end
  end
end