require 'open-uri'
require 'open3'

module Getch
  module Gentoo
    class Stage

      def initialize
        @mirror = "https://mirrors.soeasyto.com/distfiles.gentoo.org"
        @release = release
        @stage_file="stage3-amd64-systemd-#{@release}.tar.xz"
      end

      def stage3
        @mirror + '/releases/amd64/autobuilds/latest-stage3-amd64-systemd.txt'
      end

      def release
        URI.open(stage3) do |file|
          file.read.match(/^[[:alnum:]]+/)
        end
      end

      def file
        "#{@release}/#{@stage_file}"
      end

      def get_stage3
        Dir.chdir(MOUNTPOINT)
        return if File.exist?(@stage_file)
        puts "Download the last #{@stage_file}, please wait..."
        Helpers::get_file_online(@mirror + "/releases/amd64/autobuilds/" + file, @stage_file)
      end

      def control_files
        puts "Download the DIGESTS"
        Helpers::get_file_online(@mirror + "/releases/amd64/autobuilds/" + file + ".DIGESTS", "#{@stage_file}.DIGESTS")
        puts "Download the DIGESTS.asc"
        Helpers::get_file_online(@mirror + "/releases/amd64/autobuilds/" + file + ".DIGESTS.asc", "#{@stage_file}.DIGESTS.asc")
        puts "Download the CONTENTS.gz"
        Helpers::get_file_online(@mirror + "/releases/amd64/autobuilds/" + file + ".CONTENTS.gz", "#{@stage_file}.CONTENTS.gz")
      end

      def checksum
        puts 'Check the SHA512 checksum.'
        command = "awk '/SHA512 HASH/{getline;print}' #{@stage_file}.DIGESTS.asc | sha512sum --check"
        _, stderr, status = Open3.capture3(command)
        if status.success? then
          puts "Checksum is ok"
          decompress
          cleaning
        else
          cleaning
          raise "Problem with the checksum, stderr\n#{stderr}"
        end
      end

      private 

      # https://wiki.gentoo.org/wiki/Handbook:AMD64/Installation/Stage
      def decompress
        puts "Decompressing archive #{@stage_file}..."
        cmd = "tar xpvf #{@stage_file} --xattrs-include='*.*' --numeric-owner"
        Helpers::exec_or_die(cmd)
      end

      def cleaning
        Dir.glob("stage3-amd64-systemd*").each do |f|
          File.delete(f)
        end
      end
    end
  end
end