#!/usr/bin/env ruby

# BEGIN: Includes & Requires

require 'erb'
require 'time'
require 'json'
require 'net/http'
require 'English'
require 'rubygems/package'
require 'fileutils'
require 'optparse'
require 'zlib'
require 'find'

# END: Includes & Requires





# BEGIN: Overrides

class Dir
  def / (path)
    output_path = File.absolute_path(self.path) + '/' + path
    if File.directory? output_path
      Dir.new(output_path)
    else
      output_path
    end
  end
end

class String
  def / (other)
    self + '/' + other
  end
end

# END: Overrides



# BEGIN: Variables
URL_DOWNLOAD_BASE='https://dl.discordapp.net/apps/linux/{VERSION}/discord-{VERSION}.tar.gz'
DOWNLOAD_URL='https://discord.com/api/download/stable?platform=linux&format=tar.gz'

$CONFIG = Hash.new
$CONFIG[:icon_dir] = Dir.new(Dir.home) / '.local' / 'share' / 'icons'
File.mkdir($CONFIG[:icon_dir]) if not File.exist?($CONFIG[:icon_dir])
$CONFIG[:discord_config_path] = Dir.new(Dir.home) / '.config' / 'discord'
$CONFIG[:local_application_install_dir] = Dir.new(Dir.home) / '.local' / 'share' / 'applications'
File.mkdir($CONFIG[:local_application_install_dir]) if not File.exist?($CONFIG[:local_application_install_dir])
$CONFIG[:desktop_path] = Dir.new(Dir.home) / '.local' / 'share' / 'applications' / 'discord.desktop'
$CONFIG[:install_dir] = Dir.new(Dir.home) / '.opt'
File.mkdir($CONFIG[:install_dir]) if not File.exist?($CONFIG[:install_dir])
$CONFIG[:discord_path] = $CONFIG[:install_dir] / 'Discord'
$CONFIG[:desktop_file_path] = $CONFIG[:discord_path] / 'discord.desktop'
$CONFIG[:discord_version_file] = $CONFIG[:discord_path] / 'resources' / 'build_info.json'
$CONFIG[:action] = 'install'
$CONFIG[:keep_installer] = false
$CONFIG[:debug] = false
DISCORD_DESKTOP_CONTENTS=<<EOF
[Desktop Entry]
Name=Discord
StartupWMClass=discord
Comment=All-in-one voice and text chat for gamers that's free, secure, and works on both your desktop and phone.
GenericName=Internet Messenger
Exec=#{$CONFIG[:install_dir].path}/Discord/Discord
Icon=discord
Type=Application
Categories=Network;InstantMessaging;
Path=#{$CONFIG[:install_dir].path}/Discord
EOF
# END: Variables



# BEGIN: Handle CLI ARgs

OptionParser.new do |parser|
  parser.banner = "#{ File.basename($0) } [action]"
  parser.separator ""
  parser.separator "  Actions"
  parser.separator "------------------------------------------------------------------------"

  parser.on('-c', '--check', "Check and report installed & remote versions") do 
    $CONFIG[:action] = 'check'
  end

  parser.on('-i', '--install', "Check for & Install new version of discord (default)") do 
    $CONFIG[:action] = 'install'
  end

  parser.on('-u', '--uninstall', "Uninstall Discord (not-implemented)") do 
    $CONFIG[:action] = 'uninstall'
  end

  parser.on('-b', '--backup [FILENAME]', "Backup Discord Installation") do |backup_filename|
    $CONFIG[:action] = 'backup'
    if backup_filename.nil?
      $CONFIG[:backup_filename] = 'discord-backup-' + Time.now.strftime('%Y-%m-%d') + '.tar.gz'
    else
      $CONFIG[:backup_filename] = backup_filename + ".tar.gz"
    end
  end

  parser.separator ""
  parser.separator "  General Flags"
  parser.separator "------------------------------------------------------------------------"
  parser.on('-h', '--help', "Show this help output") do 
    puts parser
    exit
  end

  parser.on('-d', '--debug', "Turn on debug logging") do 
    $CONFIG[:debug] = true
  end

  parser.on('--keep', 'Keep discord tar.gz file (default: False)') do 
    $CONFIG[:keep_installer] = true
  end

end.parse!

# BEGIN: Handle CLI ARgs



# BEGIN: Helper Classes

class Installer
  URL_DOWNLOAD_BASE='https://dl.discordapp.net/apps/linux/{VERSION}/discord-{VERSION}.tar.gz'
  DOWNLOAD_URL='https://discord.com/api/download/stable?platform=linux&format=tar.gz'

  def needs_update?
    local_version < remote_version
  end

  def remote_version
    if @remote_version.nil?
      uri = URI(DOWNLOAD_URL)
      response = Net::HTTP.get(uri)
      if response =~ /discord-(?<version>\d+\.\d+\.\d+).tar.gz/
        @remote_version = Gem::Version.new($LAST_MATCH_INFO['version'])
      else
        raise "Failed to retrieve remote version"
      end
    end
    @remote_version
  end

  def local_version
    if @local_version.nil?
      @local_version = if File.exist? $CONFIG[:discord_version_file]
        data = JSON.load_file($CONFIG[:discord_version_file])
        Gem::Version.new(data['version'])
      else
        Gem::Version.new('0.0.0')
      end
    end
    @local_version 
  end

  def download
    version = self.remote_version.to_s
    uri = URI(URL_DOWNLOAD_BASE.gsub('{VERSION}',version))
    puts "download_installer: Downloading The discord #{version} tar.gz"
    file_contents = Net::HTTP.get(uri)
    output_file = "discord-#{version}.tar.gz"
    puts "download_installer: Output file will #{output_file}"
    $CONFIG[:install_dir].chdir do 
      File.open(output_file, 'wb') do |file|
        file.write(file_contents)
      end
    end
    puts "download_installer: tar.gz was downloaded"
  end

  def install
    installer_file = "discord-#{self.remote_version}.tar.gz"
    puts "do_install: Extracting new installer"
    $CONFIG[:install_dir].chdir do 
      File.open(installer_file, 'rb') do |file|
        Gem::Package.new("").extract_tar_gz(file, $CONFIG[:install_dir])
      end

      if not $CONFIG[:keep_installer]
        puts "do_install: Removing new installer (#{installer_file})"
        File.unlink(installer_file)
      end
    end
  end
end

# END: Helper Classes



# BEGIN: Helper Functions

def update_desktop_file
  file_needs_updating = true
  puts "update_desktop_file: Checking if desktop entry needs updating"
  if File.exist?($CONFIG[:desktop_path])  
    puts "update_desktop_file: Desktop file exists, checking if it matches template"
    File.open($CONFIG[:desktop_path], 'r') do |file|
      if file.read() == DISCORD_DESKTOP_CONTENTS
        puts "update_desktop_file: Desktop file matches template. Not updating"
        file_needs_updating = false
      end
    end
  end

  if file_needs_updating
    File.open($CONFIG[:desktop_path], 'w') do |file|
      puts "update_desktop_file: Desktop File was written"
      file.write(DISCORD_DESKTOP_CONTENTS)
    end

    puts "update_desktop_file: Triggering desktop to install new desktop entry and refresh entries"
    %x[ desktop-file-install --dir=#{$CONFIG[:local_application_install_dir].path} #{$CONFIG[:desktop_path]} ]
  end
end

def make_backup
  files = {
    files: Array.new,
    dirs: Array.new,
    symlinks: Array.new
  }

  [ $CONFIG[:discord_config_path].path, $CONFIG[:discord_path].path ].each do |backup_dir|
    puts "make_backup: Getting Files from #{backup_dir})"
    Find.find("#{backup_dir}").each{ |item| 
      puts("#{item} was retrieved from #{backup_dir}") if $CONFIG[:debug]
      if File.file?(item) 
        puts("#{item} was found to be a file") if $CONFIG[:debug]
        files[:files] << item
      elsif File.symlink?(item)
        puts("#{item} was found to be a symlink") if $CONFIG[:debug]
        files[:symlinks] << item
      elsif File.directory?(item)
        puts("#{item} was found to be a directory") if $CONFIG[:debug]
        files[:dirs] << item
      end
    }
  end

  Dir.chdir(Dir.home) do 
    puts "make_backup: Beginning backup process (OUTPUT_FILE = #{Dir.getwd}/#{$CONFIG[:backup_filename]})"
    File.open($CONFIG[:backup_filename], "wb") do |backup_file|
      Zlib::GzipWriter.wrap(backup_file) do |gzip|
        Gem::Package::TarWriter.new(gzip) do |tar|

          puts "\nmake_backup : files : Beginning backup process for files (Count: #{files[:files].count})"
          file_count = files[:files].count
          files[:files].each_with_index { |file, i|
            puts "make_backup : files : Backing up #{file} (#{i+1}/#{file_count})" if $CONFIG[:debug]
            File.open(file, 'rb') { |file_to_archive|
              contents = file_to_archive.read()
              tar.add_file_simple(file_to_archive.path.sub("#{Dir.home}/",''), file_to_archive.stat.mode, contents.length) { |io|
                io.write(contents)
              }
            }
          }

          puts "\nmake_backup : directories : Beginning backup process for directories (Count: #{files[:dirs].count})"
          dir_count = files[:dirs].count
          files[:dirs].each_with_index {|dir,i|
            puts "make_backup : directories : Backing up #{dir} (#{i+1}/#{dir_count})" if $CONFIG[:debug]
            tar.mkdir(dir.sub("#{Dir.home}/",""), File.stat(dir).mode)
          }

          puts "\nmake_backup : symlinks : Beginning backup process for symlinks (Count: #{files[:symlinks].count})"
          symlink_count = files[:symlinks].count
          files[:symlinks].each_with_index {|symlink,i|
            puts "make_backup : symlinks : Backing up #{symlink} (#{i+1}/#{symlink_count})" if $CONFIG[:debug]
            tar.add_symlink(symlink.sub("#{Dir.home}/",""), File.readlink(symlink), File.lstat(symlink).mode)
          }

        end
      end
    end
  end

end

# END: Helper Functions



# BEGIN: Work

case $CONFIG[:action]

  when 'install'
    installer = Installer.new
    if installer.needs_update?
      puts "main: Installed Version will be updated"
      installer.download
      installer.install
    elsif installer.local_version == installer.remote_version
      puts "main: Installed Version is up-to-date"
    else
      puts "main: What?"
    end

  when 'check'
    puts
    puts "  Report"
    puts "-------------------------------------"
    puts "  Remote Version: #{remote_version.to_s}"
    puts "   Local Version: #{local_version.to_s}"
    puts "  Needs Updating: #{(remote_version > local_version) ? "Yes" : "No"}"

  when 'backup'
    make_backup

end

# END: Work