class GrubConfig

def config_for_platform(path)
  os = inspec.os
  if os.redhat? || os[:name] == 'fedora'
    config_for_redhatish(path)
  elsif os.debian?
    @conf_path = path || '/boot/grub/grub.cfg'
    @defaults_path = '/etc/default/grub'
    @version = 'grub2'
  elsif os[:name] == 'amazon' # rubocop:disable Style/GuardClause
    @conf_path = path || '/etc/grub.conf'
    @version = 'legacy'
  else
    fail UnknownGrubConfig
  end
end

def config_for_redhatish(path)
  if inspec.os[:release].to_f < 7
    @conf_path = path || '/etc/grub.conf'
    @version = 'legacy'
  else
    @conf_path = path || '/boot/grub/grub.cfg'
    @defaults_path = '/etc/default/grub'
    @version = 'grub2'
  end
end

def grub2_parse_kernel_lines(content, conf)
  # Find all "menuentry" lines and then parse them into arrays
  menu_entry = 0
  lines = content.split("\n")
  kernel_opts = {}
  kernel_opts['insmod'] = []
  lines.each_with_index do |file_line, index|
    next unless file_line =~ /(^|\s)menuentry\s.*/
    lines.drop(index+1).each do |kernel_line|
      next if kernel_line =~ /(^|\s)(menu|}).*/
      if menu_entry == conf['GRUB_DEFAULT'].to_i && @kernel == 'default'
        if kernel_line =~ /(^|\s)initrd.*/
          kernel_opts['initrd'] = kernel_line.split(' ')[1]
        end
        if kernel_line =~ /(^|\s)linux.*/
          kernel_opts['kernel'] = kernel_line.split
        end
        if kernel_line =~ /(^|\s)set root=.*/
          kernel_opts['root'] = kernel_line.split('=')[1].tr('\'', '')
        end
        if kernel_line =~ /(^|\s)insmod.*/
          kernel_opts['insmod'].push(kernel_line.split(' ')[1])
        end
      else
        menu_entry += 1
        break
      end
    end
  end
  kernel_opts
end

def initialize(path = nil, kernel = nil)
  config_for_platform(path)
  @kernel = kernel || 'default'
rescue UnknownGrubConfig
  return skip_resource 'The `grub_config` resource is not supported on your OS yet.'
end

def method_missing(name)
  read_params[name.to_s]
end

def parse_kernel_lines(content, conf)
  # Find all "title" lines and then parse them into arrays
  menu_entry = 0
  lines = content.split("\n")
  kernel_opts = {}
  lines.each_with_index do |file_line, index|
    next unless file_line =~ /^title.*/
    current_kernel = file_line.split(' ', 2)[1]
    lines.drop(index+1).each do |kernel_line|
      if kernel_line =~ /^\s.*/
        option_type = kernel_line.split(' ')[0]
        line_options = kernel_line.split(' ').drop(1)
        if (menu_entry == conf['default'].to_i && @kernel == 'default') || current_kernel == @kernel
          if option_type == 'kernel'
            kernel_opts['kernel'] = line_options
          else
            kernel_opts[option_type] = line_options[0]
          end
        end
      else
        menu_entry += 1
        break
      end
    end
  end
  kernel_opts
end

def read_file(config_file)
  file = inspec.file(config_file)
  if !file.file? && !file.symlink?
    skip_resource "Can't find file '#{@conf_path}'"
    return @params = {}
  end
  content = file.content
  if content.empty? && file.size > 0
    skip_resource "Can't read file '#{@conf_path}'"
    return @params = {}
  end
  content
end

def read_params
  return @params if defined?(@params)
  content = read_file(@conf_path)
  if @version == 'legacy'
    # parse the file
    conf = SimpleConfig.new(
      content,
      multiple_values: true,
    ).params
    # convert single entry arrays into strings
    conf.each do |key, value|
      if value.size == 1
        conf[key] = conf[key][0].to_s
      end
    end
    kernel_opts = parse_kernel_lines(content, conf)
    @params = conf.merge(kernel_opts)
  end
  if @version == 'grub2'
    # read defaults
    defaults = read_file(@defaults_path)
    conf = SimpleConfig.new(
      defaults,
      multiple_values: true,
    ).params
    # convert single entry arrays into strings
    conf.each do |key, value|
      if value.size == 1
        conf[key] = conf[key][0].to_s
      end
    end
    kernel_opts = grub2_parse_kernel_lines(content, conf)
    @params = conf.merge(kernel_opts)
  end
  @params
end

def to_s
  'Grub Config'
end