# frozen_string_literal: true

# Processes the array of arguments (ARGV by default) and returns the options, targets, and help string.
class ArgsParser
  attr_reader :args, :options, :option_parser
  private     :args, :options, :option_parser

  DEFAULT_OPTIONS =
    {
      as_array: false,
      format: 'at', # AwesomePrint for metadata, to_s for text content
      metadata: true,
      text: true,
      source: true,
      key_sort: true
    }.freeze

  # Parses the command line arguments.
  # Shorthand for ArgsParser.new.call. This call is recommended to pro tect the caller in case
  # this functionality is repackaged as a Module or otherwise modified.
  # @param [Array] args the command line arguments (overridable for testing, etc.)
  # @return [Array<Hash,String>] [options, targets, help_string],
  #   or exits if help or version requested or no targets specified.
  def self.call(args = ARGV)
    new.call(args)
  end

  # Parses the command line arguments.
  # @param [Array] args the command line arguments (overridable for testing, etc.)
  # @return [Array<Hash,String>] [options, targets, help_string],
  #   or exits if help or version requested or no targets specified.
  def call(args = ARGV)
    @args = args
    @options = DEFAULT_OPTIONS.dup
    prepend_environment_args
    @option_parser = create_option_parser
    option_parser.parse!(args)
    postprocess_format_options
    targets = create_target_array
    [options, targets, option_parser.help]
  end

  # @return [OptionParser]
  private def create_option_parser
    OptionParser.new do |opts|
      opts.banner =  <<~BANNER
        Rika v#{Rika::VERSION} (Tika v#{Rika.tika_version}) - #{Rika::PROJECT_URL}

        Usage: rika [options] <file or url> [...file or url...]
        Output formats are: [a]wesome_print, [t]o_s, [i]nspect, [j]son), [J] for pretty json, and [y]aml.
        If a format contains two letters, the first will be used for metadata, the second for text.
        Values for the text, metadata, and as_array boolean options may be specified as follows:
          Enable:  +, true,  yes, [empty]
          Disable: -, false, no, [long form option with no- prefix, e.g. --no-metadata]

      BANNER

      format_message = 'Output format (default: at)'
      opts.on('-f', '--format FORMAT', format_message) do |format|
        options[:format] = format
      end

      opts.on('-m', '--[no-]metadata [FLAG]', TrueClass, 'Output metadata (default: true)') do |v|
        options[:metadata] = (v.nil? ? true : v)
      end

      opts.on('-t', '--[no-]text [FLAG]', TrueClass, 'Output text (default: true)') do |v|
        options[:text] = (v.nil? ? true : v)
      end

      opts.on('-k', '--[no-]key-sort [FLAG]', TrueClass, 'Sort metadata keys case insensitively (default: true)') do |v|
        options[:key_sort] = (v.nil? ? true : v)
      end

      opts.on('-s', '--[no-]source [FLAG]', TrueClass, 'Output document source file or URL (default: false)') do |v|
        options[:source] = (v.nil? ? true : v)
      end

      opts.on('-a', '--[no-]as-array [FLAG]', TrueClass,
              'Output all parsed results as an array (default: false)') do |v|
        options[:as_array] = (v.nil? ? true : v)
      end

      opts.on('-v', '--version', 'Output version') do
        puts versions_string
        exit
      end

      opts.on('-h', '--help', 'Output help') do
        puts opts
        exit
      end
    end
  end

  # @return [Array] the targets specified on the command line, possibly expanded by the shell,
  #   and with any directories removed.
  private def create_target_array
    targets = args.dup.reject { |arg| File.directory?(arg) }.freeze # reject dirs to handle **/* globbing
    targets.map(&:freeze)
  end

  # Fills in the second format option character if absent, and removes any excess characters
  # @return [String] format options 2-character value, e.g. 'at'
  private def postprocess_format_options
    # If only one format letter is specified, use it for both metadata and text.
    options[:format] *= 2 if options[:format].length == 1

    # Ignore and remove extra characters after the first two format characters.
    options[:format] = options[:format][0..1]
  end

  # If the user wants to specify options in an environment variable ("RIKA_OPTIONS"),
  # then this method will insert those options at the beginning of the `args` array,
  # where they can be overridden by command line arguments.
  private def prepend_environment_args
    env_opt_string = environment_options
    args_to_prepend = Shellwords.shellsplit(env_opt_string)
    args.unshift(args_to_prepend).flatten!
  end

  # @return [String] the value of the RIKA_OPTIONS environment variable if present, else ''.
  private def environment_options
    ENV['RIKA_OPTIONS'] || ''
  end

  # @return [String] string containing versions of Rika and Tika, with labels
  private def versions_string
    "Versions: Rika: #{Rika::VERSION}, Tika: #{Rika.tika_version}"
  end
end