class RBS::CLI::Diff

def initialize(argv:, library_options:, stdout: $stdout, stderr: $stderr)
  @format = nil
  @stdout = stdout
  @stderr = stderr
  # @type var type_name: String?
  type_name = nil
  library_options = library_options
  before_path = [] #: Array[String]
  after_path = [] #: Array[String]
  detail = false
  opt = OptionParser.new do |o|
    o.banner = <<~HELP
      [Experimental] This command is experimental. API and output compatibility is not guaranteed.
      Usage:
        rbs diff --format markdown --type-name Foo --before before_sig --after after_sig
      Print diff for rbs environment dir
      Examples:
        # Diff dir1 and dir2 for Foo
        $ rbs diff --format markdown --type-name Foo --before dir1 --after dir2
        # Confirmation of methods related to Time class added by including stdlib/time
        $ rbs diff --format diff --type-name Time --after stdlib/time
    HELP
    o.on("--format NAME")    { |arg| @format = arg }
    o.on("--type-name NAME") { |arg| type_name = arg }
    o.on("--before DIR")     { |arg| before_path << arg }
    o.on("--after DIR")      { |arg| after_path << arg }
    o.on("--[no-]detail")    { |arg| detail = arg }
  end
  opt.parse!(argv)
  unless @format && type_name && ["markdown", "diff"].include?(@format)
    @stderr.puts opt.banner
    exit 1
  end
  @diff = RBS::Diff.new(
    type_name: TypeName.parse(type_name).absolute!,
    library_options: library_options,
    after_path: after_path,
    before_path: before_path,
    detail: detail,
  )
end

def run
  public_send("run_#{@format}")
end

def run_diff
  first = true
  io = RBS::CLI::ColoredIO.new(stdout: @stdout)
  @diff.each_diff do |before, after|
    io.puts if !first
    io.puts_red   "- #{before}"
    io.puts_green "+ #{after}"
    first = false
  end
end

def run_markdown
  @stdout.puts "| before | after |"
  @stdout.puts "| --- | --- |"
  @diff.each_diff do |before, after|
    before.gsub!("|", "\\|")
    after.gsub!("|", "\\|")
    @stdout.puts "| `#{before}` | `#{after}` |"
  end
end