class BenchmarkDriver::Output::Markdown

def compare_executables
  order = @metrics.first.larger_better ? :min_by : :max_by
  worst, worst_result = @job_context_result.__send__(order) do |_, result|
    result.values.first[1]
  end
  worst_result = worst_result.values.first[1]
  $stdout.print("|", " " * (@name_length + 2))
  @job_context_result.each do |context, result|
    if context == worst
      result = '-'
    else
      val = result.values.first[1]
      ratio = val.fdiv(worst_result)
      result = sprintf("%.2fx", ratio)
    end
    length = [context.name.length, NAME_LENGTH].max
    $stdout.printf("|%*s", length, result)
  end
  $stdout.puts('|')
end

def humanize(value)
  if BenchmarkDriver::Result::ERROR.equal?(value)
    return sprintf("%*s", NAME_LENGTH, 'ERROR')
  elsif value == 0.0
    return sprintf("%*.3f", NAME_LENGTH, 0.0)
  elsif value < 0
    raise ArgumentError.new("Negative value: #{value.inspect}")
  end
  scale = (Math.log10(value) / 3).to_i
  prefix = sprintf("%*.3f", NAME_LENGTH - 1, (value.to_f / (1000 ** scale)))
  suffix =
    case scale
    when 1; 'k'
    when 2; 'M'
    when 3; 'G'
    when 4; 'T'
    when 5; 'Q'
    else # < 1000 or > 10^15, no scale or suffix
      return " #{prefix}"
    end
  "#{prefix}#{suffix}"
end

def initialize(metrics:, jobs:, contexts:, options:)
  @metrics = metrics
  @contexts = contexts
  @context_names = contexts.map(&:name)
  @name_length = jobs.map(&:name).map(&:size).max
  @compare = options.fetch(:compare, false)
end

def report(result)
  if defined?(@job_context_result)
    @job_context_result[@context] = result
  end
  if @with_benchmark
    length = [NAME_LENGTH, @context.name.length].max
    $stdout.printf("|%*s", length, humanize(result.values.fetch(@metrics.first)))
  else
    $stdout.print '.'
  end
end

def with_benchmark(&block)
  @with_benchmark = true
  without_stdout_buffering do
    # Show header
    $stdout.puts "# #{@metrics.first.name} (#{@metrics.first.unit})\n\n"
    # Show executable names
    $stdout.print("|#{' ' * @name_length}  ")
    @context_names.each do |context_name|
      $stdout.printf("|%*s", NAME_LENGTH, context_name) # same size as humanize
    end
    $stdout.puts('|')
    # Show header separator
    $stdout.print("|:#{'-' * (@name_length - 1)}--")
    @context_names.each do |context_name|
      length = [context_name.length, NAME_LENGTH].max
      $stdout.print("|#{'-' * (length - 1)}:") # same size as humanize
    end
    $stdout.puts('|')
    block.call
  end
rescue
  @with_benchmark = false
end

def with_context(context, &block)
  @context = context
  block.call
end

def with_job(job, &block)
  if @with_benchmark
    @job_context_result = {} if @context_names.size > 1
    $stdout.printf("|%-*s  ", @name_length, job.name)
  end
  block.call
ensure
  if @with_benchmark
    $stdout.puts('|')
    compare_executables if @compare && @context_names.size > 1
  end
end

def with_warmup(&block)
  without_stdout_buffering do
    $stdout.print 'warming up'
    block.call
  end
ensure
  $stdout.puts
end

def without_stdout_buffering
  sync, $stdout.sync = $stdout.sync, true
  yield
ensure
  $stdout.sync = sync
end