# frozen_string_literal: true

require "benchmark"
require "benchmark/ips"
require "benchmark/memory"

module Benchable
  # Main class to perform benchmarks.
  #
  # Use the method Benchable.bench to declare a benchmark.
  class Benchmark
    DEFAULT_WIDTH = 20
    BENCHMARK_TYPES = %i[bm bmbm ips memory].freeze

    def initialize(benchmark_type, **options)
      @benchmark_type = benchmark_type
      @options = options

      raise Error, "Invalid benchmark type '#{benchmark_type}'" unless valid_benchmark_type?
    end

    def self.setup(&block)
      define_method(:setup, &block)
    end

    def self.bench(name, &block)
      define_method(:"bench_#{name}", &block)
    end

    def setup
    end

    def run
      setup
      run_benchmark
    end

    def cases
      public_methods.grep(/\Abench_/)
    end

    private

    attr_reader :benchmark_type, :options

    def valid_benchmark_type?
      BENCHMARK_TYPES.include? benchmark_type
    end

    def run_benchmark
      benchmark do |b|
        b.config(options) if benchmark_type == :ips

        cases.each do |benchmark_case|
          b.report(title_for(benchmark_case)) do
            method(benchmark_case).call
          end
        end

        b.compare! if b.respond_to? :compare!
      end
    end

    def title_for(benchmark_case)
      benchmark_case.to_s.delete_prefix("bench_")
    end

    def benchmark(&block)
      if benchmark_type == :memory
        ::Benchmark.public_send(benchmark_type, **benchmark_args, &block)
      else
        ::Benchmark.public_send(benchmark_type, *benchmark_args, &block)
      end
    end

    def benchmark_args
      if benchmark_type == :memory
        options.slice(:quiet)
      else
        options[:width] || DEFAULT_WIDTH
      end
    end
  end
end
