require 'minitest/autorun'

module Utilities
  require 'timeout'
  # tries is the number of tries to execute the code
  # on is an array of the errors
  # timeout give an upper limit to the amount of time this method will run
  # and delay specifies the number of seconds to sleep between each retry
  def self.with_retry(retries: 2, on: [StandardError], timeout: 30, delay: 1, rescued_callback: nil)

    # http://ruby-doc.org/stdlib-2.1.1/libdoc/timeout/rdoc/Timeout.html
    Timeout::timeout(timeout) do 
      begin
        return yield 
      rescue *on => e
        sleep(delay)
        # callback code in case you want to do something special on 
        # failure like write to a log or what have you.
        if rescued_callback
          rar = rescued_callback.arity 
          if rar == 0
            rescued_callback.call
          elsif rar == 1
            rescued_callback.call(e)
          end
        end
        # retry if we have retries left
        retry unless (retries -= 1).zero?
        # re-raise the error if we don't
        raise e
      end
    end
      
  end

end

# custom errors for test purposes
class CustomError < StandardError; end
class CustomError2 < StandardError; end

class TestUtilities < MiniTest::Test

  def test_timeout_after_5_seconds

    start_time = Time.now.to_i
    assert_raises Timeout::Error do
      ::Utilities.with_retry(retries: 20, timeout: 5 ) do 
        raise "an error"
      end
    end
    end_time = Time.now.to_i
    
    assert_equal 5, end_time-start_time

  end

  def test_delay_works

    called = 0
    assert_raises Timeout::Error do
      ::Utilities.with_retry(retries: 20, timeout: 4, delay: 2 ) do 
        called += 1
        raise "an error"
      end
    end
    assert called <= 3

  end

  def test_tries_works

    called = 0
    assert_raises RuntimeError do 
      ::Utilities.with_retry(retries: 20, delay: 0 ) do 
        called += 1
        raise "an error"
      end
    end
    assert_equal 20, called

  end

  def test_wont_catch_just_any_exception

    called = 0
    assert_raises CustomError do
      ::Utilities.with_retry(retries: 3, delay: 0, on: CustomError2 ) do 
        called += 1
        raise CustomError.new("my custom error")
      end
    end

    assert_equal 1, called

  end

  def test_catches_specified_exceptions

    called = 0

    assert_raises CustomError do 
      ::Utilities.with_retry(retries: 3, delay: 0, on: [CustomError, CustomError2] ) do 
        called += 1
        raise CustomError.new("my custom error")
      end
    end
    
    assert_equal 3, called

  end

  def test_rescued_callback_works
    
    called = 0
    myerr = nil
    callback = ->(err){ called += 1; myerr = err }

    assert_raises RuntimeError do
      ::Utilities.with_retry(retries: 3, timeout: 4, delay: 0, rescued_callback: callback ) do 
        raise "test errr"
      end
    end
    assert_equal 3, called
    assert_equal "test errr", myerr.to_s
  end

end