class QuackPool

# File lib/quack_pool.rb, line 8
def initialize(resource_class: , size: Float::INFINITY)
  raise ArgumentError, "'resource_class' must respond_to 'new'" unless resource_class.respond_to?(:new)
  @resource_class = resource_class
  raise ArgumentError, "'size' must be an Integer" unless size.is_a?(Integer) || size == Float::INFINITY
  @max_size = size
  @resources = []
  @available_resources = []
  @mutex = ReentrantMutex.new
  @condition_variable = ConditionVariable.new
end

# File lib/quack_pool.rb, line 19
def absorb_resource(resource)
  @mutex.synchronize do
    raise Error, "resource does not belong to this pool" unless has_resource?(resource)
    raise Error, "resource already in pool" if resource_available?(resource)
    @available_resources.push(resource)
    @condition_variable.signal
  end
  nil
end

# File lib/quack_pool.rb, line 29
def has_resource?(resource)
  @mutex.synchronize do
    raise Error, "resource is not an instance of 'resource_class'" unless resource.is_a?(@resource_class)
    @resources.include?(resource)
  end
end

# File lib/quack_pool.rb, line 36
def release_resource
  @mutex.synchronize do
    if @available_resources.any?
      release_available_resource
    elsif @resources.length < @max_size
      build_new_resource
    else
      release_next_available_resource
    end
  end
end

# File lib/quack_pool.rb, line 48
def resource_available?(resource)
  @mutex.synchronize do
    raise Error, "resource does not belong to this pool" unless has_resource?(resource)
    @available_resources.include?(resource)
  end
end

# File lib/quack_pool.rb, line 57
def build_new_resource
  new_resource = @resource_class.new
  raise Error, "'new_resource' must be unique" if has_resource?(new_resource)
  @resources << new_resource
  new_resource
end

# File lib/quack_pool.rb, line 64
def release_available_resource
  @available_resources.pop
end

# File lib/quack_pool.rb, line 68
def release_next_available_resource
  @condition_variable.wait(@mutex)
  release_available_resource
end