Location = Struct.new(:lat, :lng, :radius, :speed, :course)

class Location
  protected :[]=

  def initialize(data = {})
    super()

    case data
    when Array
      raise ArgumentError, 'unsupported location data' unless data.size == 2
      self.lat, self.lng = data
    when Hash, Location
      data.each { |key, value|
        begin
          __send__("#{key}=", value)
        rescue NameError
        end
      }
    else
      raise ArgumentError, 'unsupported location data'
    end

    yield self if block_given?
  end

  def lat=(value)
    self[:lat] = floatify(value) { |f|
      if f.abs <= 90
        f
      else
        raise ArgumentError, 'out of bounds'
      end
    }
  end

  def lng=(value)
    self[:lng] = floatify(value) { |f|
      if f.abs <= 180
        f
      else
        raise ArgumentError, 'out of bounds'
      end
    }
  end

  def radius=(value)
    self[:radius] = floatify(value) { |f| f if f >= 0 }
  end

  def speed=(value)
    self[:speed] = floatify(value) { |f| f if f >= 0 }
  end

  def course=(value)
    self[:course] = floatify(value) { |f| f if (0..360).cover?(f) }
  end

  def present?
    lat && lng
  end

  def empty?
    !present?
  end

  private

  def floatify(value)
    case value
    when nil, ''
      return nil
    else
      float = Float(value)
      if block_given?
        yield(float)
      else
        float
      end
    end
  end
end