service

type AdditionRequest struct {
	A float64 `json:"a"`
	B float64 `json:"b"`
}

type AdditionResponse struct {
	Result float64 `json:"result"`
}

type Calculator interface {
	Addition(a, b float64) float64
	Subtraction(subtrahend, minuend float64) float64
	Multiplication(a, b float64) float64
	Division(dividend, divisor float64) (float64, error)
	Graphql(ctx context.Context, request *handler.RequestOptions) *graphql.Result
}

type DivisionRequest struct {
	Dividend float64 `json:"dividend"`
	Divisor  float64 `json:"divisor"`
}

type DivisionResponse struct {
	Result float64 `json:"result"`
	Error  string  `json:"error,omitempty"` // errors do not JSON-marshal, so we use a string
}

type MetricSet struct {
	RequestCount          metrics.Counter
	RequestLatency        metrics.Histogram
	CountResult           metrics.Histogram
	GraphqlRequestCount   metrics.Counter
	GraphqlRequestLatency metrics.Histogram
}

type Middleware func(Calculator) Calculator

type MultiplicationRequest struct {
	A float64 `json:"a"`
	B float64 `json:"b"`
}

type MultiplicationResponse struct {
	Result float64 `json:"result"`
}

type SubtractionRequest struct {
	Subtrahend float64 `json:"subtrahend"`
	Minuend    float64 `json:"minuend"`
}

type SubtractionResponse struct {
	Result float64 `json:"result"`
}