// weather/temperature.go
package weather

// apiEndpoint is where the weather API lives
var apiEndpoint = "https://example.com"

// TemperatureNow fetch current temperature of specified city
func TemperatureNow(ctx context.Context, city string) (temperature float64, err error) {
	query := url.Values{
		"city":     []string{city},
	}

	var b strings.Builder
	b.WriteString(apiEndpoint)
	b.WriteString("/cgi-bin/temperature?")
	b.WriteString(query.Encode())

	req, err := http.NewRequest(http.MethodGet, b.String(), nil)
	
	// do the request, parse the result...

	return
}

// weather/temperature_test.go

// BackendMock mocks weather API, also checks incoming request
func BackendMock(t *testing.T, city string) *httptest.Server {
	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		assert.Equal(t, "/cgi-bin/temperature", r.URL.Path)
		assert.Equal(t, city, r.URL.Query().Get("city"))

		_, writeErr := io.WriteString(w, `{
  "code": 0,
  "msg": "ok",
  "celsius": 25
}`)
		require.NoError(t, writeErr)
	}))
}

// SetAPIEndpoint sets apiEndpoint
func SetAPIEndpoint(URL string) {
	apiEndpoint = URL
}

func TestTemperatureNow(t *testing.T) {
	// a made-up city name
	const city = "Fitton"

	backend := BackendMock(t, city)
	defer backend.Close()

	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()

	SetAPIEndpoint(backend.URL)
	temp, err := TemperatureNow(ctx, city)

	// do checks...
}