Issue-6: Add support to select monitor location (#9)

## Issue:
* #6

## Changes
* Added support to select monitor location
* Dedicated function for converting temperature
* Added additional test cases
* Rename test cases with better names

README.md

@@ -7,6 +7,7 @@ Show AirGradient measurements in MacOS menu bar
 Configuration location - `~user/.airdash/config.yaml`
 ```yaml
 token: <secret-token>
+locationId: <location-id>
 interval: 60
 tempUnit: F
 ```

airgradient.go

@@ -3,12 +3,13 @@ package main
 import (
 	"encoding/json"
 	"errors"
+	"fmt"
 	"io"
 	"net/http"
 	"time"
 )
 
-type AirGradientMeasures []struct {
+type AirGradientMeasures struct {
 	LocationID         int       `json:"locationId"`
 	LocationName       string    `json:"locationName"`
 	Pm01               float64   `json:"pm01"`
@@ -31,6 +32,27 @@ type AirGradientMeasures []struct {
 	NoxIndex           float64   `json:"noxIndex"`
 }
 
+var ErrBadPayload = errors.New("Error unmarshalling JSON")
+
+// getAirGradientAPIURL returns the AirGradient API URL
+func getAirGradientAPIURL(locationID int) string {
+	if locationID != 0 {
+		return fmt.Sprintf("https://api.airgradient.com/public/api/v1/locations/%d/measures/current", locationID)
+	}
+	return fmt.Sprintf("https://api.airgradient.com/public/api/v1/locations/measures/current")
+}
+
+// convertTemperature converts the temperature from Celsius to Fahrenheit if the
+// temperature unit is set to Fahrenheit
+// By default the temperature unit is Celsius
+func convertTemperature(temperature float64, tempUnit string) float64 {
+	if tempUnit == "F" {
+		return (temperature * 9 / 5) + 32
+	}
+	return temperature
+}
+
+// fetchMeasures fetches the measures from the AirGradient API
 func fetchMeasures(airGradientAPIUrl string, token string) ([]byte, error) {
 	client := &http.Client{}
 
@@ -61,16 +83,34 @@ func fetchMeasures(airGradientAPIUrl string, token string) ([]byte, error) {
 }
 
 func getAirGradientMeasures(airGradientAPIUrl string, token string) (AirGradientMeasures, error) {
+	var arrayAirGradientMeasures []AirGradientMeasures
+	var airGradientMeasures AirGradientMeasures
+
 	payload, err := fetchMeasures(airGradientAPIUrl, token)
 	if err != nil {
-		return nil, err
+		return airGradientMeasures, err
 	}
 
-	var airGradientMeasures AirGradientMeasures
+	var checkInterface interface{}
+	json.Unmarshal(payload, &checkInterface)
 
-	err = json.Unmarshal(payload, &airGradientMeasures)
-	if err != nil {
-		return nil, errors.New("Error unmarshalling JSON")
+	switch checkInterface.(type) {
+	case map[string]interface{}:
+		err = json.Unmarshal(payload, &airGradientMeasures)
+		if err != nil {
+			return airGradientMeasures, ErrBadPayload
+		}
+	case []interface{}:
+		err = json.Unmarshal(payload, &arrayAirGradientMeasures)
+		if err != nil {
+			return airGradientMeasures, ErrBadPayload
+		}
+		if len(arrayAirGradientMeasures) == 0 {
+			return airGradientMeasures, ErrBadPayload
+		}
+		airGradientMeasures = arrayAirGradientMeasures[0]
+	default:
+		return airGradientMeasures, ErrBadPayload
 	}
 
 	return airGradientMeasures, nil

airgradient_test.go

@@ -9,25 +9,81 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
+func TestGetAirGradientAPIURL(t *testing.T) {
+	var testCases = []struct {
+		name        string
+		locationID  int
+		expectedURL string
+	}{
+		{
+			"location-id-0",
+			0,
+			"https://api.airgradient.com/public/api/v1/locations/measures/current",
+		},
+		{
+			"location-id-12345",
+			12345,
+			"https://api.airgradient.com/public/api/v1/locations/12345/measures/current",
+		},
+	}
+	for _, tC := range testCases {
+		t.Run(tC.name, func(t *testing.T) {
+			assert.Equal(t, tC.expectedURL, getAirGradientAPIURL(tC.locationID))
+		})
+	}
+}
+
+func TestConvertTemp(t *testing.T) {
+	var testCases = []struct {
+		name     string
+		temp     float64
+		tempUnit string
+		expected float64
+	}{
+		{
+			"convert-celsius-to-fahrenheit",
+			20,
+			"F",
+			68,
+		},
+		{
+			"no-conversion",
+			20,
+			"C",
+			20,
+		},
+	}
+	for _, tC := range testCases {
+		t.Run(tC.name, func(t *testing.T) {
+			assert.Equal(t, tC.expected, convertTemperature(tC.temp, tC.tempUnit))
+		})
+	}
+}
+
 func TestGetAirGradientMeasures(t *testing.T) {
 	var testCases = []struct {
 		name        string
 		payloadFile string
 		err         error
 	}{
 		{
-			"correct-response",
-			"testdata/correct_response1.json",
+			"correct-api-v1-locations-measures-current",
+			"testdata/api-v1-locations-measures-current.json",
+			nil,
+		},
+		{
+			"correct-api-v1-locations-measures-current-with-more-float64",
+			"testdata/api-v1-locations-measures-current-with-more-float64.json",
 			nil,
 		},
 		{
-			"correct-response2",
-			"testdata/correct_response2.json",
+			"correct-api-v1-locations-12345-measures-current",
+			"testdata/api-v1-locations-12345-measures-current.json",
 			nil,
 		},
 		{
-			"incorrect-response",
-			"testdata/incorrect_response1.json",
+			"incorrect-response-404",
+			"testdata/incorrect-response-404.json",
 			errors.New("Error unmarshalling JSON"),
 		},
 	}

config.go

@@ -8,11 +8,13 @@ import (
 )
 
 type Config struct {
-	Token    string `yaml:"token"`
-	Interval int    `yaml:"interval"`
-	TempUnit string `yaml:"tempUnit"`
+	Token      string `yaml:"token"`
+	LocationID int    `yaml:"locationId"`
+	Interval   int    `yaml:"interval"`
+	TempUnit   string `yaml:"tempUnit"`
 }
 
+// LoadConfig loads the config from the given path
 func LoadConfig(path string) (*Config, error) {
 	f, err := os.ReadFile(filepath.Clean(path))
 	if err != nil {

config.sample.yaml

@@ -1,3 +1,4 @@
 token: <your-secret-token>
+locationId: 0
 interval: 60
 tempUnit: F

config_test.go

@@ -30,14 +30,16 @@ func TestLoadConfig(t *testing.T) {
 		name          string
 		configContent []byte
 		token         string
+		locationID    int
 		interval      int
 		tempUnit      string
 		err           error
 	}{
 		{
 			"full-token",
-			[]byte(fmt.Sprintf("token: \"1234567890\"\ninterval: 60\ntempUnit: \"C\"")),
+			[]byte(fmt.Sprintf("token: \"1234567890\"\nlocationId: 0\ninterval: 60\ntempUnit: \"C\"")),
 			"1234567890",
+			0,
 			60,
 			"C",
 			nil,
@@ -47,6 +49,7 @@ func TestLoadConfig(t *testing.T) {
 			[]byte(fmt.Sprintf("token: \"1234567890\"\ntempUnit: \"F\"")),
 			"1234567890",
 			0,
+			0,
 			"F",
 			nil,
 		},
@@ -55,6 +58,7 @@ func TestLoadConfig(t *testing.T) {
 			[]byte(`foobar-invalid`),
 			"",
 			0,
+			0,
 			"",
 			&yaml.TypeError{Errors: []string{"line 1: cannot unmarshal !!str `foobar-...` into main.Config"}}},
 	}
@@ -68,6 +72,7 @@ func TestLoadConfig(t *testing.T) {
 			cfg, err := LoadConfig(tempFile.Name())
 			if err == nil {
 				assert.Equal(t, tC.token, cfg.Token)
+				assert.Equal(t, tC.locationID, cfg.LocationID)
 				assert.Equal(t, tC.interval, cfg.Interval)
 				assert.Equal(t, tC.tempUnit, cfg.TempUnit)
 			}

main.go

@@ -11,8 +11,6 @@ import (
 	"github.com/progrium/macdriver/objc"
 )
 
-const AIR_GRADIENT_API_URL = "https://api.airgradient.com/public/api/v1/locations/measures/current"
-
 func main() {
 	macos.RunApp(launched)
 }
@@ -38,6 +36,8 @@ func launched(app appkit.Application, delegate *appkit.ApplicationDelegate) {
 		cfg.Interval = 60
 	}
 
+	airGradientAPIURL := getAirGradientAPIURL(cfg.LocationID)
+
 	item := appkit.StatusBar_SystemStatusBar().StatusItemWithLength(-1)
 	objc.Retain(&item)
 	item.Button().SetTitle("🔄 AirDash")
@@ -46,32 +46,24 @@ func launched(app appkit.Application, delegate *appkit.ApplicationDelegate) {
 		for {
 			select {
 			case <-time.After(time.Duration(cfg.Interval) * time.Second):
-				airGradientMeasures, err = getAirGradientMeasures(AIR_GRADIENT_API_URL, cfg.Token)
+				airGradientMeasures, err = getAirGradientMeasures(airGradientAPIURL, cfg.Token)
 				if err != nil {
 					logger.Error("Fetching measures", "error", err)
 					continue
 				}
 			}
+			logger.Debug("AirGradientMeasures", "measures", airGradientMeasures)
 
-			if len(airGradientMeasures) == 0 {
-				logger.Error("No measurements found")
-				return
-			}
-
-			logger.Debug("AirGradientMeasures", "measures", airGradientMeasures[0])
-
-			temperature := airGradientMeasures[0].Atmp
-			if cfg.TempUnit == "F" {
-				temperature = (airGradientMeasures[0].Atmp * 9 / 5) + 32
-			}
+			// convert the temperature to the desired unit
+			temperature := convertTemperature(airGradientMeasures.Atmp, cfg.TempUnit)
 
 			// updates to the ui should happen on the main thread to avoid segfaults
 			dispatch.MainQueue().DispatchAsync(func() {
 				item.Button().SetTitle(fmt.Sprintf("🌡️ %.2f  💨 %.0f  💧 %.1f  🫧 %.0f",
 					temperature,
-					airGradientMeasures[0].Pm02,
-					airGradientMeasures[0].Rhum,
-					airGradientMeasures[0].Rco2,
+					airGradientMeasures.Pm02,
+					airGradientMeasures.Rhum,
+					airGradientMeasures.Rco2,
 				))
 			})
 		}

testdata/api-v1-locations-12345-measures-current.json

@@ -0,0 +1 @@
+{"locationId":12345,"locationName":"Test Loc","pm01":null,"pm02":5,"pm10":null,"pm003Count":null,"atmp":23.3,"rhum":53,"rco2":537,"tvoc":93.979355,"wifi":-52,"timestamp":"2023-10-11T04:50:46.000Z","ledMode":"co2","ledCo2Threshold1":1000,"ledCo2Threshold2":2000,"ledCo2ThresholdEnd":4000,"serialno":"aabb12","firmwareVersion":null,"tvocIndex":100,"noxIndex":1}