solar: Collect metrics periodically

cmd/main.go

@@ -52,7 +52,8 @@ func main() {
 	solar := internal.NewSolar(client, deyeUser, deyePassword)
 
 	myCron := cron.New()
-	myCron.AddFunc("0 0 18 * * *", solar.SendDailyReport)
+	myCron.AddFunc("0 0 18 * * *", solar.CronSendDailyReport)
+	myCron.AddFunc("0 */15 * * * *", solar.CronCollectMetrics)
 	myCron.Start()
 
 	// Listen to Ctrl+C (you can also do something else that prevents the program from exiting)

internal/solar.go

@@ -12,15 +12,23 @@ import (
 
 const adminStatusEndpoint = "http://deye-solar-inverter/status.html"
 const expectedDailyOutput float64 = 20
+const criticalBelowDailyOutput float64 = 10
 
 var yieldTodayPattern = regexp.MustCompile(`var webdata_today_e = "([^"]+)";`)
 var yieldTotalPattern = regexp.MustCompile(`var webdata_total_e = "([^"]+)";`)
 
+type SolarMetrics struct {
+	lastUpdatedAt time.Time
+	today         float64
+	total         float64
+}
+
 type Solar struct {
 	client        *Client
 	channelId     string
 	adminUser     string
 	adminPassword string
+	metrics       SolarMetrics
 }
 
 func NewSolar(client *Client, adminUser, adminPassword string) *Solar {
@@ -38,39 +46,36 @@ func NewSolar(client *Client, adminUser, adminPassword string) *Solar {
 	}
 }
 
-func (this *Solar) SendDailyReport() {
-	metrics, err := this.querySolarMetrics()
+func (this *Solar) CronSendDailyReport() {
+	// TODO: Add retries?
+	fmt.Println("[SOLAR] Cron job invoked to send daily report")
+	defer fmt.Println("[SOLAR] Cron job completed to send daily report")
+
+	if this.metrics.lastUpdatedAt.IsZero() {
+		fmt.Println("[SOLAR] Got zero value for lastUpdatedAt, means either inverter is not working properly or there was a long power outage or network connectivity problems")
+
+		this.client.SendTextMessage(
+			this.channelId,
+			messageHeaderLine()+
+				"🔴 Couldn't collect any data today. Check logs, inverter and connectivity.",
+		)
 
-	if err != nil {
-		fmt.Println("Error querying soalr metrics:", err)
 		return
 	}
 
-	fmt.Printf("[SOLAR] Metrics: %v\n", metrics)
-
-	deltaYieldToday := metrics.today - expectedDailyOutput
-
-	var summary string
-
-	if deltaYieldToday < 0 {
-		summary = fmt.Sprintf("☹️ Below expected daily yield of %.2f kWh", expectedDailyOutput)
-	} else {
-		summary = fmt.Sprintf("😁 Above expected daily yield by %.2f kWh", deltaYieldToday)
-	}
-
-	var todayFormatted = time.Now().Format("Monday, 2 Jan 2006")
+	fmt.Printf("[SOLAR] Metrics: %v\n", this.metrics)
 
 	message := fmt.Sprintf(
-		"*🔆 Solar Production Report — %s*\n\n"+
-			summary+
+		messageHeaderLine()+
+			this.getSummary()+
 			"\n\n"+
 			"*Today: %.2f kWh*\n"+
 			"Total: %.2f kWh\n\n"+
-			"`DO NOT CLICK: %d`",
-		todayFormatted,
-		metrics.today,
-		metrics.total,
-		time.Now().Unix(),
+			"_Last updated: %s_\n\n"+
+			messageDoNotClickLine(),
+		this.metrics.today,
+		this.metrics.total,
+		time.Now().Format("03:04 PM, 2006-01-02"),
 	)
 
 	fmt.Printf("[SOLAR] Message to be sent:\n%s", message)
@@ -81,10 +86,40 @@ func (this *Solar) SendDailyReport() {
 	)
 }
 
-func (this *Solar) querySolarMetrics() (*struct {
-	today float64
-	total float64
-}, error) {
+func (this *Solar) getSummary() string {
+	deltaYieldToday := this.metrics.today - expectedDailyOutput
+
+	if this.metrics.today < criticalBelowDailyOutput {
+		return fmt.Sprintf("⚠️ Yield was only %.2f kWh today, well below expected %.2f kWh. Check if this was due to bad weather/powercut or if panels need maintenance.", this.metrics.today, expectedDailyOutput)
+	} else if deltaYieldToday < 0 {
+		return fmt.Sprintf("☹️ Below expected daily yield of %.2f kWh", expectedDailyOutput)
+	} else {
+		return fmt.Sprintf("😁 Above expected daily yield by %.2f kWh", deltaYieldToday)
+	}
+}
+
+func (this *Solar) CronCollectMetrics() {
+	fmt.Println("[SOLAR] Cron job invoked to collect fresh metrics")
+	defer fmt.Println("[SOLAR] Cron job completed to collect fresh metrics")
+
+	// Reset if we rolled over to next day
+	if !AreSameDay(time.Now(), this.metrics.lastUpdatedAt) {
+		this.metrics = SolarMetrics{}
+	}
+
+	metrics, err := this.querySolarMetrics()
+
+	if err != nil {
+		fmt.Println("[SOLAR] Error querying solar metrics:", err)
+		return
+	}
+
+	this.metrics = *metrics
+
+	fmt.Printf("[SOLAR] Updated metrics: %+v\n", this.metrics)
+}
+
+func (this *Solar) querySolarMetrics() (*SolarMetrics, error) {
 	req, err := http.NewRequest("GET", adminStatusEndpoint, nil)
 	if err != nil {
 		panic(err)
@@ -92,7 +127,6 @@ func (this *Solar) querySolarMetrics() (*struct {
 
 	req.SetBasicAuth(this.adminUser, this.adminPassword)
 	res, err := http.DefaultClient.Do(req)
-
 	if err != nil {
 		panic(err)
 	}
@@ -104,7 +138,6 @@ func (this *Solar) querySolarMetrics() (*struct {
 	defer res.Body.Close()
 
 	rawBody, err := io.ReadAll(res.Body)
-
 	if err != nil {
 		return nil, err
 	}
@@ -117,7 +150,6 @@ func (this *Solar) querySolarMetrics() (*struct {
 	}
 
 	yieldToday, err := strconv.ParseFloat(matches[1], 64)
-
 	if err != nil {
 		return nil, fmt.Errorf("Failed to convert %s to float64: %w", matches[1], err)
 	}
@@ -129,16 +161,21 @@ func (this *Solar) querySolarMetrics() (*struct {
 	}
 
 	yieldTotal, err := strconv.ParseFloat(matches[1], 64)
-
 	if err != nil {
 		return nil, fmt.Errorf("Failed to convert %s to float64: %w", matches[1], err)
 	}
 
-	return &struct {
-		today float64
-		total float64
-	}{
-		today: yieldToday,
-		total: yieldTotal,
+	return &SolarMetrics{
+		lastUpdatedAt: time.Now(),
+		today:         yieldToday,
+		total:         yieldTotal,
 	}, nil
 }
+
+func messageDoNotClickLine() string {
+	return fmt.Sprintf("`DO NOT CLICK: %d`", time.Now().Unix())
+}
+
+func messageHeaderLine() string {
+	return fmt.Sprintf("*🔆 Solar Production Report — %s*\n\n", time.Now().Format("2 Jan 2006"))
+}