feat: Add ocr-incr-only flag

Author: dcelasun

README.md

@@ -131,6 +131,7 @@ All options can be set via CLI flags or environment variables. Flags take preced
 | `--mqtt-device-manufacturer` | `MQTT_DEVICE_MANUFACTURER` | `Generic` | Manufacturer shown in Home Assistant |
 | `--mqtt-device-model` | `MQTT_DEVICE_MODEL` | `Generic` | Model shown in Home Assistant |
 | `--meter-divisor` | `METER_DIVISOR` | `1000` | Divisor to convert raw reading to m³ (e.g. `000354225` / `1000` = `354.225`) |
+| `--ocr-incr-only` | `OCR_INCR_ONLY` | `false` | Only publish readings that are ≥ the previous value (after dividing by `meter-divisor`), discarding likely OCR errors |
 
 ### MQTT / Home Assistant
 

http.go

@@ -3,13 +3,20 @@ package main
 import (
 	"io"
 	"log"
+	"math"
 	"net/http"
 	"os"
 	"path/filepath"
 	"strconv"
+	"sync"
 	"time"
 )
 
+var (
+	lastReadingMu sync.Mutex
+	lastReading   = math.NaN()
+)
+
 func handleOCR(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
 		http.Error(w, "POST only", http.StatusMethodNotAllowed)
@@ -96,22 +103,41 @@ func processOCR(imageData []byte, batLevel, batVoltage int) {
 
 	reading := extractReading(ocrOut.Texts, ocrMatchRe, ocrFixRules)
 
-	if reading != "" {
-		if val, err := strconv.ParseFloat(reading, 64); err == nil {
-			metricMeterReading.Set(val)
-		}
+	// Append reading to CSV unconditionally so discarded values are still on disk.
+	storeReading(imagePath, reading)
+
+	if reading == "" {
+		log.Printf("OCR completed in %s: no reading found, texts=%v", elapsed, ocrOut.Texts)
+		return
 	}
 
-	// Append reading to CSV now that we have a result.
-	storeReading(imagePath, reading)
+	val, err := strconv.ParseFloat(reading, 64)
+	if err != nil {
+		log.Printf("OCR completed in %s: invalid reading %q, texts=%v", elapsed, reading, ocrOut.Texts)
+		return
+	}
+
+	divided := val / meterDivisor
 
-	if mqttBroker != "" && reading != "" {
-		if val, err := strconv.ParseFloat(reading, 64); err == nil {
-			publishReading(val/meterDivisor, batLevel, batVoltage)
+	if ocrIncrOnly {
+		lastReadingMu.Lock()
+		prev := lastReading
+		if !math.IsNaN(prev) && divided < prev {
+			lastReadingMu.Unlock()
+			log.Printf("OCR incr-only: discarding reading %.3f < previous %.3f", divided, prev)
+			return
 		}
+		lastReading = divided
+		lastReadingMu.Unlock()
+	}
+
+	metricMeterReading.Set(val)
+
+	if mqttBroker != "" {
+		publishReading(divided, batLevel, batVoltage)
 	}
 
-	log.Printf("OCR completed in %s: reading=%s texts=%v", elapsed, reading, ocrOut.Texts)
+	log.Printf("OCR completed in %s: reading=%s (%.3f m³) texts=%v", elapsed, reading, divided, ocrOut.Texts)
 }
 
 func handleHealth(w http.ResponseWriter, r *http.Request) {

main.go

@@ -29,6 +29,7 @@ var (
 	mqttDeviceManufacturer string
 	mqttDeviceModel        string
 	meterDivisor           float64
+	ocrIncrOnly            bool
 )
 
 func main() {
@@ -120,6 +121,11 @@ func main() {
 				Usage:   "Divisor to convert the raw OCR reading to m³ (e.g. 000354225 / 1000 = 354.225)",
 				Sources: cli.EnvVars("METER_DIVISOR"),
 			},
+			&cli.BoolFlag{
+				Name:    "ocr-incr-only",
+				Usage:   "Only publish readings that are >= the previous reading (after dividing by meter-divisor), discarding likely OCR errors",
+				Sources: cli.EnvVars("OCR_INCR_ONLY"),
+			},
 		},
 		Action: run,
 	}
@@ -146,6 +152,7 @@ func run(_ context.Context, cmd *cli.Command) error {
 	mqttDeviceManufacturer = cmd.String("mqtt-device-manufacturer")
 	mqttDeviceModel = cmd.String("mqtt-device-model")
 	meterDivisor = cmd.Float("meter-divisor")
+	ocrIncrOnly = cmd.Bool("ocr-incr-only")
 
 	if mqttBroker != "" {
 		initMQTT()