Add initial MQTT scrubber service scaffold

internal/parser/tasmota.go

@@ -0,0 +1,158 @@
+package parser
+
+import (
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"sort"
+	"strings"
+	"time"
+
+	"mqqt-scrubber/internal/model"
+)
+
+var invalidNameCharacters = regexp.MustCompile(`[^a-z0-9_]+`)
+var acronymBoundary = regexp.MustCompile(`([A-Z]+)([A-Z][a-z])`)
+var camelBoundary = regexp.MustCompile(`([a-z0-9])([A-Z])`)
+
+var tasmotaTimeLayouts = []string{
+	time.RFC3339Nano,
+	time.RFC3339,
+	"2006-01-02T15:04:05",
+}
+
+func ParseTasmota(message model.RawMessage) ([]model.Record, error) {
+	parts := strings.Split(message.Topic, "/")
+	if len(parts) != 3 {
+		return nil, fmt.Errorf("unsupported topic shape: %s", message.Topic)
+	}
+	if parts[0] != "tele" {
+		return nil, fmt.Errorf("unsupported topic root: %s", message.Topic)
+	}
+
+	measurement := "tasmota_" + sanitizeName(parts[2])
+	tags := map[string]string{
+		"device":       sanitizeDeviceName(parts[1]),
+		"message_type": sanitizeName(parts[2]),
+		"source":       "tasmota",
+	}
+
+	if strings.EqualFold(parts[2], "LWT") {
+		return []model.Record{parseLWT(message, measurement, tags)}, nil
+	}
+
+	var payload map[string]any
+	if err := json.Unmarshal(message.Payload, &payload); err != nil {
+		return nil, fmt.Errorf("invalid json payload: %w", err)
+	}
+
+	fields := flattenPayload(payload, nil)
+	delete(fields, "time")
+	if len(fields) == 0 {
+		return nil, fmt.Errorf("no usable fields in payload for topic %s", message.Topic)
+	}
+
+	timestamp := parsePayloadTimestamp(payload, message.ReceivedAt)
+
+	record := model.Record{
+		Measurement: measurement,
+		Tags:        tags,
+		Fields:      fields,
+		Timestamp:   timestamp,
+	}
+
+	return []model.Record{record}, nil
+}
+
+func parseLWT(message model.RawMessage, measurement string, tags map[string]string) model.Record {
+	state := strings.TrimSpace(string(message.Payload))
+	return model.Record{
+		Measurement: measurement,
+		Tags:        tags,
+		Fields: map[string]any{
+			"state":  state,
+			"online": strings.EqualFold(state, "Online"),
+		},
+		Timestamp: message.ReceivedAt,
+	}
+}
+
+func parsePayloadTimestamp(payload map[string]any, fallback time.Time) time.Time {
+	rawTime, ok := payload["Time"].(string)
+	if !ok || strings.TrimSpace(rawTime) == "" {
+		return fallback
+	}
+
+	for _, layout := range tasmotaTimeLayouts {
+		var (
+			parsed time.Time
+			err    error
+		)
+
+		if layout == "2006-01-02T15:04:05" {
+			parsed, err = time.ParseInLocation(layout, rawTime, time.UTC)
+		} else {
+			parsed, err = time.Parse(layout, rawTime)
+		}
+
+		if err == nil {
+			return parsed
+		}
+	}
+
+	return fallback
+}
+
+func flattenPayload(payload map[string]any, prefix []string) map[string]any {
+	result := make(map[string]any)
+
+	keys := make([]string, 0, len(payload))
+	for key := range payload {
+		keys = append(keys, key)
+	}
+	sort.Strings(keys)
+
+	for _, key := range keys {
+		value := payload[key]
+		nameParts := append(prefix, sanitizeName(key))
+
+		switch typed := value.(type) {
+		case map[string]any:
+			nested := flattenPayload(typed, nameParts)
+			for nestedKey, nestedValue := range nested {
+				result[nestedKey] = nestedValue
+			}
+		case float64, bool, string:
+			result[strings.Join(nameParts, "_")] = typed
+		}
+	}
+
+	return result
+}
+
+func sanitizeName(value string) string {
+	normalized := strings.TrimSpace(value)
+	normalized = strings.ReplaceAll(normalized, "-", "_")
+	normalized = strings.ReplaceAll(normalized, " ", "_")
+	normalized = acronymBoundary.ReplaceAllString(normalized, `${1}_${2}`)
+	normalized = camelBoundary.ReplaceAllString(normalized, `${1}_${2}`)
+	normalized = strings.ToLower(normalized)
+	normalized = invalidNameCharacters.ReplaceAllString(normalized, "_")
+	normalized = strings.Trim(normalized, "_")
+	if normalized == "" {
+		return "unknown"
+	}
+	return normalized
+}
+
+func sanitizeDeviceName(value string) string {
+	normalized := strings.ToLower(strings.TrimSpace(value))
+	normalized = strings.ReplaceAll(normalized, "-", "_")
+	normalized = strings.ReplaceAll(normalized, " ", "_")
+	normalized = invalidNameCharacters.ReplaceAllString(normalized, "_")
+	normalized = strings.Trim(normalized, "_")
+	if normalized == "" {
+		return "unknown"
+	}
+	return normalized
+}