Initila commit

collector/factory.go

@@ -0,0 +1,85 @@
+// Package collector maps Shelly product types to Prometheus collectors.
+package collector
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+	"sync"
+	"unicode"
+
+	"github.com/prometheus/client_golang/prometheus"
+	"lostak.dev/shelly-exporter/configuration"
+	"lostak.dev/shelly-exporter/shelly"
+)
+
+// Factory constructs a collector for one configured device.
+type Factory func(configuration.DeviceConfiguration, shelly.StatusClient) (prometheus.Collector, error)
+
+var (
+	factoriesMutex sync.RWMutex
+	factories      = make(map[string]Factory)
+)
+
+// RegisterProduct adds support for a product identifier. Product packages call it from init.
+func RegisterProduct(product string, factory Factory) error {
+	product = normalizeProduct(product)
+	if product == "" {
+		return fmt.Errorf("product identifier cannot be empty")
+	}
+	if factory == nil {
+		return fmt.Errorf("factory for product %q cannot be nil", product)
+	}
+
+	factoriesMutex.Lock()
+	defer factoriesMutex.Unlock()
+	if _, exists := factories[product]; exists {
+		return fmt.Errorf("product %q is already registered", product)
+	}
+	factories[product] = factory
+	return nil
+}
+
+// NewDeviceCollector creates the registered collector for a configured product.
+func NewDeviceCollector(config configuration.DeviceConfiguration, client shelly.StatusClient) (prometheus.Collector, error) {
+	product := normalizeProduct(config.Product)
+
+	factoriesMutex.RLock()
+	factory, exists := factories[product]
+	factoriesMutex.RUnlock()
+	if !exists {
+		return nil, fmt.Errorf("unsupported Shelly product %q (supported: %s)", config.Product, strings.Join(SupportedProducts(), ", "))
+	}
+	config.Product = product
+	return factory(config, client)
+}
+
+// SupportedProducts returns all registered identifiers in stable order.
+func SupportedProducts() []string {
+	factoriesMutex.RLock()
+	defer factoriesMutex.RUnlock()
+
+	products := make([]string, 0, len(factories))
+	for product := range factories {
+		products = append(products, product)
+	}
+	sort.Strings(products)
+	return products
+}
+
+func normalizeProduct(product string) string {
+	var normalized strings.Builder
+	separator := false
+	for _, character := range strings.ToLower(strings.TrimSpace(product)) {
+		if unicode.IsLetter(character) || unicode.IsDigit(character) {
+			if separator && normalized.Len() > 0 {
+				normalized.WriteByte('_')
+			}
+			normalized.WriteRune(character)
+			separator = false
+		} else {
+			separator = true
+		}
+	}
+	return normalized.String()
+}