example: add library usage example

Author: psmohan

cmd/example/main.go

@@ -0,0 +1,109 @@
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"github.com/psmohan/configmate/pkg/configmate"
+)
+
+// Config defines the application configuration structure
+type Config struct {
+	// Server configuration
+	Server ServerConfig `config:"server"`
+
+	// Database configuration
+	Database DatabaseConfig `config:"database"`
+
+	// Application settings
+	AppName string `config:"app_name,required"`
+	Debug   bool   `config:"debug,default=false"`
+	Port    int    `config:"port,default=8080"`
+}
+
+// ServerConfig holds server-specific settings
+type ServerConfig struct {
+	Host         string `config:"host,default=localhost"`
+	ReadTimeout  int    `config:"read_timeout,default=30"`
+	WriteTimeout int    `config:"write_timeout,default=30"`
+}
+
+// DatabaseConfig holds database connection settings
+type DatabaseConfig struct {
+	URL             string `config:"url,required"`
+	MaxConnections  int    `config:"max_connections,default=10"`
+	ConnMaxLifetime int    `config:"conn_max_lifetime,default=300"`
+}
+
+func main() {
+	// Create logger and metrics
+	logger := configmate.NewDefaultLogger(configmate.LogLevelInfo)
+	metrics := configmate.NewDefaultMetrics()
+
+	var cfg Config
+
+	// Load configuration with all features enabled
+	loader := configmate.NewLoader(
+		configmate.WithPrefix("APP"),
+		configmate.WithLogger(logger),
+		configmate.WithMetrics(metrics),
+		configmate.WithCache(true),
+		configmate.WithCacheTTL(5*time.Minute),
+		configmate.WithWatch(true),
+		configmate.WithSecureMode(true),
+		configmate.WithOnReload(func(newCfg interface{}) {
+			fmt.Println("🔄 Configuration reloaded!")
+			printConfig(newCfg.(*Config))
+		}),
+	)
+
+	// Load configuration
+	err := loader.Load(&cfg, ".env", "config.yaml")
+	if err != nil {
+		log.Fatalf("Failed to load config: %v", err)
+	}
+
+	// Print loaded configuration
+	fmt.Println("✅ Configuration loaded successfully!")
+	printConfig(&cfg)
+
+	// Print metrics
+	fmt.Println("\n📊 Metrics:")
+	stats := metrics.GetStats()
+	fmt.Printf("  Load Count: %d\n", stats.LoadCount)
+	fmt.Printf("  Average Duration: %v\n", stats.AverageDuration)
+	fmt.Printf("  Cache Hits: %d\n", stats.CacheHits)
+	fmt.Printf("  Cache Misses: %d\n", stats.CacheMisses)
+
+	// Wait for interrupt signal
+	fmt.Println("\n👀 Watching for configuration changes... (Press Ctrl+C to exit)")
+
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, os.Interrupt, syscall.SIGTERM)
+
+	<-sigChan
+
+	fmt.Println("\n👋 Shutting down...")
+	if err := loader.Close(); err != nil {
+		log.Printf("Error closing loader: %v", err)
+	}
+}
+
+func printConfig(cfg *Config) {
+	fmt.Println("\n=== Configuration ===")
+	fmt.Printf("App Name: %s\n", cfg.AppName)
+	fmt.Printf("Debug Mode: %v\n", cfg.Debug)
+	fmt.Printf("Port: %d\n", cfg.Port)
+	fmt.Println("\nServer:")
+	fmt.Printf("  Host: %s\n", cfg.Server.Host)
+	fmt.Printf("  Read Timeout: %ds\n", cfg.Server.ReadTimeout)
+	fmt.Printf("  Write Timeout: %ds\n", cfg.Server.WriteTimeout)
+	fmt.Println("\nDatabase:")
+	fmt.Printf("  URL: %s\n", cfg.Database.URL)
+	fmt.Printf("  Max Connections: %d\n", cfg.Database.MaxConnections)
+	fmt.Printf("  Conn Max Lifetime: %ds\n", cfg.Database.ConnMaxLifetime)
+}