Add executable

cmd/converter/main.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"context"
+	"converter/app"
+	"converter/domain"
+	"converter/infrastructure/coinmarketcap"
+	"fmt"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+)
+
+const (
+	expectedArgs = 4 // program name + 3 arguments
+	apiKeyEnvVar = "CMC_API_KEY"
+)
+
+func main() {
+	// Check command line arguments
+	if len(os.Args) != expectedArgs {
+		fmt.Fprintf(os.Stderr, "Usage: %s <amount> <from_currency> <to_currency>\n", os.Args[0])
+		fmt.Fprintf(os.Stderr, "Example: %s 100.50 USD BTC\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	// Parse arguments
+	amount := os.Args[1]
+	fromCurrency := os.Args[2]
+	toCurrency := os.Args[3]
+
+	// Get API key from environment
+	apiKey := os.Getenv(apiKeyEnvVar)
+	if apiKey == "" {
+		fmt.Fprintf(os.Stderr, "Error: %s environment variable is required\n", apiKeyEnvVar)
+		fmt.Fprintf(os.Stderr, "Please set your CoinMarketCap API key:\n")
+		fmt.Fprintf(os.Stderr, "export %s=your_api_key_here\n", apiKeyEnvVar)
+		os.Exit(1)
+	}
+
+	// Initialize dependencies
+	client := coinmarketcap.NewClient(apiKey)
+	converter := domain.NewCurrencyConverter()
+	useCase := app.NewConvertCurrencyUseCase(client, converter)
+
+	// Create context with timeout and signal handling
+	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
+	defer cancel()
+
+	// Set up graceful shutdown on interrupt signals
+	sigChan := make(chan os.Signal, 1)
+	signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
+
+	go func() {
+		<-sigChan
+		fmt.Fprintf(os.Stderr, "\nReceived interrupt signal, shutting down...\n")
+		cancel()
+	}()
+
+	// Execute conversion
+	result, err := useCase.Execute(ctx, amount, fromCurrency, toCurrency)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "Error: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Output result
+	fmt.Printf("%s %s\n", result.Amount.StringFixed(8), result.Currency.Code)
+}