[+] improve help prompts

Signed-off-by: Seven SUN <i@sunyz.net>

src/main.go

@@ -0,0 +1,44 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/realsunyz/geofeed-tools/plugin/validate"
+)
+
+const version = "1.0.0"
+
+var help = fmt.Sprintf(
+	"Geofeed Tools Version %s (compiled to binary)\n"+
+		"Usage: ./geofeed-tools [flags] [filepath]\n\n"+
+		"Flags:\n"+
+		"  -h    Show this help message\n"+
+		"  -v    Validate a geofeed file\n", version)
+
+func main() {
+	if len(os.Args) < 2 {
+		fmt.Print(help)
+		os.Exit(1)
+	}
+
+	flag := os.Args[1]
+
+	if flag == "-h" {
+		fmt.Print(help)
+		os.Exit(1)
+	} else if flag == "-v" {
+		if len(os.Args) != 3 {
+			fmt.Println(
+				"Usage: ./geofeed-tools -v [filepath]")
+			os.Exit(1)
+		}
+		filePath := os.Args[2]
+		validate.Execute(filePath)
+	} else {
+		fmt.Printf(
+			"Error: Invalid flag \"%s\"\n"+
+				"Use \"./geofeed-tools -h\" to see available flags.\n", os.Args[1])
+		os.Exit(1)
+	}
+}