Add -h, --help flags

main.go

@@ -1,14 +1,28 @@
 package main
 
 import (
+	"flag"
 	"fmt"
 	"os"
+
 	"pg_flame/pkg/flame"
 	"pg_flame/pkg/html"
 	"pg_flame/pkg/plan"
 )
 
+var (
+	version  = "1.0"
+	hFlag    = flag.Bool("h", false, "print help info")
+	helpFlag = flag.Bool("help", false, "print help info")
+)
+
 func main() {
+	flag.Parse()
+
+	if *hFlag || *helpFlag {
+		printHelp()
+	}
+
 	err, p := plan.New(os.Stdin)
 	if err != nil {
 		handleErr(err)
@@ -27,3 +41,26 @@ func handleErr(err error) {
 	fmt.Println(msg)
 	os.Exit(1)
 }
+
+func printHelp() {
+	help := `pg_flame %s
+
+Turn Postgres query plans into flamegraphs.
+
+Usage:
+
+  pg_flame [options]
+
+Without Options:
+
+  Reads a JSON query plan from standard input and writes the
+  flamegraph html to standard output.
+
+Options:
+
+  -h, --help	print help information
+`
+
+	fmt.Printf(help, version)
+	os.Exit(0)
+}