add new flags, add the ability to print to stdout

rgb2rgb8.go

@@ -4,17 +4,21 @@ import (
 	"bufio"
 	"encoding/hex"
 	"fmt"
-	"github.com/ogier/pflag"
+	"github.com/spf13/pflag"
 	"github.com/wayneashleyberry/truecolor/pkg/color"
 	"math"
 	"os"
 )
 
+var output *os.File
+
 var (
 	outputFile string
 	verbose    bool
 	version    bool
 	colors     bool
+	print      bool
+	help       bool
 )
 
 func init() {
@@ -26,13 +30,12 @@ func init() {
 		"output file",
 	)
 	pflag.BoolVarP(
-		&verbose,
-		"verbose",
-		"v",
+		&print,
+		"print",
+		"p",
 		false,
-		"verbose output",
+		"print to stdout instead of output file. -o will have no effect",
 	)
-
 	pflag.BoolVarP(
 		&colors,
 		"colors",
@@ -40,16 +43,30 @@ func init() {
 		false,
 		"print colors to terminal (needs 24 bit color support)",
 	)
+	pflag.BoolVarP(
+		&verbose,
+		"verbose",
+		"v",
+		false,
+		"verbose output",
+	)
 	pflag.BoolVar(
 		&version,
 		"version",
 		false,
 		"version info",
 	)
+	pflag.BoolVarP(
+		&help,
+		"help",
+		"h",
+		false,
+		"displays help",
+	)
 }
 
-//converts different size bytes to float64 to compare
-//high and low and return the one thats closer
+// converts different size bytes to float64 to compare
+// high and low and return the one thats closer
 func compareChannels(base, high, low byte) byte {
 	absHigh := math.Abs(float64(high - base))
 	absLow := math.Abs(float64(low - base))
@@ -59,24 +76,33 @@ func compareChannels(base, high, low byte) byte {
 	return low
 }
 
+func printDefaults() {
+	fmt.Fprintf(os.Stderr, "Usage: %s [options] [-o outfile] infile\n", os.Args[0])
+	fmt.Fprintf(os.Stderr, "Options:\n")
+	pflag.PrintDefaults()
+}
+
 func main() {
-	pflag.Usage = func() {
-		fmt.Fprintf(os.Stderr, "%s is a utility that converts RGB24 hex palette files to 8bit 3-3-2 RGB.\n", os.Args[0])
-		fmt.Fprintf(os.Stderr, "Usage:\n")
-		pflag.PrintDefaults()
-	}
+	pflag.Usage = printDefaults
 
 	pflag.Parse()
 
 	if version {
-		fmt.Println("rgb2rgb8 v0.1")
+		fmt.Fprintf(os.Stderr, "%s is a utility that converts RGB24 hex palette files to 8bit 3-3-2 RGB.\n", os.Args[0])
+		fmt.Println("rgb2rgb8 v0.1.0")
 		fmt.Println("(c) 2025 Amber Zeller")
 		fmt.Println("Distributed under the MIT license")
 		os.Exit(0)
 	}
 
+	if help {
+		printDefaults()
+		os.Exit(0)
+	}
+
 	if len(pflag.Args()) == 0 {
 		fmt.Println("Error: No file specified.")
+		printDefaults()
 		os.Exit(1)
 	}
 
@@ -97,14 +123,14 @@ func main() {
 	defer input.Close()
 
 	//create output file
-	output, err := os.OpenFile(outputFile, os.O_WRONLY|os.O_CREATE, 0644)
-	if err != nil {
-		fmt.Println("Error: Cannot create output file.", err)
-		os.Exit(3)
+	if !print {
+		output, err = os.Create(outputFile)
+		if err != nil {
+			fmt.Println("Error: Cannot create output file.", err)
+			os.Exit(3)
+		}
 	}
 
-	defer output.Close()
-
 	//scan through input
 	scanner := bufio.NewScanner(input)
 	var data string
@@ -177,9 +203,14 @@ func main() {
 		fmt.Println(scanner.Err())
 	}
 
-	_, err = output.WriteString(data)
-	if err != nil {
-		fmt.Println("Error: Failed to write output file.", err)
-		os.Exit(4)
+	if print {
+		fmt.Fprintf(os.Stderr, "%s", data)
+	} else {
+		_, err = output.WriteString(data)
+		if err != nil {
+			fmt.Println("Error: Failed to write output file.", err)
+			os.Exit(4)
+		}
+		output.Close()
 	}
 }