change --image flag to accept an image format png or svg

cmd/maze/action.go

@@ -38,12 +38,15 @@ func action(ctx *cli.Context) error {
 		defer termbox.Close()
 		interactive(maze, config.Format)
 	} else {
-		if config.Image {
-			maze.PrintImage(config.Output, config.Format, config.Scale)
-		} else if config.SVG {
-			maze.PrintSVG(config.Output, config.Format, config.Scale)
-		} else {
+		switch config.Image {
+		case "":
 			maze.Print(config.Output, config.Format)
+		case "png":
+			maze.PrintPNG(config.Output, config.Format, config.Scale)
+		case "svg":
+			maze.PrintSVG(config.Output, config.Format, config.Scale)
+		default:
+			return fmt.Errorf("unsupported image format: %s", config.Image)
 		}
 	}
 	return nil

cmd/maze/config.go

@@ -22,8 +22,7 @@ type Config struct {
 	Start       *maze.Point
 	Goal        *maze.Point
 	Interactive bool
-	Image       bool
-	SVG         bool
+	Image       string
 	Scale       int
 	Solution    bool
 	Format      *maze.Format
@@ -108,14 +107,13 @@ func makeConfig(ctx *cli.Context) (*Config, []error) {
 		}
 	}
 
-	image := ctx.GlobalBool("image")
-	if image {
+	image := ctx.GlobalString("image")
+	if image != "" {
 		if file, ok := output.(*os.File); ok && isatty.IsTerminal(file.Fd()) {
-			errs = append(errs, errors.New("cannot write binary data into the terminal\nuse -output flag"))
+			errs = append(errs, errors.New("cannot write image data into the terminal\nuse -output flag"))
 		}
 	}
 
-	svg := ctx.GlobalBool("svg")
 	scale := ctx.GlobalInt("scale")
 
 	seed := int64(ctx.GlobalInt("seed"))
@@ -134,7 +132,6 @@ func makeConfig(ctx *cli.Context) (*Config, []error) {
 		Goal:        goal,
 		Interactive: interactive,
 		Image:       image,
-		SVG:         svg,
 		Scale:       scale,
 		Solution:    solution,
 		Format:      format,

cmd/maze/flag.go

@@ -35,13 +35,9 @@ var flags = []cli.Flag{
 		Name:  "output, o",
 		Usage: "Output file name",
 	},
-	cli.BoolFlag{
+	cli.StringFlag{
 		Name:  "image",
-		Usage: "Generate image",
-	},
-	cli.BoolFlag{
-		Name:  "svg",
-		Usage: "Generate svg",
+		Usage: "Generate image, `png` or `svg`",
 	},
 	cli.IntFlag{
 		Name:  "scale",

maze.go

@@ -322,8 +322,8 @@ func plot(img *image.RGBA, x, y, scale int, c color.Color) {
 	}
 }
 
-// PrintImage outputs the maze to the IO writer as PNG image
-func (maze *Maze) PrintImage(writer io.Writer, format *Format, scale int) {
+// PrintPNG outputs the maze to the IO writer as PNG image
+func (maze *Maze) PrintPNG(writer io.Writer, format *Format, scale int) {
 	var sb strings.Builder
 	maze.Print(&sb, format)
 	lines := strings.Split(strings.TrimSpace(sb.String()), "\n")
@@ -361,6 +361,7 @@ func (maze *Maze) PrintImage(writer io.Writer, format *Format, scale int) {
 	png.Encode(writer, img)
 }
 
+// PrintSVG outputs the maze to the IO writer as SVG image
 func (maze *Maze) PrintSVG(writer io.Writer, format *Format, scale int) {
 	var sb strings.Builder
 	maze.Print(&sb, format)