to save up a progress

cmd/repalette/repalette.go

@@ -0,0 +1,91 @@
+package main
+
+func parseMap(fields []string) (map[string]string, error) {
+	m := map[string]string{}
+	var k, v string
+
+	for i, v := range fields {
+		if v == "=" {
+			return nil, errors.New("bad field")
+		}
+		if len(v) > 1 {
+			// check if "=" is the last or first character 
+			if "=" == v[0] {
+				return nil, errors.New("no key")
+			}
+			if "=" == v[len(v)-1] {
+				return nil, errors.New("no value")
+			}
+		}
+		if strings.Contains(v, "=") {
+			splitted := strings.Split(v, "=")
+			k, v = splitted[0], splitted[1]
+			m[k] = v
+			if i == len(fields)-1 {
+				return m, nil 
+			}
+			continue
+		} 
+		return nil, errors.New("no equality sign in field")
+	}
+	return nil, errors.New("everything is wrong!")
+}
+
+type Map map[color.Color]color.Color
+type repalette struct {
+	image.Image
+	Map
+}
+
+func (r repalette) ColorModel() color.Model {
+	return r.Image.ColorModel()
+}
+func (r repalette) Bounds() image.Rectangle {
+	return r.Image.Bounds() 
+}
+func (r repalette) At(x, y int) color.Color {
+	v := r.Image.At(x, y)
+	newColor, ok := r.Map[v]
+	if !ok {
+		return v 
+	}
+	return newColor
+}
+
+func main() {
+	fields := os.Args[1:]
+	m, err := parseMap(fields)
+	if err != nil {
+		panic("parseMap:", err)
+	}
+
+	errParseHexColor := errors.New("parse hex color:")
+	newPalette, err := 
+	func(m map[string]string) (newMap map[color.Color]color.Color, err error) {
+		for k, v := range m {
+			newKey, err := util.ParseHexColor(k)
+			if err != nil {
+				return nil, errors.Join(
+					errors.New("bad key hex value."),
+						errors.Join(errParseHexColor, err),
+					)
+			}
+			newValue, err := util.ParseHexColor(v)
+			if err != nil {
+				return nil, errors.Join(
+					errors.New("bad value hex value."),
+						errors.Join(errParseHexColor, err),
+					)
+			}
+			newMap[newKey] = newValue
+		}
+		return 
+	}(fields)
+	if err != nil {
+		panic(errors.Join(errors.New("palette parsing:"), err))
+	}
+	err = util.ProcessStdio(func(img image.Image) image.Image { return repalette{img, newPalette} })
+	if err != nil {
+		panic(errors.Join(errors.New("process stdio:"), err))
+	}
+}