Added a way to save configuration files

config/config.go

@@ -2,13 +2,13 @@ package config
 
 import "io"
 import "os"
+import "fmt"
 import "bufio"
 import "strings"
 import "strconv"
 import "image/color"
 import "path/filepath"
 
-
 // when making changes to this file, look at
 // https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html
 
@@ -118,28 +118,15 @@ type Config struct {
 // <home>/.config/<name>/<name>.conf, unless the corresponding XDG environment
 // variables are set - then it uses those.
 func (config *Config) Load (name string) (err error) {
-	if strings.ContainsAny(name, "/\\|:.%") {
+	if !nameIsLegal(name) {
 		err = ErrorIllegalName
 		return
 	}
 
-	if config.LegalParameters == nil {
-		config.LegalParameters = make(map[string] Type)
-	}
-	
-	if config.Parameters == nil {
-		config.Parameters = make(map[string] any)
-	}
-	
-	var homeDirectory string
-	homeDirectory, err = os.UserHomeDir()
+	var configHome string
+	configHome, err = getConfigHome()
 	if err != nil { return }
 
-	configHome := os.Getenv("XDG_CONFIG_HOME")
-	if configHome == "" {
-		configHome = filepath.Join(homeDirectory, "/.config/")
-	}
-
 	configDirsString := os.Getenv("XDG_CONFIG_DIRS")
 	if configDirsString == "" {
 		configDirsString = "/etc/xdg/"
@@ -173,6 +160,14 @@ func (config *Config) Load (name string) (err error) {
 // Before they are processed, leading and trailing whitespace is trimmed from
 // the key and the value. Keys are case sensitive.
 func (config *Config) LoadFrom (reader io.Reader) (err error) {
+	if config.LegalParameters == nil {
+		config.LegalParameters = make(map[string] Type)
+	}
+	
+	if config.Parameters == nil {
+		config.Parameters = make(map[string] any)
+	}
+	
 	scanner := bufio.NewScanner(reader)
 	for scanner.Scan() {
 		line := strings.TrimSpace(scanner.Text())
@@ -241,6 +236,63 @@ func (config *Config) LoadFrom (reader io.Reader) (err error) {
 	return
 }
 
+// Save overwrites the main user configuration file, which is located at
+// <home>/.config/<name>/<name>.conf unless $XDG_CONFIG_HOME has been set, in
+// which case the value of that variable is used instead.
+func (config *Config) Save (name string) (err error) {
+	if !nameIsLegal(name) {
+		err = ErrorIllegalName
+		return
+	}
+
+	var configHome string
+	configHome, err = getConfigHome()
+	if err != nil { return }
+
+	err = os.MkdirAll(configHome, 0755)
+	if err != nil { return }
+	
+	file, err := os.OpenFile (
+		filepath.Join(configHome, name, name + ".conf"),
+		os.O_WRONLY | os.O_CREATE | os.O_TRUNC, 0744)
+	if err != nil { return }
+	defer file.Close()
+
+	err = config.SaveTo(file)
+	if err != nil { return }
+
+	return
+}
+
+// SaveTo writes the configuration data to the specified io.Writer.
+func (config *Config) SaveTo (writer io.Writer) (err error) {
+	for key, value := range config.Parameters {
+		switch value.(type) {
+		case string:
+			fmt.Fprintf(writer,"%s: %s\n", key, value.(string))
+			
+		case color.RGBA:
+			colorValue := value.(color.RGBA)
+			colorInt := uint64 (
+				colorValue.R << 16 |
+				colorValue.G << 8  |
+				colorValue.B)
+			fmt.Fprintf(writer,"%s: #%x\n", key, colorInt)
+			
+		case int:
+			fmt.Fprintf(writer,"%s: %i\n", key, value.(int))
+			
+		case float64:
+			fmt.Fprintf(writer,"%s: %f\n", key, value.(float64))
+			
+		case bool:
+			fmt.Fprintf(writer,"%s: %t\n", key, value.(bool))
+		}
+	}
+
+	return
+}
+
 func parseColor (value string) (valueColor color.Color, err error) {
 	if value[0] == '#' {
 		if len(value) != 7  {
@@ -268,3 +320,21 @@ func parseColor (value string) (valueColor color.Color, err error) {
 
 	return
 }
+
+func getConfigHome () (home string, err error) {
+	var homeDirectory string
+	homeDirectory, err = os.UserHomeDir()
+	if err != nil { return }
+
+	configHome := os.Getenv("XDG_CONFIG_HOME")
+	if configHome == "" {
+		configHome = filepath.Join(homeDirectory, "/.config/")
+	}
+
+	return
+}
+
+func nameIsLegal (name string) (legal bool) {
+	legal = strings.ContainsAny(name, "/\\|:.%")
+	return
+}