Move to yaml-based configuration

This commit updates the configuration to be yaml-based and updates the
configuration to read in a yaml file.

internal/config/legacy/stringparser/parse.go

@@ -0,0 +1,65 @@
+package stringparser
+
+import (
+	"reflect"
+	"strings"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/environment"
+	"github.com/pkg/errors"
+)
+
+var errUnknownParser = errors.New("unknown parser")
+
+// Parse parses the provided value with the parser.
+func Parse(env environment.Environment, name, value string, vField reflect.Value) error {
+
+	// use the validator
+	parser, ok := knownParsers[strings.ToLower(name)]
+	if parser == nil || !ok {
+		return errUnknownParser
+	}
+
+	// get the parsed value
+	checked, err := parser(env, value)
+	if err != nil {
+		return err
+	}
+
+	// set the value of the field
+	var errSet interface{}
+	func() {
+		defer func() {
+			errSet = recover()
+		}()
+		vField.Set(reflect.ValueOf(checked))
+	}()
+
+	// capture any error
+	if errSet != nil {
+		return errors.Errorf("set returned %v", name, errSet)
+	}
+
+	return nil
+}
+
+// knownParsers holds the known parsers
+var knownParsers map[string]Parser[any] = map[string]Parser[any]{
+	"abspath":   asGenericParser(ParseAbspath),
+	"domain":    asGenericParser(ParseValidDomain),
+	"domains":   asGenericParser(ParseValidDomains),
+	"duration":  asGenericParser(ParseDuration),
+	"number":    asGenericParser(ParseNumber),
+	"port":      asGenericParser(ParsePort),
+	"https_url": asGenericParser(ParseHttpsURL),
+	"slug":      asGenericParser(ParseSlug),
+	"file":      asGenericParser(ParseFile),
+	"email":     asGenericParser(ParseEmail),
+	"nonempty":  asGenericParser(ParseNonEmpty),
+}
+
+func asGenericParser[T any](parser Parser[T]) Parser[any] {
+	return func(env environment.Environment, s string) (value any, err error) {
+		value, err = parser(env, s)
+		return
+	}
+}