Rename packages

internal/config/read.go

@@ -0,0 +1,60 @@
+package config
+
+import (
+	"io"
+	"reflect"
+
+	"github.com/FAU-CDI/wisski-distillery/pkg/envreader"
+	"github.com/FAU-CDI/wisski-distillery/pkg/stringparser"
+)
+
+// Unmarshal updates this configuration from the provided [io.Reader].
+//
+// Data is read using the [envreader.ReadAll] method, see the appropriate documentation for the file format.
+//
+// The `env` and `parser` reflect tags of the [Config] struct determine the keys to read from, and the types to expect.
+// When a key is missing, it is set to the default value.
+//
+// See also [stringparser.Parse].
+func (config *Config) Unmarshal(src io.Reader) error {
+	// read all the values!
+	values, err := envreader.ReadAll(src)
+	if err != nil {
+		return err
+	}
+
+	vConfig := reflect.ValueOf(config).Elem()
+	tConfig := vConfig.Type()
+
+	// iterate over the types
+	numValues := tConfig.NumField()
+	for i := 0; i < numValues; i++ {
+		tField := tConfig.Field(i)
+		vField := vConfig.FieldByName(tField.Name)
+
+		env := tField.Tag.Get("env")
+		dflt := tField.Tag.Get("default")
+		parser := tField.Tag.Get("parser")
+
+		// skip it if it isn't loaded!
+		if env == "" {
+			continue
+		}
+
+		// read the value with a default
+		value, ok := values[env]
+		if !ok || value == "" {
+			if dflt == "" {
+				continue
+			}
+			value = dflt
+		}
+
+		// parse the value!
+		if err := stringparser.Parse(parser, value, vField); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}