Initial implementation of config file

internal/config.go

@@ -0,0 +1,28 @@
+package magellan
+
+import (
+	"fmt"
+
+	"github.com/bikeshack/magellan/internal/util"
+	"github.com/spf13/viper"
+)
+
+func LoadConfig(path string) error {
+	dir, filename, ext := util.SplitPathForViper(path)
+	// fmt.Printf("dir: %s\nfilename: %s\nextension: %s\n", dir, filename, ext)
+	viper.AddConfigPath(dir)
+	viper.SetConfigName(filename)
+	viper.SetConfigType(ext)
+	// ...no search paths set intentionally, so config has to be set explicitly
+	// ...also, the config file will not save anything
+	// ...and finally, parameters passed to CLI have precedence over config values
+	if err := viper.ReadInConfig(); err != nil {
+		if _, ok := err.(viper.ConfigFileNotFoundError); ok {
+			return fmt.Errorf("config file not found: %w", err)
+		} else {
+			return fmt.Errorf("could not load config file: %w", err)
+		}
+	}
+
+	return nil
+}

internal/util/util.go

@@ -8,6 +8,8 @@ import (
 	"net"
 	"net/http"
 	"os"
+	"path/filepath"
+	"strings"
 	"time"
 )
 
@@ -78,4 +80,10 @@ func MakeOutputDirectory(path string) (string, error) {
 		return final, fmt.Errorf("could not make directory: %v", err)
 	}
 	return final, nil
-}
+}
+
+func SplitPathForViper(path string) (string, string, string) {
+	filename := filepath.Base(path)
+	ext := filepath.Ext(filename)
+	return filepath.Dir(path), strings.TrimSuffix(filename, ext), strings.TrimPrefix(ext, ".")
+}