Implementing prettier printing of validation errors

First pass was JSON output.

cmd/obp/cmd/validate.go

@@ -6,7 +6,6 @@ package cmd
 import (
 	"fmt"
 	"io/fs"
-	"log"
 	"os"
 	"path/filepath"
 
@@ -51,7 +50,6 @@ var validateCmd = &cobra.Command{
 				return nil
 			}
 
-			log.Printf("scanning %q\n", path)
 			absPath, err := filepath.Abs(filepath.Join(target, path))
 			if err != nil {
 				return fmt.Errorf("error generating absolute path for %q", target)
@@ -63,7 +61,8 @@ var validateCmd = &cobra.Command{
 			defer target.Close()
 			err = obp.Validate(schema, target)
 			if err != nil {
-				log.Printf("error validating input file %q: %#+v\n", path, err.(*jsonschema.ValidationError).DetailedOutput())
+				details := err.(*jsonschema.ValidationError).DetailedOutput()
+				obp.PrettyDetails(cmd.OutOrStdout(), obp.JSON, details)
 			}
 			return nil
 		})

validate.go

@@ -1,6 +1,7 @@
 package obp
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 
@@ -9,6 +10,14 @@ import (
 	"gopkg.in/yaml.v3"
 )
 
+type PrettyDetailFormat int
+
+const (
+	JSON = iota
+	Markdown
+	CSV
+)
+
 func Validate(schemaURL string, r io.Reader) error {
 	var m interface{}
 
@@ -29,3 +38,30 @@ func Validate(schemaURL string, r io.Reader) error {
 
 	return nil
 }
+
+func recurseDetails(detailed jsonschema.Detailed, acc []jsonschema.Detailed) []jsonschema.Detailed {
+	acc = append(acc, detailed)
+	for _, e := range detailed.Errors {
+		acc = append(acc, recurseDetails(e, acc)...)
+	}
+
+	return acc
+}
+
+func PrettyDetails(w io.Writer, format PrettyDetailFormat, details jsonschema.Detailed) error {
+	acc := make([]jsonschema.Detailed, 0)
+	errors := recurseDetails(details, acc)
+	switch format {
+	case JSON:
+		enc := json.NewEncoder(w)
+		err := enc.Encode(errors)
+		if err != nil {
+			return fmt.Errorf("error writing JSON payload to provided writer: %w", err)
+		}
+	default:
+		return fmt.Errorf("unknown format")
+
+	}
+
+	return nil
+}