From 110ef68af305f2e6cf1dd68b84475493e9c1395b Mon Sep 17 00:00:00 2001
From: Tom van Dinther <39470469+tvandinther@users.noreply.github.com>
Date: Sun, 5 Jan 2025 15:34:49 +0100
Subject: [PATCH] Improve error handling (#13)

---
 pkg/plugin/helm.go    | 16 ++++++----
 pkg/util/manifests.go | 69 ++++++++++++++++++++++++++++++++++---------
 2 files changed, 65 insertions(+), 20 deletions(-)

diff --git a/pkg/plugin/helm.go b/pkg/plugin/helm.go
index f9634e2..68c88f1 100644
--- a/pkg/plugin/helm.go
+++ b/pkg/plugin/helm.go
@@ -41,11 +41,14 @@ func init() {
 					}
 
 					var chart ChartArg
-					util.MapToStruct(chartArgMap, &chart)
+					err := util.MapToStruct(chartArgMap, &chart)
+					if err != nil {
+						return nil, fmt.Errorf("unable to map chart to struct: %w", err)
+					}
 
-					err := validate(&chart)
+					err = validate(&chart)
 					if err != nil {
-						return nil, err
+						return nil, fmt.Errorf("invalid chart: %w", err)
 					}
 
 					release, err := helm.RunTemplate(&helm.ChartRef{
@@ -54,16 +57,17 @@ func init() {
 						Version:    chart.Version,
 					}, chart.Values, chart.ReleaseName, chart.Namespace, chart.Capabilities.APIVersions)
 					if err != nil {
-						return nil, err
+						return nil, fmt.Errorf("problem templating helm chart: %w", err)
 					}
 
 					splitManifests := releaseutil.SplitManifests(release.Manifest)
-
 					var manifestSlice []types.Manifest
 					for _, manifestString := range splitManifests {
 						var manifest types.Manifest
 						yaml.Unmarshal([]byte(manifestString), &manifest)
-						manifestSlice = append(manifestSlice, manifest)
+						if len(manifest) > 0 {
+							manifestSlice = append(manifestSlice, manifest)
+						}
 					}
 
 					util.SortManifests(manifestSlice)
diff --git a/pkg/util/manifests.go b/pkg/util/manifests.go
index ce1da75..caff611 100644
--- a/pkg/util/manifests.go
+++ b/pkg/util/manifests.go
@@ -1,36 +1,77 @@
 package util
 
 import (
+	"fmt"
 	"slices"
 	"strings"
 
 	"knit/pkg/types"
 )
 
-func SortManifests(manifests []types.Manifest) {
+func SortManifests(manifests []types.Manifest) error {
+	errors := make([]error, 0)
 	slices.SortFunc(manifests, func(a, b types.Manifest) int {
-		return compareManifests(a, b,
-			func(x types.Manifest) string { return x["apiVersion"].(string) },
-			func(x types.Manifest) string { return x["kind"].(string) },
-			func(x types.Manifest) string {
-				metadata := x["metadata"].(map[string]any)
-				return metadata["name"].(string)
+		comp, err := compareManifests(a, b,
+			func(x types.Manifest) (string, error) { return getFromMap[string](x, "apiVersion") },
+			func(x types.Manifest) (string, error) { return getFromMap[string](x, "kind") },
+			func(x types.Manifest) (string, error) {
+				metadata, err := getFromMap[map[string]any](x, "metadata")
+				if err != nil {
+					return "", err
+				}
+				return getFromMap[string](metadata, "name")
 			},
-			func(x types.Manifest) string {
-				metadata := x["metadata"].(map[string]any)
-				return metadata["generateName"].(string)
+			func(x types.Manifest) (string, error) {
+				metadata, err := getFromMap[map[string]any](x, "metadata")
+				if err != nil {
+					return "", err
+				}
+				return getFromMap[string](metadata, "generateName")
 			})
+		if err != nil {
+			errors = append(errors, err)
+		}
+
+		return comp
 	})
+
+	if len(errors) != 0 {
+		var errorString string
+		for _, err := range errors {
+			errorString += err.Error()
+		}
+		return fmt.Errorf("encountered %d errors during sorting\n%s", len(errors), errorString)
+	}
+
+	return nil
 }
 
-func compareManifests(a, b types.Manifest, selectors ...func(x types.Manifest) string) int {
+func getFromMap[T any](manifest map[string]any, key string) (T, error) {
+	str, ok := manifest[key].(T)
+	if !ok {
+		var none T
+		return none, fmt.Errorf("%s of manifest can not be converted to string\n%+v", key, manifest)
+	}
+
+	return str, nil
+}
+
+func compareManifests(a, b types.Manifest, selectors ...func(x types.Manifest) (string, error)) (int, error) {
 	var comparator int
 	for _, selector := range selectors {
-		comparator = strings.Compare(selector(a), selector(b))
+		strA, err := selector(a)
+		if err != nil {
+			return 0, err
+		}
+		strB, err := selector(b)
+		if err != nil {
+			return 0, err
+		}
+		comparator = strings.Compare(strA, strB)
 		if comparator != 0 {
-			return comparator
+			return comparator, nil
 		}
 	}
 
-	return 0
+	return 0, nil
 }