From 8958b6ecd7d29efe3a87dd6b3de0af1746d4ff8c Mon Sep 17 00:00:00 2001
From: andig <andi@evcc.io>
Date: Sun, 11 Aug 2024 21:49:34 +0200
Subject: [PATCH] Fix case-insensitively merging template maps (#15351)

---
 util/templates/merge.go      | 55 ++++++++++++++++++++++++++++++++++++
 util/templates/merge_test.go | 32 +++++++++++++++++++++
 util/templates/template.go   |  5 ++--
 3 files changed, 89 insertions(+), 3 deletions(-)
 create mode 100644 util/templates/merge.go
 create mode 100644 util/templates/merge_test.go

diff --git a/util/templates/merge.go b/util/templates/merge.go
new file mode 100644
index 000000000..fa9efdfc4
--- /dev/null
+++ b/util/templates/merge.go
@@ -0,0 +1,55 @@
+package templates
+
+import (
+	"reflect"
+	"strings"
+)
+
+// https://github.com/peterbourgon/mergemap
+
+const mergeMaxDepth = 100
+
+var matchKey = strings.EqualFold
+
+// mergeMaps recursively merges other into target using matchKey for key comparison
+func mergeMaps(other map[string]any, target map[string]any) error {
+	// return mergo.Map(&target, other, mergo.WithOverride)
+	// return util.DecodeOther(other, target)
+	merge(target, other, 0)
+	return nil
+}
+
+func merge(dst, src map[string]any, depth int) map[string]any {
+	if depth > mergeMaxDepth {
+		panic("too deep!")
+	}
+	for key, srcVal := range src {
+		for k := range dst {
+			if matchKey(k, key) {
+				// overwrite key
+				key = k
+
+				srcMap, srcMapOk := mapify(srcVal)
+				dstMap, dstMapOk := mapify(dst[k])
+				if srcMapOk && dstMapOk {
+					srcVal = merge(dstMap, srcMap, depth+1)
+				}
+				break
+			}
+		}
+		dst[key] = srcVal
+	}
+	return dst
+}
+
+func mapify(i any) (map[string]any, bool) {
+	value := reflect.ValueOf(i)
+	if value.Kind() == reflect.Map {
+		m := map[string]any{}
+		for _, k := range value.MapKeys() {
+			m[k.String()] = value.MapIndex(k).Interface()
+		}
+		return m, true
+	}
+	return map[string]any{}, false
+}
diff --git a/util/templates/merge_test.go b/util/templates/merge_test.go
new file mode 100644
index 000000000..b8e878872
--- /dev/null
+++ b/util/templates/merge_test.go
@@ -0,0 +1,32 @@
+package templates
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMergeMaps(t *testing.T) {
+	target := map[string]any{
+		"foo": "bar",
+		"nested": map[string]any{
+			"bar": "baz",
+		},
+	}
+	other := map[string]any{
+		"Foo": 1,
+		"Nested": map[string]any{
+			"Bar": 2,
+		},
+		"baz": 3,
+	}
+
+	require.NoError(t, mergeMaps(other, target))
+	require.Equal(t, map[string]any{
+		"foo": 1,
+		"nested": map[string]any{
+			"bar": 2,
+		},
+		"baz": 3,
+	}, target)
+}
diff --git a/util/templates/template.go b/util/templates/template.go
index b982a8f29..c2e1d09b9 100644
--- a/util/templates/template.go
+++ b/util/templates/template.go
@@ -9,7 +9,6 @@ import (
 	"strings"
 	"text/template"
 
-	"github.com/evcc-io/evcc/util"
 	"github.com/go-sprout/sprout"
 )
 
@@ -267,9 +266,9 @@ func (t *Template) RenderProxyWithValues(values map[string]interface{}, lang str
 }
 
 // RenderResult renders the result template to instantiate the proxy
-func (t *Template) RenderResult(renderMode int, other map[string]interface{}) ([]byte, map[string]interface{}, error) {
+func (t *Template) RenderResult(renderMode int, other map[string]any) ([]byte, map[string]any, error) {
 	values := t.Defaults(renderMode)
-	if err := util.DecodeOther(other, &values); err != nil {
+	if err := mergeMaps(other, values); err != nil {
 		return nil, values, err
 	}