From 0554560f9f0f8fca1e5a302e9ac3dd9d3a68562d Mon Sep 17 00:00:00 2001
From: Ian Gulliver <github@flamingcow.io>
Date: Sun, 13 Oct 2024 11:27:33 -0700
Subject: [PATCH] Support multiple $merge in a list

---
 merge.go                        |  3 +--
 parser.go                       |  1 +
 process1.go                     | 44 ++++++++++++++++++++++-----------
 process2.go                     |  2 +-
 tests/merge-list-multi/a.yaml   |  9 +++++++
 tests/merge-list-multi/cmd      |  1 +
 tests/merge-list-multi/expected |  9 +++++++
 7 files changed, 51 insertions(+), 18 deletions(-)
 create mode 100644 tests/merge-list-multi/a.yaml
 create mode 100644 tests/merge-list-multi/cmd
 create mode 100644 tests/merge-list-multi/expected

diff --git a/merge.go b/merge.go
index 33284e6..3f4dea0 100644
--- a/merge.go
+++ b/merge.go
@@ -91,7 +91,7 @@ func mergeMapMap(dst map[string]any, src map[string]any) (map[string]any, error)
 	return dst, nil
 }
 
-func mergeList(dst []any, src any) (any, error) {
+func mergeList(dst []any, src any) ([]any, error) {
 	switch src2 := src.(type) {
 	case []any:
 		return mergeListList(dst, src2)
@@ -171,7 +171,6 @@ func mergeListDelete(obj []any, del any) ([]any, error) {
 
 		return []any{v}, nil
 	})
-
 	if err != nil {
 		return nil, err
 	}
diff --git a/parser.go b/parser.go
index f6b6e0a..f208ff4 100644
--- a/parser.go
+++ b/parser.go
@@ -44,6 +44,7 @@ import (
 // Phase 5
 //   - $""
 //   - $encode
+//   - $decode
 //   - $env
 //   - $repeat
 //   - $value
diff --git a/process1.go b/process1.go
index d0677b8..605983d 100644
--- a/process1.go
+++ b/process1.go
@@ -82,16 +82,35 @@ func process1MapReplace(obj map[string]any, mergeFrom *Document, mergeFromDocs [
 }
 
 func process1List(obj []any, mergeFrom *Document, mergeFromDocs []*Document, depth int) (any, error) {
-	m, obj, err := popListMapValue(obj, "$merge")
-	if err != nil {
-		return nil, err
+	merge := []any{}
+
+	obj, err := filterList(obj, func(v any) ([]any, error) {
+		v2, ok := v.(map[string]any)
+		if !ok {
+			return []any{v}, nil
+		}
+
+		if len(v2) != 1 {
+			return []any{v}, nil
+		}
+
+		found, val, v2 := popMapValue(v2, "$merge")
+		if found {
+			merge = append(merge, val)
+			return nil, nil
+		}
+
+		return []any{v2}, nil
+	})
+
+	for _, m := range merge {
+		obj, err = process1ListMerge(obj, mergeFrom, mergeFromDocs, m, depth)
+		if err != nil {
+			return nil, err
+		}
 	}
 
-	if m != nil {
-		return process1ListMerge(obj, mergeFrom, mergeFromDocs, m, depth)
-	}
-
-	m, obj, err = popListMapValue(obj, "$replace")
+	m, obj, err := popListMapValue(obj, "$replace")
 	if err != nil {
 		return nil, err
 	}
@@ -114,18 +133,13 @@ func process1List(obj []any, mergeFrom *Document, mergeFromDocs []*Document, dep
 	})
 }
 
-func process1ListMerge(obj []any, mergeFrom *Document, mergeFromDocs []*Document, m any, depth int) (any, error) {
+func process1ListMerge(obj []any, mergeFrom *Document, mergeFromDocs []*Document, m any, depth int) ([]any, error) {
 	in, err := get(mergeFrom, mergeFromDocs, m)
 	if err != nil {
 		return nil, err
 	}
 
-	next, err := mergeList(obj, in)
-	if err != nil {
-		return nil, err
-	}
-
-	return process1(next, mergeFrom, mergeFromDocs, depth)
+	return mergeList(obj, in)
 }
 
 func process1ListReplace(obj []any, mergeFrom *Document, mergeFromDocs []*Document, m any, depth int) (any, error) {
diff --git a/process2.go b/process2.go
index fa4f842..5aae5cd 100644
--- a/process2.go
+++ b/process2.go
@@ -236,7 +236,7 @@ func process2DecodeString(obj any, mergeFrom *Document, mergeFromDocs []*Documen
 func process2DecodeStringMap(obj map[string]any, mergeFrom *Document, mergeFromDocs []*Document, v string, depth int) (any, error) {
 	found, val, obj := popMapValue(obj, "$value")
 	if !found {
-		return nil, fmt.Errorf("$decode: missing $value in %#v (#w)", obj, ErrInvalidType)
+		return nil, fmt.Errorf("$decode: missing $value in %#v (%w)", obj, ErrInvalidType)
 	}
 
 	val2, ok := val.(string)
diff --git a/tests/merge-list-multi/a.yaml b/tests/merge-list-multi/a.yaml
new file mode 100644
index 0000000..b8c5f44
--- /dev/null
+++ b/tests/merge-list-multi/a.yaml
@@ -0,0 +1,9 @@
+foo:
+  bar:
+    - a: 1
+  zag:
+    - c: 3
+zig:
+  - b: 2
+  - $merge: foo.zag
+  - $merge: foo.bar
diff --git a/tests/merge-list-multi/cmd b/tests/merge-list-multi/cmd
new file mode 100644
index 0000000..d3724ee
--- /dev/null
+++ b/tests/merge-list-multi/cmd
@@ -0,0 +1 @@
+bkl a.yaml
diff --git a/tests/merge-list-multi/expected b/tests/merge-list-multi/expected
new file mode 100644
index 0000000..7adf756
--- /dev/null
+++ b/tests/merge-list-multi/expected
@@ -0,0 +1,9 @@
+foo:
+  bar:
+    - a: 1
+  zag:
+    - c: 3
+zig:
+  - b: 2
+  - c: 3
+  - a: 1