feat: implement copy action

README.md

@@ -2,7 +2,6 @@
 [![Go Report Card](https://goreportcard.com/badge/github.com/speakeasy-api/openapi-overlay)](https://goreportcard.com/report/github.com/speakeasy-api/openapi-overlay)
 [![GoDoc](https://godoc.org/github.com/speakeasy-api/openapi-overlay?status.svg)](https://godoc.org/github.com/speakeasy-api/openapi-overlay)
 
-
 # OpenAPI Overlay
 
 <a href="https://speakeasy.com/openapi/overlays"><img src="https://custom-icon-badges.demolab.com/badge/-Overlay%20Reference-212015?style=for-the-badge&logoColor=FBE331&logo=speakeasy&labelColor=545454" /></a>
@@ -15,7 +14,9 @@ Specification](https://github.com/OAI/Overlay-Specification/blob/3f398c6/version
 (2023-10-12). This specification defines a means of editing a OpenAPI
 Specification file by applying a list of actions. Each action is either a remove
 action that prunes nodes or an update that merges a value into nodes. The nodes
-impacted are selected by a target expression which uses JSONPath.
+impacted are selected by a target expression which uses JSONPath. This
+implementation also supports [version 1.1.0](https://github.com/OAI/Overlay-Specification/blob/e2c3cec/versions/1.1.0-dev.md)
+which adds a `copy` action for duplicating or moving nodes within the document.
 
 The specification itself says very little about the input file to be modified or
 the output file. The presumed intention is that the input and output be an

pkg/overlay/apply.go

@@ -2,21 +2,27 @@ package overlay
 
 import (
 	"fmt"
+	"strings"
+
 	"github.com/speakeasy-api/jsonpath/pkg/jsonpath/config"
 	"github.com/speakeasy-api/jsonpath/pkg/jsonpath/token"
 	"gopkg.in/yaml.v3"
-	"strings"
 )
 
 // ApplyTo will take an overlay and apply its changes to the given YAML
 // document.
 func (o *Overlay) ApplyTo(root *yaml.Node) error {
+	// Priority is: remove > update > copy
+	// Copy has no impact if remove is true or update contains a value
 	for _, action := range o.Actions {
 		var err error
-		if action.Remove {
+		switch {
+		case action.Remove:
 			err = o.applyRemoveAction(root, action, nil)
-		} else {
+		case !action.Update.IsZero():
 			err = o.applyUpdateAction(root, action, &[]string{})
+		case action.Copy != "":
+			err = o.applyCopyAction(root, action, &[]string{})
 		}
 
 		if err != nil {
@@ -27,10 +33,13 @@ func (o *Overlay) ApplyTo(root *yaml.Node) error {
 	return nil
 }
 
-func (o *Overlay) ApplyToStrict(root *yaml.Node) (error, []string) {
+func (o *Overlay) ApplyToStrict(root *yaml.Node) ([]string, error) {
 	multiError := []string{}
 	warnings := []string{}
 	hasFilterExpression := false
+
+	// Priority is: remove > update > copy
+	// Copy has no impact if remove is true or update contains a value
 	for i, action := range o.Actions {
 		tokens := token.NewTokenizer(action.Target, config.WithPropertyNameExtension()).Tokenize()
 		for _, tok := range tokens {
@@ -44,13 +53,27 @@ func (o *Overlay) ApplyToStrict(root *yaml.Node) (error, []string) {
 		if err != nil {
 			multiError = append(multiError, err.Error())
 		}
-		if action.Remove {
+
+		// Determine action type based on priority: remove > update > copy
+		actionType := "unknown"
+		switch {
+		case action.Remove:
+			actionType = "remove"
 			err = o.applyRemoveAction(root, action, &actionWarnings)
-		} else {
+		case !action.Update.IsZero():
+			actionType = "update"
 			err = o.applyUpdateAction(root, action, &actionWarnings)
+		case action.Copy != "":
+			actionType = "copy"
+			err = o.applyCopyAction(root, action, &actionWarnings)
+		default:
+			err = fmt.Errorf("unknown action type: %v", action)
+		}
+		if err != nil {
+			return nil, err
 		}
 		for _, warning := range actionWarnings {
-			warnings = append(warnings, fmt.Sprintf("update action (%v / %v) target=%s: %s", i+1, len(o.Actions), action.Target, warning))
+			warnings = append(warnings, fmt.Sprintf("%s action (%v / %v) target=%s: %s", actionType, i+1, len(o.Actions), action.Target, warning))
 		}
 	}
 
@@ -59,9 +82,9 @@ func (o *Overlay) ApplyToStrict(root *yaml.Node) (error, []string) {
 	}
 
 	if len(multiError) > 0 {
-		return fmt.Errorf("error applying overlay (strict): %v", strings.Join(multiError, ",")), warnings
+		return warnings, fmt.Errorf("error applying overlay (strict): %v", strings.Join(multiError, ","))
 	}
-	return nil, warnings
+	return warnings, nil
 }
 
 func (o *Overlay) validateSelectorHasAtLeastOneTarget(root *yaml.Node, action Action) error {
@@ -80,6 +103,24 @@ func (o *Overlay) validateSelectorHasAtLeastOneTarget(root *yaml.Node, action Ac
 		return fmt.Errorf("selector %q did not match any targets", action.Target)
 	}
 
+	// For copy actions, validate the source path (only if copy will actually be applied)
+	// Copy has no impact if remove is true or update contains a value
+	if action.Copy != "" && !action.Remove && action.Update.IsZero() {
+		sourcePath, err := o.NewPath(action.Copy, nil)
+		if err != nil {
+			return err
+		}
+
+		sourceNodes := sourcePath.Query(root)
+		if len(sourceNodes) == 0 {
+			return fmt.Errorf("copy source selector %q did not match any nodes", action.Copy)
+		}
+
+		if len(sourceNodes) > 1 {
+			return fmt.Errorf("copy source selector %q matched multiple nodes (%d), expected exactly one", action.Copy, len(sourceNodes))
+		}
+	}
+
 	return nil
 }
 
@@ -96,9 +137,6 @@ func (o *Overlay) applyRemoveAction(root *yaml.Node, action Action, warnings *[]
 	}
 
 	nodes := p.Query(root)
-	if err != nil {
-		return err
-	}
 
 	for _, node := range nodes {
 		removeNode(idx, node)
@@ -185,6 +223,13 @@ func mergeNode(node *yaml.Node, merge *yaml.Node) bool {
 // node.
 func mergeMappingNode(node *yaml.Node, merge *yaml.Node) bool {
 	anyChange := false
+
+	// If the target is an empty flow-style mapping and we're merging content,
+	// convert to block style for better readability
+	if len(node.Content) == 0 && node.Style == yaml.FlowStyle && len(merge.Content) > 0 {
+		node.Style = 0 // Reset to default (block) style
+	}
+
 NextKey:
 	for i := 0; i < len(merge.Content); i += 2 {
 		mergeKey := merge.Content[i].Value
@@ -232,3 +277,63 @@ func clone(node *yaml.Node) *yaml.Node {
 	}
 	return newNode
 }
+
+// applyCopyAction applies a copy action to the document
+// This is a stub implementation for the copy feature from Overlay Specification v1.1.0
+func (o *Overlay) applyCopyAction(root *yaml.Node, action Action, warnings *[]string) error {
+	if action.Target == "" {
+		return nil
+	}
+
+	if action.Copy == "" {
+		return nil
+	}
+
+	// Parse the source path
+	sourcePath, err := o.NewPath(action.Copy, warnings)
+	if err != nil {
+		return fmt.Errorf("invalid copy source path %q: %w", action.Copy, err)
+	}
+
+	// Query the source nodes
+	sourceNodes := sourcePath.Query(root)
+	if len(sourceNodes) == 0 {
+		// Source not found - in non-strict mode this is silently ignored
+		// In strict mode, this will be caught by validateSelectorHasAtLeastOneTarget
+		if warnings != nil {
+			*warnings = append(*warnings, fmt.Sprintf("copy source %q not found", action.Copy))
+		}
+		return nil
+	}
+
+	if len(sourceNodes) > 1 {
+		return fmt.Errorf("copy source path %q matched multiple nodes (%d), expected exactly one", action.Copy, len(sourceNodes))
+	}
+
+	sourceNode := sourceNodes[0]
+
+	// Parse the target path
+	targetPath, err := o.NewPath(action.Target, warnings)
+	if err != nil {
+		return fmt.Errorf("invalid target path %q: %w", action.Target, err)
+	}
+
+	// Query the target nodes
+	targetNodes := targetPath.Query(root)
+
+	// Copy the source node to each target
+	didMakeChange := false
+	for _, targetNode := range targetNodes {
+		// Clone the source node to avoid reference issues
+		copiedNode := clone(sourceNode)
+
+		// Merge the copied node into the target
+		didMakeChange = mergeNode(targetNode, copiedNode) || didMakeChange
+	}
+
+	if !didMakeChange && warnings != nil {
+		*warnings = append(*warnings, "does nothing")
+	}
+
+	return nil
+}

pkg/overlay/apply_test.go

@@ -2,15 +2,16 @@ package overlay_test
 
 import (
 	"bytes"
+	"os"
+	"strconv"
+	"testing"
+
 	"github.com/speakeasy-api/jsonpath/pkg/jsonpath"
 	"github.com/speakeasy-api/openapi-overlay/pkg/loader"
 	"github.com/speakeasy-api/openapi-overlay/pkg/overlay"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"gopkg.in/yaml.v3"
-	"os"
-	"strconv"
-	"testing"
 )
 
 // NodeMatchesFile is a test that marshals the YAML file from the given node,
@@ -65,14 +66,14 @@ func TestApplyToStrict(t *testing.T) {
 	o, err := loader.LoadOverlay("testdata/overlay-mismatched.yaml")
 	require.NoError(t, err)
 
-	err, warnings := o.ApplyToStrict(node)
+	warnings, err := o.ApplyToStrict(node)
 	assert.Error(t, err, "error applying overlay (strict): selector \"$.unknown-attribute\" did not match any targets")
 	assert.Len(t, warnings, 2)
 	o.Actions = o.Actions[1:]
 	node, err = loader.LoadSpecification("testdata/openapi.yaml")
 	require.NoError(t, err)
 
-	err, warnings = o.ApplyToStrict(node)
+	warnings, err = o.ApplyToStrict(node)
 	assert.NoError(t, err)
 	assert.Len(t, warnings, 1)
 	assert.Equal(t, "update action (2 / 2) target=$.info.title: does nothing", warnings[0])
@@ -268,6 +269,21 @@ func cloneNode(node *yaml.Node) *yaml.Node {
 	return clone
 }
 
+func TestApplyTo_CopyVersionToHeader(t *testing.T) {
+	t.Parallel()
+
+	node, err := loader.LoadSpecification("testdata/openapi-version-header.yaml")
+	require.NoError(t, err)
+
+	o, err := loader.LoadOverlay("testdata/overlay-version-header.yaml")
+	require.NoError(t, err)
+
+	err = o.ApplyTo(node)
+	assert.NoError(t, err)
+
+	NodeMatchesFile(t, node, "testdata/openapi-version-header-expected.yaml")
+}
+
 func TestApplyToOld(t *testing.T) {
 	t.Parallel()
 
@@ -280,7 +296,7 @@ func TestApplyToOld(t *testing.T) {
 	o, err := loader.LoadOverlay("testdata/overlay-old.yaml")
 	require.NoError(t, err)
 
-	err, warnings := o.ApplyToStrict(nodeOld)
+	warnings, err := o.ApplyToStrict(nodeOld)
 	require.NoError(t, err)
 	require.Len(t, warnings, 2)
 	require.Contains(t, warnings[0], "invalid rfc9535 jsonpath")
@@ -292,15 +308,15 @@ func TestApplyToOld(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, 0, len(result))
 	o.JSONPathVersion = "rfc9535"
-	err, warnings = o.ApplyToStrict(nodeNew)
+	_, err = o.ApplyToStrict(nodeNew)
 	require.ErrorContains(t, err, "unexpected token") // should error out: invalid nodepath
 	// now lets fix it.
 	o.Actions[0].Target = "$.paths.*[?(@[\"x-my-ignore\"])]"
-	err, warnings = o.ApplyToStrict(nodeNew)
+	_, err = o.ApplyToStrict(nodeNew)
 	require.ErrorContains(t, err, "did not match any targets")
 	// Now lets fix it.
 	o.Actions[0].Target = "$.paths[?(@[\"x-my-ignore\"])]" // @ should always refer to the child node in RFC 9535..
-	err, warnings = o.ApplyToStrict(nodeNew)
+	_, err = o.ApplyToStrict(nodeNew)
 	require.NoError(t, err)
 	result = path.Query(nodeNew)
 	require.NoError(t, err)