From 99f1da009b091769a6be5332bb28771849a2ccba Mon Sep 17 00:00:00 2001
From: Furkan Senharputlu <furkan_senharputlu@hotmail.com>
Date: Fri, 22 Dec 2023 18:34:51 +0300
Subject: [PATCH] [TT-10868] Implement OAS api level response header
 transformation (#5905)

Parent: https://tyktech.atlassian.net/browse/TT-4851
Subtask: https://tyktech.atlassian.net/browse/TT-10868
---
 apidef/migration.go                      | 10 ++++++++
 apidef/oas/middleware.go                 | 31 ++++++++++++++++++++++++
 apidef/oas/oas_test.go                   |  4 +--
 apidef/oas/schema/x-tyk-api-gateway.json |  3 +++
 apidef/oas/schema/x-tyk-gateway.md       |  5 ++++
 5 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/apidef/migration.go b/apidef/migration.go
index 80fe0ca228a9..d09d8b56593b 100644
--- a/apidef/migration.go
+++ b/apidef/migration.go
@@ -247,10 +247,12 @@ func (a *APIDefinition) Migrate() (versions []APIDefinition, err error) {
 	a.MigrateEndpointMeta()
 	a.MigrateCachePlugin()
 	a.migrateGlobalHeaders()
+	a.migrateGlobalResponseHeaders()
 	for i := 0; i < len(versions); i++ {
 		versions[i].MigrateEndpointMeta()
 		versions[i].MigrateCachePlugin()
 		versions[i].migrateGlobalHeaders()
+		versions[i].migrateGlobalResponseHeaders()
 	}
 
 	return versions, nil
@@ -321,6 +323,14 @@ func (a *APIDefinition) migrateGlobalHeaders() {
 	}
 }
 
+func (a *APIDefinition) migrateGlobalResponseHeaders() {
+	vInfo := a.VersionData.Versions[""]
+	if len(vInfo.GlobalResponseHeaders) == 0 && len(vInfo.GlobalResponseHeadersRemove) == 0 {
+		vInfo.GlobalResponseHeadersDisabled = true
+		a.VersionData.Versions[""] = vInfo
+	}
+}
+
 func (a *APIDefinition) MigrateCachePlugin() {
 	vInfo := a.VersionData.Versions[""]
 	list := vInfo.ExtendedPaths.Cached
diff --git a/apidef/oas/middleware.go b/apidef/oas/middleware.go
index c82c99997804..572d86302aad 100644
--- a/apidef/oas/middleware.go
+++ b/apidef/oas/middleware.go
@@ -73,6 +73,10 @@ type Global struct {
 	// TransformRequestHeaders contains the configurations related to API level request header transformation.
 	// Tyk classic API definition: `global_headers`/`global_headers_remove`.
 	TransformRequestHeaders *TransformHeaders `bson:"transformRequestHeaders,omitempty" json:"transformRequestHeaders,omitempty"`
+
+	// TransformResponseHeaders contains the configurations related to API level response header transformation.
+	// Tyk classic API definition: `global_response_headers`/`global_response_headers_remove`.
+	TransformResponseHeaders *TransformHeaders `bson:"transformResponseHeaders,omitempty" json:"transformResponseHeaders,omitempty"`
 }
 
 // Fill fills *Global from apidef.APIDefinition.
@@ -153,6 +157,19 @@ func (g *Global) Fill(api apidef.APIDefinition) {
 	if ShouldOmit(g.TransformRequestHeaders) {
 		g.TransformRequestHeaders = nil
 	}
+
+	if g.TransformResponseHeaders == nil {
+		g.TransformResponseHeaders = &TransformHeaders{}
+	}
+
+	g.TransformResponseHeaders.Fill(apidef.HeaderInjectionMeta{
+		Disabled:      vInfo.GlobalResponseHeadersDisabled,
+		AddHeaders:    vInfo.GlobalResponseHeaders,
+		DeleteHeaders: vInfo.GlobalResponseHeadersRemove,
+	})
+	if ShouldOmit(g.TransformResponseHeaders) {
+		g.TransformResponseHeaders = nil
+	}
 }
 
 // ExtractTo extracts *Global into *apidef.APIDefinition.
@@ -230,6 +247,16 @@ func (g *Global) ExtractTo(api *apidef.APIDefinition) {
 	var headerMeta apidef.HeaderInjectionMeta
 	g.TransformRequestHeaders.ExtractTo(&headerMeta)
 
+	if g.TransformResponseHeaders == nil {
+		g.TransformResponseHeaders = &TransformHeaders{}
+		defer func() {
+			g.TransformResponseHeaders = nil
+		}()
+	}
+
+	var resHeaderMeta apidef.HeaderInjectionMeta
+	g.TransformResponseHeaders.ExtractTo(&resHeaderMeta)
+
 	if len(api.VersionData.Versions) == 0 {
 		api.VersionData.Versions = map[string]apidef.VersionInfo{
 			Main: {},
@@ -240,6 +267,10 @@ func (g *Global) ExtractTo(api *apidef.APIDefinition) {
 	vInfo.GlobalHeadersDisabled = headerMeta.Disabled
 	vInfo.GlobalHeaders = headerMeta.AddHeaders
 	vInfo.GlobalHeadersRemove = headerMeta.DeleteHeaders
+
+	vInfo.GlobalResponseHeadersDisabled = resHeaderMeta.Disabled
+	vInfo.GlobalResponseHeaders = resHeaderMeta.AddHeaders
+	vInfo.GlobalResponseHeadersRemove = resHeaderMeta.DeleteHeaders
 	api.VersionData.Versions[Main] = vInfo
 }
 
diff --git a/apidef/oas/oas_test.go b/apidef/oas/oas_test.go
index 78148a653f43..e6e965c7b6d1 100644
--- a/apidef/oas/oas_test.go
+++ b/apidef/oas/oas_test.go
@@ -169,6 +169,7 @@ func TestOAS_ExtractTo_ResetAPIDefinition(t *testing.T) {
 	vInfo.Paths.BlackList = nil
 	vInfo.OverrideTarget = ""
 	vInfo.GlobalHeadersDisabled = false
+	vInfo.GlobalResponseHeadersDisabled = false
 	vInfo.UseExtendedPaths = false
 	vInfo.ExtendedPaths.MockResponse = nil
 	vInfo.ExtendedPaths.Cached = nil
@@ -245,9 +246,6 @@ func TestOAS_ExtractTo_ResetAPIDefinition(t *testing.T) {
 		"APIDefinition.VersionData.Versions[0].ExtendedPaths.PersistGraphQL[0].Method",
 		"APIDefinition.VersionData.Versions[0].ExtendedPaths.PersistGraphQL[0].Operation",
 		"APIDefinition.VersionData.Versions[0].ExtendedPaths.PersistGraphQL[0].Variables[0]",
-		"APIDefinition.VersionData.Versions[0].GlobalResponseHeaders[0]",
-		"APIDefinition.VersionData.Versions[0].GlobalResponseHeadersRemove[0]",
-		"APIDefinition.VersionData.Versions[0].GlobalResponseHeadersDisabled",
 		"APIDefinition.VersionData.Versions[0].IgnoreEndpointCase",
 		"APIDefinition.VersionData.Versions[0].GlobalSizeLimit",
 		"APIDefinition.UptimeTests.CheckList[0].CheckURL",
diff --git a/apidef/oas/schema/x-tyk-api-gateway.json b/apidef/oas/schema/x-tyk-api-gateway.json
index c81781db9ff2..58ef4778aac0 100644
--- a/apidef/oas/schema/x-tyk-api-gateway.json
+++ b/apidef/oas/schema/x-tyk-api-gateway.json
@@ -497,6 +497,9 @@
         },
         "transformRequestHeaders": {
           "$ref": "#/definitions/X-Tyk-TransformHeaders"
+        },
+        "transformResponseHeaders": {
+          "$ref": "#/definitions/X-Tyk-TransformHeaders"
         }
       }
     },
diff --git a/apidef/oas/schema/x-tyk-gateway.md b/apidef/oas/schema/x-tyk-gateway.md
index f7688f6727e5..ed9ff133cf3b 100644
--- a/apidef/oas/schema/x-tyk-gateway.md
+++ b/apidef/oas/schema/x-tyk-gateway.md
@@ -670,6 +670,11 @@ TransformRequestHeaders contains the configurations related to API level request
 
 Tyk classic API definition: `global_headers`/`global_headers_remove`.
 
+**Field: `transformResponseHeaders` ([TransformHeaders](#transformheaders))**
+TransformResponseHeaders contains the configurations related to API level response header transformation.
+
+Tyk classic API definition: `global_response_headers`/`global_response_headers_remove`.
+
 
 ### **PluginConfig**