From ffa7c9fdf5901d45aafdd96ebb7b72f30374b421 Mon Sep 17 00:00:00 2001
From: Philip Gough <philip.p.gough@gmail.com>
Date: Thu, 21 Feb 2019 09:00:26 +0000
Subject: [PATCH] client: Expose rate limit extensions in response

---
 client/auth_rep.go |  2 +-
 client/authz.go    |  4 ++--
 client/client.go   | 35 +++++++++++++++++++++++++++++++++--
 client/report.go   |  2 +-
 client/types.go    | 10 ++++++----
 5 files changed, 43 insertions(+), 10 deletions(-)

diff --git a/client/auth_rep.go b/client/auth_rep.go
index 2eb9a05..1f07bf2 100644
--- a/client/auth_rep.go
+++ b/client/auth_rep.go
@@ -51,7 +51,7 @@ func (client *ThreeScaleClient) authRep(values url.Values, extensions map[string
 	}
 
 	req.URL.RawQuery = values.Encode()
-	resp, err = client.doHttpReq(req)
+	resp, err = client.doHttpReq(req, extensions)
 	if err != nil {
 		return resp, fmt.Errorf("error calling 3Scale API - %s", err.Error())
 	}
diff --git a/client/authz.go b/client/authz.go
index d2aa016..ac802c4 100644
--- a/client/authz.go
+++ b/client/authz.go
@@ -23,7 +23,7 @@ func (client *ThreeScaleClient) Authorize(appId string, serviceToken string, ser
 	values.Add("service_id", serviceId)
 
 	req.URL.RawQuery = values.Encode()
-	authRepRes, err := client.doHttpReq(req)
+	authRepRes, err := client.doHttpReq(req, extensions)
 	if err != nil {
 		return authRepResp, fmt.Errorf("error calling 3Scale API - %s", err.Error())
 	}
@@ -45,7 +45,7 @@ func (client *ThreeScaleClient) AuthorizeKey(userKey string, serviceToken string
 	values.Add("service_id", serviceId)
 
 	req.URL.RawQuery = values.Encode()
-	resp, err = client.doHttpReq(req)
+	resp, err = client.doHttpReq(req, extensions)
 	if err != nil {
 		return resp, fmt.Errorf("error calling 3Scale API - %s", err.Error())
 	}
diff --git a/client/client.go b/client/client.go
index fa947c1..703b1de 100644
--- a/client/client.go
+++ b/client/client.go
@@ -14,6 +14,7 @@ import (
 const (
 	defaultBackendUrl = "https://su1.3scale.net:443"
 	queryTag          = "query"
+	limitExtensions   = "limit_headers"
 )
 
 var httpReqError = errors.New("error building http request")
@@ -52,7 +53,7 @@ func NewThreeScale(backEnd *Backend, httpClient *http.Client) *ThreeScaleClient
 }
 
 // GetPeer - a utility method that returns the remote hostname of the client
-func (client  *ThreeScaleClient) GetPeer() string {
+func (client *ThreeScaleClient) GetPeer() string {
 	return client.backend.host
 }
 
@@ -93,7 +94,7 @@ func encodeExtensions(extensions map[string]string) string {
 }
 
 // Call 3scale backend with the provided HTTP request
-func (client *ThreeScaleClient) doHttpReq(req *http.Request) (ApiResponse, error) {
+func (client *ThreeScaleClient) doHttpReq(req *http.Request, ext map[string]string) (ApiResponse, error) {
 	var authRepRes ApiResponse
 
 	resp, err := client.httpClient.Do(req)
@@ -108,10 +109,40 @@ func (client *ThreeScaleClient) doHttpReq(req *http.Request) (ApiResponse, error
 	if err != nil {
 		return authRepRes, err
 	}
+
+	if ext != nil {
+		if _, ok := ext[limitExtensions]; ok {
+			if limitRem := resp.Header.Get("3scale-limit-remaining"); limitRem != "" {
+				remainingLimit, _ := strconv.Atoi(limitRem)
+				authRepRes.limitRemaining = &remainingLimit
+			}
+
+			if limReset := resp.Header.Get("3scale-limit-reset"); limReset != "" {
+				resetLimit, _ := strconv.Atoi(limReset)
+				authRepRes.limitReset = &resetLimit
+			}
+		}
+	}
+
 	authRepRes.StatusCode = resp.StatusCode
 	return authRepRes, nil
 }
 
+// GetLimitRemaining - An integer stating the amount of hits left for the full combination of metrics authorized in this call
+// before the rate limiting logic would start denying authorizations for the current period.
+// A negative integer value means there is no limit in the amount of hits.
+// Nil value will indicate the extension has not been used.
+func (r ApiResponse) GetLimitRemaining() *int {
+	return r.limitRemaining
+}
+
+// GetLimitReset - An integer stating the amount of seconds left for the current limiting period to elapse.
+// A negative integer value means there is no limit in time.
+// Nil value will indicate the extension has not been used.
+func (r ApiResponse) GetLimitReset() *int {
+	return r.limitReset
+}
+
 // Add a metric to list of metrics to be reported
 // Returns error if provided value is non-positive and entry will be ignored
 func (m Metrics) Add(name string, value int) error {
diff --git a/client/report.go b/client/report.go
index 1052782..f79c5e4 100644
--- a/client/report.go
+++ b/client/report.go
@@ -44,7 +44,7 @@ func (client *ThreeScaleClient) report(values url.Values, extensions map[string]
 	}
 
 	req.URL.RawQuery = values.Encode()
-	resp, err = client.doHttpReq(req)
+	resp, err = client.doHttpReq(req, extensions)
 	if err != nil {
 		return resp, fmt.Errorf("error calling 3Scale API - %s", err.Error())
 	}
diff --git a/client/types.go b/client/types.go
index d499868..2c74826 100644
--- a/client/types.go
+++ b/client/types.go
@@ -12,9 +12,11 @@ const providerKey = "provider_key"
 
 // ApiResponse - formatted response to client
 type ApiResponse struct {
-	Reason     string
-	Success    bool
-	StatusCode int
+	Reason         string
+	Success        bool
+	StatusCode     int
+	limitRemaining *int
+	limitReset     *int
 }
 
 // ApiResponseXML - response from backend API
@@ -80,7 +82,7 @@ type TokenAuth struct {
 	Value string
 }
 
-func (auth *TokenAuth) SetURLValues(values *url.Values) (error) {
+func (auth *TokenAuth) SetURLValues(values *url.Values) error {
 
 	switch auth.Type {
 	case serviceToken: