feat: fetch v2 for remote eval client (#26)

* feat: fetch v2 for remote eval client

* simplify

* use v2 fetch in cmd

cmd/xpmt/main.go

@@ -90,7 +90,7 @@ func fetch() {
 
 	client := remote.Initialize(*apiKey, config)
 	start := time.Now()
-	variants, err := client.Fetch(user)
+	variants, err := client.FetchV2(user)
 	if err != nil {
 		fmt.Printf("error: %v\n", err)
 		os.Exit(1)

pkg/experiment/remote/client.go

@@ -1,8 +1,8 @@
 package remote
 
 import (
-	"bytes"
 	"context"
+	"encoding/base64"
 	"encoding/json"
 	"fmt"
 	"math"
@@ -47,7 +47,19 @@ func Initialize(apiKey string, config *Config) *Client {
 	return client
 }
 
+// Deprecated: Use FetchV2
 func (c *Client) Fetch(user *experiment.User) (map[string]experiment.Variant, error) {
+	variants, err := c.FetchV2(user)
+	if err != nil {
+		return nil, err
+	}
+	results := filterDefaultVariants(variants)
+	return results, nil
+}
+
+// FetchV2 fetches variants for a user from the remote evaluation service.
+// Unlike Fetch, this method returns all variants, including default variants.
+func (c *Client) FetchV2(user *experiment.User) (map[string]experiment.Variant, error) {
 	variants, err := c.doFetch(user, c.config.FetchTimeout)
 	if err != nil {
 		c.log.Error("fetch error: %v", err)
@@ -66,7 +78,7 @@ func (c *Client) doFetch(user *experiment.User, timeout time.Duration) (map[stri
 	if err != nil {
 		return nil, err
 	}
-	endpoint.Path = "sdk/vardata"
+	endpoint.Path = "sdk/v2/vardata"
 	if c.config.Debug {
 		endpoint.RawQuery = fmt.Sprintf("d=%s", randStringRunes(5))
 	}
@@ -77,13 +89,13 @@ func (c *Client) doFetch(user *experiment.User, timeout time.Duration) (map[stri
 	c.log.Debug("fetch variants for user %s", string(jsonBytes))
 	ctx, cancel := context.WithTimeout(context.Background(), timeout)
 	defer cancel()
-	req, err := http.NewRequest("POST", endpoint.String(), bytes.NewBuffer(jsonBytes))
+	req, err := http.NewRequestWithContext(ctx, "GET", endpoint.String(), nil)
 	if err != nil {
 		return nil, err
 	}
-	req = req.WithContext(ctx)
 	req.Header.Set("Authorization", fmt.Sprintf("Api-Key %s", c.apiKey))
 	req.Header.Set("Content-Type", "application/json; charset=UTF-8")
+	req.Header.Set("X-Amp-Exp-User", base64.StdEncoding.EncodeToString(jsonBytes))
 	c.log.Debug("fetch request: %v", req)
 	resp, err := c.client.Do(req)
 	if err != nil {
@@ -122,24 +134,11 @@ func (c *Client) retryFetch(user *experiment.User) (map[string]experiment.Varian
 }
 
 func (c *Client) parseResponse(resp *http.Response) (map[string]experiment.Variant, error) {
-	interop := make(interopVariants)
-	err := json.NewDecoder(resp.Body).Decode(&interop)
+	variants := make(map[string]experiment.Variant)
+	err := json.NewDecoder(resp.Body).Decode(&variants)
 	if err != nil {
 		return nil, err
 	}
-	variants := make(map[string]experiment.Variant)
-	for k, iv := range interop {
-		var value string
-		if iv.Value != "" {
-			value = iv.Value
-		} else if iv.Key != "" {
-			value = iv.Key
-		}
-		variants[k] = experiment.Variant{
-			Value:   value,
-			Payload: iv.Payload,
-		}
-	}
 	c.log.Debug("parsed variants from response: %v", variants)
 	return variants, nil
 }
@@ -172,3 +171,21 @@ func shouldRetryFetch(err error) bool {
 	}
 	return true
 }
+
+func filterDefaultVariants(variants map[string]experiment.Variant) map[string]experiment.Variant {
+	results := make(map[string]experiment.Variant)
+	for key, variant := range variants {
+		isDefault, ok := variant.Metadata["default"].(bool)
+		if !ok {
+			isDefault = false
+		}
+		isDeployed, ok := variant.Metadata["deployed"].(bool)
+		if !ok {
+			isDeployed = true
+		}
+		if !isDefault && isDeployed {
+			results[key] = variant
+		}
+	}
+	return results
+}

pkg/experiment/remote/client_test.go

@@ -12,6 +12,28 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func TestClient_Fetch_DoesNotReturnDefaultVariants(t *testing.T) {
+	client := Initialize("server-qz35UwzJ5akieoAdIgzM4m9MIiOLXLoz", nil)
+	user := &experiment.User{}
+	result, err := client.Fetch(user)
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	variant := result["sdk-ci-test"]
+	require.Empty(t, variant)
+}
+
+
+func TestClient_FetchV2_ReturnsDefaultVariants(t *testing.T) {
+	client := Initialize("server-qz35UwzJ5akieoAdIgzM4m9MIiOLXLoz", nil)
+	user := &experiment.User{}
+	result, err := client.FetchV2(user)
+	require.NoError(t, err)
+	require.NotNil(t, result)
+	variant := result["sdk-ci-test"]
+	require.NotNil(t, variant)
+	require.Equal(t, "off", variant.Key)
+}
+
 func TestClient_FetchRetryWithDifferentResponseCodes(t *testing.T) {
 	// Test data: Response code, error message, and expected number of fetch calls
 	testData := []struct {