Add evaluation context support

Author: khvn26

Makefile

@@ -0,0 +1,8 @@
+.EXPORT_ALL_VARIABLES:
+
+EVALUATION_CONTEXT_SCHEMA_URL ?= https://raw.githubusercontent.com/Flagsmith/flagsmith/feat/evaluation-context-schema/sdk/evaluation-context.json
+
+
+.PHONY: generate-evaluation-context
+generate-evaluation-context:
+	npx quicktype ${EVALUATION_CONTEXT_SCHEMA_URL} --src-lang schema --lang go --package flagsmith --omit-empty --just-types-and-package > evaluationcontext.go

client.go

@@ -14,9 +14,13 @@ import (
 	"github.com/Flagsmith/flagsmith-go-client/v3/flagengine/segments"
 	"github.com/Flagsmith/flagsmith-go-client/v3/internal/flaghttp"
 
-	. "github.com/Flagsmith/flagsmith-go-client/v3/flagengine/identities/traits"
+	enginetraits "github.com/Flagsmith/flagsmith-go-client/v3/flagengine/identities/traits"
 )
 
+type contextKey string
+
+var contextKeyEvaluationContext = contextKey("evaluationContext")
+
 // Client provides various methods to query Flagsmith API.
 type Client struct {
 	apiKey string
@@ -44,8 +48,8 @@ func NewClient(apiKey string, options ...Option) *Client {
 	}
 
 	c.client.SetHeaders(map[string]string{
-		"Accept":            "application/json",
-		"X-Environment-Key": c.apiKey,
+		"Accept":                      "application/json",
+		flaghttp.EnvironmentKeyHeader: c.apiKey,
 	})
 	c.client.SetTimeout(c.config.timeout)
 	c.log = createLogger()
@@ -87,9 +91,34 @@ func NewClient(apiKey string, options ...Option) *Client {
 
 // Returns `Flags` struct holding all the flags for the current environment.
 //
+// Provide `EvaluationContext` to evaluate flags for a specific environment or identity.
+//
 // If local evaluation is enabled this function will not call the Flagsmith API
 // directly, but instead read the asynchronously updated local environment or
 // use the default flag handler in case it has not yet been updated.
+//
+// Notes:
+//
+// * `EvaluationContext.Environment` is ignored in local evaluation mode.
+//
+// * `EvaluationContext.Feature` is not yet supported.
+func (c *Client) GetFlags(ctx context.Context, ec *EvaluationContext) (f Flags, err error) {
+	if ec != nil {
+		ctx = context.WithValue(ctx, contextKeyEvaluationContext, ec)
+		if ec.Identity != nil {
+			return c.GetIdentityFlags(ctx, ec.Identity.Identifier, mapIdentityEvaluationContextToTraits(*ec.Identity))
+		}
+	}
+	return c.GetEnvironmentFlags(ctx)
+}
+
+// Returns `Flags` struct holding all the flags for the current environment.
+//
+// If local evaluation is enabled this function will not call the Flagsmith API
+// directly, but instead read the asynchronously updated local environment or
+// use the default flag handler in case it has not yet been updated.
+//
+// Deprecated: Use `GetFlags` instead.
 func (c *Client) GetEnvironmentFlags(ctx context.Context) (f Flags, err error) {
 	if c.config.localEvaluation || c.config.offlineMode {
 		if f, err = c.getEnvironmentFlagsFromEnvironment(); err == nil {
@@ -108,10 +137,6 @@ func (c *Client) GetEnvironmentFlags(ctx context.Context) (f Flags, err error) {
 	return Flags{}, &FlagsmithClientError{msg: fmt.Sprintf("Failed to fetch flags with error: %s", err)}
 }
 
-type GetIdentityFlagsOpts struct {
-	Transient bool `json:"transient,omitempty"`
-}
-
 // Returns `Flags` struct holding all the flags for the current environment for
 // a given identity.
 //
@@ -122,13 +147,15 @@ type GetIdentityFlagsOpts struct {
 // If local evaluation is enabled this function will not call the Flagsmith API
 // directly, but instead read the asynchronously updated local environment or
 // use the default flag handler in case it has not yet been updated.
-func (c *Client) GetIdentityFlags(ctx context.Context, identifier string, traits []*Trait, opts *GetIdentityFlagsOpts) (f Flags, err error) {
+//
+// Deprecated: Use `GetFlags` providing `EvaluationContext.Identity` instead.
+func (c *Client) GetIdentityFlags(ctx context.Context, identifier string, traits []*Trait) (f Flags, err error) {
 	if c.config.localEvaluation || c.config.offlineMode {
 		if f, err = c.getIdentityFlagsFromEnvironment(identifier, traits); err == nil {
 			return f, nil
 		}
 	} else {
-		if f, err = c.GetIdentityFlagsFromAPI(ctx, identifier, traits, opts); err == nil {
+		if f, err = c.GetIdentityFlagsFromAPI(ctx, identifier, traits); err == nil {
 			return f, nil
 		}
 	}
@@ -180,7 +207,15 @@ func (c *Client) BulkIdentify(ctx context.Context, batch []*IdentityTraits) erro
 // GetEnvironmentFlagsFromAPI tries to contact the Flagsmith API to get the latest environment data.
 // Will return an error in case of failure or unexpected response.
 func (c *Client) GetEnvironmentFlagsFromAPI(ctx context.Context) (Flags, error) {
-	resp, err := c.client.NewRequest().
+	req := c.client.NewRequest()
+	maybeEc := ctx.Value(contextKeyEvaluationContext)
+	if maybeEc != nil {
+		envCtx := maybeEc.(*EvaluationContext).Environment
+		if envCtx != nil {
+			req.SetHeader(flaghttp.EnvironmentKeyHeader, envCtx.APIKey)
+		}
+	}
+	resp, err := req.
 		SetContext(ctx).
 		ForceContentType("application/json").
 		Get(c.config.baseURL + "flags/")
@@ -195,16 +230,27 @@ func (c *Client) GetEnvironmentFlagsFromAPI(ctx context.Context) (Flags, error)
 
 // GetIdentityFlagsFromAPI tries to contact the Flagsmith API to get the latest identity flags.
 // Will return an error in case of failure or unexpected response.
-func (c *Client) GetIdentityFlagsFromAPI(ctx context.Context, identifier string, traits []*Trait, opts *GetIdentityFlagsOpts) (Flags, error) {
+func (c *Client) GetIdentityFlagsFromAPI(ctx context.Context, identifier string, traits []*Trait) (Flags, error) {
 	body := struct {
 		Identifier string   `json:"identifier"`
 		Traits     []*Trait `json:"traits,omitempty"`
-		GetIdentityFlagsOpts
+		Transient  *bool    `json:"transient,omitempty"`
 	}{Identifier: identifier, Traits: traits}
-	if opts != nil {
-		body.Transient = opts.Transient
+	req := c.client.NewRequest()
+	maybeEc := ctx.Value(contextKeyEvaluationContext)
+	if maybeEc != nil {
+		ec := maybeEc.(*EvaluationContext)
+		envCtx := ec.Environment
+		if envCtx != nil {
+			req.SetHeader(flaghttp.EnvironmentKeyHeader, envCtx.APIKey)
+		}
+		idCtx := ec.Identity
+		if idCtx != nil {
+			// `Identifier` and `Traits` had been set by `GetFlags` earlier.
+			body.Transient = &idCtx.Transient
+		}
 	}
-	resp, err := c.client.NewRequest().
+	resp, err := req.
 		SetBody(&body).
 		SetContext(ctx).
 		ForceContentType("application/json").
@@ -295,7 +341,7 @@ func (c *Client) UpdateEnvironment(ctx context.Context) error {
 }
 
 func (c *Client) getIdentityModel(identifier string, apiKey string, traits []*Trait) identities.IdentityModel {
-	identityTraits := make([]*TraitModel, len(traits))
+	identityTraits := make([]*enginetraits.TraitModel, len(traits))
 	for i, trait := range traits {
 		identityTraits[i] = trait.ToTraitModel()
 	}