feat: add java output for codegen initial version

cmd/generate/generate.go

@@ -2,6 +2,7 @@ package generate
 
 import (
 	"github.com/open-feature/cli/cmd/generate/golang"
+	"github.com/open-feature/cli/cmd/generate/java"
 	"github.com/open-feature/cli/cmd/generate/react"
 	"github.com/open-feature/cli/internal/flagkeys"
 
@@ -20,6 +21,7 @@ func init() {
 	// Add subcommands.
 	Root.AddCommand(golang.Cmd)
 	Root.AddCommand(react.Cmd)
+	Root.AddCommand(java.Cmd)
 
 	// Add flags.
 	Root.PersistentFlags().String(flagkeys.FlagManifestPath, "", "Path to the flag manifest.")

cmd/generate/generate_test.go

@@ -65,6 +65,32 @@ func TestGenerateReactSuccess(t *testing.T) {
 	compareOutput(t, testFileReact, memoryOutputPath, fs)
 }
 
+func TestGenerateJavaSuccess(t *testing.T) {
+	// Constant paths.
+	const memoryManifestPath = "manifest/path.json"
+	const memoryOutputPath = "example_java/ExperimentFlags.java"
+	const testFileManifest = "testdata/success_manifest.golden"
+	const testFileReact = "testdata/success_java.golden"
+
+	// Prepare in-memory files.
+	fs := afero.NewMemMapFs()
+	viper.Set(flagkeys.FileSystem, fs)
+	readOsFileAndWriteToMemMap(t, testFileManifest, memoryManifestPath, fs)
+
+	// Prepare command.
+	Root.SetArgs([]string{"java",
+		"--flag_manifest_path", memoryManifestPath,
+		"--output_path", memoryOutputPath,
+		"--package_name", "example_java",
+	})
+
+	// Run command.
+	Root.Execute()
+
+	// Compare result.
+	compareOutput(t, testFileReact, memoryOutputPath, fs)
+}
+
 func readOsFileAndWriteToMemMap(t *testing.T, inputPath string, memPath string, memFs afero.Fs) {
 	data, err := os.ReadFile(inputPath)
 	if err != nil {

cmd/generate/golang/golang.go

@@ -9,7 +9,8 @@ import (
 	"github.com/spf13/viper"
 )
 
-// Cmd for `generate“ command, handling code generation for flag accessors
+// Cmd for `generate go` command, handling code generation for flag accessors
+// for Golang.
 var Cmd = &cobra.Command{
 	Use:   "go",
 	Short: "Generate Golang flag accessors for OpenFeature.",

cmd/generate/java/java.go

@@ -0,0 +1,33 @@
+package java
+
+import (
+	"github.com/open-feature/cli/internal/flagkeys"
+	"github.com/open-feature/cli/internal/generate"
+	"github.com/open-feature/cli/internal/generate/plugins/java"
+
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+)
+
+// Cmd for `generate java“ command, handling code generation for flag accessors
+// for Java.
+var Cmd = &cobra.Command{
+	Use:   "java",
+	Short: "Generate Java flag accessors for OpenFeature.",
+	Long:  `Generate Java flag accessors for OpenFeature.`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		params := java.Params{
+			JavaPackage: viper.GetString(flagkeys.JavaPackageName),
+		}
+		gen := java.NewGenerator(params)
+		err := generate.CreateFlagAccessors(gen)
+		return err
+	},
+}
+
+func init() {
+	Cmd.Flags().String(flagkeys.JavaPackageName, "", "Name of the Java package to be generated.")
+	Cmd.MarkFlagRequired(flagkeys.JavaPackageName)
+	viper.BindPFlag(flagkeys.JavaPackageName, Cmd.Flags().Lookup(flagkeys.JavaPackageName))
+
+}

cmd/generate/testdata/success_java.golden

@@ -0,0 +1,56 @@
+// AUTOMATICALLY GENERATED BY OPENFEATURE CODEGEN, DO NOT EDIT.
+package example_java;
+import dev.openfeature.sdk.*;
+
+
+public class ExperimentFlags {
+    private static Client client = OpenFeatureAPI.getInstance().getClient();
+    /**
+     * Discount percentage applied to purchases.
+     */
+    public static class DiscountPercentage {
+        public static Double getValue(EvaluationContext evaluationContext) {
+            return client.getDoubleValue("discountPercentage", 0.15, evaluationContext);
+        }
+
+        public static FlagEvaluationDetails<Double> getValueDetails(EvaluationContext evaluationContext) {
+            return client.getDoubleDetails("discountPercentage", 0.15, evaluationContext);
+        }
+    }
+    /**
+     * Controls whether Feature A is enabled.
+     */
+    public static class EnableFeatureA {
+        public static Boolean getValue(EvaluationContext evaluationContext) {
+            return client.getBooleanValue("enableFeatureA", false, evaluationContext);
+        }
+
+        public static FlagEvaluationDetails<Boolean> getValueDetails(EvaluationContext evaluationContext) {
+            return client.getBooleanDetails("enableFeatureA", false, evaluationContext);
+        }
+    }
+    /**
+     * The message to use for greeting users.
+     */
+    public static class GreetingMessage {
+        public static String getValue(EvaluationContext evaluationContext) {
+            return client.getStringValue("greetingMessage", "Hello there!", evaluationContext);
+        }
+
+        public static FlagEvaluationDetails<String> getValueDetails(EvaluationContext evaluationContext) {
+            return client.getStringDetails("greetingMessage", "Hello there!", evaluationContext);
+        }
+    }
+    /**
+     * Maximum allowed length for usernames.
+     */
+    public static class UsernameMaxLength {
+        public static Integer getValue(EvaluationContext evaluationContext) {
+            return client.getIntegerValue("usernameMaxLength", 50, evaluationContext);
+        }
+
+        public static FlagEvaluationDetails<Integer> getValueDetails(EvaluationContext evaluationContext) {
+            return client.getIntegerDetails("usernameMaxLength", 50, evaluationContext);
+        }
+    }
+}

internal/flagkeys/flagkeys.go

@@ -14,6 +14,10 @@ const (
 	// GoPackageName is the key for the flag that stores the Golang package name.
 	GoPackageName = "package_name"
 
+	// `generate java` flags:
+	// JavaPackageName is the key for the flag that stores the Java package name.
+	JavaPackageName = "package_name"
+
 	//internal keys:
 	// FileSystem is the key for the flag that stores the filesystem interface.
 	FileSystem = "filesystem"

internal/generate/plugins/java/java.go

@@ -0,0 +1,123 @@
+package java
+
+import (
+	_ "embed"
+	"html/template"
+	"path/filepath"
+	"sort"
+	"strconv"
+	"strings"
+
+	"github.com/iancoleman/strcase"
+	"github.com/open-feature/cli/internal/generate"
+	"github.com/open-feature/cli/internal/generate/types"
+)
+
+// TmplData contains the Java-specific data and the base data for the codegen.
+type TmplData struct {
+	*types.BaseTmplData
+	JavaPackage string
+}
+
+type genImpl struct {
+	javaPackage string
+}
+
+// BaseTmplDataInfo provides the base template data for the codegen.
+func (td *TmplData) BaseTmplDataInfo() *types.BaseTmplData {
+	return td.BaseTmplData
+}
+
+// supportedFlagTypes is the flag types supported by the Java template.
+var supportedFlagTypes = map[types.FlagType]bool{
+	types.FloatType:  true,
+	types.StringType: true,
+	types.IntType:    true,
+	types.BoolType:   true,
+	types.ObjectType: false,
+}
+
+func (*genImpl) SupportedFlagTypes() map[types.FlagType]bool {
+	return supportedFlagTypes
+}
+
+//go:embed java.tmpl
+var javaTmpl string
+
+// Java Funcs BEGIN
+
+func flagClass(flagName string) string {
+	return strcase.ToCamel(flagName)
+}
+
+func topLevelClass(outputPath string) string {
+	return strings.TrimSuffix(filepath.Base(outputPath), filepath.Ext(outputPath))
+}
+
+func flagInitParam(flagName string) string {
+	return strconv.Quote(flagName)
+}
+
+func javaType(t types.FlagType) string {
+	switch t {
+	case types.IntType:
+		return "Integer"
+	case types.FloatType:
+		return "Double"
+	case types.BoolType:
+		return "Boolean"
+	case types.StringType:
+		return "String"
+	default:
+		return ""
+	}
+}
+
+func supportImports(flags []*types.FlagTmplData) []string {
+	var res []string
+	if len(flags) > 0 {
+		res = append(res, "dev.openfeature.sdk.*")
+	}
+	sort.Strings(res)
+	return res
+}
+
+func defaultValueLiteral(flag *types.FlagTmplData) string {
+	switch flag.Type {
+	case types.StringType:
+		return strconv.Quote(flag.DefaultValue)
+	default:
+		return flag.DefaultValue
+	}
+}
+
+// Java Funcs END
+
+// Generate generates the Java flag accessors for OpenFeature.
+func (g *genImpl) Generate(input types.Input) error {
+	funcs := template.FuncMap{
+		"FlagClass":           flagClass,
+		"TopLevelClass":       topLevelClass,
+		"FlagInitParam":       flagInitParam,
+		"JavaType":            javaType,
+		"SupportImports":      supportImports,
+		"DefaultValueLiteral": defaultValueLiteral,
+	}
+	td := TmplData{
+		BaseTmplData: input.BaseData,
+		JavaPackage:  g.javaPackage,
+	}
+	return generate.GenerateFile(funcs, javaTmpl, &td)
+}
+
+// Params are parameters for creating a Generator
+type Params struct {
+	JavaPackage string
+}
+
+// NewGenerator creates a generator for Java.
+func NewGenerator(params Params) types.Generator {
+	return &genImpl{
+		javaPackage: params.JavaPackage,
+	}
+}

internal/generate/plugins/java/java.tmpl

@@ -0,0 +1,27 @@
+// AUTOMATICALLY GENERATED BY OPENFEATURE CODEGEN, DO NOT EDIT.
+package {{.JavaPackage}};
+
+
+{{- range $_, $p := SupportImports .Flags}}
+import {{$p}};
+{{- end}}
+
+
+public class {{TopLevelClass .OutputPath}} {
+    private static Client client = OpenFeatureAPI.getInstance().getClient();
+
+{{- range .Flags}}
+    /**
+     * {{.Docs}}
+     */
+    public static class {{FlagClass .Name}} {
+        public static {{JavaType .Type}} getValue(EvaluationContext evaluationContext) {
+            return client.get{{JavaType .Type}}Value({{FlagInitParam .Name}}, {{DefaultValueLiteral .}}, evaluationContext);
+        }
+
+        public static FlagEvaluationDetails<{{JavaType .Type}}> getValueDetails(EvaluationContext evaluationContext) {
+            return client.get{{JavaType .Type}}Details({{FlagInitParam .Name}}, {{DefaultValueLiteral .}}, evaluationContext);
+        }
+    }
+{{- end}}
+}