feat: add basic react support (#31)

## This PR

- proof-of-concept React code gen implementation

### How to test

#### Run:
`go run main.go generate react --flag_manifest_path
./sample/sample_manifest.json --output_path ./output.ts`

#### Output

```ts
'use client';

import {
	useBooleanFlagDetails,
	useNumberFlagDetails,
	useStringFlagDetails,
} from "@openfeature/react-sdk";

/**
* Discount percentage applied to purchases.
* 
* **Details:**
* - flag key: `discountPercentage`
* - default value: `0.15`
* - type: `number`
*/
export const useDiscountPercentage = (options: Parameters<typeof useNumberFlagDetails>[2]) => {
  return useNumberFlagDetails("discountPercentage", 0.15, options);
};

/**
* Controls whether Feature A is enabled.
* 
* **Details:**
* - flag key: `enableFeatureA`
* - default value: `false`
* - type: `boolean`
*/
export const useEnableFeatureA = (options: Parameters<typeof useBooleanFlagDetails>[2]) => {
  return useBooleanFlagDetails("enableFeatureA", false, options);
};

/**
* Maximum allowed length for usernames.
* 
* **Details:**
* - flag key: `usernameMaxLength`
* - default value: `50`
* - type: `number`
*/
export const useUsernameMaxLength = (options: Parameters<typeof useNumberFlagDetails>[2]) => {
  return useNumberFlagDetails("usernameMaxLength", 50, options);
};

/**
* The message to use for greeting users.
* 
* **Details:**
* - flag key: `greetingMessage`
* - default value: `Hello there!`
* - type: `string`
*/
export const useGreetingMessage = (options: Parameters<typeof useStringFlagDetails>[2]) => {
  return useStringFlagDetails("greetingMessage", "Hello there!", options);
};

```

Signed-off-by: Michael Beemer <[email protected]>

cmd/generate/generate.go

@@ -2,6 +2,7 @@ package generate
 
 import (
 	"codegen/cmd/generate/golang"
+	"codegen/cmd/generate/react"
 	"codegen/internal/flagkeys"
 
 	"github.com/spf13/cobra"
@@ -18,6 +19,7 @@ var Root = &cobra.Command{
 func init() {
 	// Add subcommands.
 	Root.AddCommand(golang.Cmd)
+	Root.AddCommand(react.Cmd)
 
 	// Add flags.
 	Root.PersistentFlags().String(flagkeys.FlagManifestPath, "", "Path to the flag manifest.")

cmd/generate/react/react.go

@@ -0,0 +1,24 @@
+package react
+
+import (
+	"codegen/internal/generate"
+	"codegen/internal/generate/plugins/react"
+
+	"github.com/spf13/cobra"
+)
+
+// Cmd for "generate" command, handling code generation for flag accessors
+var Cmd = &cobra.Command{
+	Use:   "react",
+	Short: "Generate typesafe React Hooks.",
+	Long:  `Generate typesafe React Hooks compatible with the OpenFeature React SDK.`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		params := react.Params{}
+		gen := react.NewGenerator(params)
+		err := generate.CreateFlagAccessors(gen)
+		return err
+	},
+}
+
+func init() {
+}

internal/generate/generate.go

@@ -16,7 +16,7 @@ import (
 )
 
 // GenerateFile receives data for the Go template engine and outputs the contents to the file.
-// Intended to be invoked by each language generator with appropiate data.
+// Intended to be invoked by each language generator with appropriate data.
 func GenerateFile(funcs template.FuncMap, contents string, data types.TmplDataInterface) error {
 	contentsTmpl, err := template.New("contents").Funcs(funcs).Parse(contents)
 	if err != nil {
@@ -47,7 +47,7 @@ func GenerateFile(funcs template.FuncMap, contents string, data types.TmplDataIn
 	return nil
 }
 
-// Takes as input a generator and outputs file with the appropiate flag accessors.
+// Takes as input a generator and outputs file with the appropriate flag accessors.
 // The flag data is taken from the provided flag manifest.
 func CreateFlagAccessors(gen types.Generator) error {
 	bt, err := manifestutils.LoadData(viper.GetString(flagkeys.FlagManifestPath), gen.SupportedFlagTypes())

internal/generate/plugins/react/react.go

@@ -0,0 +1,121 @@
+package react
+
+import (
+	_ "embed"
+	"sort"
+	"strconv"
+	"text/template"
+
+	"codegen/internal/generate"
+	"codegen/internal/generate/types"
+
+	"github.com/iancoleman/strcase"
+)
+
+type TmplData struct {
+	*types.BaseTmplData
+}
+
+type genImpl struct {
+}
+
+// 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 Go 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 react.tmpl
+var reactTmpl string
+
+func flagVarName(flagName string) string {
+	return strcase.ToCamel(flagName)
+}
+
+func flagInitParam(flagName string) string {
+	return strconv.Quote(flagName)
+}
+
+func flagAccessFunc(t types.FlagType) string {
+	switch t {
+	case types.IntType, types.FloatType:
+		return "useNumberFlagDetails"
+	case types.BoolType:
+		return "useBooleanFlagDetails"
+	case types.StringType:
+		return "useStringFlagDetails"
+	default:
+		return ""
+	}
+}
+
+func supportImports(flags []*types.FlagTmplData) []string {
+	imports := make(map[string]struct{})
+	for _, flag := range flags {
+		imports[flagAccessFunc(flag.Type)] = struct{}{}
+	}
+	var result []string
+	for k := range imports {
+		result = append(result, k)
+	}
+	sort.Strings(result)
+	return result
+}
+
+func defaultValueLiteral(flag *types.FlagTmplData) string {
+	switch flag.Type {
+	case types.StringType:
+		return strconv.Quote(flag.DefaultValue)
+	default:
+		return flag.DefaultValue
+	}
+}
+
+func typeString(flagType types.FlagType) string {
+	switch flagType {
+	case types.StringType:
+		return "string"
+	case types.IntType, types.FloatType:
+		return "number"
+	case types.BoolType:
+		return "boolean"
+	default:
+		return ""
+	}
+}
+
+func (g *genImpl) Generate(input types.Input) error {
+	funcs := template.FuncMap{
+		"FlagVarName":         flagVarName,
+		"FlagInitParam":       flagInitParam,
+		"FlagAccessFunc":      flagAccessFunc,
+		"SupportImports":      supportImports,
+		"DefaultValueLiteral": defaultValueLiteral,
+		"TypeString":          typeString,
+	}
+	td := TmplData{
+		BaseTmplData: input.BaseData,
+	}
+	return generate.GenerateFile(funcs, reactTmpl, &td)
+}
+
+// Params are parameters for creating a Generator
+type Params struct {
+}
+
+// NewGenerator creates a generator for React.
+func NewGenerator(params Params) types.Generator {
+	return &genImpl{}
+}

internal/generate/plugins/react/react.tmpl

@@ -0,0 +1,20 @@
+'use client';
+
+import {
+{{- range $_, $p := SupportImports .Flags}}
+	{{$p}},
+{{- end}}
+} from "@openfeature/react-sdk";
+{{ range .Flags}}
+/**
+* {{.Docs}}
+* 
+* **Details:**
+* - flag key: `{{ .Name}}`
+* - default value: `{{ .DefaultValue}}`
+* - type: `{{TypeString .Type}}`
+*/
+export const use{{FlagVarName .Name}} = (options: Parameters<typeof {{FlagAccessFunc .Type}}>[2]) => {
+  return {{FlagAccessFunc .Type}}({{FlagInitParam .Name}}, {{DefaultValueLiteral .}}, options);
+};
+{{ end}}