goCode generation by dummies for dummies (#275)

* goCode generation by dummies for dummies

* make path stuff less jank

* proto codegen (#281)

* part 1

* make codegen work for internal w/ protos

* fix

* code review

---------

Co-authored-by: Konrad Niemiec <42159882+konradjniemiec@users.noreply.github.com>

cmd/lekko/gen.go

@@ -0,0 +1,333 @@
+// Copyright 2022 Lekko Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
+	"sort"
+	"strings"
+	"text/template"
+
+	featurev1beta1 "buf.build/gen/go/lekkodev/cli/protocolbuffers/go/lekko/feature/v1beta1"
+	"github.com/lekkodev/cli/pkg/repo"
+	"github.com/lekkodev/cli/pkg/secrets"
+	"github.com/pkg/errors"
+	"github.com/spf13/cobra"
+	"golang.org/x/mod/modfile"
+	"google.golang.org/protobuf/proto"
+)
+
+func genGoCmd() *cobra.Command {
+	var ns string
+	var wd string
+	var of string
+	cmd := &cobra.Command{
+		Use:   "go",
+		Short: "generate Go library code from configs",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			b, err := os.ReadFile("go.mod")
+			if err != nil {
+				return err
+			}
+			mf, err := modfile.ParseLax("go.mod", b, nil)
+			if err != nil {
+				return err
+			}
+			moduleRoot := mf.Module.Mod.Path
+
+			rs := secrets.NewSecretsOrFail()
+			r, err := repo.NewLocal(wd, rs)
+			if err != nil {
+				return errors.Wrap(err, "new repo")
+			}
+			ffs, err := r.GetFeatureFiles(cmd.Context(), ns)
+			if err != nil {
+				return err
+			}
+			sort.SliceStable(ffs, func(i, j int) bool {
+				return ffs[i].CompiledProtoBinFileName < ffs[j].CompiledProtoBinFileName
+			})
+			var protoAsByteStrings []string
+			var codeStrings []string
+			protoImportSet := make(map[string]*protoImport)
+			for _, ff := range ffs {
+				fff, err := os.ReadFile(wd + "/" + ns + "/" + ff.CompiledProtoBinFileName)
+				if err != nil {
+					return err
+				}
+				f := &featurev1beta1.Feature{}
+				if err := proto.Unmarshal(fff, f); err != nil {
+					return err
+				}
+				codeString, err := genGoForFeature(f, ns)
+				if err != nil {
+					return err
+				}
+				if f.Type == featurev1beta1.FeatureType_FEATURE_TYPE_PROTO {
+					protoImport := unpackProtoType(moduleRoot, f.Tree.Default.TypeUrl)
+					protoImportSet[protoImport.ImportPath] = &protoImport
+				}
+				protoAsBytes := fmt.Sprintf("\t\t\"%s\": []byte{", f.Key)
+				for idx, b := range fff {
+					if idx%16 == 0 {
+						protoAsBytes += "\n\t\t\t"
+					} else {
+						protoAsBytes += " "
+					}
+					protoAsBytes += fmt.Sprintf("0x%02x,", b)
+				}
+				protoAsBytes += "\n\t\t},\n"
+				protoAsByteStrings = append(protoAsByteStrings, protoAsBytes)
+				codeStrings = append(codeStrings, codeString)
+			}
+			const templateBody = `package lekko{{$.Namespace}}
+
+import (
+{{range  $.ProtoImports}}
+	{{ . }}{{end}}
+	"context"
+	client "github.com/lekkodev/go-sdk/client"
+)
+
+type LekkoClient struct {
+	client.Client
+	Close client.CloseFunc
+}
+
+type SafeLekkoClient struct {
+	client.Client
+	Close client.CloseFunc
+}
+
+func (c *SafeLekkoClient) GetBool(ctx context.Context, namespace string, key string) bool {
+	res, err := c.Client.GetBool(ctx, namespace, key)
+	if err != nil {
+		panic(err)
+	}
+	return res
+}
+func (c *SafeLekkoClient) GetString(ctx context.Context, namespace string, key string) string {
+	res, err := c.Client.GetString(ctx, namespace, key)
+	if err != nil {
+		panic(err)
+	}
+	return res
+}
+
+func (c *SafeLekkoClient) GetFloat(ctx context.Context, namespace string, key string) float64 {
+	res, err := c.Client.GetFloat(ctx, namespace, key)
+	if err != nil {
+		panic(err)
+	}
+	return res
+}
+
+func (c *SafeLekkoClient) GetInt(ctx context.Context, namespace string, key string) int64 {
+	res, err := c.Client.GetInt(ctx, namespace, key)
+	if err != nil {
+		panic(err)
+	}
+	return res
+}
+
+var StaticConfig = map[string]map[string][]byte{
+	"{{$.Namespace}}": {
+{{range  $.ProtoAsByteStrings}}{{ . }}{{end}}	},
+}
+{{range  $.CodeStrings}}
+{{ . }}{{end}}`
+
+			// buf generate --template '{"version":"v1","plugins":[{"plugin":"go","out":"gen/go"}]}'
+			//
+			// This generates the code for the config repo, assuming it has a buf.gen.yml in that repo.
+			// In OUR repos, and maybe some of our customers, they may already have a buf.gen.yml, so if
+			// that is the case, we should identify that, not run code gen (maybe?) and instead need to
+			// take the prefix by parsing the buf.gen.yml to understand where the go code goes.
+			pCmd := exec.Command(
+				"buf",
+				"generate",
+				fmt.Sprintf(`--template={"managed": {"enabled": true, "go_package_prefix": {"default": "%s/internal/lekko/proto"}}, "version":"v1","plugins":[{"plugin":"go","out":"internal/lekko/proto", "opt": "paths=source_relative"}]}`, moduleRoot),
+				"--include-imports",
+				wd) // #nosec G204
+			pCmd.Dir = "."
+			fmt.Println("executing in wd: " + wd + " command: " + pCmd.String())
+			if out, err := pCmd.CombinedOutput(); err != nil {
+				fmt.Printf("Error when generating code with buf: %s\n %e\n", out, err)
+				return err
+			}
+			if err := os.MkdirAll("./internal/lekko/"+ns, 0770); err != nil {
+				return err
+			}
+			f, err := os.Create("./internal/lekko/" + ns + "/" + of)
+			if err != nil {
+				return err
+			}
+			var protoImports []string
+			for _, imp := range protoImportSet {
+				protoImports = append(protoImports, fmt.Sprintf(`%s "%s"`, imp.PackageAlias, imp.ImportPath))
+			}
+			data := struct {
+				ProtoImports       []string
+				Namespace          string
+				ProtoAsByteStrings []string
+				CodeStrings        []string
+			}{
+				protoImports,
+				ns,
+				protoAsByteStrings,
+				codeStrings,
+			}
+			templ := template.Must(template.New("").Parse(templateBody))
+			return templ.Execute(f, data)
+		},
+	}
+	cmd.Flags().StringVarP(&ns, "namespace", "n", "default", "namespace to generate code from")
+	cmd.Flags().StringVarP(&wd, "config-path", "c", ".", "path to configuration repository")
+	cmd.Flags().StringVarP(&of, "output", "o", "lekko.go", "output file")
+	return cmd
+}
+
+var genCmd = &cobra.Command{
+	Use:   "gen",
+	Short: "generate library code from configs",
+}
+
+func genGoForFeature(f *featurev1beta1.Feature, ns string) (string, error) {
+	const defaultTemplateBody = `// {{$.Description}}
+func (c *LekkoClient) {{$.FuncName}}(ctx context.Context) ({{$.RetType}}, error) {
+	return c.{{$.GetFunction}}(ctx, "{{$.Namespace}}", "{{$.Key}}")
+}
+
+// {{$.Description}}
+func (c *SafeLekkoClient) {{$.FuncName}}(ctx context.Context) {{$.RetType}} {
+	return c.{{$.GetFunction}}(ctx, "{{$.Namespace}}", "{{$.Key}}")
+}
+`
+
+	const protoTemplateBody = `// {{$.Description}}
+func (c *LekkoClient) {{$.FuncName}}(ctx context.Context) (*{{$.RetType}}, error) {
+	result := &{{$.RetType}}{}
+	err := c.{{$.GetFunction}}(ctx, "{{$.Namespace}}", "{{$.Key}}", result)
+	return result, err
+}
+
+// {{$.Description}}
+func (c *SafeLekkoClient) {{$.FuncName}}(ctx context.Context) *{{$.RetType}} {
+	result := &{{$.RetType}}{}
+	c.{{$.GetFunction}}(ctx, "{{$.Namespace}}", "{{$.Key}}", result)
+	return result
+}
+`
+	const jsonTemplateBody = `// {{$.Description}}
+func (c *LekkoClient) {{$.FuncName}}(ctx context.Context, result interface{}) error {
+	return c.{{$.GetFunction}}(ctx, "{{$.Namespace}}", "{{$.Key}}", result)
+}
+
+// {{$.Description}}
+func (c *SafeLekkoClient) {{$.FuncName}}(ctx context.Context, result interface{}) {
+	c.{{$.GetFunction}}(ctx, "{{$.Namespace}}", "{{$.Key}}", result)
+}
+`
+	var funcNameBuilder strings.Builder
+	funcNameBuilder.WriteString("Get")
+	for _, word := range regexp.MustCompile("[_-]+").Split(f.Key, -1) {
+		funcNameBuilder.WriteString(strings.ToUpper(word[:1]) + word[1:])
+	}
+	funcName := funcNameBuilder.String()
+	var retType string
+	var getFunction string
+	templateBody := defaultTemplateBody
+	switch f.Type {
+	case 1:
+		retType = "bool"
+		getFunction = "GetBool"
+	case 2:
+		retType = "int64"
+		getFunction = "GetInt"
+	case 3:
+		retType = "float64"
+		getFunction = "GetFloat"
+	case 4:
+		retType = "string"
+		getFunction = "GetString"
+	case 5:
+		getFunction = "GetJSON"
+		templateBody = jsonTemplateBody
+	case 6:
+		getFunction = "GetProto"
+		templateBody = protoTemplateBody
+		// we don't need the import path so sending in empty string
+		protoType := unpackProtoType("", f.Tree.Default.TypeUrl)
+		// creates configv1beta1.DBConfig
+		retType = fmt.Sprintf("%s.%s", protoType.PackageAlias, protoType.Type)
+	}
+
+	data := struct {
+		Description string
+		FuncName    string
+		GetFunction string
+		RetType     string
+		Namespace   string
+		Key         string
+	}{
+		f.Description,
+		funcName,
+		getFunction,
+		retType,
+		ns,
+		f.Key,
+	}
+	templ, err := template.New("go func").Parse(templateBody)
+	if err != nil {
+		return "", err
+	}
+	var ret bytes.Buffer
+	err = templ.Execute(&ret, data)
+	return ret.String(), err
+}
+
+type protoImport struct {
+	PackageAlias string
+	ImportPath   string
+	Type         string
+}
+
+func unpackProtoType(moduleRoot string, typeURL string) protoImport {
+	anyURLSplit := strings.Split(typeURL, "/")
+	if anyURLSplit[0] != "type.googleapis.com" {
+		panic("invalid any type url: " + typeURL)
+	}
+	// turn default.config.v1beta1.DBConfig into:
+	// moduleRoot/internal/lekko/proto/default/config/v1beta1
+	typeParts := strings.Split(anyURLSplit[1], ".")
+
+	importPath := strings.Join(append([]string{moduleRoot + "/internal/lekko/proto"}, typeParts[:len(typeParts)-1]...), "/")
+
+	prefix := fmt.Sprintf(`%s%s`, typeParts[len(typeParts)-3], typeParts[len(typeParts)-2])
+
+	// TODO do google.protobuf.X
+	switch anyURLSplit[1] {
+	case "google.protobuf.Duration":
+		importPath = "google.golang.org/protobuf/types/known/durationpb"
+		prefix = "durationpb"
+	default:
+	}
+
+	return protoImport{PackageAlias: prefix, ImportPath: importPath, Type: typeParts[len(typeParts)-1]}
+}