Add command to scan for new translation

cmd/fyne/internal/commands/translate.go

@@ -0,0 +1,374 @@
+package commands
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"go/ast"
+	"go/parser"
+	"go/token"
+	"io"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strconv"
+
+	"github.com/urfave/cli/v2"
+)
+
+// Translate returns the cli command to scan for new translation strings.
+func Translate() *cli.Command {
+	return &cli.Command{
+		Name:  "translate",
+		Usage: "Scans for new translation strings.",
+		Flags: []cli.Flag{
+			&cli.BoolFlag{
+				Name:    "verbose",
+				Aliases: []string{"v"},
+				Usage:   "Show files that are being scanned etc.",
+			},
+			&cli.BoolFlag{
+				Name:    "update",
+				Aliases: []string{"u"},
+				Usage:   "Update existing translations (use with care).",
+			},
+			&cli.BoolFlag{
+				Name:    "dry-run",
+				Aliases: []string{"n"},
+				Usage:   "Scan without storing the results.",
+			},
+			&cli.StringFlag{
+				Name:    "sourceDir",
+				Aliases: []string{"d"},
+				Usage:   "Directory to scan recursively for go files.",
+				Value:   ".",
+			},
+			&cli.StringFlag{
+				Name:    "translationsFile",
+				Aliases: []string{"f"},
+				Usage:   "File to read from and write translations to.",
+				Value:   "translations/en.json",
+			},
+		},
+		Action: func(ctx *cli.Context) error {
+			sourceDir := ctx.String("sourceDir")
+			translationsFile := ctx.String("translationsFile")
+			files := ctx.Args().Slice()
+			opts := translateOpts{
+				DryRun:  ctx.Bool("dry-run"),
+				Update:  ctx.Bool("update"),
+				Verbose: ctx.Bool("verbose"),
+			}
+
+			// without any argument find all .go files in the source directory
+			if len(files) == 0 {
+				sources, err := findFilesExt(sourceDir, ".go")
+				if err != nil {
+					return err
+				}
+				files = sources
+			}
+
+			// update the translation file by scanning the given source files
+			return updateTranslationsFile(&opts, translationsFile, files)
+		},
+	}
+}
+
+// Recursively walk the given directory and return all files with the matching extension
+func findFilesExt(dir, ext string) ([]string, error) {
+	files := []string{}
+	err := filepath.Walk(dir, func(path string, fi fs.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if filepath.Ext(path) != ext || fi.IsDir() || !fi.Mode().IsRegular() {
+			return nil
+		}
+
+		files = append(files, path)
+
+		return nil
+	})
+	return files, err
+}
+
+type translateOpts struct {
+	DryRun  bool
+	Update  bool
+	Verbose bool
+}
+
+// Create or add to translations file by scanning the given files for translation calls
+func updateTranslationsFile(opts *translateOpts, file string, files []string) error {
+	translations := make(map[string]interface{})
+
+	// try to get current translations first
+	f, err := os.Open(file)
+	if err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	defer f.Close()
+
+	// only try to parse translations that exist
+	if f != nil {
+		dec := json.NewDecoder(f)
+		if err := dec.Decode(&translations); err != nil {
+			return err
+		}
+	}
+
+	//if ctx.Bool("verbose") {
+	if opts.Verbose {
+		fmt.Fprintf(os.Stderr, "scanning files: %v\n", files)
+	}
+
+	// update translations hash
+	if err := updateTranslationsHash(opts, translations, files); err != nil {
+		return err
+	}
+
+	// serialize in readable format for humas to change
+	b, err := json.MarshalIndent(translations, "", "\t")
+	if err != nil {
+		return err
+	}
+
+	// avoid writing an empty file
+	if len(translations) == 0 {
+		fmt.Fprintln(os.Stderr, "No translations found")
+		return nil
+	}
+
+	// stop without making any changes
+	if opts.DryRun {
+		return nil
+	}
+
+	// support writing to stdout
+	if file == "-" {
+		fmt.Printf("%s\n", string(b))
+		return nil
+	}
+
+	return writeTranslationsFile(b, file, f)
+}
+
+// Write data to given file, optionally using same permissions as the original file
+func writeTranslationsFile(b []byte, file string, f *os.File) error {
+	// default permissions
+	perm := fs.FileMode(0644)
+
+	// use same permissions as original file when possible
+	if f != nil {
+		fi, err := f.Stat()
+		if err != nil {
+			return err
+		}
+		perm = fi.Mode().Perm()
+	}
+
+	// use temporary file to do atomic change
+	nf, err := os.CreateTemp(filepath.Dir(file), filepath.Base(file)+"-*")
+	if err != nil {
+		return err
+	}
+
+	n, err := nf.Write(b)
+	if err != nil {
+		return err
+	}
+
+	if n < len(b) {
+		return io.ErrShortWrite
+	}
+
+	if err := nf.Chmod(perm); err != nil {
+		return err
+	}
+
+	if err := nf.Close(); err != nil {
+		return err
+	}
+
+	// atomic switch to new file
+	return os.Rename(nf.Name(), file)
+}
+
+// Update translations hash by scanning the given files
+func updateTranslationsHash(opts *translateOpts, m map[string]interface{}, srcs []string) error {
+	for _, src := range srcs {
+		// get AST by parsing source
+		fset := token.NewFileSet()
+		af, err := parser.ParseFile(fset, src, nil, parser.AllErrors)
+		if err != nil {
+			return err
+		}
+
+		// walk AST to find known translation calls
+		ast.Walk(&visitor{opts: opts, m: m}, af)
+	}
+
+	return nil
+}
+
+// Visitor pattern with state machine to find translations fallback (and key)
+type visitor struct {
+	opts     *translateOpts
+	state    stateFn
+	name     string
+	key      string
+	fallback string
+	m        map[string]interface{}
+}
+
+// Method to walk AST using interface for ast.Walk
+func (v *visitor) Visit(node ast.Node) ast.Visitor {
+	if node == nil {
+		return nil
+	}
+
+	// start over any time there is no state
+	if v.state == nil {
+		v.state = translateNew
+		v.name = ""
+		v.key = ""
+		v.fallback = ""
+	}
+
+	// run and get next state
+	v.state = v.state(v, node)
+
+	return v
+}
+
+// State machine to pick out translation key and fallback from AST
+type stateFn func(*visitor, ast.Node) stateFn
+
+// All translation calls need to start with the literal "lang"
+func translateNew(v *visitor, node ast.Node) stateFn {
+	ident, ok := node.(*ast.Ident)
+	if !ok {
+		return nil
+	}
+
+	if ident.Name != "lang" {
+		return nil
+	}
+
+	return translateCall
+}
+
+// A known translation method needs to be used
+func translateCall(v *visitor, node ast.Node) stateFn {
+	ident, ok := node.(*ast.Ident)
+	if !ok {
+		return nil
+	}
+
+	v.name = ident.Name
+
+	switch ident.Name {
+	// simple cases: only the first argument is relevant
+	case "L", "Localize":
+		return translateLocalize
+	case "N", "LocalizePlural":
+		return translateLocalize
+	// more complex cases: first two arguments matter
+	case "X", "LocalizeKey":
+		return translateKey
+	case "XN", "LocalizePluralKey":
+		return translateKey
+	}
+
+	return nil
+}
+
+// Parse first argument, use string as key and fallback, and finish
+func translateLocalize(v *visitor, node ast.Node) stateFn {
+	basiclit, ok := node.(*ast.BasicLit)
+	if !ok {
+		return nil
+	}
+
+	val, err := strconv.Unquote(basiclit.Value)
+	if err != nil {
+		return nil
+	}
+
+	v.key = val
+	v.fallback = val
+
+	return translateFinish(v, node)
+}
+
+// Parse first argument and use as key
+func translateKey(v *visitor, node ast.Node) stateFn {
+	basiclit, ok := node.(*ast.BasicLit)
+	if !ok {
+		return nil
+	}
+
+	val, err := strconv.Unquote(basiclit.Value)
+	if err != nil {
+		return nil
+	}
+
+	v.key = val
+
+	return translateKeyFallback
+}
+
+// Parse second argument and use as fallback, and finish
+func translateKeyFallback(v *visitor, node ast.Node) stateFn {
+	basiclit, ok := node.(*ast.BasicLit)
+	if !ok {
+		return nil
+	}
+
+	val, err := strconv.Unquote(basiclit.Value)
+	if err != nil {
+		return nil
+	}
+
+	v.fallback = val
+
+	return translateFinish(v, node)
+}
+
+// Finish scan for translation and add to translation hash with the right type (singular or plural)
+func translateFinish(v *visitor, node ast.Node) stateFn {
+	// only adding new keys, ignoring changed or removed (ha!) ones
+	// removing is dangerous as there could be dynamic keys that get removed
+
+	// Ignore existing translations to prevent unintentional overwriting
+	_, found := v.m[v.key]
+	if found {
+		if !v.opts.Update {
+			if v.opts.Verbose {
+				fmt.Fprintf(os.Stderr, "ignoring: %s\n", v.key)
+			}
+			return nil
+		}
+		if v.opts.Verbose {
+			fmt.Fprintf(os.Stderr, "updating: %s\n", v.key)
+		}
+	} else {
+		if v.opts.Verbose {
+			fmt.Fprintf(os.Stderr, "adding: %s\n", v.key)
+		}
+	}
+
+	switch v.name {
+	// Plural translations use a nested map
+	case "LocalizePlural", "LocalizePluralKey", "N", "XN":
+		m := make(map[string]string)
+		m["other"] = v.fallback
+		v.m[v.key] = m
+	default:
+		v.m[v.key] = v.fallback
+	}
+
+	return nil
+}