feat: add translation API (#297)

* feat: add translation

* feat: resurface translation by Google Translation

* feat: renamed the service as `translate` to make more readable

* fix: renamed response and request name to match rpc name

* chore: delete useless blank line

* Update publicapi.json

* Update publicapi.json

* Update README.md

Co-authored-by: Asim Aslam <asim@aslam.me>

translate/handler/translate.go

@@ -0,0 +1,76 @@
+package handler
+
+import (
+	"context"
+
+	"github.com/micro/micro/v3/service/config"
+	"github.com/micro/micro/v3/service/logger"
+	"github.com/pkg/errors"
+	"golang.org/x/text/language"
+	"google.golang.org/api/option"
+
+	pb "github.com/micro/services/translate/proto"
+
+	"cloud.google.com/go/translate"
+)
+
+type translation struct {
+	ApiKey string
+}
+
+func NewTranslation() *translation {
+
+	v, err := config.Get("translate.google.api_key")
+	if err != nil {
+		logger.Fatalf("translate.google.api_key config not found: %v", err)
+	}
+	key := v.String("")
+
+	if key == "" {
+		logger.Fatalf("translate.google.api_key config can not be an empty string")
+	}
+
+	return &translation{
+		ApiKey: key,
+	}
+}
+
+// Text calls Google Cloud Translation Basic edition API
+// For more information: https://cloud.google.com/translate/docs/samples/translate-text-with-model
+func (t *translation) Text(ctx context.Context, req *pb.TextRequest, rsp *pb.TextResponse) error {
+	client, err := translate.NewClient(ctx, option.WithAPIKey(t.ApiKey))
+	if err != nil {
+		return errors.Wrap(err, "new google translation client error")
+	}
+	defer client.Close()
+
+	source, err := language.Parse(req.Source)
+	if err != nil {
+		return errors.Wrap(err, "google translation parse source language error")
+	}
+
+	target, err := language.Parse(req.Target)
+	if err != nil {
+		return errors.Wrap(err, "google translation parse target language error")
+	}
+
+	result, err := client.Translate(ctx, req.Contents, target, &translate.Options{
+		Source: source,
+		Format: translate.Format(req.Format),
+		Model:  req.Model,
+	})
+
+	if err != nil {
+		return errors.Wrap(err, "get google translation error")
+	}
+
+	for _, v := range result {
+		rsp.Translations = append(rsp.Translations, &pb.BasicTranslation{
+			Text:   v.Text,
+			Source: v.Source.String(),
+			Model:  v.Model,
+		})
+	}
+
+	return nil
+}