Add Contact API (#340)

* feat: add basic files of contact

* chore: code review
1. delete redundant suffix
2. use tab replace whitespace in pb file

* chore: add some comments and check post data validation

* chore: add some comments

* chore: add publicapi.json and examples.json

* chore: update README.md

* fix: code review conversations

contact/domain/contact.go

@@ -0,0 +1,119 @@
+package domain
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/micro/micro/v3/service/store"
+	"github.com/pkg/errors"
+
+	pb "github.com/micro/services/contact/proto"
+)
+
+type Contact interface {
+	Create(ctx context.Context, info *pb.ContactInfo) error
+	Update(ctx context.Context, id string, info *pb.ContactInfo) error
+	Read(ctx context.Context, id string) (result *pb.ContactInfo, err error)
+	Delete(ctx context.Context, id string) error
+	List(ctx context.Context, offset, limit uint) (result []*pb.ContactInfo, err error)
+}
+
+type contact struct {
+	store store.Store
+}
+
+func NewContactDomain(s store.Store) *contact {
+	return &contact{
+		store: s,
+	}
+}
+
+// contactIdPrefix return the contact prefix of the store key
+func contactIdPrefix() string {
+	return "contact/id/"
+}
+
+// contactIdPrefix return the store key of one contact
+func contactIdKey(id string) string {
+	return fmt.Sprintf("%s%s", contactIdPrefix(), id)
+}
+
+// Create a contact
+func (c *contact) Create(ctx context.Context, info *pb.ContactInfo) error {
+	info.CreatedAt = time.Now().Format(time.RFC3339)
+	info.UpdatedAt = time.Now().Format(time.RFC3339)
+
+	val, err := json.Marshal(info)
+	if err != nil {
+		return err
+	}
+
+	return store.Write(&store.Record{
+		Key:   contactIdKey(info.Id),
+		Value: val,
+	})
+}
+
+// Update contact information by id
+func (c *contact) Update(ctx context.Context, id string, info *pb.ContactInfo) error {
+	info.UpdatedAt = time.Now().Format(time.RFC3339)
+
+	val, err := json.Marshal(info)
+	if err != nil {
+		return err
+	}
+
+	return store.Write(&store.Record{
+		Key:   contactIdKey(id),
+		Value: val,
+	})
+}
+
+// Read one contact by id
+func (c *contact) Read(ctx context.Context, id string) (*pb.ContactInfo, error) {
+	records, err := c.store.Read(contactIdKey(id))
+	if err != nil {
+		return nil, err
+	}
+
+	if len(records) == 0 {
+		return nil, errors.New("not found")
+	}
+
+	info := &pb.ContactInfo{}
+	if err := json.Unmarshal(records[0].Value, info); err != nil {
+		return nil, err
+	}
+
+	return info, err
+}
+
+// Delete one contact by id
+func (c *contact) Delete(ctx context.Context, id string) error {
+	return c.store.Delete(contactIdKey(id))
+}
+
+// List contacts by offset and limit
+func (c *contact) List(ctx context.Context, offset, limit uint) (result []*pb.ContactInfo, err error) {
+	records, err := c.store.Read(contactIdPrefix(),
+		store.ReadPrefix(),
+		store.ReadOffset(offset),
+		store.ReadLimit(limit))
+	if err != nil {
+		return nil, err
+	}
+
+	if len(records) == 0 {
+		return nil, errors.New("not found")
+	}
+
+	for _, rec := range records {
+		cinfo := &pb.ContactInfo{}
+		json.Unmarshal(rec.Value, cinfo)
+		result = append(result, cinfo)
+	}
+
+	return result, err
+}