Seen Service (#39)

* Seen Service

* Fixes for model

* Update import

* More fixes

* Complete seen service

seen/handler/handler.go

@@ -0,0 +1,119 @@
+package handler
+
+import (
+	"context"
+	"time"
+
+	"github.com/google/uuid"
+	"github.com/micro/services/seen/domain"
+
+	"github.com/micro/micro/v3/service/errors"
+	"github.com/micro/micro/v3/service/logger"
+	pb "github.com/micro/services/seen/proto"
+	"google.golang.org/protobuf/types/known/timestamppb"
+)
+
+var (
+	ErrMissingUserID       = errors.BadRequest("MISSING_USER_ID", "Missing UserID")
+	ErrMissingResourceID   = errors.BadRequest("MISSING_RESOURCE_ID", "Missing ResourceID")
+	ErrMissingResourceIDs  = errors.BadRequest("MISSING_RESOURCE_IDS", "Missing ResourceIDs")
+	ErrMissingResourceType = errors.BadRequest("MISSING_RESOURCE_TYPE", "Missing ResourceType")
+	ErrStore               = errors.InternalServerError("STORE_ERROR", "Error connecting to the store")
+)
+
+type Seen struct {
+	Domain *domain.Domain
+}
+
+// Set a resource as seen by a user. If no timestamp is provided, the current time is used.
+func (s *Seen) Set(ctx context.Context, req *pb.SetRequest, rsp *pb.SetResponse) error {
+	// validate the request
+	if len(req.UserId) == 0 {
+		return ErrMissingUserID
+	}
+	if len(req.ResourceId) == 0 {
+		return ErrMissingResourceID
+	}
+	if len(req.ResourceType) == 0 {
+		return ErrMissingResourceType
+	}
+
+	// default the timestamp
+	if req.Timestamp == nil {
+		req.Timestamp = timestamppb.New(time.Now())
+	}
+
+	// write the object to the store
+	err := s.Domain.Create(domain.Seen{
+		ID:           uuid.New().String(),
+		UserID:       req.UserId,
+		ResourceID:   req.ResourceId,
+		ResourceType: req.ResourceType,
+		Timestamp:    req.Timestamp.AsTime(),
+	})
+	if err != nil {
+		logger.Errorf("Error with store: %v", err)
+		return ErrStore
+	}
+
+	return nil
+}
+
+// Unset a resource as seen, used in cases where a user viewed a resource but wants to override
+// this so they remember to action it in the future, e.g. "Mark this as unread".
+func (s *Seen) Unset(ctx context.Context, req *pb.UnsetRequest, rsp *pb.UnsetResponse) error {
+	// validate the request
+	if len(req.UserId) == 0 {
+		return ErrMissingUserID
+	}
+	if len(req.ResourceId) == 0 {
+		return ErrMissingResourceID
+	}
+	if len(req.ResourceType) == 0 {
+		return ErrMissingResourceType
+	}
+
+	// delete the object from the store
+	err := s.Domain.Delete(domain.Seen{
+		UserID:       req.UserId,
+		ResourceID:   req.ResourceId,
+		ResourceType: req.ResourceType,
+	})
+	if err != nil {
+		logger.Errorf("Error with store: %v", err)
+		return ErrStore
+	}
+
+	return nil
+}
+
+// Read returns the timestamps at which various resources were seen by a user. If no timestamp
+// is returned for a given resource_id, it indicates that resource has not yet been seen by the
+// user.
+func (s *Seen) Read(ctx context.Context, req *pb.ReadRequest, rsp *pb.ReadResponse) error {
+	// validate the request
+	if len(req.UserId) == 0 {
+		return ErrMissingUserID
+	}
+	if len(req.ResourceIds) == 0 {
+		return ErrMissingResourceIDs
+	}
+	if len(req.ResourceType) == 0 {
+		return ErrMissingResourceType
+	}
+
+	// query the store
+	data, err := s.Domain.Read(req.UserId, req.ResourceType, req.ResourceIds)
+	if err != nil {
+		logger.Errorf("Error with store: %v", err)
+		return ErrStore
+	}
+
+	// serialize the response
+	rsp.Timestamps = make(map[string]*timestamppb.Timestamp, len(data))
+	for uid, ts := range data {
+		rsp.Timestamps[uid] = timestamppb.New(ts)
+	}
+
+	return nil
+}