refactor: introduce concept of durations (resolve #261)

services/duration.go

@@ -0,0 +1,77 @@
+package services
+
+import (
+	"github.com/muety/wakapi/config"
+	"github.com/muety/wakapi/models"
+	"time"
+)
+
+const HeartbeatDiffThreshold = 2 * time.Minute
+
+type DurationService struct {
+	config           *config.Config
+	heartbeatService IHeartbeatService
+}
+
+func NewDurationService(heartbeatService IHeartbeatService) *DurationService {
+	srv := &DurationService{
+		config:           config.Get(),
+		heartbeatService: heartbeatService,
+	}
+	return srv
+}
+
+func (srv *DurationService) Get(from, to time.Time, user *models.User) ([]*models.Duration, error) {
+	heartbeats, err := srv.heartbeatService.GetAllWithin(from, to, user)
+	if err != nil {
+		return nil, err
+	}
+
+	// Aggregation
+	var count int
+	var latest *models.Duration
+
+	mapping := make(map[string][]*models.Duration)
+
+	for _, h := range heartbeats {
+		d1 := models.NewDurationFromHeartbeat(h)
+
+		if list, ok := mapping[d1.GroupHash]; !ok || len(list) < 1 {
+			mapping[d1.GroupHash] = []*models.Duration{d1}
+		}
+
+		if latest == nil {
+			latest = d1
+			continue
+		}
+
+		dur := d1.Time.T().Sub(latest.Time.T().Add(latest.Duration))
+		if dur > HeartbeatDiffThreshold {
+			dur = HeartbeatDiffThreshold
+		}
+		latest.Duration += dur
+
+		if dur >= HeartbeatDiffThreshold || latest.GroupHash != d1.GroupHash {
+			list := mapping[d1.GroupHash]
+			if d0 := list[len(list)-1]; d0 != d1 {
+				mapping[d1.GroupHash] = append(mapping[d1.GroupHash], d1)
+			}
+			latest = d1
+		}
+
+		count++
+	}
+
+	durations := make([]*models.Duration, 0, count)
+
+	for _, list := range mapping {
+		for _, d := range list {
+			if d.Duration == 0 {
+				d.Duration = HeartbeatDiffThreshold
+			}
+			durations = append(durations, d)
+		}
+	}
+
+	return durations, nil
+}