Publish ITWorx Pulse source

internal/reconciliation/engine.go

@@ -0,0 +1,103 @@
+package reconciliation
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/itworx/pulse/internal/datasource"
+)
+
+type Observation struct {
+	SourceID, ExternalType, ExternalID, EntityType, CanonicalName, DisplayName string
+	ObservedAt                                                                 time.Time
+}
+
+type Existing struct {
+	EntityID                           string
+	SourceID, ExternalType, ExternalID string
+	CanonicalName, DisplayName         string
+	Tombstoned                         bool
+	// TombstonedAt records when the entity was tombstoned. It is the zero time
+	// while the entity is live and maps onto entities.tombstoned_at.
+	TombstonedAt time.Time
+}
+type Override struct{ EntityID, FieldName, Value string }
+type Result struct {
+	Entities                   []Existing
+	Added, Updated, Tombstoned []string
+	Aliases                    map[string]string
+	Warnings                   []string
+}
+
+func StableEntityID(sourceID, externalType, externalID string) string {
+	hash := sha256.Sum256([]byte("itworx-pulse/entity/v1/" + sourceID + "\x00" + externalType + "\x00" + externalID))
+	b := hash[:16]
+	b[6] = (b[6] & 0x0f) | 0x50
+	b[8] = (b[8] & 0x3f) | 0x80
+	return fmt.Sprintf("%s-%s-%s-%s-%s", hex.EncodeToString(b[0:4]), hex.EncodeToString(b[4:6]), hex.EncodeToString(b[6:8]), hex.EncodeToString(b[8:10]), hex.EncodeToString(b[10:16]))
+}
+
+func Reconcile(sourceID string, health datasource.HealthState, observations []Observation, previous []Existing, overrides []Override, now time.Time) (Result, error) {
+	if strings.TrimSpace(sourceID) == "" {
+		return Result{}, errors.New("source id is required")
+	}
+	if health == datasource.HealthUnknown || health == datasource.HealthDisabled {
+		return Result{Entities: previous, Warnings: []string{"SOURCE_NOT_HEALTHY_NO_TOMBSTONES"}}, nil
+	}
+	seen := make(map[string]struct{}, len(observations))
+	result := Result{Aliases: make(map[string]string)}
+	overrideMap := make(map[string]string)
+	for _, o := range overrides {
+		overrideMap[o.EntityID+"\x00"+o.FieldName] = o.Value
+	}
+	previousByAlias := make(map[string]Existing)
+	for _, e := range previous {
+		previousByAlias[e.SourceID+"\x00"+e.ExternalType+"\x00"+e.ExternalID] = e
+	}
+	for _, o := range observations {
+		if o.SourceID != sourceID || o.ExternalType == "" || o.ExternalID == "" || o.EntityType == "" || o.CanonicalName == "" || o.ObservedAt.IsZero() {
+			return Result{}, errors.New("invalid observation")
+		}
+		key := o.SourceID + "\x00" + o.ExternalType + "\x00" + o.ExternalID
+		if _, ok := seen[key]; ok {
+			return Result{}, fmt.Errorf("duplicate observation %q", key)
+		}
+		seen[key] = struct{}{}
+		id := StableEntityID(o.SourceID, o.ExternalType, o.ExternalID)
+		if old, ok := previousByAlias[key]; ok {
+			id = old.EntityID
+		}
+		display := o.DisplayName
+		if value, ok := overrideMap[id+"\x00displayName"]; ok {
+			display = value
+		}
+		entity := Existing{EntityID: id, SourceID: o.SourceID, ExternalType: o.ExternalType, ExternalID: o.ExternalID, CanonicalName: o.CanonicalName, DisplayName: display}
+		result.Entities = append(result.Entities, entity)
+		result.Aliases[key] = id
+		if _, ok := previousByAlias[key]; ok {
+			result.Updated = append(result.Updated, id)
+		} else {
+			result.Added = append(result.Added, id)
+		}
+	}
+	if now.IsZero() {
+		now = time.Now().UTC()
+	}
+	now = now.UTC()
+	for _, old := range previous {
+		key := old.SourceID + "\x00" + old.ExternalType + "\x00" + old.ExternalID
+		if old.SourceID == sourceID {
+			if _, ok := seen[key]; !ok && !old.Tombstoned {
+				old.Tombstoned = true
+				old.TombstonedAt = now
+				result.Entities = append(result.Entities, old)
+				result.Tombstoned = append(result.Tombstoned, old.EntityID)
+			}
+		}
+	}
+	return result, nil
+}