Recognize local app states (T-202)

core/domain/status_resolver.go

@@ -0,0 +1,73 @@
+package domain
+
+import (
+	"errors"
+	"fmt"
+)
+
+var ErrInvalidStatusFacts = errors.New("invalid app status facts")
+
+// AppStatusFacts are IO-free observations used to derive one visible state.
+type AppStatusFacts struct {
+	Operation        AppStatus
+	Running          bool
+	RecoveryPending  bool
+	Incompatible     bool
+	InstalledVersion string
+	CatalogVersion   string
+}
+
+// ResolveAppStatus derives the single user-visible state from local and
+// background-operation facts.
+func ResolveAppStatus(facts AppStatusFacts) (AppStatus, error) {
+	if facts.RecoveryPending {
+		return StatusRollbackPending, nil
+	}
+	if facts.Operation != "" {
+		if !validOperationStatus(facts.Operation) {
+			return "", fmt.Errorf(
+				"%w: operation %q",
+				ErrInvalidStatusFacts,
+				facts.Operation,
+			)
+		}
+		return facts.Operation, nil
+	}
+	if facts.Running {
+		return StatusRunning, nil
+	}
+	if facts.Incompatible {
+		return StatusIncompatible, nil
+	}
+	if facts.InstalledVersion == "" {
+		return StatusNotInstalled, nil
+	}
+	if _, err := ParseSemVer(facts.InstalledVersion); err != nil {
+		return "", fmt.Errorf("%w: installed version: %v", ErrInvalidStatusFacts, err)
+	}
+	if facts.CatalogVersion == "" {
+		return StatusInstalled, nil
+	}
+	comparison, err := CompareSemVer(facts.InstalledVersion, facts.CatalogVersion)
+	if err != nil {
+		return "", fmt.Errorf("%w: catalog version: %v", ErrInvalidStatusFacts, err)
+	}
+	if comparison < 0 {
+		return StatusUpdateAvailable, nil
+	}
+	return StatusInstalled, nil
+}
+
+func validOperationStatus(status AppStatus) bool {
+	switch status {
+	case StatusQueued,
+		StatusDownloading,
+		StatusVerifying,
+		StatusExtracting,
+		StatusInstalling,
+		StatusFailed:
+		return true
+	default:
+		return false
+	}
+}