1 files changed, 105 insertions, 0 deletions
diff --git a/submitqueue/serie.go b/submitqueue/serie.go
new file mode 100644
index 000000000000..b2cf4ef01c55
--- /dev/null
+++ b/submitqueue/serie.go
@@ -0,0 +1,105 @@
+package submitqueue
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/tweag/gerrit-queue/gerrit"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// Serie represents a list of successive changesets with an unbroken parent -> child relation,
+// starting from the parent.
+type Serie struct {
+	ChangeSets []*gerrit.Changeset
+}
+
+// GetParentCommitIDs returns the parent commit IDs
+func (s *Serie) GetParentCommitIDs() ([]string, error) {
+	if len(s.ChangeSets) == 0 {
+		return nil, fmt.Errorf("Can't return parent on a serie with zero ChangeSets")
+	}
+	return s.ChangeSets[0].ParentCommitIDs, nil
+}
+
+// GetLeafCommitID returns the commit id of the last commit in ChangeSets
+func (s *Serie) GetLeafCommitID() (string, error) {
+	if len(s.ChangeSets) == 0 {
+		return "", fmt.Errorf("Can't return leaf on a serie with zero ChangeSets")
+	}
+	return s.ChangeSets[len(s.ChangeSets)-1].CommitID, nil
+}
+
+// CheckIntegrity checks that the series contains a properly ordered and connected chain of commits
+func (s *Serie) CheckIntegrity() error {
+	logger := log.WithFields(log.Fields{
+		"serie": s,
+	})
+	// an empty serie is invalid
+	if len(s.ChangeSets) == 0 {
+		return fmt.Errorf("An empty serie is invalid")
+	}
+
+	previousCommitID := ""
+	for i, changeset := range s.ChangeSets {
+		// we can't really check the parent of the first commit
+		// so skip verifying that one
+		logger.WithFields(log.Fields{
+			"changeset":        changeset.String(),
+			"previousCommitID": fmt.Sprintf("%.7s", previousCommitID),
+		}).Debug(" - verifying changeset")
+
+		parentCommitIDs := changeset.ParentCommitIDs
+		if len(parentCommitIDs) == 0 {
+			return fmt.Errorf("Changesets without any parent are not supported")
+		}
+		// we don't check parents of the first changeset in a series
+		if i != 0 {
+			if len(parentCommitIDs) != 1 {
+				return fmt.Errorf("Merge commits in the middle of a series are not supported (only at the beginning)")
+			}
+			if parentCommitIDs[0] != previousCommitID {
+				return fmt.Errorf("changesets parent commit id doesn't match previous commit id")
+			}
+		}
+		// update previous commit id for the next loop iteration
+		previousCommitID = changeset.CommitID
+	}
+	return nil
+}
+
+func (s *Serie) String() string {
+	var sb strings.Builder
+	sb.WriteString(fmt.Sprintf("Serie[%d]", len(s.ChangeSets)))
+	if len(s.ChangeSets) == 0 {
+		sb.WriteString("()\n")
+		return sb.String()
+	}
+	parentCommitIDs, err := s.GetParentCommitIDs()
+	if err == nil {
+		if len(parentCommitIDs) == 1 {
+			sb.WriteString(fmt.Sprintf("(parent: %.7s)", parentCommitIDs[0]))
+		} else {
+			sb.WriteString("(merge: ")
+
+			for i, parentCommitID := range parentCommitIDs {
+				sb.WriteString(fmt.Sprintf("%.7s", parentCommitID))
+				if i < len(parentCommitIDs) {
+					sb.WriteString(", ")
+				}
+			}
+
+			sb.WriteString(")")
+
+		}
+	}
+	sb.WriteString(fmt.Sprintf("(%.7s..%.7s)",
+		s.ChangeSets[0].CommitID,
+		s.ChangeSets[len(s.ChangeSets)-1].CommitID))
+	return sb.String()
+}
+
+func shortCommitID(commitID string) string {
+	return commitID[:6]
+}