gitlab: refactor the iterator, fix bugs

Notably, properly reset sub iterators when changing to the next issue

1 files changed, 99 insertions, 0 deletions

diff --git a/bridge/gitlab/iterator/labelEvent.go b/bridge/gitlab/iterator/labelEvent.go
new file mode 100644
index 00000000..7ee2604b
--- /dev/null
+++ b/bridge/gitlab/iterator/labelEvent.go
@@ -0,0 +1,99 @@
+package iterator
+
+import (
+	"context"
+	"sort"
+
+	"github.com/xanzy/go-gitlab"
+)
+
+// Since Gitlab does not return the label events items in the correct order
+// we need to sort the list ourselves and stop relying on the pagination model
+// #BecauseGitlab
+type labelEventIterator struct {
+	issue int
+	index int
+	cache []*gitlab.LabelEvent
+}
+
+func newLabelEventIterator() *labelEventIterator {
+	lei := &labelEventIterator{}
+	lei.Reset(-1)
+	return lei
+}
+
+func (lei *labelEventIterator) Next(ctx context.Context, conf config) (bool, error) {
+	// first query
+	if lei.cache == nil {
+		return lei.getNext(ctx, conf)
+	}
+
+	// move cursor index
+	if lei.index < len(lei.cache)-1 {
+		lei.index++
+		return true, nil
+	}
+
+	return false, nil
+}
+
+func (lei *labelEventIterator) Value() *gitlab.LabelEvent {
+	return lei.cache[lei.index]
+}
+
+func (lei *labelEventIterator) getNext(ctx context.Context, conf config) (bool, error) {
+	ctx, cancel := context.WithTimeout(ctx, conf.timeout)
+	defer cancel()
+
+	// since order is not guaranteed we should query all label events
+	// and sort them by ID
+	page := 1
+	for {
+		labelEvents, _, err := conf.gc.ResourceLabelEvents.ListIssueLabelEvents(
+			conf.project,
+			lei.issue,
+			&gitlab.ListLabelEventsOptions{
+				ListOptions: gitlab.ListOptions{
+					Page:    page,
+					PerPage: conf.capacity,
+				},
+			},
+			gitlab.WithContext(ctx),
+		)
+		if err != nil {
+			lei.Reset(-1)
+			return false, err
+		}
+
+		if len(labelEvents) == 0 {
+			break
+		}
+		lei.cache = append(lei.cache, labelEvents...)
+		page++
+	}
+
+	sort.Sort(lei)
+	lei.index = 0
+
+	return len(lei.cache) > 0, nil
+}
+
+func (lei *labelEventIterator) Reset(issue int) {
+	lei.issue = issue
+	lei.index = -1
+	lei.cache = nil
+}
+
+// ORDERING
+
+func (lei *labelEventIterator) Len() int {
+	return len(lei.cache)
+}
+
+func (lei *labelEventIterator) Swap(i, j int) {
+	lei.cache[i], lei.cache[j] = lei.cache[j], lei.cache[i]
+}
+
+func (lei *labelEventIterator) Less(i, j int) bool {
+	return lei.cache[i].ID < lei.cache[j].ID
+}