gitlab: refactor the iterator, fix bugs

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

1 files changed, 79 insertions, 0 deletions

diff --git a/bridge/gitlab/iterator/issue.go b/bridge/gitlab/iterator/issue.go
new file mode 100644
index 00000000..a6bcebf1
--- /dev/null
+++ b/bridge/gitlab/iterator/issue.go
@@ -0,0 +1,79 @@
+package iterator
+
+import (
+	"context"
+
+	"github.com/xanzy/go-gitlab"
+)
+
+type issueIterator struct {
+	page  int
+	index int
+	cache []*gitlab.Issue
+}
+
+func newIssueIterator() *issueIterator {
+	ii := &issueIterator{}
+	ii.Reset()
+	return ii
+}
+
+func (ii *issueIterator) Next(ctx context.Context, conf config) (bool, error) {
+	// first query
+	if ii.cache == nil {
+		return ii.getNext(ctx, conf)
+	}
+
+	// move cursor index
+	if ii.index < len(ii.cache)-1 {
+		ii.index++
+		return true, nil
+	}
+
+	return ii.getNext(ctx, conf)
+}
+
+func (ii *issueIterator) Value() *gitlab.Issue {
+	return ii.cache[ii.index]
+}
+
+func (ii *issueIterator) getNext(ctx context.Context, conf config) (bool, error) {
+	ctx, cancel := context.WithTimeout(ctx, conf.timeout)
+	defer cancel()
+
+	issues, _, err := conf.gc.Issues.ListProjectIssues(
+		conf.project,
+		&gitlab.ListProjectIssuesOptions{
+			ListOptions: gitlab.ListOptions{
+				Page:    ii.page,
+				PerPage: conf.capacity,
+			},
+			Scope:        gitlab.String("all"),
+			UpdatedAfter: &conf.since,
+			Sort:         gitlab.String("asc"),
+		},
+		gitlab.WithContext(ctx),
+	)
+
+	if err != nil {
+		ii.Reset()
+		return false, err
+	}
+
+	// if repository doesn't have any issues
+	if len(issues) == 0 {
+		return false, nil
+	}
+
+	ii.cache = issues
+	ii.index = 0
+	ii.page++
+
+	return true, nil
+}
+
+func (ii *issueIterator) Reset() {
+	ii.index = -1
+	ii.page = -1
+	ii.cache = nil
+}