Deal with github bridge import rate limit

4 files changed, 687 insertions, 737 deletions

diff --git a/bridge/github/import.go b/bridge/github/import.go
index e8a4d3cb..2e36f5fe 100644
--- a/bridge/github/import.go
+++ b/bridge/github/import.go
@@ -3,6 +3,7 @@ package github
 import (
 	"context"
 	"fmt"
+	"strconv"
 	"time"
 
 	"github.com/shurcooL/githubv4"
@@ -19,41 +20,40 @@ import (
 type githubImporter struct {
 	conf core.Configuration
 
-	// default client
-	client *githubv4.Client
-
-	// iterator
-	iterator *iterator
+	// mediator to access the Github API
+	mediator *importMediator
 
 	// send only channel
 	out chan<- core.ImportResult
+
+	// closure to get the username from github without any additional parameters
+	ghUser func(string) (*user, error)
 }
 
-func (gi *githubImporter) Init(_ context.Context, repo *cache.RepoCache, conf core.Configuration) error {
+func (gi *githubImporter) Init(_ context.Context, _ *cache.RepoCache, conf core.Configuration) error {
 	gi.conf = conf
+	return nil
+}
 
+// ImportAll iterate over all the configured repository issues and ensure the creation of the
+// missing issues / timeline items / edits / label events ...
+func (gi *githubImporter) ImportAll(ctx context.Context, repo *cache.RepoCache, since time.Time) (<-chan core.ImportResult, error) {
 	creds, err := auth.List(repo,
 		auth.WithTarget(target),
 		auth.WithKind(auth.KindToken),
-		auth.WithMeta(auth.MetaKeyLogin, conf[confKeyDefaultLogin]),
+		auth.WithMeta(auth.MetaKeyLogin, gi.conf[confKeyDefaultLogin]),
 	)
 	if err != nil {
-		return err
+		return nil, err
 	}
-
-	if len(creds) == 0 {
-		return ErrMissingIdentityToken
+	if len(creds) <= 0 {
+		return nil, ErrMissingIdentityToken
+	}
+	client := buildClient(creds[0].(*auth.Token))
+	gi.mediator = NewImportMediator(ctx, client, gi.conf[confKeyOwner], gi.conf[confKeyProject], since)
+	gi.ghUser = func(login string) (*user, error) {
+		return gi.mediator.User(ctx, login)
 	}
-
-	gi.client = buildClient(creds[0].(*auth.Token))
-
-	return nil
-}
-
-// ImportAll iterate over all the configured repository issues and ensure the creation of the
-// missing issues / timeline items / edits / label events ...
-func (gi *githubImporter) ImportAll(ctx context.Context, repo *cache.RepoCache, since time.Time) (<-chan core.ImportResult, error) {
-	gi.iterator = NewIterator(ctx, gi.client, 10, gi.conf[confKeyOwner], gi.conf[confKeyProject], since)
 	out := make(chan core.ImportResult)
 	gi.out = out
 
@@ -61,19 +61,19 @@ func (gi *githubImporter) ImportAll(ctx context.Context, repo *cache.RepoCache,
 		defer close(gi.out)
 
 		// Loop over all matching issues
-		for gi.iterator.NextIssue() {
-			issue := gi.iterator.IssueValue()
+		for issue := range gi.mediator.Issues() {
+			// fmt.Println("issue loop")
 			// create issue
-			b, err := gi.ensureIssue(repo, issue)
+			b, err := gi.ensureIssue(repo, &issue)
 			if err != nil {
 				err := fmt.Errorf("issue creation: %v", err)
 				out <- core.NewImportError(err, "")
 				return
 			}
 
+			// fmt.Println("Just before timeline items loop")
 			// loop over timeline items
-			for gi.iterator.NextTimelineItem() {
-				item := gi.iterator.TimelineItemValue()
+			for item := range gi.mediator.TimelineItems(&issue) {
 				err := gi.ensureTimelineItem(repo, b, item)
 				if err != nil {
 					err = fmt.Errorf("timeline item creation: %v", err)
@@ -92,7 +92,7 @@ func (gi *githubImporter) ImportAll(ctx context.Context, repo *cache.RepoCache,
 			}
 		}
 
-		if err := gi.iterator.Error(); err != nil {
+		if err := gi.mediator.Error(); err != nil {
 			gi.out <- core.NewImportError(err, "")
 		}
 	}()
@@ -100,8 +100,8 @@ func (gi *githubImporter) ImportAll(ctx context.Context, repo *cache.RepoCache,
 	return out, nil
 }
 
-func (gi *githubImporter) ensureIssue(repo *cache.RepoCache, issue issue) (*cache.BugCache, error) {
-	// ensure issue author
+func (gi *githubImporter) ensureIssue(repo *cache.RepoCache, issue *issue) (*cache.BugCache, error) {
+	// fmt.Printf("ensureIssue()\n")
 	author, err := gi.ensurePerson(repo, issue.Author)
 	if err != nil {
 		return nil, err
@@ -116,94 +116,73 @@ func (gi *githubImporter) ensureIssue(repo *cache.RepoCache, issue issue) (*cach
 		return nil, err
 	}
 
-	// get issue edits
-	var issueEdits []userContentEdit
-	for gi.iterator.NextIssueEdit() {
-		issueEdits = append(issueEdits, gi.iterator.IssueEditValue())
+	// get first issue edit
+	// if it exists, then it holds the bug creation
+	firstEdit, hasEdit := <-gi.mediator.IssueEdits(issue)
+	// fmt.Printf("hasEdit == %v\n", hasEdit)
+	//fmt.Printf("%v\n", firstEdit)
+
+	title := string(issue.Title)
+	if title == "" {
+		fmt.Printf("%v\n", issue)
+		fmt.Println("title == \"\" holds")
+		title = "#" + strconv.Itoa(int(issue.Number))
+		fmt.Println("setting title := ", title)
 	}
 
-	// if issueEdits is empty
-	if len(issueEdits) == 0 {
-		if err == bug.ErrBugNotExist {
-			cleanText, err := text.Cleanup(string(issue.Body))
-			if err != nil {
-				return nil, err
-			}
-
-			// create bug
-			b, _, err = repo.NewBugRaw(
-				author,
-				issue.CreatedAt.Unix(),
-				issue.Title,
-				cleanText,
-				nil,
-				map[string]string{
-					core.MetaKeyOrigin: target,
-					metaKeyGithubId:    parseId(issue.Id),
-					metaKeyGithubUrl:   issue.Url.String(),
-				})
-			if err != nil {
-				return nil, err
-			}
-
-			// importing a new bug
-			gi.out <- core.NewImportBug(b.Id())
+	if err == bug.ErrBugNotExist {
+		var textInput string
+		if hasEdit {
+			// use the first issue edit: it represents the bug creation itself
+			textInput = string(*firstEdit.Diff)
+		} else {
+			// if there are no issue edits then the issue struct holds the bug creation
+			textInput = string(issue.Body)
 		}
-	} else {
-		// create bug from given issueEdits
-		for i, edit := range issueEdits {
-			if i == 0 && b != nil {
-				// The first edit in the github result is the issue creation itself, we already have that
-				continue
-			}
-
-			cleanText, err := text.Cleanup(string(*edit.Diff))
-			if err != nil {
-				return nil, err
-			}
-
-			// if the bug doesn't exist
-			if b == nil {
-				// we create the bug as soon as we have a legit first edition
-				b, _, err = repo.NewBugRaw(
-					author,
-					issue.CreatedAt.Unix(),
-					issue.Title, // TODO: this is the *current* title, not the original one
-					cleanText,
-					nil,
-					map[string]string{
-						core.MetaKeyOrigin: target,
-						metaKeyGithubId:    parseId(issue.Id),
-						metaKeyGithubUrl:   issue.Url.String(),
-					},
-				)
-
-				if err != nil {
-					return nil, err
-				}
-				// importing a new bug
-				gi.out <- core.NewImportBug(b.Id())
-				continue
-			}
-
-			// other edits will be added as CommentEdit operations
-			target, err := b.ResolveOperationWithMetadata(metaKeyGithubId, parseId(issue.Id))
-			if err == cache.ErrNoMatchingOp {
-				// original comment is missing somehow, issuing a warning
-				gi.out <- core.NewImportWarning(fmt.Errorf("comment ID %s to edit is missing", parseId(issue.Id)), b.Id())
-				continue
-			}
-			if err != nil {
-				return nil, err
-			}
-
-			err = gi.ensureCommentEdit(repo, b, target, edit)
-			if err != nil {
-				return nil, err
-			}
+		cleanText, err := text.Cleanup(textInput)
+		if err != nil {
+			return nil, err
 		}
+		// create bug
+		b, _, err = repo.NewBugRaw(
+			author,
+			issue.CreatedAt.Unix(),
+			title, // TODO: this is the *current* title, not the original one
+			cleanText,
+			nil,
+			map[string]string{
+				core.MetaKeyOrigin: target,
+				metaKeyGithubId:    parseId(issue.Id),
+				metaKeyGithubUrl:   issue.Url.String(),
+			})
+		if err != nil {
+			fmt.Printf("%v\n", issue)
+			return nil, err
+		}
+		// importing a new bug
+		gi.out <- core.NewImportBug(b.Id())
+	}
+	if b == nil {
+		return nil, fmt.Errorf("finding or creating issue")
 	}
+	// process remaining issue edits, if they exist
+	for edit := range gi.mediator.IssueEdits(issue) {
+		// other edits will be added as CommentEdit operations
+		target, err := b.ResolveOperationWithMetadata(metaKeyGithubId, parseId(issue.Id))
+		if err == cache.ErrNoMatchingOp {
+			// original comment is missing somehow, issuing a warning
+			gi.out <- core.NewImportWarning(fmt.Errorf("comment ID %s to edit is missing", parseId(issue.Id)), b.Id())
+			continue
+		}
+		if err != nil {
+			return nil, err
+		}
 
+		err = gi.ensureCommentEdit(repo, b, target, edit)
+		if err != nil {
+			return nil, err
+		}
+	}
 	return b, nil
 }
 
@@ -211,14 +190,7 @@ func (gi *githubImporter) ensureTimelineItem(repo *cache.RepoCache, b *cache.Bug
 
 	switch item.Typename {
 	case "IssueComment":
-		// collect all comment edits
-		var commentEdits []userContentEdit
-		for gi.iterator.NextCommentEdit() {
-			commentEdits = append(commentEdits, gi.iterator.CommentEditValue())
-		}
-
-		// ensureTimelineComment send import events over out chanel
-		err := gi.ensureTimelineComment(repo, b, item.IssueComment, commentEdits)
+		err := gi.ensureComment(repo, b, &item.IssueComment)
 		if err != nil {
 			return fmt.Errorf("timeline comment creation: %v", err)
 		}
@@ -366,90 +338,64 @@ func (gi *githubImporter) ensureTimelineItem(repo *cache.RepoCache, b *cache.Bug
 	return nil
 }
 
-func (gi *githubImporter) ensureTimelineComment(repo *cache.RepoCache, b *cache.BugCache, item issueComment, edits []userContentEdit) error {
-	// ensure person
-	author, err := gi.ensurePerson(repo, item.Author)
+func (gi *githubImporter) ensureComment(repo *cache.RepoCache, b *cache.BugCache, comment *issueComment) error {
+	author, err := gi.ensurePerson(repo, comment.Author)
 	if err != nil {
 		return err
 	}
 
-	targetOpID, err := b.ResolveOperationWithMetadata(metaKeyGithubId, parseId(item.Id))
+	targetOpID, err := b.ResolveOperationWithMetadata(metaKeyGithubId, parseId(comment.Id))
 	if err != nil && err != cache.ErrNoMatchingOp {
 		// real error
 		return err
 	}
-
-	// if no edits are given we create the comment
-	if len(edits) == 0 {
-		if err == cache.ErrNoMatchingOp {
-			cleanText, err := text.Cleanup(string(item.Body))
-			if err != nil {
-				return err
-			}
-
-			// add comment operation
-			op, err := b.AddCommentRaw(
-				author,
-				item.CreatedAt.Unix(),
-				cleanText,
-				nil,
-				map[string]string{
-					metaKeyGithubId:  parseId(item.Id),
-					metaKeyGithubUrl: parseId(item.Url.String()),
-				},
-			)
-			if err != nil {
-				return err
-			}
-
-			gi.out <- core.NewImportComment(op.Id())
-			return nil
+	firstEdit, hasEdit := <-gi.mediator.CommentEdits(comment)
+	if err == cache.ErrNoMatchingOp {
+		var textInput string
+		if hasEdit {
+			// use the first comment edit: it represents the comment creation itself
+			textInput = string(*firstEdit.Diff)
+		} else {
+			// if there are not comment edits, then the comment struct holds the comment creation
+			textInput = string(comment.Body)
+		}
+		cleanText, err := text.Cleanup(textInput)
+		if err != nil {
+			return err
 		}
 
-	} else {
-		for i, edit := range edits {
-			if i == 0 && targetOpID != "" {
-				// The first edit in the github result is the comment creation itself, we already have that
-				continue
-			}
-
-			// ensure editor identity
-			editor, err := gi.ensurePerson(repo, edit.Editor)
-			if err != nil {
-				return err
-			}
-
-			// create comment when target is empty
-			if targetOpID == "" {
-				cleanText, err := text.Cleanup(string(*edit.Diff))
-				if err != nil {
-					return err
-				}
-
-				op, err := b.AddCommentRaw(
-					editor,
-					edit.CreatedAt.Unix(),
-					cleanText,
-					nil,
-					map[string]string{
-						metaKeyGithubId:  parseId(item.Id),
-						metaKeyGithubUrl: item.Url.String(),
-					},
-				)
-				if err != nil {
-					return err
-				}
-				gi.out <- core.NewImportComment(op.Id())
+		// add comment operation
+		op, err := b.AddCommentRaw(
+			author,
+			comment.CreatedAt.Unix(),
+			cleanText,
+			nil,
+			map[string]string{
+				metaKeyGithubId:  parseId(comment.Id),
+				metaKeyGithubUrl: comment.Url.String(),
+			},
+		)
+		if err != nil {
+			return err
+		}
 
-				// set target for the next edit now that the comment is created
-				targetOpID = op.Id()
-				continue
-			}
+		gi.out <- core.NewImportComment(op.Id())
+		targetOpID = op.Id()
+	}
+	if targetOpID == "" {
+		return fmt.Errorf("finding or creating issue comment")
+	}
+	// process remaining comment edits, if they exist
+	for edit := range gi.mediator.CommentEdits(comment) {
+		// ensure editor identity
+		_, err := gi.ensurePerson(repo, edit.Editor)
+		if err != nil {
+			return err
+		}
 
-			err = gi.ensureCommentEdit(repo, b, targetOpID, edit)
-			if err != nil {
-				return err
-			}
+		err = gi.ensureCommentEdit(repo, b, targetOpID, edit)
+		if err != nil {
+			return err
 		}
 	}
 	return nil
@@ -521,7 +467,6 @@ func (gi *githubImporter) ensurePerson(repo *cache.RepoCache, actor *actor) (*ca
 	}
 
 	// importing a new identity
-
 	var name string
 	var email string
 
@@ -565,41 +510,27 @@ func (gi *githubImporter) ensurePerson(repo *cache.RepoCache, actor *actor) (*ca
 }
 
 func (gi *githubImporter) getGhost(repo *cache.RepoCache) (*cache.IdentityCache, error) {
+	loginName := "ghost"
 	// Look first in the cache
-	i, err := repo.ResolveIdentityImmutableMetadata(metaKeyGithubLogin, "ghost")
+	i, err := repo.ResolveIdentityImmutableMetadata(metaKeyGithubLogin, loginName)
 	if err == nil {
 		return i, nil
 	}
 	if entity.IsErrMultipleMatch(err) {
 		return nil, err
 	}
-
-	var q ghostQuery
-
-	variables := map[string]interface{}{
-		"login": githubv4.String("ghost"),
+	user, err := gi.ghUser(loginName)
+	userName := ""
+	if user.Name != nil {
+		userName = string(*user.Name)
 	}
-
-	ctx, cancel := context.WithTimeout(gi.iterator.ctx, defaultTimeout)
-	defer cancel()
-
-	err = gi.client.Query(ctx, &q, variables)
-	if err != nil {
-		return nil, err
-	}
-
-	var name string
-	if q.User.Name != nil {
-		name = string(*q.User.Name)
-	}
-
 	return repo.NewIdentityRaw(
-		name,
+		userName,
 		"",
-		string(q.User.Login),
-		string(q.User.AvatarUrl),
+		string(user.Login),
+		string(user.AvatarUrl),
 		map[string]string{
-			metaKeyGithubLogin: string(q.User.Login),
+			metaKeyGithubLogin: string(user.Login),
 		},
 	)
 }
diff --git a/bridge/github/import_mediator.go b/bridge/github/import_mediator.go
new file mode 100644
index 00000000..428c5d36
--- /dev/null
+++ b/bridge/github/import_mediator.go
@@ -0,0 +1,394 @@
+package github
+
+import (
+	"context"
+	"fmt"
+	"runtime"
+	"sync"
+	"time"
+
+	"github.com/shurcooL/githubv4"
+)
+
+type varmap map[string]interface{}
+
+func trace() {
+	pc := make([]uintptr, 15)
+	n := runtime.Callers(2, pc)
+	frames := runtime.CallersFrames(pc[:n])
+	frame, _ := frames.Next()
+	fmt.Printf("%s:%d %s\n", frame.File, frame.Line, frame.Function)
+}
+
+const (
+	NUM_ISSUES         = 50
+	NUM_ISSUE_EDITS    = 99
+	NUM_TIMELINE_ITEMS = 99
+	NUM_COMMENT_EDITS  = 99
+
+	CHAN_CAPACITY = 128
+)
+
+// TODO: remove all debug output and trace() in all files. Use ag
+
+type importMediator struct {
+	// Github graphql client
+	gc      *githubv4.Client
+	owner   string
+	project string
+	// The iterator will only query issues updated or created after the date given in
+	// the variable since.
+	since time.Time
+
+	issues           chan issue
+	issueEditsMut    sync.Mutex
+	timelineItemsMut sync.Mutex
+	commentEditsMut  sync.Mutex
+	issueEdits       map[githubv4.ID]chan userContentEdit
+	timelineItems    map[githubv4.ID]chan timelineItem
+	commentEdits     map[githubv4.ID]chan userContentEdit
+
+	// Sticky error
+	err error
+}
+
+func NewImportMediator(ctx context.Context, client *githubv4.Client, owner, project string, since time.Time) *importMediator {
+	mm := importMediator{
+		gc:               client,
+		owner:            owner,
+		project:          project,
+		since:            since,
+		issues:           make(chan issue, CHAN_CAPACITY),
+		issueEditsMut:    sync.Mutex{},
+		timelineItemsMut: sync.Mutex{},
+		commentEditsMut:  sync.Mutex{},
+		issueEdits:       make(map[githubv4.ID]chan userContentEdit),
+		timelineItems:    make(map[githubv4.ID]chan timelineItem),
+		commentEdits:     make(map[githubv4.ID]chan userContentEdit),
+		err:              nil,
+	}
+	go func() {
+		defer close(mm.issues)
+		mm.fillChannels(ctx)
+	}()
+	return &mm
+}
+
+func (mm *importMediator) Issues() <-chan issue {
+	return mm.issues
+}
+
+func (mm *importMediator) IssueEdits(issue *issue) <-chan userContentEdit {
+	mm.issueEditsMut.Lock()
+	channel := mm.issueEdits[issue.Id]
+	mm.issueEditsMut.Unlock()
+	return channel
+}
+
+func (mm *importMediator) TimelineItems(issue *issue) <-chan timelineItem {
+	mm.timelineItemsMut.Lock()
+	channel := mm.timelineItems[issue.Id]
+	mm.timelineItemsMut.Unlock()
+	return channel
+}
+
+func (mm *importMediator) CommentEdits(comment *issueComment) <-chan userContentEdit {
+	mm.commentEditsMut.Lock()
+	channel := mm.commentEdits[comment.Id]
+	mm.commentEditsMut.Unlock()
+	return channel
+}
+
+func (mm *importMediator) Error() error {
+	return mm.err
+}
+
+func (mm *importMediator) User(ctx context.Context, loginName string) (*user, error) {
+	query := userQuery{}
+	vars := varmap{"login": githubv4.String(loginName)}
+	c, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+	if err := mm.mQuery(c, &query, vars); err != nil {
+		return nil, err
+	}
+	return &query.User, nil
+}
+
+func (mm *importMediator) fillChannels(ctx context.Context) {
+	issueCursor := githubv4.String("")
+	for {
+		issues, hasIssues := mm.queryIssue(ctx, issueCursor)
+		if !hasIssues {
+			break
+		}
+		issueCursor = issues.PageInfo.EndCursor
+		for _, issueNode := range issues.Nodes {
+			// fmt.Printf(">>> issue: %v\n", issueNode.issue.Title)
+			mm.fillChannelIssueEdits(ctx, &issueNode)
+			mm.fillChannelTimeline(ctx, &issueNode)
+			// To avoid race conditions add the issue only after all its edits,
+			// timeline times, etc. are added to their respective channels.
+			mm.issues <- issueNode.issue
+		}
+	}
+}
+
+func (mm *importMediator) fillChannelIssueEdits(ctx context.Context, issueNode *issueNode) {
+	// fmt.Printf("fillChannelIssueEdit() issue id == %v\n", issueNode.issue.Id)
+	// fmt.Printf("%v\n", issueNode)
+	channel := make(chan userContentEdit, CHAN_CAPACITY)
+	defer close(channel)
+	mm.issueEditsMut.Lock()
+	mm.issueEdits[issueNode.issue.Id] = channel
+	mm.issueEditsMut.Unlock()
+	edits := &issueNode.UserContentEdits
+	hasEdits := true
+	for hasEdits {
+		// fmt.Println("before the reversed loop")
+		for edit := range reverse(edits.Nodes) {
+			// fmt.Println("in the reversed loop")
+			if edit.Diff == nil || string(*edit.Diff) == "" {
+				// issueEdit.Diff == nil happen if the event is older than
+				// early 2018, Github doesn't have the data before that.
+				// Best we can do is to ignore the event.
+				continue
+			}
+			// fmt.Printf("about to push issue edit\n")
+			channel <- edit
+		}
+		// fmt.Printf("has next ? %v\n", edits.PageInfo.HasNextPage)
+		// fmt.Printf("has previous ? %v\n", edits.PageInfo.HasPreviousPage)
+		if !edits.PageInfo.HasPreviousPage {
+			break
+		}
+		edits, hasEdits = mm.queryIssueEdits(ctx, issueNode.issue.Id, edits.PageInfo.EndCursor)
+	}
+}
+
+func (mm *importMediator) fillChannelTimeline(ctx context.Context, issueNode *issueNode) {
+	// fmt.Printf("fullChannelTimeline()\n")
+	channel := make(chan timelineItem, CHAN_CAPACITY)
+	defer close(channel)
+	mm.timelineItemsMut.Lock()
+	mm.timelineItems[issueNode.issue.Id] = channel
+	mm.timelineItemsMut.Unlock()
+	items := &issueNode.TimelineItems
+	hasItems := true
+	for hasItems {
+		for _, item := range items.Nodes {
+			channel <- item
+			mm.fillChannelCommentEdits(ctx, &item)
+		}
+		// fmt.Printf("has next ? %v\n", items.PageInfo.HasNextPage)
+		// fmt.Printf("has previous ? %v\n", items.PageInfo.HasPreviousPage)
+		if !items.PageInfo.HasNextPage {
+			break
+		}
+		items, hasItems = mm.queryTimelineItems(ctx, issueNode.issue.Id, items.PageInfo.EndCursor)
+	}
+}
+
+func (mm *importMediator) fillChannelCommentEdits(ctx context.Context, item *timelineItem) {
+	// This concerns only timeline items of type comment
+	if item.Typename != "IssueComment" {
+		return
+	}
+	comment := &item.IssueComment
+	channel := make(chan userContentEdit, CHAN_CAPACITY)
+	defer close(channel)
+	mm.commentEditsMut.Lock()
+	mm.commentEdits[comment.Id] = channel
+	mm.commentEditsMut.Unlock()
+	edits := &comment.UserContentEdits
+	hasEdits := true
+	for hasEdits {
+		for edit := range reverse(edits.Nodes) {
+			if edit.Diff == nil || string(*edit.Diff) == "" {
+				// issueEdit.Diff == nil happen if the event is older than
+				// early 2018, Github doesn't have the data before that.
+				// Best we can do is to ignore the event.
+				continue
+			}
+			channel <- edit
+		}
+		if !edits.PageInfo.HasPreviousPage {
+			break
+		}
+		edits, hasEdits = mm.queryCommentEdits(ctx, comment.Id, edits.PageInfo.EndCursor)
+	}
+}
+
+func (mm *importMediator) queryCommentEdits(ctx context.Context, nid githubv4.ID, cursor githubv4.String) (*userContentEditConnection, bool) {
+	// trace()
+	vars := varmap{
+		"gqlNodeId":       nid,
+		"commentEditLast": githubv4.Int(NUM_COMMENT_EDITS),
+	}
+	if cursor == "" {
+		vars["commentEditBefore"] = (*githubv4.String)(nil)
+	} else {
+		vars["commentEditBefore"] = cursor
+	}
+	c, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+	query := commentEditQuery{}
+	if err := mm.mQuery(c, &query, vars); err != nil {
+		mm.err = err
+		return nil, false
+	}
+	connection := &query.Node.IssueComment.UserContentEdits
+	if len(connection.Nodes) <= 0 {
+		return nil, false
+	}
+	return connection, true
+}
+
+func (mm *importMediator) queryTimelineItems(ctx context.Context, nid githubv4.ID, cursor githubv4.String) (*timelineItemsConnection, bool) {
+	// trace()
+	vars := varmap{
+		"gqlNodeId":         nid,
+		"timelineFirst":     githubv4.Int(NUM_TIMELINE_ITEMS),
+		"commentEditLast":   githubv4.Int(NUM_COMMENT_EDITS),
+		"commentEditBefore": (*githubv4.String)(nil),
+	}
+	if cursor == "" {
+		vars["timelineAfter"] = (*githubv4.String)(nil)
+	} else {
+		vars["timelineAfter"] = cursor
+	}
+	c, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+	query := timelineQuery{}
+	if err := mm.mQuery(c, &query, vars); err != nil {
+		mm.err = err
+		return nil, false
+	}
+	connection := &query.Node.Issue.TimelineItems
+	if len(connection.Nodes) <= 0 {
+		return nil, false
+	}
+	return connection, true
+}
+
+func (mm *importMediator) queryIssueEdits(ctx context.Context, nid githubv4.ID, cursor githubv4.String) (*userContentEditConnection, bool) {
+	// trace()
+	vars := varmap{
+		"gqlNodeId":     nid,
+		"issueEditLast": githubv4.Int(NUM_ISSUE_EDITS),
+	}
+	if cursor == "" {
+		vars["issueEditBefore"] = (*githubv4.String)(nil)
+	} else {
+		vars["issueEditBefore"] = cursor
+	}
+	c, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+	query := issueEditQuery{}
+	if err := mm.mQuery(c, &query, vars); err != nil {
+		mm.err = err
+		return nil, false
+	}
+	connection := &query.Node.Issue.UserContentEdits
+	if len(connection.Nodes) <= 0 {
+		return nil, false
+	}
+	return connection, true
+}
+
+func (mm *importMediator) queryIssue(ctx context.Context, cursor githubv4.String) (*issueConnection, bool) {
+	// trace()
+	vars := varmap{
+		"owner":             githubv4.String(mm.owner),
+		"name":              githubv4.String(mm.project),
+		"issueSince":        githubv4.DateTime{Time: mm.since},
+		"issueFirst":        githubv4.Int(NUM_ISSUES),
+		"issueEditLast":     githubv4.Int(NUM_ISSUE_EDITS),
+		"issueEditBefore":   (*githubv4.String)(nil),
+		"timelineFirst":     githubv4.Int(NUM_TIMELINE_ITEMS),
+		"timelineAfter":     (*githubv4.String)(nil),
+		"commentEditLast":   githubv4.Int(NUM_COMMENT_EDITS),
+		"commentEditBefore": (*githubv4.String)(nil),
+	}
+	if cursor == "" {
+		vars["issueAfter"] = (*githubv4.String)(nil)
+	} else {
+		vars["issueAfter"] = githubv4.String(cursor)
+	}
+	c, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+	query := issueQuery{}
+	if err := mm.mQuery(c, &query, vars); err != nil {
+		mm.err = err
+		return nil, false
+	}
+	connection := &query.Repository.Issues
+	if len(connection.Nodes) <= 0 {
+		return nil, false
+	}
+	return connection, true
+}
+
+func reverse(eds []userContentEdit) chan userContentEdit {
+	ret := make(chan userContentEdit)
+	go func() {
+		for i := range eds {
+			ret <- eds[len(eds)-1-i]
+		}
+		close(ret)
+	}()
+	return ret
+}
+
+type rateLimiter interface {
+	rateLimit() rateLimit
+}
+
+// TODO: move that into its own file
+//
+// mQuery executes a single GraphQL query. The variable query is used to derive the GraphQL
+// query and it is used to populate the response into it. It should be a pointer to a struct
+// that corresponds to the Github graphql schema and it should implement the rateLimiter
+// interface. This function queries Github for the remaining rate limit points before
+// executing the actual query. The function waits, if there are not enough rate limiting
+// points left.
+func (mm *importMediator) mQuery(ctx context.Context, query rateLimiter, vars map[string]interface{}) error {
+	// First: check the cost of the query and wait if necessary
+	vars["dryRun"] = githubv4.Boolean(true)
+	qctx, cancel := context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+	if err := mm.gc.Query(qctx, query, vars); err != nil {
+		return err
+	}
+	fmt.Printf("%v\n", query)
+	rateLimit := query.rateLimit()
+	if rateLimit.Cost > rateLimit.Remaining {
+		resetTime := rateLimit.ResetAt.Time
+		fmt.Println("Github rate limit exhausted")
+		fmt.Printf("Sleeping until %s\n", resetTime.String())
+		// Add a few seconds (8) for good measure
+		timer := time.NewTimer(time.Until(resetTime.Add(8 * time.Second)))
+		select {
+		case <-ctx.Done():
+			stop(timer)
+			return ctx.Err()
+		case <-timer.C:
+		}
+	}
+	// Second: Do the actual query
+	vars["dryRun"] = githubv4.Boolean(false)
+	qctx, cancel = context.WithTimeout(ctx, defaultTimeout)
+	defer cancel()
+	if err := mm.gc.Query(qctx, query, vars); err != nil {
+		return err
+	}
+	return nil
+}
+
+func stop(t *time.Timer) {
+	if !t.Stop() {
+		select {
+		case <-t.C:
+		default:
+		}
+	}
+}
diff --git a/bridge/github/import_query.go b/bridge/github/import_query.go
index 228d204a..77c95e1d 100644
--- a/bridge/github/import_query.go
+++ b/bridge/github/import_query.go
@@ -2,37 +2,123 @@ package github
 
 import "github.com/shurcooL/githubv4"
 
-type pageInfo struct {
-	EndCursor       githubv4.String
-	HasNextPage     bool
-	StartCursor     githubv4.String
-	HasPreviousPage bool
+type userQuery struct {
+	RateLimit rateLimit `graphql:"rateLimit(dryRun: $dryRun)"`
+	User      user      `graphql:"user(login: $login)"`
 }
 
-type actor struct {
-	Typename  githubv4.String `graphql:"__typename"`
+func (q userQuery) rateLimit() rateLimit {
+	return q.RateLimit
+}
+
+type labelsQuery struct {
+	//RateLimit rateLimit `graphql:"rateLimit(dryRun: $dryRun)"`
+	Repository struct {
+		Labels struct {
+			Nodes []struct {
+				ID          string `graphql:"id"`
+				Name        string `graphql:"name"`
+				Color       string `graphql:"color"`
+				Description string `graphql:"description"`
+			}
+			PageInfo pageInfo
+		} `graphql:"labels(first: $first, after: $after)"`
+	} `graphql:"repository(owner: $owner, name: $name)"`
+}
+
+type loginQuery struct {
+	//RateLimit rateLimit `graphql:"rateLimit(dryRun: $dryRun)"`
+	Viewer struct {
+		Login string `graphql:"login"`
+	} `graphql:"viewer"`
+}
+
+type issueQuery struct {
+	RateLimit  rateLimit `graphql:"rateLimit(dryRun: $dryRun)"`
+	Repository struct {
+		Issues issueConnection `graphql:"issues(first: $issueFirst, after: $issueAfter, orderBy: {field: CREATED_AT, direction: ASC}, filterBy: {since: $issueSince})"`
+	} `graphql:"repository(owner: $owner, name: $name)"`
+}
+
+func (q issueQuery) rateLimit() rateLimit {
+	return q.RateLimit
+}
+
+type issueEditQuery struct {
+	RateLimit rateLimit `graphql:"rateLimit(dryRun: $dryRun)"`
+	Node      struct {
+		Typename githubv4.String `graphql:"__typename"`
+		Issue    struct {
+			UserContentEdits userContentEditConnection `graphql:"userContentEdits(last: $issueEditLast, before: $issueEditBefore)"`
+		} `graphql:"... on Issue"`
+	} `graphql:"node(id: $gqlNodeId)"`
+}
+
+func (q issueEditQuery) rateLimit() rateLimit {
+	return q.RateLimit
+}
+
+type timelineQuery struct {
+	RateLimit rateLimit `graphql:"rateLimit(dryRun: $dryRun)"`
+	Node      struct {
+		Typename githubv4.String `graphql:"__typename"`
+		Issue    struct {
+			TimelineItems timelineItemsConnection `graphql:"timelineItems(first: $timelineFirst, after: $timelineAfter)"`
+		} `graphql:"... on Issue"`
+	} `graphql:"node(id: $gqlNodeId)"`
+}
+
+func (q timelineQuery) rateLimit() rateLimit {
+	return q.RateLimit
+}
+
+type commentEditQuery struct {
+	RateLimit rateLimit `graphql:"rateLimit(dryRun: $dryRun)"`
+	Node      struct {
+		Typename     githubv4.String `graphql:"__typename"`
+		IssueComment struct {
+			UserContentEdits userContentEditConnection `graphql:"userContentEdits(last: $commentEditLast, before: $commentEditBefore)"`
+		} `graphql:"... on IssueComment"`
+	} `graphql:"node(id: $gqlNodeId)"`
+}
+
+func (q commentEditQuery) rateLimit() rateLimit {
+	return q.RateLimit
+}
+
+type user struct {
 	Login     githubv4.String
 	AvatarUrl githubv4.String
-	User      struct {
-		Name  *githubv4.String
-		Email githubv4.String
-	} `graphql:"... on User"`
-	Organization struct {
-		Name  *githubv4.String
-		Email *githubv4.String
-	} `graphql:"... on Organization"`
+	Name      *githubv4.String
 }
 
-type actorEvent struct {
-	Id        githubv4.ID
-	CreatedAt githubv4.DateTime
-	Actor     *actor
+type issueConnection struct {
+	Nodes    []issueNode
+	PageInfo pageInfo
 }
 
-type authorEvent struct {
-	Id        githubv4.ID
-	CreatedAt githubv4.DateTime
-	Author    *actor
+type issueNode struct {
+	issue
+	UserContentEdits userContentEditConnection `graphql:"userContentEdits(last: $issueEditLast, before: $issueEditBefore)"`
+	TimelineItems    timelineItemsConnection   `graphql:"timelineItems(first: $timelineFirst, after: $timelineAfter)"`
+}
+
+type issue struct {
+	authorEvent
+	Title  githubv4.String
+	Number githubv4.Int
+	Body   githubv4.String
+	Url    githubv4.URI
+}
+
+type timelineItemsConnection struct {
+	Nodes    []timelineItem
+	PageInfo pageInfo
+}
+
+type userContentEditConnection struct {
+	Nodes    []userContentEdit
+	PageInfo pageInfo
 }
 
 type userContentEdit struct {
@@ -46,12 +132,6 @@ type userContentEdit struct {
 	Diff      *githubv4.String
 }
 
-type issueComment struct {
-	authorEvent // NOTE: contains Id
-	Body        githubv4.String
-	Url         githubv4.URI
-}
-
 type timelineItem struct {
 	Typename githubv4.String `graphql:"__typename"`
 
@@ -91,84 +171,52 @@ type timelineItem struct {
 	} `graphql:"... on RenamedTitleEvent"`
 }
 
-type ghostQuery struct {
-	User struct {
-		Login     githubv4.String
-		AvatarUrl githubv4.String
-		Name      *githubv4.String
-	} `graphql:"user(login: $login)"`
-}
-
-type labelsQuery struct {
-	Repository struct {
-		Labels struct {
-			Nodes []struct {
-				ID          string `graphql:"id"`
-				Name        string `graphql:"name"`
-				Color       string `graphql:"color"`
-				Description string `graphql:"description"`
-			}
-			PageInfo pageInfo
-		} `graphql:"labels(first: $first, after: $after)"`
-	} `graphql:"repository(owner: $owner, name: $name)"`
-}
+type issueComment struct {
+	authorEvent // NOTE: contains Id
+	Body        githubv4.String
+	Url         githubv4.URI
 
-type loginQuery struct {
-	Viewer struct {
-		Login string `graphql:"login"`
-	} `graphql:"viewer"`
+	UserContentEdits userContentEditConnection `graphql:"userContentEdits(last: $commentEditLast, before: $commentEditBefore)"`
 }
 
-type issueQuery struct {
-	Repository struct {
-		Issues struct {
-			Nodes    []issue
-			PageInfo pageInfo
-		} `graphql:"issues(first: $issueFirst, after: $issueAfter, orderBy: {field: CREATED_AT, direction: ASC}, filterBy: {since: $issueSince})"`
-	} `graphql:"repository(owner: $owner, name: $name)"`
+type actor struct {
+	Typename  githubv4.String `graphql:"__typename"`
+	Login     githubv4.String
+	AvatarUrl githubv4.String
+	User      struct {
+		Name  *githubv4.String
+		Email githubv4.String
+	} `graphql:"... on User"`
+	Organization struct {
+		Name  *githubv4.String
+		Email *githubv4.String
+	} `graphql:"... on Organization"`
 }
 
-type issue struct {
-	authorEvent
-	Title  string
-	Number githubv4.Int
-	Body   githubv4.String
-	Url    githubv4.URI
+type actorEvent struct {
+	Id        githubv4.ID
+	CreatedAt githubv4.DateTime
+	Actor     *actor
 }
 
-type issueEditQuery struct {
-	Node struct {
-		Typename githubv4.String `graphql:"__typename"`
-		Issue    struct {
-			UserContentEdits struct {
-				Nodes      []userContentEdit
-				TotalCount githubv4.Int
-				PageInfo   pageInfo
-			} `graphql:"userContentEdits(last: $issueEditLast, before: $issueEditBefore)"`
-		} `graphql:"... on Issue"`
-	} `graphql:"node(id: $gqlNodeId)"`
+type authorEvent struct {
+	Id        githubv4.ID
+	CreatedAt githubv4.DateTime
+	Author    *actor
 }
 
-type timelineQuery struct {
-	Node struct {
-		Typename githubv4.String `graphql:"__typename"`
-		Issue    struct {
-			TimelineItems struct {
-				Nodes    []timelineItem
-				PageInfo pageInfo
-			} `graphql:"timelineItems(first: $timelineFirst, after: $timelineAfter)"`
-		} `graphql:"... on Issue"`
-	} `graphql:"node(id: $gqlNodeId)"`
+type pageInfo struct {
+	EndCursor       githubv4.String
+	HasNextPage     bool
+	StartCursor     githubv4.String
+	HasPreviousPage bool
 }
 
-type commentEditQuery struct {
-	Node struct {
-		Typename     githubv4.String `graphql:"__typename"`
-		IssueComment struct {
-			UserContentEdits struct {
-				Nodes    []userContentEdit
-				PageInfo pageInfo
-			} `graphql:"userContentEdits(last: $commentEditLast, before: $commentEditBefore)"`
-		} `graphql:"... on IssueComment"`
-	} `graphql:"node(id: $gqlNodeId)"`
+type rateLimit struct {
+	Cost      githubv4.Int
+	Limit     githubv4.Int
+	NodeCount githubv4.Int
+	Remaining githubv4.Int
+	ResetAt   githubv4.DateTime
+	Used      githubv4.Int
 }
diff --git a/bridge/github/iterator.go b/bridge/github/iterator.go
deleted file mode 100644
index d21faae8..00000000
--- a/bridge/github/iterator.go
+++ /dev/null
@@ -1,423 +0,0 @@
-package github
-
-import (
-	"context"
-	"time"
-
-	"github.com/pkg/errors"
-	"github.com/shurcooL/githubv4"
-)
-
-type iterator struct {
-	// Github graphql client
-	gc *githubv4.Client
-
-	// The iterator will only query issues updated or created after the date given in
-	// the variable since.
-	since time.Time
-
-	// Shared context, which is used for all graphql queries.
-	ctx context.Context
-
-	// Sticky error
-	err error
-
-	// Issue iterator
-	issueIter issueIter
-}
-
-type issueIter struct {
-	iterVars
-	query         issueQuery
-	issueEditIter []issueEditIter
-	timelineIter  []timelineIter
-}
-
-type issueEditIter struct {
-	iterVars
-	query issueEditQuery
-}
-
-type timelineIter struct {
-	iterVars
-	query           timelineQuery
-	commentEditIter []commentEditIter
-}
-
-type commentEditIter struct {
-	iterVars
-	query commentEditQuery
-}
-
-type iterVars struct {
-	// Iterator index
-	index int
-
-	// capacity is the number of elements (issues, issue edits, timeline items, or
-	// comment edits) to query at a time. More capacity = more used memory =
-	// less queries to make.
-	capacity int
-
-	// Variable assignments for graphql query
-	variables varmap
-}
-
-type varmap map[string]interface{}
-
-func newIterVars(capacity int) iterVars {
-	return iterVars{
-		index:     -1,
-		capacity:  capacity,
-		variables: varmap{},
-	}
-}
-
-// NewIterator creates and initialize a new iterator.
-func NewIterator(ctx context.Context, client *githubv4.Client, capacity int, owner, project string, since time.Time) *iterator {
-	i := &iterator{
-		gc:    client,
-		since: since,
-		ctx:   ctx,
-		issueIter: issueIter{
-			iterVars:      newIterVars(capacity),
-			timelineIter:  make([]timelineIter, capacity),
-			issueEditIter: make([]issueEditIter, capacity),
-		},
-	}
-	i.issueIter.variables.setOwnerProject(owner, project)
-	for idx := range i.issueIter.issueEditIter {
-		ie := &i.issueIter.issueEditIter[idx]
-		ie.iterVars = newIterVars(capacity)
-	}
-	for i1 := range i.issueIter.timelineIter {
-		tli := &i.issueIter.timelineIter[i1]
-		tli.iterVars = newIterVars(capacity)
-		tli.commentEditIter = make([]commentEditIter, capacity)
-		for i2 := range tli.commentEditIter {
-			cei := &tli.commentEditIter[i2]
-			cei.iterVars = newIterVars(capacity)
-		}
-	}
-	i.resetIssueVars()
-	return i
-}
-
-func (v *varmap) setOwnerProject(owner, project string) {
-	(*v)["owner"] = githubv4.String(owner)
-	(*v)["name"] = githubv4.String(project)
-}
-
-func (i *iterator) resetIssueVars() {
-	vars := &i.issueIter.variables
-	(*vars)["issueFirst"] = githubv4.Int(i.issueIter.capacity)
-	(*vars)["issueAfter"] = (*githubv4.String)(nil)
-	(*vars)["issueSince"] = githubv4.DateTime{Time: i.since}
-	i.issueIter.query.Repository.Issues.PageInfo.HasNextPage = true
-	i.issueIter.query.Repository.Issues.PageInfo.EndCursor = ""
-}
-
-func (i *iterator) resetIssueEditVars() {
-	for idx := range i.issueIter.issueEditIter {
-		ie := &i.issueIter.issueEditIter[idx]
-		ie.variables["issueEditLast"] = githubv4.Int(ie.capacity)
-		ie.variables["issueEditBefore"] = (*githubv4.String)(nil)
-		ie.query.Node.Issue.UserContentEdits.PageInfo.HasNextPage = true
-		ie.query.Node.Issue.UserContentEdits.PageInfo.EndCursor = ""
-	}
-}
-
-func (i *iterator) resetTimelineVars() {
-	for idx := range i.issueIter.timelineIter {
-		ip := &i.issueIter.timelineIter[idx]
-		ip.variables["timelineFirst"] = githubv4.Int(ip.capacity)
-		ip.variables["timelineAfter"] = (*githubv4.String)(nil)
-		ip.query.Node.Issue.TimelineItems.PageInfo.HasNextPage = true
-		ip.query.Node.Issue.TimelineItems.PageInfo.EndCursor = ""
-	}
-}
-
-func (i *iterator) resetCommentEditVars() {
-	for i1 := range i.issueIter.timelineIter {
-		for i2 := range i.issueIter.timelineIter[i1].commentEditIter {
-			ce := &i.issueIter.timelineIter[i1].commentEditIter[i2]
-			ce.variables["commentEditLast"] = githubv4.Int(ce.capacity)
-			ce.variables["commentEditBefore"] = (*githubv4.String)(nil)
-			ce.query.Node.IssueComment.UserContentEdits.PageInfo.HasNextPage = true
-			ce.query.Node.IssueComment.UserContentEdits.PageInfo.EndCursor = ""
-		}
-	}
-}
-
-// Error return last encountered error
-func (i *iterator) Error() error {
-	if i.err != nil {
-		return i.err
-	}
-	return i.ctx.Err() // might return nil
-}
-
-func (i *iterator) HasError() bool {
-	return i.err != nil || i.ctx.Err() != nil
-}
-
-func (i *iterator) currIssueItem() *issue {
-	return &i.issueIter.query.Repository.Issues.Nodes[i.issueIter.index]
-}
-
-func (i *iterator) currIssueEditIter() *issueEditIter {
-	return &i.issueIter.issueEditIter[i.issueIter.index]
-}
-
-func (i *iterator) currTimelineIter() *timelineIter {
-	return &i.issueIter.timelineIter[i.issueIter.index]
-}
-
-func (i *iterator) currCommentEditIter() *commentEditIter {
-	timelineIter := i.currTimelineIter()
-	return &timelineIter.commentEditIter[timelineIter.index]
-}
-
-func (i *iterator) currIssueGqlNodeId() githubv4.ID {
-	return i.currIssueItem().Id
-}
-
-// NextIssue returns true if there exists a next issue and advances the iterator by one.
-// It is used to iterate over all issues. Queries to github are made when necessary.
-func (i *iterator) NextIssue() bool {
-	if i.HasError() {
-		return false
-	}
-	index := &i.issueIter.index
-	issues := &i.issueIter.query.Repository.Issues
-	issueItems := &issues.Nodes
-	if 0 <= *index && *index < len(*issueItems)-1 {
-		*index += 1
-		return true
-	}
-
-	if !issues.PageInfo.HasNextPage {
-		return false
-	}
-	nextIssue := i.queryIssue()
-	return nextIssue
-}
-
-// IssueValue returns the actual issue value.
-func (i *iterator) IssueValue() issue {
-	return *i.currIssueItem()
-}
-
-func (i *iterator) queryIssue() bool {
-	ctx, cancel := context.WithTimeout(i.ctx, defaultTimeout)
-	defer cancel()
-	if endCursor := i.issueIter.query.Repository.Issues.PageInfo.EndCursor; endCursor != "" {
-		i.issueIter.variables["issueAfter"] = endCursor
-	}
-	if err := i.gc.Query(ctx, &i.issueIter.query, i.issueIter.variables); err != nil {
-		i.err = err
-		return false
-	}
-	i.resetIssueEditVars()
-	i.resetTimelineVars()
-	issueItems := &i.issueIter.query.Repository.Issues.Nodes
-	if len(*issueItems) <= 0 {
-		i.issueIter.index = -1
-		return false
-	}
-	i.issueIter.index = 0
-	return true
-}
-
-// NextIssueEdit returns true if there exists a next issue edit and advances the iterator
-// by one. It is used to iterate over all the issue edits. Queries to github are made when
-// necessary.
-func (i *iterator) NextIssueEdit() bool {
-	if i.HasError() {
-		return false
-	}
-	ieIter := i.currIssueEditIter()
-	ieIdx := &ieIter.index
-	ieItems := ieIter.query.Node.Issue.UserContentEdits
-	if 0 <= *ieIdx && *ieIdx < len(ieItems.Nodes)-1 {
-		*ieIdx += 1
-		return i.nextValidIssueEdit()
-	}
-	if !ieItems.PageInfo.HasNextPage {
-		return false
-	}
-	querySucc := i.queryIssueEdit()
-	if !querySucc {
-		return false
-	}
-	return i.nextValidIssueEdit()
-}
-
-func (i *iterator) nextValidIssueEdit() bool {
-	// issueEdit.Diff == nil happen if the event is older than early 2018, Github doesn't have
-	// the data before that. Best we can do is to ignore the event.
-	if issueEdit := i.IssueEditValue(); issueEdit.Diff == nil || string(*issueEdit.Diff) == "" {
-		return i.NextIssueEdit()
-	}
-	return true
-}
-
-// IssueEditValue returns the actual issue edit value.
-func (i *iterator) IssueEditValue() userContentEdit {
-	iei := i.currIssueEditIter()
-	return iei.query.Node.Issue.UserContentEdits.Nodes[iei.index]
-}
-
-func (i *iterator) queryIssueEdit() bool {
-	ctx, cancel := context.WithTimeout(i.ctx, defaultTimeout)
-	defer cancel()
-	iei := i.currIssueEditIter()
-	if endCursor := iei.query.Node.Issue.UserContentEdits.PageInfo.EndCursor; endCursor != "" {
-		iei.variables["issueEditBefore"] = endCursor
-	}
-	iei.variables["gqlNodeId"] = i.currIssueGqlNodeId()
-	if err := i.gc.Query(ctx, &iei.query, iei.variables); err != nil {
-		i.err = err
-		return false
-	}
-	issueEditItems := iei.query.Node.Issue.UserContentEdits.Nodes
-	if len(issueEditItems) <= 0 {
-		iei.index = -1
-		return false
-	}
-	// The UserContentEditConnection in the Github API serves its elements in reverse chronological
-	// order. For our purpose we have to reverse the edits.
-	reverseEdits(issueEditItems)
-	iei.index = 0
-	return true
-}
-
-// NextTimelineItem returns true if there exists a next timeline item and advances the iterator
-// by one. It is used to iterate over all the timeline items. Queries to github are made when
-// necessary.
-func (i *iterator) NextTimelineItem() bool {
-	if i.HasError() {
-		return false
-	}
-	tlIter := &i.issueIter.timelineIter[i.issueIter.index]
-	tlIdx := &tlIter.index
-	tlItems := tlIter.query.Node.Issue.TimelineItems
-	if 0 <= *tlIdx && *tlIdx < len(tlItems.Nodes)-1 {
-		*tlIdx += 1
-		return true
-	}
-	if !tlItems.PageInfo.HasNextPage {
-		return false
-	}
-	nextTlItem := i.queryTimeline()
-	return nextTlItem
-}
-
-// TimelineItemValue returns the actual timeline item value.
-func (i *iterator) TimelineItemValue() timelineItem {
-	tli := i.currTimelineIter()
-	return tli.query.Node.Issue.TimelineItems.Nodes[tli.index]
-}
-
-func (i *iterator) queryTimeline() bool {
-	ctx, cancel := context.WithTimeout(i.ctx, defaultTimeout)
-	defer cancel()
-	tli := i.currTimelineIter()
-	if endCursor := tli.query.Node.Issue.TimelineItems.PageInfo.EndCursor; endCursor != "" {
-		tli.variables["timelineAfter"] = endCursor
-	}
-	tli.variables["gqlNodeId"] = i.currIssueGqlNodeId()
-	if err := i.gc.Query(ctx, &tli.query, tli.variables); err != nil {
-		i.err = err
-		return false
-	}
-	i.resetCommentEditVars()
-	timelineItems := &tli.query.Node.Issue.TimelineItems
-	if len(timelineItems.Nodes) <= 0 {
-		tli.index = -1
-		return false
-	}
-	tli.index = 0
-	return true
-}
-
-// NextCommentEdit returns true if there exists a next comment edit and advances the iterator
-// by one. It is used to iterate over all issue edits. Queries to github are made when
-// necessary.
-func (i *iterator) NextCommentEdit() bool {
-	if i.HasError() {
-		return false
-	}
-
-	tmlnVal := i.TimelineItemValue()
-	if tmlnVal.Typename != "IssueComment" {
-		// The timeline iterator does not point to a comment.
-		i.err = errors.New("Call to NextCommentEdit() while timeline item is not a comment")
-		return false
-	}
-
-	cei := i.currCommentEditIter()
-	ceIdx := &cei.index
-	ceItems := &cei.query.Node.IssueComment.UserContentEdits
-	if 0 <= *ceIdx && *ceIdx < len(ceItems.Nodes)-1 {
-		*ceIdx += 1
-		return i.nextValidCommentEdit()
-	}
-	if !ceItems.PageInfo.HasNextPage {
-		return false
-	}
-	querySucc := i.queryCommentEdit()
-	if !querySucc {
-		return false
-	}
-	return i.nextValidCommentEdit()
-}
-
-func (i *iterator) nextValidCommentEdit() bool {
-	// if comment edit diff is a nil pointer or points to an empty string look for next value
-	if commentEdit := i.CommentEditValue(); commentEdit.Diff == nil || string(*commentEdit.Diff) == "" {
-		return i.NextCommentEdit()
-	}
-	return true
-}
-
-// CommentEditValue returns the actual comment edit value.
-func (i *iterator) CommentEditValue() userContentEdit {
-	cei := i.currCommentEditIter()
-	return cei.query.Node.IssueComment.UserContentEdits.Nodes[cei.index]
-}
-
-func (i *iterator) queryCommentEdit() bool {
-	ctx, cancel := context.WithTimeout(i.ctx, defaultTimeout)
-	defer cancel()
-	cei := i.currCommentEditIter()
-
-	if endCursor := cei.query.Node.IssueComment.UserContentEdits.PageInfo.EndCursor; endCursor != "" {
-		cei.variables["commentEditBefore"] = endCursor
-	}
-	tmlnVal := i.TimelineItemValue()
-	if tmlnVal.Typename != "IssueComment" {
-		i.err = errors.New("Call to queryCommentEdit() while timeline item is not a comment")
-		return false
-	}
-	cei.variables["gqlNodeId"] = tmlnVal.IssueComment.Id
-	if err := i.gc.Query(ctx, &cei.query, cei.variables); err != nil {
-		i.err = err
-		return false
-	}
-	ceItems := cei.query.Node.IssueComment.UserContentEdits.Nodes
-	if len(ceItems) <= 0 {
-		cei.index = -1
-		return false
-	}
-	// The UserContentEditConnection in the Github API serves its elements in reverse chronological
-	// order. For our purpose we have to reverse the edits.
-	reverseEdits(ceItems)
-	cei.index = 0
-	return true
-}
-
-func reverseEdits(edits []userContentEdit) {
-	for i, j := 0, len(edits)-1; i < j; i, j = i+1, j-1 {
-		edits[i], edits[j] = edits[j], edits[i]
-	}
-}