From 054e02546a9b65c3a9bc0667ead5a36d1a520371 Mon Sep 17 00:00:00 2001
From: George MacRorie <me@georgemac.com>
Date: Wed, 5 Aug 2020 11:23:23 +0100
Subject: [PATCH] feat(paging): add support for after id parameter in find
 options

---
 kv/bucket.go              | 22 +++++++++++++++---
 paging.go                 | 17 ++++++++++++++
 tenant/storage_bucket.go  | 12 +++++++++-
 testing/bucket_service.go | 48 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 95 insertions(+), 4 deletions(-)

diff --git a/kv/bucket.go b/kv/bucket.go
index abacaad23a6..e652672bf1f 100644
--- a/kv/bucket.go
+++ b/kv/bucket.go
@@ -403,18 +403,34 @@ func (s *Service) findBuckets(ctx context.Context, tx Tx, filter influxdb.Bucket
 		filter.OrganizationID = &o.ID
 	}
 
-	var offset, limit, count int
-	var descending bool
+	var (
+		offset, limit, count int
+		descending           bool
+	)
+
+	after := func(*influxdb.Bucket) bool {
+		return true
+	}
+
 	if len(opts) > 0 {
 		offset = opts[0].Offset
 		limit = opts[0].Limit
 		descending = opts[0].Descending
+		if opts[0].After != nil {
+			after = func(b *influxdb.Bucket) bool {
+				if descending {
+					return b.ID < *opts[0].After
+				}
+
+				return b.ID > *opts[0].After
+			}
+		}
 	}
 
 	filterFn := filterBucketsFn(filter)
 	err := s.forEachBucket(ctx, tx, descending, func(b *influxdb.Bucket) bool {
 		if filterFn(b) {
-			if count >= offset {
+			if count >= offset && after(b) {
 				bs = append(bs, b)
 			}
 			count++
diff --git a/paging.go b/paging.go
index 87075311e30..71667132918 100644
--- a/paging.go
+++ b/paging.go
@@ -29,6 +29,7 @@ type PagingLinks struct {
 type FindOptions struct {
 	Limit      int
 	Offset     int
+	After      *ID
 	SortBy     string
 	Descending bool
 }
@@ -50,6 +51,18 @@ func DecodeFindOptions(r *http.Request) (*FindOptions, error) {
 		opts.Offset = o
 	}
 
+	if after := qp.Get("after"); after != "" {
+		id, err := IDFromString(after)
+		if err != nil {
+			return nil, &Error{
+				Code: EInvalid,
+				Err:  fmt.Errorf("decoding after: %w", err),
+			}
+		}
+
+		opts.After = id
+	}
+
 	if limit := qp.Get("limit"); limit != "" {
 		l, err := strconv.Atoi(limit)
 		if err != nil {
@@ -109,6 +122,10 @@ func (f FindOptions) QueryParams() map[string][]string {
 		"offset":     {strconv.Itoa(f.Offset)},
 	}
 
+	if f.After != nil {
+		qp["after"] = []string{f.After.String()}
+	}
+
 	if f.Limit > 0 {
 		qp["limit"] = []string{strconv.Itoa(f.Limit)}
 	}
diff --git a/tenant/storage_bucket.go b/tenant/storage_bucket.go
index bae48d012fa..7bd9d3dacd4 100644
--- a/tenant/storage_bucket.go
+++ b/tenant/storage_bucket.go
@@ -190,7 +190,17 @@ func (s *Store) ListBuckets(ctx context.Context, tx kv.Tx, filter BucketFilter,
 	if o.Descending {
 		opts = append(opts, kv.WithCursorDirection(kv.CursorDescending))
 	}
-	cursor, err := b.ForwardCursor(nil, opts...)
+
+	var seek []byte
+	if o.After != nil {
+		after := (*o.After) + 1
+		seek, err = after.Encode()
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	cursor, err := b.ForwardCursor(seek, opts...)
 	if err != nil {
 		return nil, err
 	}
diff --git a/testing/bucket_service.go b/testing/bucket_service.go
index 46c6e843550..da49f082582 100644
--- a/testing/bucket_service.go
+++ b/testing/bucket_service.go
@@ -617,6 +617,54 @@ func FindBuckets(
 				},
 			},
 		},
+		{
+			name: "find all buckets by after and limit",
+			fields: BucketFields{
+				BucketIDs: mock.NewIncrementingIDGenerator(idOne),
+				Organizations: []*influxdb.Organization{
+					{
+						Name: "theorg",
+					},
+				},
+				Buckets: []*influxdb.Bucket{
+					{
+						// ID(1)
+						OrgID: idOne,
+						Name:  "abc",
+					},
+					{
+						// ID(2)
+						OrgID: idOne,
+						Name:  "def",
+					},
+					{
+						// ID(3)
+						OrgID: idOne,
+						Name:  "xyz",
+					},
+				},
+			},
+			args: args{
+				findOptions: influxdb.FindOptions{
+					After: idPtr(idOne),
+					Limit: 2,
+				},
+			},
+			wants: wants{
+				buckets: []*influxdb.Bucket{
+					{
+						ID:    idTwo,
+						OrgID: idOne,
+						Name:  "def",
+					},
+					{
+						ID:    idThree,
+						OrgID: idOne,
+						Name:  "xyz",
+					},
+				},
+			},
+		},
 		{
 			name: "find all buckets by descending",
 			fields: BucketFields{