Update slack vendor to master (#958)

vendor/github.com/nlopes/slack/stars.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"net/url"
 	"strconv"
+	"time"
 )
 
 const (
@@ -158,3 +159,105 @@ func (api *Client) GetStarredContext(ctx context.Context, params StarsParameters
 	}
 	return starredItems, paging, nil
 }
+
+type listResponsePaginated struct {
+	Items []Item `json:"items"`
+	SlackResponse
+	Metadata ResponseMetadata `json:"response_metadata"`
+}
+
+// StarredItemPagination allows for paginating over the starred items
+type StarredItemPagination struct {
+	Items        []Item
+	limit        int
+	previousResp *ResponseMetadata
+	c            *Client
+}
+
+// ListStarsOption options for the GetUsers method call.
+type ListStarsOption func(*StarredItemPagination)
+
+// ListAllStars returns the complete list of starred items
+func (api *Client) ListAllStars() ([]Item, error) {
+	return api.ListAllStarsContext(context.Background())
+}
+
+// ListAllStarsContext returns the list of users (with their detailed information) with a custom context
+func (api *Client) ListAllStarsContext(ctx context.Context) (results []Item, err error) {
+	p := api.ListStarsPaginated()
+	for err == nil {
+		p, err = p.next(ctx)
+		if err == nil {
+			results = append(results, p.Items...)
+		} else if rateLimitedError, ok := err.(*RateLimitedError); ok {
+			select {
+			case <-ctx.Done():
+				err = ctx.Err()
+			case <-time.After(rateLimitedError.RetryAfter):
+				err = nil
+			}
+		}
+	}
+
+	return results, p.failure(err)
+}
+
+// ListStarsPaginated fetches users in a paginated fashion, see ListStarsPaginationContext for usage.
+func (api *Client) ListStarsPaginated(options ...ListStarsOption) StarredItemPagination {
+	return newStarPagination(api, options...)
+}
+
+func newStarPagination(c *Client, options ...ListStarsOption) (sip StarredItemPagination) {
+	sip = StarredItemPagination{
+		c:     c,
+		limit: 200, // per slack api documentation.
+	}
+
+	for _, opt := range options {
+		opt(&sip)
+	}
+
+	return sip
+}
+
+// done checks if the pagination has completed
+func (StarredItemPagination) done(err error) bool {
+	return err == errPaginationComplete
+}
+
+// done checks if pagination failed.
+func (t StarredItemPagination) failure(err error) error {
+	if t.done(err) {
+		return nil
+	}
+
+	return err
+}
+
+// next gets the next list of starred items based on the cursor value
+func (t StarredItemPagination) next(ctx context.Context) (_ StarredItemPagination, err error) {
+	var (
+		resp *listResponsePaginated
+	)
+
+	if t.c == nil || (t.previousResp != nil && t.previousResp.Cursor == "") {
+		return t, errPaginationComplete
+	}
+
+	t.previousResp = t.previousResp.initialize()
+
+	values := url.Values{
+		"limit":  {strconv.Itoa(t.limit)},
+		"token":  {t.c.token},
+		"cursor": {t.previousResp.Cursor},
+	}
+
+	if err = t.c.postMethod(ctx, "stars.list", values, &resp); err != nil {
+		return t, err
+	}
+
+	t.previousResp = &resp.Metadata
+	t.Items = resp.Items
+
+	return t, nil
+}