From 03d02d67f7ae16b19d9933648d5cbd49915c76e0 Mon Sep 17 00:00:00 2001
From: Junegunn Choi <junegunn.c@gmail.com>
Date: Wed, 4 Jan 2023 22:00:00 +0900
Subject: [PATCH] Fix cyclic scrolling with non-zero preview header lines

e.g. fzf --preview-window 'cycle,~2' --preview 'echo foo; echo bar; seq 100'
---
 src/terminal.go | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/terminal.go b/src/terminal.go
index 48f9f1d5..f4435a61 100644
--- a/src/terminal.go
+++ b/src/terminal.go
@@ -2652,10 +2652,12 @@ func (t *Terminal) Loop() {
 			}
 			t.previewer.following = false
 			numLines := len(t.previewer.lines)
+			headerLines := t.previewOpts.headerLines
 			if t.previewOpts.cycle {
-				newOffset = (newOffset + numLines) % numLines
+				offsetRange := numLines - headerLines
+				newOffset = ((newOffset-headerLines)+offsetRange)%offsetRange + headerLines
 			}
-			newOffset = util.Constrain(newOffset, t.previewOpts.headerLines, numLines-1)
+			newOffset = util.Constrain(newOffset, headerLines, numLines-1)
 			if t.previewer.offset != newOffset {
 				t.previewer.offset = newOffset
 				req(reqPreviewRefresh)