fix(nvim): smooth scroll cursor at boundaries

1 files changed, 17 insertions, 7 deletions

diff --git a/.config/nvim/plugin/50-smooth_scroll.lua b/.config/nvim/plugin/50-smooth_scroll.lua
index 3c2ef05..6b31bf4 100644
--- a/.config/nvim/plugin/50-smooth_scroll.lua
+++ b/.config/nvim/plugin/50-smooth_scroll.lua
@@ -4,18 +4,25 @@ local Dir = {
 }
 
 local function smooth_scroll(dir)
-	local at_boundary
+	local scroll_at_boundary, cursor_at_boundary
 	if dir == Dir.DOWN then
-		at_boundary = function()
+		scroll_at_boundary = function()
 			return vim.fn.line("w$") == vim.api.nvim_buf_line_count(0)
 		end
+		cursor_at_boundary = function()
+			return vim.fn.line(".") == vim.api.nvim_buf_line_count(0)
+		end
 	else
-		at_boundary = function()
+		scroll_at_boundary = function()
 			return vim.fn.line("w0") == 1
 		end
+		cursor_at_boundary = function()
+			return vim.fn.line(".") == 1
+		end
 	end
-	-- bail at boundaries: <C-e>/<C-y> would no-op but j/k would still walk the cursor
-	if at_boundary() then
+	-- bail only when the cursor itself can't move further; at the viewport
+	-- boundary <C-e>/<C-y> no-op but we still want j/k to walk the cursor
+	if cursor_at_boundary() then
 		return
 	end
 	local win_height = vim.api.nvim_win_get_height(0)
@@ -23,7 +30,8 @@ local function smooth_scroll(dir)
 	local distance = math.floor(win_height / 2)
 	local steps_number = math.ceil(duration / sleep_duration) -- We want a movement every `sleep_duration` msec
 	local step = distance / steps_number
-	local keys = dir == Dir.DOWN and "\\<C-e>j" or "\\<C-y>k"
+	local scroll_keys = dir == Dir.DOWN and "\\<C-e>j" or "\\<C-y>k"
+	local cursor_keys = dir == Dir.DOWN and "j" or "k"
 	local prev = 0
 	for i = 1, steps_number do
 		local cur = math.ceil(step * i)
@@ -31,9 +39,11 @@ local function smooth_scroll(dir)
 		prev = cur
 		vim.defer_fn(function()
 			for _ = 1, delta do
-				if at_boundary() then
+				if cursor_at_boundary() then
 					return
 				end
+				-- past the viewport boundary <C-e>/<C-y> no-op; just walk the cursor
+				local keys = scroll_at_boundary() and cursor_keys or scroll_keys
 				vim.cmd('exec "normal! ' .. keys .. '"')
 			end
 		end, sleep_duration * i)