From f762ad498ef8c47ef8f65bf6029bf3907d09e87e Mon Sep 17 00:00:00 2001
From: Steven Xu <stevenxxiu@gmail.com>
Date: Sun, 25 Feb 2024 19:00:49 +1100
Subject: [PATCH] feat: add `slide_to()`, to slide the buffer to position

---
 lua/bufferline.lua          |  1 +
 lua/bufferline/commands.lua | 22 +++++++++++++++++++++-
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/lua/bufferline.lua b/lua/bufferline.lua
index 1930a88a..8114e6c2 100644
--- a/lua/bufferline.lua
+++ b/lua/bufferline.lua
@@ -23,6 +23,7 @@ local api = vim.api
 local M = {
   move = commands.move,
   move_to = commands.move_to,
+  slide_to = commands.slide_to,
   exec = commands.exec,
   go_to = commands.go_to,
   cycle = commands.cycle,
diff --git a/lua/bufferline/commands.lua b/lua/bufferline/commands.lua
index 55a07152..3860bd34 100644
--- a/lua/bufferline/commands.lua
+++ b/lua/bufferline/commands.lua
@@ -155,7 +155,7 @@ function M.move_to(to_index, from_index)
   if not index then return utils.notify("Unable to find buffer to move, sorry", "warn") end
   -- Calculate next index depending on the sign of `to_index`
   local next_index = to_index > 0 and to_index or #state.components + 1 + to_index
-  if next_index >= 1 and next_index <= #state.components then
+  if next_index >= 1 and next_index <= #state.components and next_index ~= from_index then
     local item = state.components[index]
     local destination_buf = state.components[next_index]
     state.components[next_index] = item
@@ -167,6 +167,26 @@ function M.move_to(to_index, from_index)
   end
 end
 
+--- Slide the buffer at index `from_index` (or current index if not specified) to position `to_index`
+--- @param to_index number negative indices are accepted (counting from the right instead of the left, e.g. -1 for the last position, -2 for the second-last, etc.)
+--- @param from_index number?
+function M.slide_to(to_index, from_index)
+  -- Calculate next index depending on the sign of `to_index`
+  local next_index = to_index > 0 and to_index or #state.components + 1 + to_index
+  if next_index >= 1 and next_index <= #state.components and next_index ~= from_index then
+    local step = (from_index < next_index and 1) or -1
+    local from_buf = state.components[from_index]
+    for cur_index = from_index, next_index - step, step do
+      state.components[cur_index] = state.components[cur_index + step]
+    end
+    state.components[next_index] = from_buf
+    state.custom_sort = utils.get_ids(state.components)
+    local opts = config.options
+    if opts.persist_buffer_sort then utils.save_positions(state.custom_sort) end
+    ui.refresh()
+  end
+end
+
 --- @param direction number
 function M.move(direction)
   local index, element = M.get_current_element_index(state)