1 files changed, 84 insertions, 0 deletions
diff --git a/lua/quicker/follow.lua b/lua/quicker/follow.lua
new file mode 100644
index 0000000..d5500a2
--- /dev/null
+++ b/lua/quicker/follow.lua
@@ -0,0 +1,84 @@
+local util = require("quicker.util")
+local M = {}
+
+M.seek_to_position = function()
+  if util.is_open(0) then
+    local qf_list = vim.fn.getloclist(0, { winid = 0, items = 0 })
+    local new_pos = M.calculate_pos(qf_list.items)
+    if new_pos then
+      M.set_pos(qf_list.winid, new_pos)
+    end
+  end
+
+  if util.is_open() then
+    local qf_list = vim.fn.getqflist({ winid = 0, items = 0 })
+    local new_pos = M.calculate_pos(qf_list.items)
+    if new_pos then
+      M.set_pos(qf_list.winid, new_pos)
+    end
+  end
+end
+
+---Calculate the current buffer/cursor location in the quickfix list
+---@param list QuickFixItem[]
+---@return nil|integer
+M.calculate_pos = function(list)
+  if vim.bo.buftype ~= "" then
+    return
+  end
+  local bufnr = vim.api.nvim_get_current_buf()
+  local cursor = vim.api.nvim_win_get_cursor(0)
+  local lnum, col = cursor[1], cursor[2] + 1
+  local prev_lnum = -1
+  local prev_col = -1
+  local found_buf = false
+  local ret
+  for i, entry in ipairs(list) do
+    if entry.bufnr ~= bufnr then
+      if found_buf then
+        return ret
+      end
+    else
+      found_buf = true
+
+      -- If we detect that the list isn't sorted, bail.
+      if
+        prev_lnum > -1
+        and (entry.lnum < prev_lnum or (entry.lnum == prev_lnum and entry.col <= prev_col))
+      then
+        return
+      end
+
+      if prev_lnum == -1 or lnum > entry.lnum or (lnum == entry.lnum and col >= entry.col) then
+        ret = i
+      end
+      prev_lnum = entry.lnum
+      prev_col = entry.col
+    end
+  end
+
+  return ret
+end
+
+local timers = {}
+---@param winid integer
+---@param pos integer
+M.set_pos = function(winid, pos)
+  local timer = timers[winid]
+  if timer then
+    timer:close()
+  end
+  timer = assert(vim.uv.new_timer())
+  timers[winid] = timer
+  timer:start(10, 0, function()
+    timer:close()
+    timers[winid] = nil
+    vim.schedule(function()
+      if vim.api.nvim_win_is_valid(winid) then
+        pcall(vim.api.nvim_win_set_cursor, winid, { pos, 0 })
+      end
+    end)
+  end)
+end
+
+return M