feat: Automatically open files in file buffers

lua/fff/picker_ui.lua

@@ -1219,6 +1219,42 @@ function M.scroll_preview_down()
   preview.scroll(scroll_lines)
 end
 
+--- Find the first visible window with a normal file buffer
+--- @return number|nil Window ID of the first suitable window, or nil if none found
+local function find_suitable_window()
+  local current_tabpage = vim.api.nvim_get_current_tabpage()
+  local windows = vim.api.nvim_tabpage_list_wins(current_tabpage)
+
+  for _, win in ipairs(windows) do
+    if vim.api.nvim_win_is_valid(win) then
+      local buf = vim.api.nvim_win_get_buf(win)
+      if vim.api.nvim_buf_is_valid(buf) then
+        local buftype = vim.api.nvim_buf_get_option(buf, 'buftype')
+        local modifiable = vim.api.nvim_buf_get_option(buf, 'modifiable')
+        local filetype = vim.api.nvim_buf_get_option(buf, 'filetype')
+
+        local is_picker_window = (
+          win == M.state.input_win
+          or win == M.state.list_win
+          or win == M.state.preview_win
+          or win == M.state.file_info_win
+        )
+
+        if
+          (buftype == '' or buftype == 'acwrite')
+          and modifiable
+          and not is_picker_window
+          and filetype ~= 'undotree'
+        then
+          return win
+        end
+      end
+    end
+  end
+
+  return nil
+end
+
 function M.select(action)
   if not M.state.active then return end
 
@@ -1235,6 +1271,21 @@ function M.select(action)
   M.close()
 
   if action == 'edit' then
+    local current_buf = vim.api.nvim_get_current_buf()
+    local current_buftype = vim.api.nvim_buf_get_option(current_buf, 'buftype')
+    local current_buf_modifiable = vim.api.nvim_buf_get_option(current_buf, 'modifiable')
+
+    -- If current active buffer is not a normal buffer we find a suitable window with a tab otherwise opening a new split
+    if current_buftype ~= '' or not current_buf_modifiable then
+      local suitable_win = find_suitable_window()
+      if suitable_win then
+        vim.api.nvim_set_current_win(suitable_win)
+      else
+        vim.cmd('split ' .. vim.fn.fnameescape(relative_path))
+        return
+      end
+    end
+
     vim.cmd('edit ' .. vim.fn.fnameescape(relative_path))
   elseif action == 'split' then
     vim.cmd('split ' .. vim.fn.fnameescape(relative_path))