feat(terminal): add mechanism to fetch last focused terminal (#411)

This is useful for plugins like flatten.nvim where you (read: I) want to be able to check if the last toggled terminal was a float and if not not bother re-opening it

Author: akinsho

lua/toggleterm/terminal.lua

@@ -121,6 +121,11 @@ function M.get_focused_id()
   return nil
 end
 
+function M.get_last_focused()
+  local last_focus = ui.get_terminal_view().focus_term_id
+  return M.get(last_focus, true)
+end
+
 --- @param bufnr number
 local function setup_buffer_mappings(bufnr)
   local mapping = config.open_mapping
@@ -526,10 +531,11 @@ end
 
 ---Get a single terminal by id, unless it is hidden
 ---@param id number?
+---@param include_hidden boolean? whether or nor to filter out hidden
 ---@return Terminal?
-function M.get(id)
+function M.get(id, include_hidden)
   local term = terminals[id]
-  return (term and not term.hidden) and term or nil
+  return (term and (include_hidden == true or not term.hidden)) and term or nil
 end
 
 ---Return the potentially non contiguous map of terminals as a sorted array

lua/toggleterm/ui.lua

@@ -19,6 +19,9 @@ local api = vim.api
 local origin_window
 local persistent = {}
 
+---@alias TerminalView {terminals: number[], focus_term_id: number}
+
+---@type TerminalView
 local terminal_view = {
   ---@type number[]
   -- A list of terminal IDs that are saved from the view on smart toggle.
@@ -454,4 +457,7 @@ function M.save_terminal_view(terminals, focus_term_id)
   terminal_view = { terminals = terminals, focus_term_id = focus_term_id }
 end
 
+---@return TerminalView
+function M.get_terminal_view() return terminal_view end
+
 return M