Revert "refactor(#2871, #2886): multi instance: node classes created (#2916)"

This reverts commit 38aac09151.

lua/nvim-tree/lib.lua

@@ -3,6 +3,7 @@ local core = require("nvim-tree.core")
 local utils = require("nvim-tree.utils")
 local events = require("nvim-tree.events")
 local notify = require("nvim-tree.notify")
+local explorer_node = require("nvim-tree.explorer.node")
 
 ---@class LibOpenOpts
 ---@field path string|nil path
@@ -14,7 +15,6 @@ local M = {
 }
 
 ---Cursor position as per vim.api.nvim_win_get_cursor
----nil on no explorer or invalid view win
 ---@return integer[]|nil
 function M.get_cursor_position()
   if not core.get_explorer() then
@@ -31,28 +31,154 @@ end
 
 ---@return Node|nil
 function M.get_node_at_cursor()
-  local explorer = core.get_explorer()
-  if not explorer then
-    return
-  end
-
   local cursor = M.get_cursor_position()
   if not cursor then
     return
   end
 
   if cursor[1] == 1 and view.is_root_folder_visible(core.get_cwd()) then
-    return explorer
+    return { name = ".." }
   end
 
-  return utils.get_nodes_by_line(explorer.nodes, core.get_nodes_starting_line())[cursor[1]]
+  return utils.get_nodes_by_line(core.get_explorer().nodes, core.get_nodes_starting_line())[cursor[1]]
+end
+
+---Create a sanitized partial copy of a node, populating children recursively.
+---@param node Node|nil
+---@return Node|nil cloned node
+local function clone_node(node)
+  if not node then
+    node = core.get_explorer()
+    if not node then
+      return nil
+    end
+  end
+
+  local n = {
+    absolute_path = node.absolute_path,
+    executable = node.executable,
+    extension = node.extension,
+    git_status = node.git_status,
+    has_children = node.has_children,
+    hidden = node.hidden,
+    link_to = node.link_to,
+    name = node.name,
+    open = node.open,
+    type = node.type,
+    fs_stat = node.fs_stat,
+  }
+
+  if type(node.nodes) == "table" then
+    n.nodes = {}
+    for _, child in ipairs(node.nodes) do
+      table.insert(n.nodes, clone_node(child))
+    end
+  end
+
+  return n
 end
 
 ---Api.tree.get_nodes
----@return Node[]?
+---@return Node[]|nil
 function M.get_nodes()
+  return clone_node(core.get_explorer())
+end
+
+-- If node is grouped, return the last node in the group. Otherwise, return the given node.
+---@param node Node
+---@return Node
+function M.get_last_group_node(node)
+  while node and node.group_next do
+    node = node.group_next
+  end
+
+  return node ---@diagnostic disable-line: return-type-mismatch -- it can't be nil
+end
+
+---Group empty folders
+-- Recursively group nodes
+---@param node Node
+---@return Node[]
+function M.group_empty_folders(node)
+  local is_root = not node.parent
+  local child_folder_only = explorer_node.has_one_child_folder(node) and node.nodes[1]
+  if M.group_empty and not is_root and child_folder_only then
+    node.group_next = child_folder_only
+    local ns = M.group_empty_folders(child_folder_only)
+    node.nodes = ns or {}
+    return ns
+  end
+  return node.nodes
+end
+
+---Ungroup empty folders
+-- If a node is grouped, ungroup it: put node.group_next to the node.nodes and set node.group_next to nil
+---@param node Node
+function M.ungroup_empty_folders(node)
+  local cur = node
+  while cur and cur.group_next do
+    cur.nodes = { cur.group_next }
+    cur.group_next = nil
+    cur = cur.nodes[1]
+  end
+end
+
+---@param node Node
+---@return Node[]
+function M.get_all_nodes_in_group(node)
+  local next_node = utils.get_parent_of_group(node)
+  local nodes = {}
+  while next_node do
+    table.insert(nodes, next_node)
+    next_node = next_node.group_next
+  end
+  return nodes
+end
+
+-- Toggle group empty folders
+---@param head_node Node
+local function toggle_group_folders(head_node)
+  local is_grouped = head_node.group_next ~= nil
+
+  if is_grouped then
+    M.ungroup_empty_folders(head_node)
+  else
+    M.group_empty_folders(head_node)
+  end
+end
+
+---@param node Node
+function M.expand_or_collapse(node, toggle_group)
   local explorer = core.get_explorer()
-  return explorer and explorer:clone()
+
+  toggle_group = toggle_group or false
+  if node.has_children then
+    node.has_children = false
+  end
+
+  if #node.nodes == 0 and explorer then
+    explorer:expand(node)
+  end
+
+  local head_node = utils.get_parent_of_group(node)
+  if toggle_group then
+    toggle_group_folders(head_node)
+  end
+
+  local open = M.get_last_group_node(node).open
+  local next_open
+  if toggle_group then
+    next_open = open
+  else
+    next_open = not open
+  end
+  for _, n in ipairs(M.get_all_nodes_in_group(head_node)) do
+    n.open = next_open
+  end
+
+  if explorer then
+    explorer.renderer:draw()
+  end
 end
 
 function M.set_target_win()