feat(explorer): file watching that works on all platforms

lua/snacks/explorer/tree.lua

@@ -115,6 +115,7 @@ function Tree:close(path)
   local dir = self:dir(path)
   local node = self:find(dir)
   node.open = false
+  node.expanded = false -- clear expanded state
 end
 
 ---@param node snacks.picker.explorer.Node

lua/snacks/explorer/watch.lua

@@ -3,38 +3,58 @@ local M = {}
 local Git = require("snacks.explorer.git")
 local Tree = require("snacks.explorer.tree")
 
+M._watches = {} ---@type table<string, uv.uv_fs_event_t>
+
 local uv = vim.uv or vim.loop
-
----@alias snacks.explorer.Watcher fun(path:string, opts:vim._watch.watch.Opts?, callback:vim._watch.Callback):fun()
-
----@return snacks.explorer.Watcher?
-function M.watcher()
-  if not vim._watch then
-    return
-  end
-  if vim.fn.has("win32") == 1 or vim.fn.has("mac") == 1 then
-    return vim._watch.watch
-  elseif vim.fn.executable("inotifywait") == 1 then
-    return vim._watch.inotify
-  end
-  -- This is horrible for performance. Don't use it!
-  -- return vim._watch.watchdirs
-end
-
-local running = {} ---@type table<string, fun()>
-
-function M.abort()
-  for _, abort in pairs(running) do
-    pcall(abort)
-  end
-  running = {}
-end
-
 local timer = assert(uv.new_timer())
 
+---@param path string
+---@param cb? fun(file:string, events: uv.fs_event_start.callback.events)
+function M.start(path, cb)
+  if M._watches[path] ~= nil then
+    return
+  end
+  local handle = assert(vim.uv.new_fs_event())
+  local ok, err = handle:start(path, {}, function(_, file, events)
+    file = path .. "/" .. file
+    if cb then
+      cb(file, events)
+    else
+      Tree:refresh(vim.fs.dirname(file))
+      M.refresh()
+    end
+  end)
+  M._watches[path] = handle
+  if not ok then
+    Snacks.notify.error("Failed to watch " .. path .. ": " .. err)
+    if not handle:is_closing() then
+      handle:close()
+    end
+    return
+  end
+end
+
+---@param path string
+function M.stop(path)
+  local handle = M._watches[path]
+  if handle then
+    if not handle:is_closing() then
+      handle:close()
+    end
+    M._watches[path] = nil
+  end
+end
+
+-- Stop all watches
+function M.abort()
+  for path in pairs(M._watches) do
+    M.stop(path)
+  end
+end
+
+-- batch updates and give explorer the time to update before the watcher
 function M.refresh()
-  -- batch updates and give explorer the time to update before the watcher
-  timer:start(500, 0, function()
+  timer:start(100, 0, function()
     local picker = Snacks.picker.get({ source = "explorer" })[1]
     if picker and not picker.closed and Tree:is_dirty(picker:cwd(), picker.opts) then
       if not picker.list.target then
@@ -45,68 +65,36 @@ function M.refresh()
   end)
 end
 
----@param cwd string
-function M.watch_git(cwd)
-  local root = Snacks.git.get_root(cwd)
-  if not root then
-    return
-  end
-  local handle = assert(vim.uv.new_fs_event())
-  handle:start(root .. "/.git", {}, function(_, file)
-    if file == "index" then
-      Git.refresh(root)
-      M.refresh()
-    end
-  end)
-  return function()
-    if handle and not handle:is_closing() then
-      handle:close()
-    end
-  end
-end
-
----@param cwd string
-function M.watch_files(cwd)
-  local watch = M.watcher()
-  if not watch then
-    return
-  end
-
-  return watch(cwd, {
-    uvflags = { recursive = true },
-  }, function(path, changes)
-    -- handle deletes
-    while not uv.fs_stat(path) do
-      local p = vim.fs.dirname(path)
-      if p == path then
-        return
-      end
-      path = p
-    end
-    Tree:refresh(path)
-    M.refresh()
-  end)
-end
-
 ---@param cwd string
 function M.watch(cwd)
-  if running[cwd] then
-    return
+  -- Track used watches
+  local used = {} ---@type table<string, boolean>
+
+  -- Watch git index
+  local root = Snacks.git.get_root(cwd)
+  if root then
+    used[root .. "/.git"] = true
+    M.start(root .. "/.git", function(file)
+      if vim.fs.basename(file) == "index" then
+        Git.refresh(root)
+        M.refresh()
+      end
+    end)
   end
 
-  local watchers = { M.watch_git, M.watch_files }
-  local cancel = {} ---@type (fun())[]
-
-  for _, watch in ipairs(watchers) do
-    local ok, c = pcall(watch, cwd)
-    if ok and c then
-      cancel[#cancel + 1] = c
+  -- Watch open directories
+  Tree:walk(Tree:find(cwd), function(node)
+    if node.dir and node.open then
+      used[node.path] = true
+      M.start(node.path)
     end
-  end
+  end)
 
-  running[cwd] = function()
-    vim.tbl_map(pcall, cancel)
-    running[cwd] = nil
+  -- Stop unused watches
+  for path in pairs(M._watches) do
+    if not used[path] then
+      M.stop(path)
+    end
   end
 end