From 1142f46a27358c8f48023382389a8b31c9628b6b Mon Sep 17 00:00:00 2001
From: Folke Lemaitre <folke.lemaitre@gmail.com>
Date: Thu, 20 Feb 2025 09:26:04 +0100
Subject: [PATCH] perf(explorer): only update tree when diagnostics actually
 changed

---
 lua/snacks/explorer/diagnostics.lua   |  4 +++
 lua/snacks/explorer/tree.lua          | 40 +++++++++++++++++++++++++++
 lua/snacks/picker/source/explorer.lua | 17 +++++++++---
 3 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/lua/snacks/explorer/diagnostics.lua b/lua/snacks/explorer/diagnostics.lua
index 3a1df33d..67290a19 100644
--- a/lua/snacks/explorer/diagnostics.lua
+++ b/lua/snacks/explorer/diagnostics.lua
@@ -6,6 +6,8 @@ function M.update(cwd)
   local Tree = require("snacks.explorer.tree")
   local node = Tree:find(cwd)
 
+  local snapshot = Tree:snapshot(node, { "severity" })
+
   Tree:walk(node, function(n)
     n.severity = nil
   end, { all = true })
@@ -31,6 +33,8 @@ function M.update(cwd)
       end
     end
   end
+
+  return Tree:changed(node, snapshot)
 end
 
 return M
diff --git a/lua/snacks/explorer/tree.lua b/lua/snacks/explorer/tree.lua
index d31796f3..8d635c5a 100644
--- a/lua/snacks/explorer/tree.lua
+++ b/lua/snacks/explorer/tree.lua
@@ -21,6 +21,8 @@
 ---@field exclude? string[] globs to exclude
 ---@field include? string[] globs to exclude
 
+---@alias snacks.picker.explorer.Snapshot {fields: string[], state:table<snacks.picker.explorer.Node, any[]>}
+
 local uv = vim.uv or vim.loop
 
 local function norm(path)
@@ -331,4 +333,42 @@ function Tree:next(cwd, filter, opts)
   return next or first
 end
 
+---@param node snacks.picker.explorer.Node
+---@param snapshot snacks.picker.explorer.Snapshot
+function Tree:changed(node, snapshot)
+  local old = snapshot.state
+  local current = self:snapshot(node, snapshot.fields).state
+  if vim.tbl_count(current) ~= vim.tbl_count(old) then
+    return true
+  end
+  for n, data in pairs(current) do
+    local prev = old[n]
+    if not prev then
+      return true
+    end
+    if not vim.deep_equal(prev, data) then
+      return true
+    end
+  end
+  return false
+end
+
+---@param node snacks.picker.explorer.Node
+---@param fields string[]
+function Tree:snapshot(node, fields)
+  ---@type snacks.picker.explorer.Snapshot
+  local ret = {
+    state = {},
+    fields = fields,
+  }
+  Tree:walk(node, function(n)
+    local data = {} ---@type any[]
+    for f, field in ipairs(fields) do
+      data[f] = n[field]
+    end
+    ret.state[n] = data
+  end, { all = true })
+  return ret
+end
+
 return Tree.new()
diff --git a/lua/snacks/picker/source/explorer.lua b/lua/snacks/picker/source/explorer.lua
index 847c1fbb..29125132 100644
--- a/lua/snacks/picker/source/explorer.lua
+++ b/lua/snacks/picker/source/explorer.lua
@@ -72,12 +72,21 @@ function State.new(picker)
   end)
 
   if opts.diagnostics then
-    picker.list.win:on("DiagnosticChanged", function(_, ev)
+    local dirty = false
+    local diag_update = Snacks.util.debounce(function()
+      dirty = false
       local p = ref()
       if p then
-        require("snacks.explorer.diagnostics").update(p:cwd())
-        p.list:set_target()
-        p:find()
+        if require("snacks.explorer.diagnostics").update(p:cwd()) then
+          p.list:set_target()
+          p:find()
+        end
+      end
+    end, { ms = 200 })
+    picker.list.win:on({ "InsertLeave", "DiagnosticChanged" }, function(_, ev)
+      dirty = dirty or ev.event == "DiagnosticChanged"
+      if vim.fn.mode() == "n" and dirty then
+        diag_update()
       end
     end)
   end