nvim/diagnostic: cycle diagnostic layout

credit: mrcjkb

.config/nvim/plugin/lsp.lua

@@ -44,6 +44,40 @@ vim.diagnostic.config {
     },
 }
 
+do
+    local index = 1
+
+    ---@type vim.diagnostic.Opts[]
+    local modes = {
+        { virtual_text = false, virtual_lines = false },
+        {
+            virtual_text = false,
+            virtual_lines = {
+                current_line = true,
+                severity = {
+                    vim.diagnostic.severity.ERROR,
+                    vim.diagnostic.severity.WARN,
+                },
+            },
+        },
+        { virtual_text = true, virtual_lines = false },
+    }
+
+    ---@param direction 'forward' | 'backward'
+    local function cycle_diagnostic_modes(direction)
+        if direction == "forward" then
+            index = (index % #modes) + 1
+        else
+            index = (index - 2 + #modes) % #modes + 1
+        end
+
+        vim.diagnostic.config(modes[index])
+    end
+
+    vim.keymap.set("n", "]d", function() cycle_diagnostic_modes("forward") end)
+    vim.keymap.set("n", "[d", function() cycle_diagnostic_modes("backward") end)
+end
+
 -- Helix style border
 local orig_util_open_floating_preview = vim.lsp.util.open_floating_preview
 function vim.lsp.util.open_floating_preview(contents, syntax, opts, ...)