nvim: lsp: Add support for lua

nvim/.config/nvim/lua/lsp.lua

@@ -179,3 +179,68 @@ for _, lsp in ipairs(servers) do
     capabilities = set_snippet_capabilities(),
   }
 end
+
+-- See https://github.com/sumneko/lua-language-server/wiki/Setting-without-VSCode#neovim-with-built-in-lsp-client
+-- on why we do this library thing
+-- Idea taken from https://gist.github.com/folke/fe5d28423ea5380929c3f7ce674c41d8
+local library = {}
+local function add_to_library(lib_path)
+    for _, p in pairs(vim.fn.expand(lib_path, false, true)) do
+    p = vim.loop.fs_realpath(p)
+    library[p] = true
+  end
+end
+
+local function add_libraries()
+  local cwd = vim.fn.getcwd()
+  if string.find(cwd, "neovim") then
+    add_to_library("$VIMRUNTIME")
+  elseif string.find(cwd, "dotfiles") then
+    add_to_library("$VIMRUNTIME")
+    add_to_library("~/.config/nvim")
+    add_to_library("~/.local/share/nvim/site/pack/packer/opt/*")
+    add_to_library("~/.local/share/nvim/site/pack/packer/start/*")
+  else
+    add_to_library(cwd .. "/*")
+  end
+end
+
+local function determine_lua_version()
+  local cwd = vim.fn.getcwd()
+  if string.find(cwd, "neovim") or string.find(cwd, "dotfiles") then
+    return "LuaJIT"
+  else
+    return "Lua 5.4"
+  end
+end
+
+add_libraries()
+
+local runtime_path = vim.split(package.path, ';')
+table.insert(runtime_path, "lua/?.lua")
+table.insert(runtime_path, "lua/?/init.lua")
+
+nvim_lsp.sumneko_lua.setup {
+  cmd = { "/usr/bin/lua-language-server" };
+  on_attach = on_attach,
+  settings = {
+    Lua = {
+      runtime = {
+        version = determine_lua_version(),
+        path = runtime_path,
+      },
+      completion = { callSnippet = "Both" },
+      diagnostics = {
+        globals = {'vim'},
+      },
+      workspace = {
+        library = library,
+        maxPreload = 2000,
+        preloadFileSize = 50000
+      },
+      telemetry = {
+        enable = false,
+      },
+    },
+  },
+}