Custom statusline/winbar

init.lua

local install_path = vim.fn.stdpath("data") .. "/site/pack/packer/start/packer.nvim"
if vim.fn.empty(vim.fn.glob(install_path)) > 0 then
	vim.fn.execute("!git clone --depth 1 https://github.com/wbthomason/packer.nvim " .. install_path)
end

require("packer").startup(function(use)
	use("wbthomason/packer.nvim")
	use({
		"rose-pine/neovim",
		as = "rose-pine",
		config = function()
			require("rose-pine").setup({ disable_italics = true })
			vim.cmd("colorscheme rose-pine")
		end,
	})
	use("editorconfig/editorconfig-vim")
	use({
		"nvim-treesitter/nvim-treesitter",
		run = ":TSUpdate",
		config = function()
			require("nvim-treesitter.configs").setup({
				ensure_installed = "all",
				ignore_install = { "phpdoc" },
				highlight = { enable = true },
			})
		end,
	})
	use({
		"numToStr/Comment.nvim",
		requires = "JoosepAlviste/nvim-ts-context-commentstring",
		config = function()
			require("nvim-treesitter.configs").setup({
				context_commentstring = {
					enable = true,
					enable_autocmd = false,
				},
			})
			require("Comment").setup({
				pre_hook = require("ts_context_commentstring.integrations.comment_nvim").create_pre_hook(),
			})
		end,
	})
	use({
		"nvim-telescope/telescope.nvim",
		requires = "nvim-lua/plenary.nvim",
		config = function()
			require("telescope").setup({})
		end,
	})
	use({
		"neovim/nvim-lspconfig",
		requires = {
			"folke/lua-dev.nvim",
			"williamboman/mason.nvim",
			"williamboman/mason-lspconfig.nvim",
			"WhoIsSethDaniel/mason-tool-installer.nvim",
		},
		config = function()
			require("mason").setup()
			require("mason-tool-installer").setup({})

			local function on_attach(_, bufnr)
				local opts = { buffer = bufnr, silent = true }
				vim.keymap.set("i", "<c-k>", vim.lsp.buf.signature_help, opts)
				vim.keymap.set("n", "<leader>a", vim.lsp.buf.code_action, opts)
				vim.keymap.set("n", "<leader>r", vim.lsp.buf.rename, opts)
				vim.keymap.set("n", "K", vim.lsp.buf.hover, opts)
				vim.keymap.set("n", "gd", vim.lsp.buf.definition, opts)
				vim.keymap.set("n", "gi", vim.lsp.buf.implementation, opts)
				vim.keymap.set("n", "gr", vim.lsp.buf.references, opts)
			end

			local capabilities = vim.lsp.protocol.make_client_capabilities()

			-- Improve compatibility with nvim-cmp completions
			local has_cmp_nvim_lsp, cmp_nvim_lsp = pcall(require, "cmp_nvim_lsp")
			if has_cmp_nvim_lsp then
				capabilities = cmp_nvim_lsp.update_capabilities(capabilities)
			end

			-- Automatically setup servers installed via `:MasonInstall`
			require("mason-lspconfig").setup_handlers({
				function(server_name)
					if server_name == "sumneko_lua" then
						require("lspconfig")[server_name].setup(require("lua-dev").setup({
							on_attach = on_attach,
							capabilities = capabilities,
						}))
					else
						require("lspconfig")[server_name].setup({
							on_attach = on_attach,
							capabilities = capabilities,
						})
					end
				end,
			})
		end,
	})
	use({
		"jose-elias-alvarez/null-ls.nvim",
		requires = "nvim-lua/plenary.nvim",
		config = function()
			local null_ls = require("null-ls")

			local sources = {
				null_ls.builtins.formatting.stylua,
			}

			null_ls.setup({
				sources = sources,
				on_attach = function(client, bufnr)
					if client.supports_method("textDocument/formatting") then
						vim.api.nvim_create_autocmd("BufWritePre", {
							buffer = bufnr,
							callback = function()
								vim.lsp.buf.format({
									bufnr = bufnr,
									filter = function(lsp_client)
										return lsp_client.name == "null-ls"
									end,
								})
							end,
						})
					end
				end,
			})
		end,
	})
end)

-- Set diagnostic sign column symbols
local signs = { "Error", "Warn", "Hint", "Info" }
for _, type in pairs(signs) do
	local hl = string.format("DiagnosticSign%s", type)
	vim.fn.sign_define(hl, { text = "●", texthl = hl, numhl = hl })
end

M = {}

--- Re-evaluate function each time the statusline is redrawn.
--- @param fn string
function M.watch_fn(fn)
	-- TODO: This seems unnecessarily hacky. Without it, however, messages
	-- will not be updated.
	--
	-- `%{luaeval(...)}` re-evaluates each time the statusline is redrawn.
	--
	-- Ideally this wouldn't require a string version of our function, as
	-- that makes typos more likely to go unnoticed and cause issues. Also,
	-- using default variables within the passed function such as "%f" or
	-- "%#SomeHighlightGroup#" no longer work with this method.
	return '%<%{luaeval("' .. fn .. '")}'
end

--- LSP loading status
function M.lsp_status()
	local messages = vim.lsp.util.get_progress_messages()
	local mode = vim.api.nvim_get_mode().mode

	-- If neovim is not in normal mode, or if there are no messages.
	if mode ~= "n" or vim.tbl_isempty(messages) then
		return ""
	end

	local percentage
	local result = {}

	for _, msg in pairs(messages) do
		if msg.message then
			table.insert(result, msg.title .. ": " .. msg.message)
		else
			table.insert(result, msg.title)
		end
		if msg.percentage then
			percentage = math.max(percentage or 0, msg.percentage)
		end
	end

	if percentage then
		return string.format("%03d: %s", percentage, table.concat(result, ", "))
	else
		return table.concat(result, ", ")
	end
end

--- Get first diagnostic message for the current line.
function M.diagnostic_message()
	local severities = { "Error", "Warning" }
	local diagnostics = vim.lsp.diagnostic.get_line_diagnostics()

	if not next(diagnostics) then
		return ""
	end

	if not severities[diagnostics[1].severity] then
		return " " .. diagnostics[1].message .. " "
	else
		return " " .. severities[diagnostics[1].severity] .. ": " .. diagnostics[1].message .. " "
	end
end

--- Get number of errors for the current buffer.
function M.diagnostic_error_status()
	local num_errors = #vim.diagnostic.get(0, { severity = vim.diagnostic.severity.ERROR })

	if num_errors > 0 then
		return "● " .. num_errors
	end
	return ""
end

--- Get number of warnings for the current buffer.
function M.diagnostic_warn_status()
	local num_warnings = #vim.diagnostic.get(0, { severity = vim.diagnostic.severity.WARN })

	if num_warnings > 0 then
		return "● " .. num_warnings
	end
	return ""
end

--- Configure statusline sections.
function M.statusline()
	local lsp_error_count = "%#DiagnosticError#" .. M.watch_fn("M.diagnostic_error_status()") .. "%*"
	local lsp_warning_count = "%#DiagnosticWarn#" .. M.watch_fn("M.diagnostic_warn_status()") .. "%*"

	local sections = {
		-- TODO: `%M` causes a layout shift between saved and unsaved buffer states
		-- "%f %M",
		"%f",
		-- TODO: Highlight groups can cause mismatching backgrounds
		-- against the statusline.
		lsp_error_count,
		lsp_warning_count,
		M.watch_fn("M.lsp_status()"),
		"%=",
		"%l:%c",
	}

	--- Combine all sections with padding between each section.
	--- TODO: Empty sections, e.g. when there are 0 errors, create an extra space.
	return " " .. table.concat(sections, " ") .. " "
end

--- Configure winbar sections
function M.winbar()
	local sections = {
		"%=",
		"%#PMenu#" .. M.watch_fn("M.diagnostic_message()") .. "%*",
	}

	--- Combine all sections with padding between each section
	--- TODO: Empty sections, e.g. when there are 0 errors, create an extra space
	return " " .. table.concat(sections, " ") .. " "
end

vim.diagnostic.config({ virtual_text = false })
vim.opt.signcolumn = "yes"
vim.opt.statusline = M.statusline()
vim.opt.winbar = M.winbar()