kickstart.nvim/lua/kickstart/autoformat.lua

-- TODO: Have to decide how we would make this easy
-- to configure and understand from init.lua...
--
-- I was hoping all of them could go in plugins, but it's a little weird
-- to do that I guess?

-- Toggle this on/off for autoformatting
local autoformatting = false
if not autoformatting then
  return
end

-- Switch for controlling whether you want autoformatting.
--  Use :KickstartFormatToggle to toggle autoformatting on or off
local format_is_enabled = true
vim.api.nvim_create_user_command('KickstartFormatToggle', function()
  format_is_enabled = not format_is_enabled
  print('Setting autoformatting to: ' .. tostring(format_is_enabled))
end, {})

-- Create an augroup that is used for managing our formatting autocmds.
--      We need one augroup per client to make sure that multiple clients
--      can attach to the same buffer without interfering with each other.
local _augroups = {}
local get_augroup = function(client)
  if not _augroups[client.id] then
    local group_name = 'kickstart-lsp-format-' .. client.name
    local id = vim.api.nvim_create_augroup(group_name, { clear = true })
    _augroups[client.id] = id
  end

  return _augroups[client.id]
end

vim.api.nvim_create_autocmd('LspAttach', {
  group = vim.api.nvim_create_augroup('kickstart-lsp-attach-format', { clear = true }),

  -- This is where we attach the autoformatting for reasonable clients
  callback = function(args)
    local client_id = args.data.client_id
    local client = vim.lsp.get_client_by_id(client_id)
    local bufnr = args.buf

    -- Only attach to clients that support document formatting
    if not client.server_capabilities.documentFormattingProvider then
      return
    end

    -- Tsserver usually works poorly. Sorry you work with bad languages
    -- You can remove this line if you know what you're doing :)
    if client.name == 'tsserver' then
      return
    end

    vim.api.nvim_create_autocmd('BufWritePre', {
      group = get_augroup(client),
      buffer = bufnr,
      callback = function()
        if not format_is_enabled then
          return
        end

        vim.lsp.buf.format { async = false }
      end,
    })
  end,
})