local config = function() 
	-- Add additional capabilities supported by nvim-cmp
	local capabilities = require("cmp_nvim_lsp").default_capabilities()
	local lspconfig = require('lspconfig')
	local on_attach = function(client, bufnr)
		local function buf_set_keymap(...) vim.api.nvim_buf_set_keymap(bufnr, ...) end
		local function buf_set_option(...) vim.api.nvim_buf_set_option(bufnr, ...) end
		-- Mappings.
		local opts = { noremap=true, silent=true }
		buf_set_keymap('n', 'K', '<cmd>lua vim.lsp.buf.hover()<CR>', opts)
		buf_set_keymap('n', 'gD', '<cmd>tab split | lua vim.lsp.buf.declaration()<CR>', opts)
		buf_set_keymap('n', 'gd', '<cmd>tab split | lua vim.lsp.buf.definition()<CR>', opts)
		buf_set_keymap('n', 'gr', '<cmd>lua vim.lsp.buf.references()<CR>', opts)
		buf_set_keymap('n', 'gR', '<cmd>lua vim.lsp.buf.rename()<CR>', opts)
--		buf_set_keymap('n', '[d', '<cmd>lua vim.lsp.diagnostic.goto_prev()<CR>', opts)
--		buf_set_keymap('n', ']d', '<cmd>lua vim.lsp.diagnostic.goto_next()<CR>', opts)
--		buf_set_keymap('n', 'gi', '<cmd>lua vim.lsp.buf.implementation()<CR>', opts)
--		buf_set_keymap('n', '<C-k>', '<cmd>lua vim.lsp.buf.signature_help()<CR>', opts)
--		buf_set_keymap('n', '<space>wa', '<cmd>lua vim.lsp.buf.add_workspace_folder()<CR>', opts)
--		buf_set_keymap('n', '<space>wr', '<cmd>lua vim.lsp.buf.remove_workspace_folder()<CR>', opts)
--		buf_set_keymap('n', '<space>wl', '<cmd>lua print(vim.inspect(vim.lsp.buf.list_workspace_folders()))<CR>', opts)
--		buf_set_keymap('n', '<space>D', '<cmd>lua vim.lsp.buf.type_definition()<CR>', opts)
--		buf_set_keymap('n', '<space>ca', '<cmd>lua vim.lsp.buf.code_action()<CR>', opts)
--		buf_set_keymap('n', '<space>e', '<cmd>lua vim.lsp.diagnostic.show_line_diagnostics()<CR>', opts)
--		buf_set_keymap('n', '<space>q', '<cmd>lua vim.lsp.diagnostic.set_loclist()<CR>', opts)
	end

	-- Enable some language servers with the additional
	-- completion capabilities offered by nvim-cmp
	local servers = { 'gopls', 'erlangls' }
	for _, lsp in ipairs(servers) do
		lspconfig[lsp].setup {
			on_attach = on_attach,
			capabilities = capabilities,
		}
	end

	local luasnip = require 'luasnip'

	local cmp = require 'cmp'

	cmp.setup {
		snippet = {
			expand = function(args)
				luasnip.lsp_expand(args.body)
			end,
		},
		mapping = cmp.mapping.preset.insert({
			['<C-u>'] = cmp.mapping.scroll_docs(-4), -- Up
			['<C-d>'] = cmp.mapping.scroll_docs(4), -- Down
			-- C-b (back) C-f (forward) for snippet placeholder navigation.
			['<C-Space>'] = cmp.mapping.complete(),
			['<CR>'] = cmp.mapping.confirm {
				behavior = cmp.ConfirmBehavior.Replace,
				select = true,
			},
			['<Tab>'] = cmp.mapping(function(fallback)
				if cmp.visible() then
					cmp.select_next_item()
				elseif luasnip.expand_or_jumpable() then
					luasnip.expand_or_jump()
				else
					fallback()
				end
			end, { 'i', 's' }),
			['<S-Tab>'] = cmp.mapping(function(fallback)
				if cmp.visible() then
					cmp.select_prev_item()
				elseif luasnip.jumpable(-1) then
					luasnip.jump(-1)
				else
					fallback()
				end
			end, { 'i', 's' }),
		}),
		sources = {
			{ name = 'nvim_lsp' },
			{ name = 'luasnip' },
		},
	}
end

return {
	"neovim/nvim-lspconfig",
	dependencies = {
		'hrsh7th/nvim-cmp',
		'hrsh7th/cmp-nvim-lsp',
		'saadparwaiz1/cmp_luasnip',
		'L3MON4D3/LuaSnip',
	},
	config = config
}