local lspconfig_ok, lspconfig = pcall(require, "lspconfig")
if not lspconfig_ok then
        return
end

local language_servers = { 'gopls' }

-- Use an on_attach function to only map the following keys
-- after the language server attaches to the current buffer
local on_attach = function(client, bufnr)
        -- Enable completion triggered by <c-x><c-o>
        vim.api.nvim_buf_set_option(bufnr, 'omnifunc', 'v:lua.vim.lsp.omnifunc')

        -- Mappings.
        -- See `:help vim.lsp.*` for documentation on any of the below functions
        local bufopts = { noremap=true, silent=true, buffer=bufnr }
        vim.keymap.set('n', 'gD', vim.lsp.buf.declaration, bufopts)
        vim.keymap.set('n', 'gd', vim.lsp.buf.definition, bufopts)
        vim.keymap.set('n', 'od', vim.lsp.buf.hover, bufopts)
        vim.keymap.set('n', 'gi', vim.lsp.buf.implementation, bufopts)
        vim.keymap.set('n', '<C-k>', vim.lsp.buf.signature_help, bufopts)
        vim.keymap.set('n', '<space>wa', vim.lsp.buf.add_workspace_folder, bufopts)
        vim.keymap.set('n', '<space>wr', vim.lsp.buf.remove_workspace_folder, bufopts)
        vim.keymap.set('n', '<space>wl', function()
                print(vim.inspect(vim.lsp.buf.list_workspace_folders()))
        end, bufopts)
        vim.keymap.set('n', '<space>D', vim.lsp.buf.type_definition, bufopts)
        vim.keymap.set('n', '<leader>rn', vim.lsp.buf.rename, bufopts)
        vim.keymap.set('n', '<leader>ca', vim.lsp.buf.code_action, bufopts)
        vim.keymap.set('n', 'gr', vim.lsp.buf.references, bufopts)
        vim.keymap.set('n', 'fd', vim.lsp.buf.formatting, bufopts)
end

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


local cmp_status_ok, cmp = pcall(require, "cmp")
if cmp_status_ok then
        local cmp_nvim_lsp_status_ok, cmp_nvim_lsp = pcall(require, "cmp_nvim_lsp")
        if cmp_nvim_lsp_status_ok then
                capabilities = cmp_nvim_lsp.update_capabilities(capabilities)
        end
end

for _, langsvr in ipairs(language_servers) do
        lspconfig[langsvr].setup({
                on_attach = on_attach,
                capabilities = capabilities,
        })
end


if not cmp_status_ok then
        return
end

cmp.setup {
        snippet = {
                expand = function(args)
                        local luasnip_status_ok, luasnip = pcall(require, "luasnip")
                        if luasnip_status_ok then
                                luasnip.lsp_expand(args.body)
                        end
                end,
        },
        mapping = cmp.mapping.preset.insert({
                ['<C-d>'] = cmp.mapping.scroll_docs(-4),
                ['<C-f>'] = cmp.mapping.scroll_docs(4),
                ['<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' },
                { name = 'buffer' },
                { name = 'path' },
        },
}