local lsp_installer = require("nvim-lsp-installer")

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

  -- Enable completion triggered by <c-x><c-o>
  buf_set_option('omnifunc', 'v:lua.vim.lsp.omnifunc')

  -- Mappings.
  local opts = { noremap=true, silent=true }

  -- See `:help vim.lsp.*` for documentation on any of the below functions
  buf_set_keymap('n', 'gD', '<cmd>lua vim.lsp.buf.declaration()<CR>', opts)
  buf_set_keymap('n', 'gd', '<cmd>lua vim.lsp.buf.definition()<CR>', opts)
  buf_set_keymap('n', 'K', '<cmd>lua vim.lsp.buf.hover()<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>rn', '<cmd>lua vim.lsp.buf.rename()<CR>', opts)
  -- buf_set_keymap('n', '<space>ca', '<cmd>lua vim.lsp.buf.code_action()<CR>', opts)
  -- buf_set_keymap('n', 'gr', '<cmd>lua vim.lsp.buf.references()<CR>', opts)
  -- buf_set_keymap('n', '<space>e', '<cmd>lua vim.diagnostic.open_float()<CR>', opts)
  -- buf_set_keymap('n', '[d', '<cmd>lua vim.diagnostic.goto_prev()<CR>', opts)
  -- buf_set_keymap('n', ']d', '<cmd>lua vim.diagnostic.goto_next()<CR>', opts)
  -- buf_set_keymap('n', '<space>q', '<cmd>lua vim.diagnostic.setloclist()<CR>', opts)
  -- buf_set_keymap('n', '<space>f', '<cmd>lua vim.lsp.buf.formatting()<CR>', opts)

  if client.resolved_capabilities.document_formatting then
    vim.cmd([[
    augroup LspFormatting
        autocmd! * <buffer>
        autocmd BufWritePre <buffer> lua vim.lsp.buf.formatting_sync()
    augroup END
    ]])
  end


    -- Setup nvim-cmp.
  local cmp = require'cmp'

  cmp.setup({
    snippet = {
      -- REQUIRED - you must specify a snippet engine
      expand = function(args)
        vim.fn["vsnip#anonymous"](args.body) -- For `vsnip` users.
        -- require('luasnip').lsp_expand(args.body) -- For `luasnip` users.
        -- require('snippy').expand_snippet(args.body) -- For `snippy` users.
        -- vim.fn["UltiSnips#Anon"](args.body) -- For `ultisnips` users.
      end,
    },
    mapping = {
      ['<C-b>'] = cmp.mapping(cmp.mapping.scroll_docs(-4), { 'i', 'c' }),
      ['<C-f>'] = cmp.mapping(cmp.mapping.scroll_docs(4), { 'i', 'c' }),
      ['<C-Space>'] = cmp.mapping(cmp.mapping.complete(), { 'i', 'c' }),
      ['<C-y>'] = cmp.config.disable, -- Specify `cmp.config.disable` if you want to remove the default `<C-y>` mapping.
      ['<C-e>'] = cmp.mapping({
        i = cmp.mapping.abort(),
        c = cmp.mapping.close(),
      }),
      ['<Tab>'] = cmp.mapping.confirm({ select = true }), -- Accept currently selected item. Set `select` to `false` to only confirm explicitly selected items.
    },
    sources = cmp.config.sources({
      { name = 'nvim_lsp' },
    }, {
      { name = 'buffer' },
    })
  })

  -- Use buffer source for `/` (if you enabled `native_menu`, this won't work anymore).
  cmp.setup.cmdline('/', {
    sources = {
      { name = 'buffer' }
    }
  })

  -- Use cmdline & path source for ':' (if you enabled `native_menu`, this won't work anymore).
  cmp.setup.cmdline(':', {
    sources = cmp.config.sources({
      { name = 'path' }
    }, {
      { name = 'cmdline' }
    })
  })
end

-- Register a handler that will be called for all installed servers.
-- Alternatively, you may also register handlers on specific server instances instead (see example below).
lsp_installer.on_server_ready(function(server)
  local opts = {
    on_attach = on_attach
  }

  -- (optional) Customize the options passed to the server
  -- if server.name == "tsserver" then
  --     opts.root_dir = function() ... end
  -- end

  -- This setup() function is exactly the same as lspconfig's setup function.
  -- Refer to https://github.com/neovim/nvim-lspconfig/blob/master/doc/server_configurations.md
  server:setup(opts)
end)