Refactor neovim config (#2)

Changes include:

- [x] Use init.lua instead of init.vim
   - Some keybindings are still to be converted
- [x] Use packer as a package manager instead of vim-plug
- [ ] Use built-in lsp instead of coc.nvim
   - [x] Set up language servers
   - [x] Completion
   - [x] Formatting (previously coc-prettier, now neoformat)
   - [ ] Snippets
- [ ] Replace fzf with telescope.nvim
- [x] Implement treesitter syntax highlighting
   - More info: https://github.com/nvim-treesitter/nvim-treesitter

Note that this requires neovim nightly until 0.5 is released

Reviewed-on: #2
Co-authored-by: Marko Korhonen <marko@korhonen.cc>
Co-committed-by: Marko Korhonen <marko@korhonen.cc>

home/.config/nvim/lua/pluginconf/lsp.lua

@@ -0,0 +1,143 @@
+-- List of servers to install
+local required_servers = {
+    "css", "html", "java", "json", "lua", "rust", "yaml", "dockerfile", "latex",
+    "bash", "typescript", "php"
+}
+
+-- keymaps
+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
+
+    buf_set_option('omnifunc', 'v:lua.vim.lsp.omnifunc')
+
+    -- Mappings.
+    local opts = {noremap = true, silent = true}
+    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', 'gr', '<cmd>lua vim.lsp.buf.references()<CR>', opts)
+    buf_set_keymap('n', '<space>e',
+                   '<cmd>lua vim.lsp.diagnostic.show_line_diagnostics()<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', '<space>q',
+                   '<cmd>lua vim.lsp.diagnostic.set_loclist()<CR>', opts)
+
+    -- Set some keybinds conditional on server capabilities
+    if client.resolved_capabilities.document_formatting then
+        buf_set_keymap("n", "<space>f", "<cmd>lua vim.lsp.buf.formatting()<CR>",
+                       opts)
+    elseif client.resolved_capabilities.document_range_formatting then
+        buf_set_keymap("n", "<space>f",
+                       "<cmd>lua vim.lsp.buf.range_formatting()<CR>", opts)
+    end
+
+    -- Set autocommands conditional on server_capabilities
+    if client.resolved_capabilities.document_highlight then
+        vim.api.nvim_exec([[
+    augroup lsp_document_highlight
+    autocmd! * <buffer>
+    autocmd CursorHold <buffer> lua vim.lsp.buf.document_highlight()
+    autocmd CursorMoved <buffer> lua vim.lsp.buf.clear_references()
+    augroup END
+    ]], false)
+    end
+end
+
+-- Configure lua language server for neovim development
+local lua_settings = {
+    Lua = {
+        runtime = {
+            -- LuaJIT in the case of Neovim
+            version = 'LuaJIT',
+            path = vim.split(package.path, ';')
+        },
+        diagnostics = {
+            -- Get the language server to recognize the `vim` global
+            globals = {'vim'}
+        },
+        workspace = {
+            -- Make the server aware of Neovim runtime files
+            library = {
+                [vim.fn.expand('$VIMRUNTIME/lua')] = true,
+                [vim.fn.expand('$VIMRUNTIME/lua/vim/lsp')] = true
+            }
+        }
+    }
+}
+
+-- config that activates keymaps and enables snippet support
+local function make_config()
+    local capabilities = vim.lsp.protocol.make_client_capabilities()
+    capabilities.textDocument.completion.completionItem.snippetSupport = true
+    return {
+        -- enable snippet support
+        capabilities = capabilities,
+        -- map buffer local keybindings when the language server attaches
+        on_attach = on_attach
+    }
+end
+
+-- lsp-install
+local function setup_servers()
+    require'lspinstall'.setup()
+
+    -- get all installed servers
+    local servers = require'lspinstall'.installed_servers()
+
+    -- install server if not already installed but required
+    -- for _, server in pairs(required_servers) do
+    --    if not vim.tbl_contains(servers) then
+    --        require'lspinstall'.install_server(server)
+    --    end
+    -- end
+
+    -- Refresh servers list in case of newly installed servers
+    servers = require'lspinstall'.installed_servers()
+
+    for _, server in pairs(servers) do
+        local config = make_config()
+
+        -- language specific config
+        if server == "lua" then config.settings = lua_settings end
+        require'lspconfig'[server].setup(config)
+
+        -- Java LSP client is started by the plugin nvim-jdtls
+        if server == "java" then return end
+
+    end
+end
+
+setup_servers()
+
+require('jdtls').start_or_attach({
+    cmd = {'java-lsp.sh'},
+    root_dir = require('jdtls.setup').find_root({'gradle.build', 'pom.xml'})
+})
+
+-- Automatically reload after `:LspInstall <server>` so we don't have to restart neovim
+require'lspinstall'.post_install_hook = function()
+    setup_servers() -- reload installed servers
+    vim.cmd("bufdo e") -- this triggers the FileType autocmd that starts the server
+end