Port coc.nvim mappings to native LSP

lua/plugins/completions.lua

@@ -4,7 +4,6 @@ return {
     'williamboman/mason.nvim',
     'williamboman/mason-lspconfig.nvim',
 
-    'neovim/nvim-lspconfig',
     'hrsh7th/cmp-nvim-lsp',
     'hrsh7th/cmp-buffer',
     'hrsh7th/cmp-path',
@@ -42,5 +41,52 @@ return {
         -- TODO: snippets
       },
     })
-  end,
+
+    -- Disable displaying diagnostics as virtual text
+    vim.diagnostic.config({
+      virtual_text = false,
+    })
+
+    -- Diagnostic mappings
+    -- TODO: trouble.nvim mappings instead? https://youtu.be/MuUrCcvE-Yw?t=631
+    vim.keymap.set('n', '<C-n>', vim.diagnostic.goto_next, { noremap = true })
+    vim.keymap.set('n', '<C-p>', vim.diagnostic.goto_prev, { noremap = true })
+    vim.keymap.set('n', '<leader>sd', vim.diagnostic.open_float, { noremap = true })
+
+    -- Mappings to create once a language server attaches to a buffer
+    local augroup = vim.api.nvim_create_augroup('lsp', { clear = true })
+    vim.api.nvim_create_autocmd('LspAttach', {
+      pattern = '*',
+      group = augroup,
+      callback = function(ev)
+        local opts = { noremap = true, buffer = ev.buf }
+
+        -- FIXME: Should I drop this? It's only for expanding snippets because
+        -- coc.nvim was being weird about it
+        -- inoremap <silent><expr> <TAB> coc#pum#visible() ? coc#pum#confirm() : "\<TAB>"
+
+        vim.keymap.set('n', '<leader>fi', function()
+          -- FIXME: This doesn't stop the prompt to select the code action when
+          -- there is only one. Also not sure if its actually filtering
+          vim.lsp.buf.code_action({ context = { only = { 'quickfix' } } })
+        end, opts)
+
+        vim.keymap.set('n', 'gd', vim.lsp.buf.definition, opts)
+
+        -- nnoremap <silent> <leader>gt <Plug>(coc-type-definition)
+
+        vim.keymap.set('n', '<leader>gr', vim.lsp.buf.references, opts)
+
+        -- nnoremap <silent> <leader>gu <Plug>(coc-references-used)
+
+        -- Refactoring mappings
+        vim.keymap.set('n', '<leader>rn', vim.lsp.buf.rename, opts)
+        -- TODO: vim.lsp.buf.format
+
+        -- Help mappings
+        vim.keymap.set('n', 'K', vim.lsp.buf.hover, opts)
+        vim.keymap.set('i', '<C-h>', vim.lsp.buf.signature_help, opts)
+      end
+    })
+  end
 }