LSP: Add textDocument/codeAction support (#11607)

* Add textDocument/codeAction

* Add callback for workspace/executeCommand
* Escape newlines in codeAction titles
* Return empty list in get_line_diagnostics if no buffer diagnostics
* Add stub documentation
* Validate context parameter in code_action
* Add support for edit in CodeAction responses
* Group diagnostics by line in vim.lsp.util.get_line_diagnostics()
* Advertise code action literal support

5 files changed, 97 insertions, 8 deletions

diff --git a/runtime/doc/lsp.txt b/runtime/doc/lsp.txt
index 249136f32f..9460e600e3 100644
--- a/runtime/doc/lsp.txt
+++ b/runtime/doc/lsp.txt
@@ -731,6 +731,9 @@ transform_schema_to_table()
 ==============================================================================
 Lua module: vim.lsp.buf                                              *lsp-buf*
 
+code_action({context})                             *vim.lsp.buf.code_action()*
+                TODO: Documentation
+
 completion({context})                               *vim.lsp.buf.completion()*
                 TODO: Documentation
 
diff --git a/runtime/lua/vim/lsp/buf.lua b/runtime/lua/vim/lsp/buf.lua
index 0b45951a56..7a819f3c3d 100644
--- a/runtime/lua/vim/lsp/buf.lua
+++ b/runtime/lua/vim/lsp/buf.lua
@@ -161,5 +161,21 @@ function M.clear_references()
   util.buf_clear_references()
 end
 
+function M.code_action(context)
+  validate { context = { context, 't', true } }
+  context = context or { diagnostics = util.get_line_diagnostics() }
+  local params = util.make_range_params()
+  params.context = context
+  request('textDocument/codeAction', params)
+end
+
+function M.execute_command(command)
+  validate {
+    command = { command.command, 's' },
+    arguments = { command.arguments, 't', true }
+  }
+  request('workspace/executeCommand', command)
+end
+
 return M
 -- vim:sw=2 ts=2 et
diff --git a/runtime/lua/vim/lsp/callbacks.lua b/runtime/lua/vim/lsp/callbacks.lua
index 09ca4b61e4..17f88a5181 100644
--- a/runtime/lua/vim/lsp/callbacks.lua
+++ b/runtime/lua/vim/lsp/callbacks.lua
@@ -3,6 +3,7 @@ local protocol = require 'vim.lsp.protocol'
 local util = require 'vim.lsp.util'
 local vim = vim
 local api = vim.api
+local buf = require 'vim.lsp.buf'
 
 local M = {}
 
@@ -11,6 +12,45 @@ local function err_message(...)
   api.nvim_command("redraw")
 end
 
+M['workspace/executeCommand'] = function(err, _)
+  if err then
+    error("Could not execute code action: "..err.message)
+  end
+end
+
+M['textDocument/codeAction'] = function(_, _, actions)
+  if vim.tbl_isempty(actions) then
+    print("No code actions available")
+    return
+  end
+
+  local option_strings = {"Code Actions:"}
+  for i, action in ipairs(actions) do
+    local title = action.title:gsub('\r\n', '\\r\\n')
+    title = title:gsub('\n', '\\n')
+    table.insert(option_strings, string.format("%d. %s", i, title))
+  end
+
+  local choice = vim.fn.inputlist(option_strings)
+  if choice < 1 or choice > #actions then
+    return
+  end
+  local action_chosen = actions[choice]
+  -- textDocument/codeAction can return either Command[] or CodeAction[].
+  -- If it is a CodeAction, it can have either an edit, a command or both.
+  -- Edits should be executed first
+  if action_chosen.edit or type(action_chosen.command) == "table" then
+    if action_chosen.edit then
+      util.apply_workspace_edit(action_chosen.edit)
+    end
+    if type(action_chosen.command) == "table" then
+      buf.execute_command(action_chosen.command)
+    end
+  else
+    buf.execute_command(action_chosen)
+  end
+end
+
 M['workspace/applyEdit'] = function(_, _, workspace_edit)
   if not workspace_edit then return end
   -- TODO(ashkan) Do something more with label?
diff --git a/runtime/lua/vim/lsp/protocol.lua b/runtime/lua/vim/lsp/protocol.lua
index ee6e29bac0..877d11411b 100644
--- a/runtime/lua/vim/lsp/protocol.lua
+++ b/runtime/lua/vim/lsp/protocol.lua
@@ -620,6 +620,15 @@ function protocol.make_client_capabilities()
         -- Send textDocument/didSave after saving (BufWritePost)
         didSave = true;
       };
+      codeAction = {
+        dynamicRegistration = false;
+
+        codeActionLiteralSupport = {
+          codeActionKind = {
+            valueSet = {};
+          };
+        };
+      };
       completion = {
         dynamicRegistration = false;
         completionItem = {
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 099a77099b..c92a317d0c 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -720,19 +720,28 @@ do
     return severity_highlights[severity]
   end
 
-  function M.show_line_diagnostics()
+  function M.get_line_diagnostics()
     local bufnr = api.nvim_get_current_buf()
-    local line = api.nvim_win_get_cursor(0)[1] - 1
+    local linenr = api.nvim_win_get_cursor(0)[1] - 1
+
+    local buffer_diagnostics = M.diagnostics_by_buf[bufnr]
+
+    if not buffer_diagnostics then
+      return {}
+    end
+
+    local diagnostics_by_line = M.diagnostics_group_by_line(buffer_diagnostics)
+    return diagnostics_by_line[linenr] or {}
+  end
+
+  function M.show_line_diagnostics()
     -- local marks = api.nvim_buf_get_extmarks(bufnr, diagnostic_ns, {line, 0}, {line, -1}, {})
     -- if #marks == 0 then
     --   return
     -- end
     local lines = {"Diagnostics:"}
     local highlights = {{0, "Bold"}}
-
-    local buffer_diagnostics = M.diagnostics_by_buf[bufnr]
-    if not buffer_diagnostics then return end
-    local line_diagnostics = M.diagnostics_group_by_line(buffer_diagnostics)[line]
+    local line_diagnostics = M.get_line_diagnostics()
     if not line_diagnostics then return end
 
     for i, diagnostic in ipairs(line_diagnostics) do
@@ -1044,14 +1053,26 @@ function M.try_trim_markdown_code_blocks(lines)
 end
 
 local str_utfindex = vim.str_utfindex
-function M.make_position_params()
+local function make_position_param()
   local row, col = unpack(api.nvim_win_get_cursor(0))
   row = row - 1
   local line = api.nvim_buf_get_lines(0, row, row+1, true)[1]
   col = str_utfindex(line, col)
+  return { line = row; character = col; }
+end
+
+function M.make_position_params()
   return {
     textDocument = M.make_text_document_params();
-    position = { line = row; character = col; }
+    position = make_position_param()
+  }
+end
+
+function M.make_range_params()
+  local position = make_position_param()
+  return {
+    textDocument = { uri = vim.uri_from_bufnr(0) },
+    range = { start = position; ["end"] = position; }
   }
 end