make the way messages are presented configurableshow-message

The two options are either using vis:message (the default) which will
keep all messages in the vis message buffer and include a header line to
distinguish the different messages.

The second option is using open and presenting messages in a separate
window supporting syntax highlighting.

3 files changed, 41 insertions, 28 deletions

diff --git a/README.md b/README.md
index 27905b3..0a9a370 100644
--- a/README.md
+++ b/README.md
@@ -138,6 +138,8 @@ Available options are:
 * `highlight_diagnostics = 'line'` - highlight the `range` or `line`number of available diagnostics
 * `workspace_edit_remember_cursor = true` - restore the primary cursor position after a workspaceEdit
 * `diagnostic_styles = { error = 'back:red', warning = 'back:yellow', information = 'back:yellow', hint = 'back:yellow', }` - styles used to highlight different diagnostics
+* `show_message = 'message'` - how to present information. `'message`: use `vis:message`; `'open'`: use a new window supporting syntax highlighting.
+* `message_level = 3` - the level of shown messages retrieved via `window/showMessage` notifications
 
 #### Configure your own Language Server
 
diff --git a/init.lua b/init.lua
index 8347899..eaadc1b 100644
--- a/init.lua
+++ b/init.lua
@@ -501,11 +501,21 @@ local function vis_apply_textEdits(win, file, textEdits)
   win:draw()
 end
 
-local function _show_message(msg)
-  vis:command("open")
+local function lspc_show_message(msg, hdr, syntax)
+  if lspc.show_message == 'message' then
+    vis:message((hdr or '') .. msg)
+
+  elseif lspc.show_message == 'open' then
+    vis:command('open')
+    if syntax then
+      vis:command('set syntax ' .. syntax)
+    end
 
-  vis.win.file:insert(0, msg)
-  vis.win.selection.pos = 0
+    vis.win.file:insert(0, msg)
+    vis.win.selection.pos = 0
+  else
+    lspc_err('invalid message configuration "' .. lspc.show_message .. '".')
+  end
 end
 
 -- apply a WorkspaceEdit received from the language server
@@ -534,7 +544,7 @@ local function vis_apply_workspaceEdit(_, _, workspaceEdit)
     end
   end
 
-  _show_message(summary)
+  lspc_show_message(summary)
   vis:redraw()
 
   -- get user confirmation
@@ -829,14 +839,6 @@ local function lspc_handle_completion_method_response(win, result, old_pos)
   lspc_err('Unsupported completion')
 end
 
-local function _show_markdown_message(msg)
-  vis:command("open")
-  vis:command("set syntax markdown")
-
-  vis.win.file:insert(0, msg)
-  vis.win.selection.pos = 0
-end
-
 local function lspc_handle_hover_method_response(win, result, old_pos)
   if not result or not result.contents then
     lspc_warn('no hover available')
@@ -845,27 +847,30 @@ local function lspc_handle_hover_method_response(win, result, old_pos)
 
   local sel = vis_pos_to_sel(win, old_pos)
 
+  local hover_header =
+      '--- hover: ' .. (win.file.path or '') .. ': ' .. sel.line .. ', ' .. sel.col .. ' ---\n'
+  local hover_msg = ''
+  -- The most common markup kind in LSP is markdown
+  local markup_kind = 'markdown'
+
   -- result is MarkedString[]
   if type(result.contents) == 'table' and #result.contents > 0 then
     lspc.log('hover returned list of length ' .. #result.contents)
 
-    local hover_header = '--- hover: ' .. (win.file.path or '') .. ': ' .. sel.line .. ', ' .. sel.col .. ' ---'
-    local hover_msg = ''
-
-    for i, v in ipairs(result.contents) do
+    for i, marked_string in ipairs(result.contents) do
       if i == 1 then
-        hover_msg = v.value or v
+        hover_msg = marked_string.value or marked_string
       else
-        hover_msg = hover_msg .. '\n---\n' .. (v.value or v)
+        hover_msg = hover_msg .. '\n---\n' .. (marked_string.value or marked_string)
       end
     end
-
-    _show_message(hover_header .. '\n' .. hover_msg)
-    -- result is either MarkedString or MarkupContent
-  else
-    _show_markdown_message(result.contents.value or result.contents)
+  else -- result is either MarkedString or MarkupContent
+    hover_msg = result.contents.value or result.contents
+    if result.contents.kind and result.contents.kind == 'plaintext' then
+      markup_kind = 'text'
+    end
   end
-
+  lspc_show_message(hover_msg, hover_header, markup_kind)
 end
 
 local function lspc_handle_signature_help_method_response(win, result, call_pos)
@@ -878,7 +883,7 @@ local function lspc_handle_signature_help_method_response(win, result, call_pos)
 
   local sel = vis_pos_to_sel(win, call_pos)
   local help_header = '--- signature help: ' .. (win.file.path or '') .. ': ' .. sel.line .. ', ' ..
-                          sel.col .. ' ---'
+                          sel.col .. ' ---\n'
 
   -- local help_msg = json.encode(result)
   local help_msg = ''
@@ -890,7 +895,9 @@ local function lspc_handle_signature_help_method_response(win, result, call_pos)
     end
     help_msg = help_msg .. '\n' .. sig_msg
   end
-  _show_message(help_header .. help_msg)
+  -- strip first new line from the message
+  help_msg = help_msg:sub(2)
+  lspc_show_message(help_msg, help_header)
 end
 
 local function lspc_handle_rename_method_response(win, result)
@@ -1398,7 +1405,7 @@ local function lspc_show_diagnostic(ls, win, line)
   end
 
   if diagnostics_msg ~= '' then
-    _show_message(diagnostics_msg)
+    lspc_show_message(diagnostics_msg)
   else
     lspc_warn('No diagnostics available for line: ' .. line)
   end
diff --git a/lspc.lua b/lspc.lua
index 1af21a5..d45811b 100644
--- a/lspc.lua
+++ b/lspc.lua
@@ -50,6 +50,10 @@ local lspc = {
   -- message level to show in the UI when receiving messages from the server
   -- Error = 1, Warning = 2, Info = 3, Log = 4
   message_level = 3,
+
+  -- How to present messages to the user.
+  -- 'message': use vis:message; 'open': use a new split window allowing for syntax highlighting
+  show_message = 'message',
 }
 
 --