From e83950a7149f364b653395cdd4d9446875a7f469 Mon Sep 17 00:00:00 2001
From: Michiel van den Heuvel <michielvdnheuvel@gmail.com>
Date: Fri, 16 Jun 2023 18:23:58 +0200
Subject: Add textDocument/formatting implementation

This is tested with the Rust language server and the Lua one. Moving
the cursor to the correct position afterwards works with Rust, but not
with Lua. Being smarter about the ranges is probably necessary for Lua
and might make other ones more robust.
---
 README.md |  2 ++
 init.lua  | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/README.md b/README.md
index 2b98a91..b9d6cae 100644
--- a/README.md
+++ b/README.md
@@ -13,6 +13,7 @@ vis-lspc currently supports:
 * `textDocument/implementation`
 * `textDocument/hover`
 * `textDocument/rename`
+* `textDocument/formatting`
 * `[Diagnostics]`
 
 ## Whats not working
@@ -109,6 +110,7 @@ vis-lspc is in a early state, but if you are brave there are some default key bi
 
 	# workspace edits
 	lspc-rename <new name> - rename the identifier under the cursor to <new name>
+	lspc-format - format the file in the current window
 
 	# development support
 	lspc-hover - hover over the current line
diff --git a/init.lua b/init.lua
index 9f3e7d4..48f7b97 100644
--- a/init.lua
+++ b/init.lua
@@ -365,6 +365,27 @@ local function vis_apply_textEdit(win, file, textEdit)
   win:draw()
 end
 
+-- apply a list of textEdits received from the language server
+local function vis_apply_textEdits(win, file, textEdits)
+  assert(win.file == file)
+
+  local edits = {}
+  for _, textEdit in ipairs(textEdits) do
+    local range = lsp_range_to_vis_range(win, textEdit.range)
+    table.insert(edits, {
+      mark = file:mark_set(range.start),
+      len = range.finish - range.start,
+      newText = textEdit.newText,
+    })
+  end
+  for _, edit in ipairs(edits) do
+    local pos = file:mark_get(edit.mark)
+    file:delete(pos, edit.len)
+    file:insert(pos, edit.newText)
+  end
+  win:draw()
+end
+
 -- concatenate all numeric values in choices and pass it on stdin to lspc.menu_cmd
 local function lspc_select(choices)
   local menu_input = ''
@@ -782,6 +803,10 @@ local function lspc_handle_rename_method_response(win, result)
   vis_apply_workspaceEdit(win, win.file, result)
 end
 
+local function lspc_handle_formatting_method_response(win, result)
+  vis_apply_textEdits(win, win.file, result)
+end
+
 local function lspc_handle_initialize_response(ls, result)
   ls.initialized = true
   ls.capabilities = result.capabilities
@@ -841,6 +866,9 @@ local function ls_handle_method_response(ls, method_response, req)
   elseif method == 'textDocument/rename' then
     lspc_handle_rename_method_response(win, result)
 
+  elseif method == 'textDocument/formatting' then
+    lspc_handle_formatting_method_response(win, result)
+
   elseif method == 'shutdown' then
     ls_send_notification(ls, 'exit')
     ls.fd:close()
@@ -1298,6 +1326,31 @@ vis:command_register('lspc-rename', function(argv, _, win)
   ls_call_text_document_method(ls, 'rename', params, win)
 end)
 
+vis:command_register('lspc-format', function(_, _, win)
+  local ls, err = lspc_get_usable_ls(win.syntax)
+  if err then
+    lspc_err(err)
+    return
+  end
+
+  -- check if the language server has a provider for this method
+  if not ls.capabilities['documentFormattingProvider'] then
+    lspc_err('language server ' .. ls.name .. ' does not provide formatting')
+    return
+  end
+
+  if not ls.open_files[win.file.path] then
+    lspc_open(ls, win, win.file)
+  end
+
+  local params = {
+    textDocument = {uri = path_to_uri(win.file.path)},
+    options = {tabSize = 2, insertSpaces = true},
+  }
+
+  ls_call_text_document_method(ls, 'formatting', params, win)
+end)
+
 vis:command_register('lspc-completion', function(_, _, win)
   local ls, err = lspc_get_usable_ls(win.syntax)
   if err then
-- 
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