>From 8e73025f048bcd5c405a19fc090f7c58cb728c5a Mon Sep 17 00:00:00 2001
From: john muhl <jm@pub.pink>
Date: Sat, 6 Jan 2024 09:36:33 -0600
Subject: [PATCH] Support indented continuation lines in lua-ts-mode

* lisp/progmodes/lua-ts-mode.el (lua-ts--simple-indent-rules):
Add a rule to indent multi-line assignments and if statements.
(lua-ts-indent-continuation-lines): New user option.
* test/lisp/progmodes/lua-ts-mode-resources/indent.erts: Add
tests.  (bug#68279)
---
 lisp/progmodes/lua-ts-mode.el                 | 47 ++++++++++++
 .../lua-ts-mode-resources/indent.erts         | 76 +++++++++++++++++++
 2 files changed, 123 insertions(+)

diff --git a/lisp/progmodes/lua-ts-mode.el b/lisp/progmodes/lua-ts-mode.el
index e9ffb47cdb2..63a33a14ed7 100644
--- a/lisp/progmodes/lua-ts-mode.el
+++ b/lisp/progmodes/lua-ts-mode.el
@@ -150,6 +150,28 @@ lua-ts-align-params-and-props
   :group 'lua-ts
   :version "30.1")
 
+(defcustom lua-ts-indent-continuation-lines t
+  "Controls how multi-line if/else statements are aligned.
+
+If t, then continuation lines are indented by `lua-ts-indent-offset':
+
+  if a
+      and b then
+      print(1)
+  end
+
+If nil, then continuation lines are aligned with the beginning of
+the statement:
+
+  if a
+  and b then
+      print(1)
+  end"
+  :type 'boolean
+  :safe 'booleanp
+  :group 'lua-ts
+  :version "30.1")
+
 (defvar lua-ts--builtins
   '("assert" "bit32" "collectgarbage" "coroutine" "debug" "dofile"
     "error" "getmetatable" "io" "ipairs" "load" "loadfile"
@@ -362,6 +384,17 @@ lua-ts--simple-indent-rules
      ((or (match "end" "function_definition")
           (node-is "end"))
       standalone-parent 0)
+     ((n-p-gp "expression_list" "assignment_statement" "variable_declaration")
+      lua-ts--variable-declaration-continuation-anchor
+      lua-ts-indent-offset)
+     ((and (parent-is "binary_expression")
+           lua-ts--variable-declaration-continuation)
+      lua-ts--variable-declaration-continuation-anchor
+      lua-ts-indent-offset)
+     ((and (lambda (&rest _) lua-ts-indent-continuation-lines)
+           (parent-is "binary_expression"))
+      standalone-parent lua-ts-indent-offset)
+     ((parent-is "binary_expression") standalone-parent 0)
      ((or (parent-is "function_declaration")
           (parent-is "function_definition")
           (parent-is "do_statement")
@@ -448,6 +481,20 @@ lua-ts--nested-function-last-function-matcher
          (treesit-induce-sparse-tree parent #'lua-ts--function-definition-p)))
     (= 1 (length (cadr sparse-tree)))))
 
+(defun lua-ts--variable-declaration-continuation (node &rest _)
+  "Matches if NODE is part of a multi-line variable declaration."
+  (treesit-parent-until node
+                        (lambda (p)
+                          (equal "variable_declaration"
+                                 (treesit-node-type p)))))
+
+(defun lua-ts--variable-declaration-continuation-anchor (node &rest _)
+  "Return the start position of the variable declaration for NODE."
+  (save-excursion
+    (goto-char (treesit-node-start
+                (lua-ts--variable-declaration-continuation node)))
+    (line-beginning-position)))
+
 (defvar lua-ts--syntax-table
   (let ((table (make-syntax-table)))
     (modify-syntax-entry ?+  "."    table)
diff --git a/test/lisp/progmodes/lua-ts-mode-resources/indent.erts b/test/lisp/progmodes/lua-ts-mode-resources/indent.erts
index 5e6ce7935f8..2e7384cac88 100644
--- a/test/lisp/progmodes/lua-ts-mode-resources/indent.erts
+++ b/test/lisp/progmodes/lua-ts-mode-resources/indent.erts
@@ -529,6 +529,46 @@ local Other = {
 }
 =-=-=
 
+Name: Continuation Indent
+
+=-=
+local very_long_variable_name =
+"ok"..
+      "ok"
+local n = a +
+b *
+c /
+1
+local x = "A"..
+"B"
+.."C"
+if a
+     and b
+           and c then
+elseif a
+     or b
+    or c then
+end
+=-=
+local very_long_variable_name =
+  "ok"..
+  "ok"
+local n = a +
+  b *
+  c /
+  1
+local x = "A"..
+  "B"
+  .."C"
+if a
+  and b
+  and c then
+elseif a
+  or b
+  or c then
+end
+=-=-=
+
 Code:
   (lambda ()
     (setq indent-tabs-mode nil)
@@ -711,3 +751,39 @@ tbl = {1,2,
   3,4,
   5,6}
 =-=-=
+
+Code:
+  (lambda ()
+    (setq indent-tabs-mode nil)
+    (setq lua-ts-indent-continuation-lines nil)
+    (setq lua-ts-indent-offset 2)
+    (lua-ts-mode)
+    (indent-region (point-min) (point-max)))
+
+Name: Unaligned Continuation Indent
+
+=-=
+local n = a +
+  b *
+  c /
+  1
+if a
+     and b
+and c then
+elseif a
+       or b
+          or c then
+end
+=-=
+local n = a +
+  b *
+  c /
+  1
+if a
+and b
+and c then
+elseif a
+or b
+or c then
+end
+=-=-=
-- 
2.41.0