From d5f0db98470c3307f51cd0168da5f1181aaa3fbb Mon Sep 17 00:00:00 2001
From: Felipe Pena <felipensp@gmail.com>
Date: Tue, 24 Sep 2024 17:59:08 -0300
Subject: [PATCH] tmpl: fix extra newline added on @if-@else-@end block
 (#22289)

---
 vlib/v/parser/tmpl.v             | 18 +++++-------------
 vlib/v/tests/tmpl/if_cond.txt    | 13 +++++++++++++
 vlib/v/tests/tmpl_if_cond_test.v | 24 ++++++++++++++++++++++++
 vlib/v/tests/tmpl_test.v         |  4 ----
 4 files changed, 42 insertions(+), 17 deletions(-)
 create mode 100644 vlib/v/tests/tmpl/if_cond.txt
 create mode 100644 vlib/v/tests/tmpl_if_cond_test.v

diff --git a/vlib/v/parser/tmpl.v b/vlib/v/parser/tmpl.v
index ee55801b5c9ef7..4fa4ce00ac359b 100644
--- a/vlib/v/parser/tmpl.v
+++ b/vlib/v/parser/tmpl.v
@@ -327,37 +327,28 @@ fn vweb_tmpl_${fn_name}() string {
 			source.writeln(tmpl_str_end)
 			pos := line.index('@if') or { continue }
 			source.writeln('if ' + line[pos + 4..] + '{')
-			source.writeln(tmpl_str_start)
+			source.write_string(tmpl_str_start)
 			continue
 		}
 		if line.contains('@end') {
-			// Remove new line byte
-			source.go_back(1)
 			source.writeln(tmpl_str_end)
 			source.writeln('}')
-			source.writeln(tmpl_str_start)
+			source.write_string(tmpl_str_start)
 			continue
 		}
 		if line.contains('@else') {
-			// Remove new line byte
-			source.go_back(1)
 			source.writeln(tmpl_str_end)
 			pos := line.index('@else') or { continue }
 			source.writeln('}' + line[pos + 1..] + '{')
 			// source.writeln(' } else { ')
-			source.writeln(tmpl_str_start)
+			source.write_string(tmpl_str_start)
 			continue
 		}
 		if line.contains('@for') {
-			// Remove an extra unnecessary newline added before in state == .simple
-			// Can break stuff like Markdown
-			if source.len > 1 {
-				source.go_back(1)
-			}
 			source.writeln(tmpl_str_end)
 			pos := line.index('@for') or { continue }
 			source.writeln('for ' + line[pos + 4..] + '{')
-			source.writeln(tmpl_str_start)
+			source.write_string(tmpl_str_start)
 			continue
 		}
 		if state == .simple {
@@ -365,6 +356,7 @@ fn vweb_tmpl_${fn_name}() string {
 			source.writeln(insert_template_code(fn_name, tmpl_str_start, line))
 			continue
 		}
+		// in_write = false
 		// The .simple mode ends here. The rest handles .html/.css/.js state transitions.
 
 		if state != .simple {
diff --git a/vlib/v/tests/tmpl/if_cond.txt b/vlib/v/tests/tmpl/if_cond.txt
new file mode 100644
index 00000000000000..9aa1ef666fc666
--- /dev/null
+++ b/vlib/v/tests/tmpl/if_cond.txt
@@ -0,0 +1,13 @@
+aaa
+@if cond
+bbb
+@else
+zzz
+@end
+ccc
+
+aaa
+@if cond
+bbb
+@end
+ccc
\ No newline at end of file
diff --git a/vlib/v/tests/tmpl_if_cond_test.v b/vlib/v/tests/tmpl_if_cond_test.v
new file mode 100644
index 00000000000000..ea92e6ea3ca8fa
--- /dev/null
+++ b/vlib/v/tests/tmpl_if_cond_test.v
@@ -0,0 +1,24 @@
+fn test_tmpl_if_cond() {
+	cond := true
+	processed := $tmpl('tmpl/if_cond.txt')
+	assert processed == 'aaa
+bbb
+ccc
+
+aaa
+bbb
+ccc
+'
+}
+
+fn test_tmpl_if_else_cond() {
+	cond := false
+	processed := $tmpl('tmpl/if_cond.txt')
+	assert processed == 'aaa
+zzz
+ccc
+
+aaa
+ccc
+'
+}
diff --git a/vlib/v/tests/tmpl_test.v b/vlib/v/tests/tmpl_test.v
index a80f6cdecd4b9b..09c6f204abb64b 100644
--- a/vlib/v/tests/tmpl_test.v
+++ b/vlib/v/tests/tmpl_test.v
@@ -46,10 +46,8 @@ numbers: [1, 2, 3]
 vlang/ui, downloaded 3201 times.
 vlang/vtl, downloaded 123 times.
 
-
 this is not ignored
 
-
 so, it's basically true"
 
 	assert one().trim_space() == expected
@@ -86,10 +84,8 @@ numbers: [1, 2, 3]
 vlang/ui, downloaded 3201 times.
 vlang/vtl, downloaded 123 times.
 
-
 this is not ignored
 
-
 so, it's basically true"
 }