From ef31d8f48fa1b7ff5bd4cd57e812fd9c91fd1bd9 Mon Sep 17 00:00:00 2001
From: HydroH <ixlesis@gmail.com>
Date: Tue, 26 Mar 2024 06:20:15 +0800
Subject: [PATCH] autodoc: better indentation handling when rendering source
 code (#19422)

Closes #19293
---
 lib/docs/wasm/main.zig | 41 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 39 insertions(+), 2 deletions(-)

diff --git a/lib/docs/wasm/main.zig b/lib/docs/wasm/main.zig
index 496fd618d5..d78f00a004 100644
--- a/lib/docs/wasm/main.zig
+++ b/lib/docs/wasm/main.zig
@@ -938,6 +938,17 @@ fn file_source_html(
 
     var cursor: usize = token_starts[start_token];
 
+    var indent: usize = 0;
+    if (std.mem.lastIndexOf(u8, ast.source[0..cursor], "\n")) |newline_index| {
+        for (ast.source[newline_index + 1 .. cursor]) |c| {
+            if (c == ' ') {
+                indent += 1;
+            } else {
+                break;
+            }
+        }
+    }
+
     for (
         token_tags[start_token..end_token],
         token_starts[start_token..end_token],
@@ -947,7 +958,7 @@ fn file_source_html(
         if (std.mem.trim(u8, between, " \t\r\n").len > 0) {
             if (!options.skip_comments) {
                 try out.appendSlice(gpa, "<span class=\"tok-comment\">");
-                try appendEscaped(out, between);
+                try appendUnindented(out, between, indent);
                 try out.appendSlice(gpa, "</span>");
             }
         } else if (between.len > 0) {
@@ -955,7 +966,7 @@ fn file_source_html(
                 if (out.items.len > 0 and out.items[out.items.len - 1] != ' ')
                     try out.append(gpa, ' ');
             } else {
-                try out.appendSlice(gpa, between);
+                try appendUnindented(out, between, indent);
             }
         }
         if (tag == .eof) break;
@@ -1188,6 +1199,32 @@ fn file_source_html(
     }
 }
 
+fn unindent(s: []const u8, indent: usize) []const u8 {
+    var indent_idx: usize = 0;
+    for (s) |c| {
+        if (c == ' ' and indent_idx < indent) {
+            indent_idx += 1;
+        } else {
+            break;
+        }
+    }
+    return s[indent_idx..];
+}
+
+fn appendUnindented(out: *std.ArrayListUnmanaged(u8), s: []const u8, indent: usize) !void {
+    var it = std.mem.split(u8, s, "\n");
+    var is_first_line = true;
+    while (it.next()) |line| {
+        if (is_first_line) {
+            try appendEscaped(out, line);
+            is_first_line = false;
+        } else {
+            try out.appendSlice(gpa, "\n");
+            try appendEscaped(out, unindent(line, indent));
+        }
+    }
+}
+
 fn resolve_ident_link(
     file_index: Walk.File.Index,
     out: *std.ArrayListUnmanaged(u8),