From b3c0afef02ee13c7f291fd26a5d64b4aee059906 Mon Sep 17 00:00:00 2001 From: Samantaz Fox Date: Wed, 5 Apr 2023 23:43:41 +0200 Subject: [PATCH] Videos: fix description text offset when emojis are present --- src/invidious/videos/description.cr | 71 +++++++++++++++++++---------- 1 file changed, 47 insertions(+), 24 deletions(-) diff --git a/src/invidious/videos/description.cr b/src/invidious/videos/description.cr index b1d851d3..2017955d 100644 --- a/src/invidious/videos/description.cr +++ b/src/invidious/videos/description.cr @@ -46,37 +46,60 @@ def parse_command(command : JSON::Any?, string : String) : String? return "(unknown YouTube desc command)" end -def parse_description(desc : JSON::Any?) : String? - if desc.nil? - return "" +private def copy_string(str : String::Builder, iter : Iterator, count : Int) : Int + copied = 0 + while copied < count + cp = iter.next + break if cp.is_a?(Iterator::Stop) + + str << cp.chr + + # A codepoint from the SMP counts twice + copied += 1 if cp > 0xFFFF + copied += 1 end + return copied +end + +def parse_description(desc : JSON::Any?) : String? + return "" if desc.nil? + content = desc["content"].as_s - if content.empty? - return "" - end + return "" if content.empty? - if commands = desc["commandRuns"]?.try &.as_a - description = String.build do |str| - index = 0 - commands.each do |command| - start_index = command["startIndex"].as_i - length = command["length"].as_i + commands = desc["commandRuns"]?.try &.as_a + return content if commands.nil? - if start_index > 0 && start_index - index > 0 - str << content[index...start_index] - index = start_index - end + # Not everything is stored in UTF-8 on youtube's side. The SMP codepoints + # (0x10000 and above) are encoded as UTF-16 surrogate pairs, which are + # automatically decoded by the JSON parser. It means that we need to count + # copied byte in a special manner, preventing the use of regular string copy. + iter = content.each_codepoint - str << parse_command(command, content[start_index, length]) - index += length - end - if index < content.size - str << content[index..content.size] + index = 0 + + return String.build do |str| + commands.each do |command| + cmd_start = command["startIndex"].as_i + cmd_length = command["length"].as_i + + # Copy the text chunk between this command and the previous if needed. + length = cmd_start - index + index += copy_string(str, iter, length) + + # We need to copy the command's text using the iterator + # and the special function defined above. + cmd_content = String.build(cmd_length) do |str2| + copy_string(str2, iter, cmd_length) end + + str << parse_command(command, cmd_content) + index += cmd_length end - return description - end - return content + # Copy the end of the string (past the last command). + remaining_length = content.size - index + copy_string(str, iter, remaining_length) if remaining_length > 0 + end end