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#include "htmlbuilder.h"
#include <QRegularExpression>
namespace {
const char *kStyle = R"CSS(
body { font-family: sans-serif; font-size: 10pt; margin: 12px; }
pre.plain { white-space: pre-wrap; word-wrap: break-word;
font-family: monospace; margin: 0; }
span.quote { color: #4a6f8a; }
.message { border-top: 1px solid #bbb; padding: 10px 0; }
.message:first-child { border-top: none; }
.msg-header { font-size: 9pt; color: #555; margin-bottom: 8px; }
.msg-header .who { font-weight: bold; color: #000; }
.stub { font-size: 9pt; color: #666; padding: 4px 0;
border-top: 1px solid #ddd; }
)CSS";
} // namespace
QString HtmlBuilder::renderPlain(const QString &text)
{
QString out;
out += QStringLiteral("<pre class=\"plain\">");
const QStringList lines = text.split(QLatin1Char('\n'));
for (int i = 0; i < lines.size(); ++i) {
const QString &line = lines.at(i);
const bool quoted = line.startsWith(QLatin1Char('>'));
if (quoted)
out += QStringLiteral("<span class=\"quote\">");
out += line.toHtmlEscaped();
if (quoted)
out += QStringLiteral("</span>");
if (i + 1 < lines.size())
out += QLatin1Char('\n');
}
out += QStringLiteral("</pre>");
return out;
}
QString HtmlBuilder::document(const QString &bodyHtml)
{
return QStringLiteral(
"<!DOCTYPE html><html><head><meta charset=\"utf-8\">"
"<style>%1</style></head><body>%2</body></html>")
.arg(QString::fromUtf8(kStyle), bodyHtml);
}
QString HtmlBuilder::namespaceCids(const QString &html, const QString &prefix)
{
if (prefix.isEmpty())
return html;
// This runs on the sender's raw, unescaped HTML markup (not on text that
// has been through toHtmlEscaped()), so no double-escaping happens here;
// it is purely a URL rewrite over the existing markup.
//
// Two independent patterns are needed:
//
// 1. Attribute values: src=, href=, background=, poster= (the common
// real-world attributes that can carry a cid: reference in HTML
// email), quoted with " or ', quoted the other way, or entirely
// unquoted (<img src=cid:x> is valid HTML and unquoted references are
// seen in the wild). Attribute name is matched case-insensitively and
// whitespace/newlines are tolerated around '='.
//
// 2. CSS url(cid:...): appears both inside a style="" attribute value
// and inside a <style> block, quoted or unquoted. This is handled as
// a separate pass since it has different quoting/terminator rules
// (a bare url(...) form terminates on ')', not on a matching quote).
//
// srcset= is not handled: it is a list of URL/descriptor pairs with a
// different quoting grammar, and cid: URLs in srcset are not something
// real-world mail has been observed to use; treating it is out of scope
// for this task.
QString out = html;
{
// (?:"([^"]*)"|'([^']*)'|([^\s"'<>]+)) picks the correctly-bounded
// value for whichever quoting style is used, so a quoted value can
// never be captured past its own closing quote (fixing the greedy
// [^"']+ that the naive version used, which is provably safe here
// since each alternative's character class already excludes its own
// terminator). capturedStart(N) (rather than testing the captured
// text for emptiness) is what disambiguates which alternative
// matched, so an empty-but-present cid ("cid:\"\"") is handled
// correctly too.
static const QRegularExpression re(
QStringLiteral(
"\\b(src|href|background|poster)"
"\\s*=\\s*"
"(?:\"cid:([^\"]*)\"|'cid:([^']*)'|cid:([^\\s\"'<>]+))"),
QRegularExpression::CaseInsensitiveOption);
QString rewritten;
qsizetype last = 0;
auto it = re.globalMatch(out);
while (it.hasNext()) {
const QRegularExpressionMatch m = it.next();
QString id;
QChar quote;
if (m.capturedStart(2) != -1) {
id = m.captured(2);
quote = QLatin1Char('"');
} else if (m.capturedStart(3) != -1) {
id = m.captured(3);
quote = QLatin1Char('\'');
} else {
id = m.captured(4);
}
rewritten += out.mid(last, m.capturedStart() - last);
rewritten += m.captured(1);
rewritten += QStringLiteral("=");
if (!quote.isNull())
rewritten += quote;
rewritten += QStringLiteral("cid:%1!%2").arg(prefix, id);
if (!quote.isNull())
rewritten += quote;
last = m.capturedEnd();
}
rewritten += out.mid(last);
out = rewritten;
}
{
// CSS url(cid:...), quoted (' or ") or bare, inside a style="" value
// or a <style> block. Bare form terminates at ')'.
static const QRegularExpression re(
QStringLiteral(
"url\\(\\s*"
"(?:\"cid:([^\"]*)\"|'cid:([^']*)'|cid:([^)\\s]+))"
"\\s*\\)"),
QRegularExpression::CaseInsensitiveOption);
QString rewritten;
qsizetype last = 0;
auto it = re.globalMatch(out);
while (it.hasNext()) {
const QRegularExpressionMatch m = it.next();
QString id;
QChar quote;
if (m.capturedStart(1) != -1) {
id = m.captured(1);
quote = QLatin1Char('"');
} else if (m.capturedStart(2) != -1) {
id = m.captured(2);
quote = QLatin1Char('\'');
} else {
id = m.captured(3);
}
rewritten += out.mid(last, m.capturedStart() - last);
rewritten += QStringLiteral("url(");
if (!quote.isNull())
rewritten += quote;
rewritten += QStringLiteral("cid:%1!%2").arg(prefix, id);
if (!quote.isNull())
rewritten += quote;
rewritten += QStringLiteral(")");
last = m.capturedEnd();
}
rewritten += out.mid(last);
out = rewritten;
}
return out;
}
QString HtmlBuilder::renderBody(const ThreadRenderItem &item, Mode mode)
{
if (mode == PreferHtml && item.message.hasHtml())
return namespaceCids(item.message.htmlBody, item.cidPrefix);
return renderPlain(item.message.plainBody);
}
QString HtmlBuilder::renderStub(const ParsedMessage &message)
{
return QStringLiteral("<div class=\"stub\">%1 — %2</div>")
.arg(message.from.toHtmlEscaped(), message.subject.toHtmlEscaped());
}
QString HtmlBuilder::build(const ParsedMessage &message, Mode mode)
{
ThreadRenderItem item;
item.message = message;
item.expanded = true;
return document(renderBody(item, mode));
}
QString HtmlBuilder::buildThread(const QList<ThreadRenderItem> &items, Mode mode)
{
QString body;
for (int i = 0; i < items.size(); ++i) {
const ThreadRenderItem &item = items.at(i);
if (!item.expanded) {
body += renderStub(item.message);
continue;
}
body += QStringLiteral(
"<div class=\"message\" id=\"msg-%1\">"
"<div class=\"msg-header\"><span class=\"who\">%2</span><br>%3</div>"
"%4</div>")
.arg(QString::number(i),
item.message.from.toHtmlEscaped(),
item.message.date.toHtmlEscaped(),
renderBody(item, mode));
}
return document(body);
}
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