From 0221eb08bc7b0a58a110cc7a942159afa755aeec Mon Sep 17 00:00:00 2001
From: Kitsune Ral <Kitsune-Ral@users.sf.net>
Date: Thu, 18 Jan 2018 08:51:29 +0900
Subject: Move links pretty-printing code from Quaternion to lib

This code is useful for all clients, and extensions to pretty-printing
can be later added either via making prettyPrint() virtual or even by
providing a registry of additional "text transformers" or even "event
content renderers" applied to visualise the event.
---
 room.cpp | 43 +++++++++++++++++++++++++++++++++++++++++++
 room.h   |  5 +++++
 2 files changed, 48 insertions(+)

diff --git a/room.cpp b/room.cpp
index 3481f684..f8640573 100644
--- a/room.cpp
+++ b/room.cpp
@@ -43,6 +43,7 @@
 #include <QtCore/QElapsedTimer>
 #include <QtCore/QPointer>
 #include <QtCore/QDir>
+#include <QtCore/QRegularExpression>
 
 #include <array>
 #include <functional>
@@ -490,6 +491,48 @@ FileTransferInfo Room::fileTransferInfo(const QString& id) const
 #endif
 }
 
+static const auto RegExpOptions =
+    QRegularExpression::CaseInsensitiveOption
+    | QRegularExpression::OptimizeOnFirstUsageOption
+    | QRegularExpression::UseUnicodePropertiesOption;
+
+// regexp is originally taken from Konsole (https://github.com/KDE/konsole)
+// full url:
+// protocolname:// or www. followed by anything other than whitespaces,
+// <, >, ' or ", and ends before whitespaces, <, >, ', ", ], !, ), :,
+// comma or dot
+// Note: outer parentheses are a part of C++ raw string delimiters, not of
+// the regex (see http://en.cppreference.com/w/cpp/language/string_literal).
+static const QRegularExpression FullUrlRegExp(QStringLiteral(
+        R"(((www\.(?!\.)|[a-z][a-z0-9+.-]*://)(&(?![lg]t;)|[^&\s<>'"])+(&(?![lg]t;)|[^&!,.\s<>'"\]):])))"
+    ), RegExpOptions);
+// email address:
+// [word chars, dots or dashes]@[word chars, dots or dashes].[word chars]
+static const QRegularExpression EmailAddressRegExp(QStringLiteral(
+        R"((mailto:)?(\b(\w|\.|-)+@(\w|\.|-)+\.\w+\b))"
+    ), RegExpOptions);
+
+/** Converts all that looks like a URL into HTML links */
+static void linkifyUrls(QString& htmlEscapedText)
+{
+    // NOTE: htmlEscapedText is already HTML-escaped (no literal <,>,&)!
+
+    htmlEscapedText.replace(EmailAddressRegExp,
+                 QStringLiteral(R"(<a href="mailto:\2">\1\2</a>)"));
+    htmlEscapedText.replace(FullUrlRegExp,
+                 QStringLiteral(R"(<a href="\1">\1</a>")"));
+}
+
+QString Room::prettyPrint(const QString& plainText) const
+{
+    auto pt = QStringLiteral("<span style='white-space:pre-wrap'>") +
+            plainText.toHtmlEscaped() + QStringLiteral("</span>");
+    pt.replace('\n', "<br/>");
+
+    linkifyUrls(pt);
+    return pt;
+}
+
 QList< User* > Room::usersTyping() const
 {
     return d->usersTyping;
diff --git a/room.h b/room.h
index f5bf0839..ac540fea 100644
--- a/room.h
+++ b/room.h
@@ -192,6 +192,11 @@ namespace QMatrixClient
 
             Q_INVOKABLE FileTransferInfo fileTransferInfo(const QString& id) const;
 
+            /** Pretty-prints plain text into HTML
+             * This includes HTML escaping of <,>,",& and URLs linkification.
+             */
+            QString prettyPrint(const QString& plainText) const;
+
             MemberSorter memberSorter() const;
 
             QJsonObject toJson() const;
-- 
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