feat: strip prefixes and suffixes in links

CHANGELOG.md

@@ -17,6 +17,7 @@
 - Minor: Add channel points indication for new bits power-up redemptions. (#5471)
 - Minor: Added `/warn <username> <reason>` command for mods. This prevents the user from chatting until they acknowledge the warning. (#5474)
 - Minor: Introduce HTTP API for plugins. (#5383)
+- Minor: Links can now have prefixes and suffixes such as parentheses. (#5486)
 - Bugfix: Fixed tab move animation occasionally failing to start after closing a tab. (#5426)
 - Bugfix: If a network request errors with 200 OK, Qt's error code is now reported instead of the HTTP status. (#5378)
 - Bugfix: Fixed restricted users usernames not being clickable. (#5405)

src/common/LinkParser.cpp

@@ -113,19 +113,57 @@ bool startsWithPort(QStringView string)
     return true;
 }
 
+/// @brief Strips ignored characters off @a source
+///
+/// As per https://github.github.com/gfm/#autolinks-extension-:
+///
+/// '<', '*', '_', '~', and '(' are ignored at the beginning
+/// '>', '?', '!', '.', ',', ':', '*', '_', '~', and ')' are ignored at the end
+///
+/// A difference to GFM is that the source isn't scanned for parentheses.
+void strip(QStringView &source)
+{
+    while (!source.isEmpty())
+    {
+        auto c = source.first();
+        if (c == u'<' || c == u'*' || c == u'_' || c == u'~' || c == u'(')
+        {
+            source = source.mid(1);
+            continue;
+        }
+        break;
+    }
+
+    while (!source.isEmpty())
+    {
+        auto c = source.last();
+        if (c == u'>' || c == u'?' || c == u'!' || c == u'.' || c == u',' ||
+            c == u':' || c == u'*' || c == u'_' || c == u'~' || c == u')')
+        {
+            source.chop(1);
+            continue;
+        }
+        break;
+    }
+}
+
 }  // namespace
 
-namespace chatterino {
+namespace chatterino::linkparser {
 
-LinkParser::LinkParser(const QString &unparsedString)
+std::optional<Parsed> parse(const QString &source) noexcept
 {
-    ParsedLink result;
+    std::optional<Parsed> result;
     // This is not implemented with a regex to increase performance.
-    QStringView remaining(unparsedString);
-    QStringView protocol(remaining);
+
+    QStringView link{source};
+    strip(link);
+
+    QStringView remaining = link;
+    QStringView protocol;
 
     // Check protocol for https?://
-    if (remaining.startsWith(QStringLiteral("http"), Qt::CaseInsensitive) &&
+    if (remaining.startsWith(u"http", Qt::CaseInsensitive) &&
         remaining.length() >= 4 + 3 + 1)  // 'http' + '://' + [any]
     {
         // optimistic view assuming there's a protocol (http or https)
@@ -136,11 +174,11 @@ LinkParser::LinkParser(const QString &unparsedString)
             withProto = withProto.mid(1);
         }
 
-        if (withProto.startsWith(QStringLiteral("://")))
+        if (withProto.startsWith(u"://"))
         {
             // there's really a protocol => consume it
             remaining = withProto.mid(3);
-            result.protocol = {protocol.begin(), remaining.begin()};
+            protocol = {link.begin(), remaining.begin()};
         }
     }
 
@@ -161,7 +199,7 @@ LinkParser::LinkParser(const QString &unparsedString)
         {
             if (lastWasDot)  // no double dots ..
             {
-                return;
+                return result;
             }
             lastDotPos = i;
             lastWasDot = true;
@@ -181,7 +219,7 @@ LinkParser::LinkParser(const QString &unparsedString)
 
             if (!startsWithPort(remaining))
             {
-                return;
+                return result;
             }
 
             break;
@@ -198,23 +236,22 @@ LinkParser::LinkParser(const QString &unparsedString)
 
     if (lastWasDot || lastDotPos <= 0)
     {
-        return;
+        return result;
     }
 
     // check host/tld
     if ((nDots == 3 && isValidIpv4(host)) ||
         isValidTld(host.mid(lastDotPos + 1)))
     {
-        result.host = host;
-        result.rest = rest;
-        result.source = unparsedString;
-        this->result_ = std::move(result);
+        result = Parsed{
+            .protocol = protocol,
+            .host = host,
+            .rest = rest,
+            .link = link,
+        };
     }
-}
 
-const std::optional<ParsedLink> &LinkParser::result() const
-{
-    return this->result_;
+    return result;
 }
 
-}  // namespace chatterino
+}  // namespace chatterino::linkparser

src/common/LinkParser.hpp

@@ -4,43 +4,124 @@
 
 #include <optional>
 
-namespace chatterino {
+namespace chatterino::linkparser {
 
-struct ParsedLink {
+/// @brief Represents a parsed link
+///
+/// A parsed link is represented as views over the source string for its
+/// different segments. In this simplified model, a link consists of an optional
+/// @a protocol, a mandatory @a host and an optional @a rest. These segments are
+/// always next to eachother in the input string, however together, they don't
+/// span the whole input as it could contain prefixes or suffixes.
+///
+/// Prefixes and suffixes are identical to the ones in GitHub Flavored Markdown
+/// (GFM - https://github.github.com/gfm/#autolinks-extension-).
+/// Matching is done case insensitive (e.g. 'HTTp://a.com' would be valid).
+///
+/// A @a protocol can either be empty, "http://", or "https://".
+/// A @a host can either be an IPv4 address or a hostname. The hostname must end
+/// in a valid top level domain. Otherwise, there are no restrictions on it.
+/// The @a rest can start with an optional port followed by either a '/', '?',
+/// or '#'.
+///
+/// @b Example
+///
+/// ```text
+/// (https://wiki.chatterino.com/Help/#overview)
+/// ▏▏proto ▕       host        ▏     rest     ▏▏
+/// ▏▏                link                     ▏▏
+/// ▏                source                     ▏
+/// ```
+struct Parsed {
     /// The parsed protocol of the link. Can be empty.
     ///
+    /// ```text
     /// https://www.forsen.tv/commands
-    /// ^------^
+    /// ▏╌╌╌╌╌╌▕
+    ///
+    /// www.forsen.tv/commands
+    /// (empty)
+    /// ```
     QStringView protocol;
 
     /// The parsed host of the link. Can not be empty.
     ///
+    /// ```text
     /// https://www.forsen.tv/commands
-    ///         ^-----------^
+    ///         ▏╌╌╌╌╌╌╌╌╌╌╌▕
+    /// ```
     QStringView host;
 
     /// The remainder of the link. Can be empty.
     ///
+    /// ```text
     /// https://www.forsen.tv/commands
-    ///                      ^-------^
+    ///                      ▏╌╌╌╌╌╌╌▕
+    ///
+    /// https://www.forsen.tv
+    /// (empty)
+    /// ```
     QStringView rest;
 
-    /// The original unparsed link.
+    /// The matched link. Can not be empty.
     ///
-    /// https://www.forsen.tv/commands
-    /// ^----------------------------^
-    QString source;
-};
+    /// ```text
+    /// (https://www.forsen.tv/commands)
+    ///  ▏╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌▕
+    /// ```
+    QStringView link;
+
+    /// Checks if the parsed link contains a prefix
+    bool hasPrefix(const QString &source) const noexcept
+    {
+        return this->link.begin() != source.begin();
+    }
 
-class LinkParser
-{
-public:
-    explicit LinkParser(const QString &unparsedString);
+    /// The prefix before the parsed link inside @a source. May be empty.
+    ///
+    /// ```text
+    /// (https://www.forsen.tv/commands)
+    /// ^
+    ///
+    /// https://www.forsen.tv/commands
+    /// (empty)
+    /// ```
+    QStringView prefix(const QString &source) const noexcept
+    {
+        return {source.data(), this->link.begin()};
+    }
 
-    const std::optional<ParsedLink> &result() const;
+    /// Checks if the parsed link contains a suffix
+    bool hasSuffix(const QString &source) const noexcept
+    {
+        return this->link.end() != source.end();
+    }
 
-private:
-    std::optional<ParsedLink> result_{};
+    /// The suffix after the parsed link inside @a source. May be empty.
+    ///
+    /// ```text
+    /// (https://www.forsen.tv/commands)
+    ///                                ^
+    ///
+    /// https://www.forsen.tv/commands
+    /// (empty)
+    /// ```
+    QStringView suffix(const QString &source) const noexcept
+    {
+        return {
+            this->link.begin() + this->link.size(),
+            source.data() + source.length(),
+        };
+    }
 };
 
-}  // namespace chatterino
+/// @brief Parses a link from @a source into its segments
+///
+/// If no link is contained in @a source, `std::nullopt` will be returned.
+/// The returned value is valid as long as @a source exists, as it contains
+/// views into @a source.
+///
+/// For the accepted links, see Parsed.
+std::optional<Parsed> parse(const QString &source) noexcept;
+
+}  // namespace chatterino::linkparser

src/controllers/commands/builtin/twitch/SendWhisper.cpp

@@ -152,10 +152,10 @@ bool appendWhisperMessageWordsLocally(const QStringList &words)
                     void operator()(const QString &string,
                                     MessageBuilder &b) const
                     {
-                        LinkParser parser(string);
-                        if (parser.result())
+                        auto link = linkparser::parse(string);
+                        if (link)
                         {
-                            b.addLink(*parser.result());
+                            b.addLink(*link, string);
                         }
                         else
                         {