Improvements to Message Search (#1237)

* Ran clang-format

* Implement user-specific search in message history

This functionality was originally requested in #1236.

This commit changes the SearchPopup::performSearch method so that only
messages from specific users can be shown.

In order to filter for a specific user, enter their username with a
leading '@' in the search popup. You can also add an additional search
phrase which will also be considered in the search.

* Naive implementation for "from:" tags

Rebase later?

* Cleverer (?) version using Predicates

Commit adds two POC predicates: one for the author of messages, and one
for substring search in messages.

Problems/TODOs:
* Best way to register new predicates?
* Clean up tags (e.g. "from:") or not?
* Test combinations of different predicates

* Add a predicate to check for links in messages

* Remove a dumb TODO

* Rewrite SearchPopup::performSearch to be cleaner

* Ran clang-format on all files

* Remove TODO I missed earlier

* Forgot to run clang-format

peepoSadDank

* Re-use {}-initialization

Was accidentally removed when fixing earlier merge conflict.

* Does this fix line endings?

No diffs are shown locally, hopefully Git doesn't lie to me.

* Rename "predicates" directory to "search"

Resolving one conversation in the review of #1237.

* Use LinkParser in LinkPredicate

Resolving a conversation in the review of #1237.

* Predicates: Use unique_ptr instead of shared_ptr

Resolves a conversation in the review of #1237.

* Refactor of SearchPopup and AuthorPredicate

Resolving some points from the review in #1237.

* Moved parsing of comma-seperated values into AuthorPredicate
  constructor.
* Rewrite SearchPopup::parsePredicates as suggested.
* Deleted now redundant methods in SearchPopup.

* MessagePredicate::appliesTo now takes a Message&

... instead of a MessagePtr.

This resolves a conversation in the review of #1237.

* Run clang-format on two files I missed

* AuthorPredicate: Check for displayName & loginName

Resolving conversation on #1237.

src/widgets/helper/SearchPopup.cpp

@@ -7,29 +7,45 @@
 
 #include "common/Channel.hpp"
 #include "messages/Message.hpp"
+#include "messages/search/AuthorPredicate.hpp"
+#include "messages/search/LinkPredicate.hpp"
+#include "messages/search/SubstringPredicate.hpp"
 #include "widgets/helper/ChannelView.hpp"
 
 namespace chatterino {
-namespace {
-    ChannelPtr filter(const QString &text, const QString &channelName,
-                      const LimitedQueueSnapshot<MessagePtr> &snapshot)
+
+ChannelPtr SearchPopup::filter(const QString &text, const QString &channelName,
+                               const LimitedQueueSnapshot<MessagePtr> &snapshot)
+{
+    ChannelPtr channel(new Channel(channelName, Channel::Type::None));
+
+    // Parse predicates from tags in "text"
+    auto predicates = parsePredicates(text);
+
+    // Check for every message whether it fulfills all predicates that have
+    // been registered
+    for (size_t i = 0; i < snapshot.size(); ++i)
     {
-        ChannelPtr channel(new Channel(channelName, Channel::Type::None));
+        MessagePtr message = snapshot[i];
 
-        for (size_t i = 0; i < snapshot.size(); i++)
+        bool accept = true;
+        for (const auto &pred : predicates)
         {
-            MessagePtr message = snapshot[i];
-
-            if (text.isEmpty() ||
-                message->searchText.indexOf(text, 0, Qt::CaseInsensitive) != -1)
+            // Discard the message as soon as one predicate fails
+            if (!pred->appliesTo(*message))
             {
-                channel->addMessage(message);
+                accept = false;
+                break;
             }
         }
 
-        return channel;
+        // If all predicates match, add the message to the channel
+        if (accept)
+            channel->addMessage(message);
     }
-}  // namespace
+
+    return channel;
+}
 
 SearchPopup::SearchPopup()
 {
@@ -113,4 +129,55 @@ void SearchPopup::initLayout()
     }
 }
 
+std::vector<std::unique_ptr<MessagePredicate>> SearchPopup::parsePredicates(
+    const QString &input)
+{
+    static QRegularExpression predicateRegex(R"(^(\w+):([\w,]+)$)");
+
+    auto predicates = std::vector<std::unique_ptr<MessagePredicate>>();
+    auto words = input.split(' ', QString::SkipEmptyParts);
+    auto authors = QStringList();
+
+    for (auto it = words.begin(); it != words.end();)
+    {
+        if (auto match = predicateRegex.match(*it); match.hasMatch())
+        {
+            QString name = match.captured(1);
+            QString value = match.captured(2);
+
+            bool remove = true;
+
+            // match predicates
+            if (name == "from")
+            {
+                authors.append(value);
+            }
+            else if (name == "has" && value == "link")
+            {
+                predicates.push_back(std::make_unique<LinkPredicate>());
+            }
+            else
+            {
+                remove = false;
+            }
+
+            // remove or advance
+            it = remove ? words.erase(it) : ++it;
+        }
+        else
+        {
+            ++it;
+        }
+    }
+
+    if (!authors.empty())
+        predicates.push_back(std::make_unique<AuthorPredicate>(authors));
+
+    if (!words.empty())
+        predicates.push_back(
+            std::make_unique<SubstringPredicate>(words.join(" ")));
+
+    return predicates;
+}
+
 }  // namespace chatterino