Consolidate input completion code in preparation for advanced completion strategies (#4639)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/controllers/completion/TabCompletionModel.cpp

@@ -0,0 +1,119 @@
+#include "controllers/completion/TabCompletionModel.hpp"
+
+#include "common/Channel.hpp"
+#include "controllers/completion/sources/CommandSource.hpp"
+#include "controllers/completion/sources/EmoteSource.hpp"
+#include "controllers/completion/sources/UnifiedSource.hpp"
+#include "controllers/completion/sources/UserSource.hpp"
+#include "controllers/completion/strategies/ClassicEmoteStrategy.hpp"
+#include "controllers/completion/strategies/ClassicUserStrategy.hpp"
+#include "controllers/completion/strategies/CommandStrategy.hpp"
+#include "singletons/Settings.hpp"
+
+namespace chatterino {
+
+TabCompletionModel::TabCompletionModel(Channel &channel, QObject *parent)
+    : QStringListModel(parent)
+    , channel_(channel)
+{
+}
+
+void TabCompletionModel::updateResults(const QString &query, bool isFirstWord)
+{
+    this->updateSourceFromQuery(query);
+
+    if (this->source_)
+    {
+        this->source_->update(query);
+
+        // Copy results to this model
+        QStringList results;
+        this->source_->addToStringList(results, 0, isFirstWord);
+        this->setStringList(results);
+    }
+}
+
+void TabCompletionModel::updateSourceFromQuery(const QString &query)
+{
+    auto deducedKind = this->deduceSourceKind(query);
+    if (!deducedKind)
+    {
+        // unable to determine what kind of completion is occurring
+        this->sourceKind_ = std::nullopt;
+        this->source_ = nullptr;
+        return;
+    }
+
+    if (this->sourceKind_ == *deducedKind)
+    {
+        // Source already properly configured
+        return;
+    }
+
+    this->sourceKind_ = *deducedKind;
+    this->source_ = this->buildSource(*deducedKind);
+}
+
+std::optional<TabCompletionModel::SourceKind>
+    TabCompletionModel::deduceSourceKind(const QString &query) const
+{
+    if (query.length() < 2 || !this->channel_.isTwitchChannel())
+    {
+        return std::nullopt;
+    }
+
+    // Check for cases where we can definitively say what kind of completion is taking place.
+
+    if (query.startsWith('@'))
+    {
+        return SourceKind::User;
+    }
+    else if (query.startsWith(':'))
+    {
+        return SourceKind::Emote;
+    }
+    else if (query.startsWith('/') || query.startsWith('.'))
+    {
+        return SourceKind::Command;
+    }
+
+    // At this point, we note that emotes can be completed without using a :
+    // Therefore, we must also consider that the user could be completing an emote
+    // OR a mention depending on their completion settings.
+
+    if (getSettings()->userCompletionOnlyWithAt)
+    {
+        return SourceKind::Emote;
+    }
+
+    // Either is possible, use unified source
+    return SourceKind::EmoteAndUser;
+}
+
+std::unique_ptr<completion::Source> TabCompletionModel::buildSource(
+    SourceKind kind) const
+{
+    switch (kind)
+    {
+        case SourceKind::Emote:
+            return std::make_unique<completion::EmoteSource>(
+                &this->channel_,
+                std::make_unique<completion::ClassicTabEmoteStrategy>());
+        case SourceKind::User:
+            return std::make_unique<completion::UserSource>(
+                &this->channel_,
+                std::make_unique<completion::ClassicUserStrategy>());
+        case SourceKind::Command:
+            return std::make_unique<completion::CommandSource>(
+                std::make_unique<completion::CommandStrategy>(true));
+        case SourceKind::EmoteAndUser:
+            return std::make_unique<completion::UnifiedSource>(
+                &this->channel_,
+                std::make_unique<completion::ClassicTabEmoteStrategy>(),
+                std::make_unique<completion::ClassicUserStrategy>());
+        default:
+            return nullptr;
+    }
+}
+
+}  // namespace chatterino