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

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

src/controllers/completion/sources/CommandSource.cpp

@@ -0,0 +1,101 @@
+#include "controllers/completion/sources/CommandSource.hpp"
+
+#include "Application.hpp"
+#include "controllers/commands/Command.hpp"
+#include "controllers/commands/CommandController.hpp"
+#include "controllers/completion/sources/Helpers.hpp"
+#include "providers/twitch/TwitchCommon.hpp"
+
+namespace chatterino::completion {
+
+namespace {
+
+    void addCommand(const QString &command, std::vector<CommandItem> &out)
+    {
+        if (command.startsWith('/') || command.startsWith('.'))
+        {
+            out.push_back({command.mid(1), command.at(0)});
+        }
+        else
+        {
+            out.push_back({command, '/'});
+        }
+    }
+
+}  // namespace
+
+CommandSource::CommandSource(std::unique_ptr<CommandStrategy> strategy,
+                             ActionCallback callback)
+    : strategy_(std::move(strategy))
+    , callback_(std::move(callback))
+{
+    this->initializeItems();
+}
+
+void CommandSource::update(const QString &query)
+{
+    this->output_.clear();
+    if (this->strategy_)
+    {
+        this->strategy_->apply(this->items_, this->output_, query);
+    }
+}
+
+void CommandSource::addToListModel(GenericListModel &model,
+                                   size_t maxCount) const
+{
+    addVecToListModel(this->output_, model, maxCount,
+                      [this](const CommandItem &command) {
+                          return std::make_unique<InputCompletionItem>(
+                              nullptr, command.name, this->callback_);
+                      });
+}
+
+void CommandSource::addToStringList(QStringList &list, size_t maxCount,
+                                    bool /* isFirstWord */) const
+{
+    addVecToStringList(this->output_, list, maxCount,
+                       [](const CommandItem &command) {
+                           return command.prefix + command.name + " ";
+                       });
+}
+
+void CommandSource::initializeItems()
+{
+    std::vector<CommandItem> commands;
+
+#ifdef CHATTERINO_HAVE_PLUGINS
+    for (const auto &command : getApp()->commands->pluginCommands())
+    {
+        addCommand(command, commands);
+    }
+#endif
+
+    // Custom Chatterino commands
+    for (const auto &command : getIApp()->getCommands()->items)
+    {
+        addCommand(command.name, commands);
+    }
+
+    // Default Chatterino commands
+    auto x = getIApp()->getCommands()->getDefaultChatterinoCommandList();
+    for (const auto &command : x)
+    {
+        addCommand(command, commands);
+    }
+
+    // Default Twitch commands
+    for (const auto &command : TWITCH_DEFAULT_COMMANDS)
+    {
+        addCommand(command, commands);
+    }
+
+    this->items_ = std::move(commands);
+}
+
+const std::vector<CommandItem> &CommandSource::output() const
+{
+    return this->output_;
+}
+
+}  // namespace chatterino::completion