Rate limit outgoing JOIN messages (#3115)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>
Co-authored-by: Tal Neoran <talneoran@gmail.com>

src/util/RatelimitBucket.hpp

@@ -0,0 +1,40 @@
+#pragma once
+
+#include <QList>
+#include <QObject>
+#include <QString>
+
+namespace chatterino {
+
+class RatelimitBucket : public QObject
+{
+public:
+    RatelimitBucket(int budget, int cooldown,
+                    std::function<void(QString)> callback, QObject *parent);
+
+    void send(QString channel);
+
+private:
+    /**
+     * @brief budget_ denotes the amount of calls that can be handled before we need to wait for the cooldown
+     **/
+    int budget_;
+
+    /**
+     * @brief This is the amount of time in milliseconds it takes for one used up budget to be put back into the bucket for use elsewhere
+     **/
+    const int cooldown_;
+
+    std::function<void(QString)> callback_;
+    QList<QString> queue_;
+
+    /**
+     * @brief Run the callback on one entry in the queue.
+     *
+     * This will start a timer that runs after cooldown_ milliseconds that
+     * gives back one "token" to the bucket and calls handleOne again.
+     **/
+    void handleOne();
+};
+
+}  // namespace chatterino