refactor: load Twitch emotes from Helix (#5239)

src/providers/twitch/TwitchUsers.hpp

@@ -0,0 +1,55 @@
+#pragma once
+
+#include "common/Aliases.hpp"
+
+#include <memory>
+
+namespace chatterino {
+
+struct TwitchUser;
+class TwitchChannel;
+
+class ITwitchUsers
+{
+public:
+    ITwitchUsers() = default;
+    virtual ~ITwitchUsers() = default;
+    ITwitchUsers(const ITwitchUsers &) = delete;
+    ITwitchUsers(ITwitchUsers &&) = delete;
+    ITwitchUsers &operator=(const ITwitchUsers &) = delete;
+    ITwitchUsers &operator=(ITwitchUsers &&) = delete;
+
+    /// @brief Resolve a TwitchUser by their ID
+    ///
+    /// Users are cached. If the user wasn't resolved yet, a request will be
+    /// scheduled. The returned shared pointer must only be used on the GUI
+    /// thread as it will be updated from there.
+    ///
+    /// @returns A shared reference to the TwitchUser. The `name` and
+    ///          `displayName` might be empty if the user wasn't resolved yet or
+    ///          they don't exist.
+    virtual std::shared_ptr<TwitchUser> resolveID(const UserId &id) = 0;
+};
+
+class TwitchUsersPrivate;
+class TwitchUsers : public ITwitchUsers
+{
+public:
+    TwitchUsers();
+    ~TwitchUsers() override;
+    TwitchUsers(const TwitchUsers &) = delete;
+    TwitchUsers(TwitchUsers &&) = delete;
+    TwitchUsers &operator=(const TwitchUsers &) = delete;
+    TwitchUsers &operator=(TwitchUsers &&) = delete;
+
+    /// @see ITwitchUsers::resolveID()
+    std::shared_ptr<TwitchUser> resolveID(const UserId &id) override;
+
+private:
+    // Using a shared_ptr to pass to network callbacks
+    std::shared_ptr<TwitchUsersPrivate> private_;
+
+    friend TwitchUsersPrivate;
+};
+
+}  // namespace chatterino