Reaction Model

Create a reaction model that provides all the required data for `ReactionDelegate` so that none need to be calculated in QML.

This also cleans up the API for `ReactionDelegate`

src/models/reactionmodel.h

@@ -0,0 +1,72 @@
+// SPDX-FileCopyrightText: 2023 James Graham <james.h.graham@protonmail.com>
+// SPDX-License-Identifier: GPL-2.0-only OR GPL-3.0-only OR LicenseRef-KDE-Accepted-GPL
+
+#pragma once
+
+#include <QAbstractListModel>
+
+class NeoChatUser;
+
+/**
+ * @class ReactionModel
+ *
+ * This class defines the model for visualising a list of reactions to an event.
+ */
+class ReactionModel : public QAbstractListModel
+{
+    Q_OBJECT
+
+public:
+    /**
+     * @brief Definition of an reaction.
+     */
+    struct Reaction {
+        QString reaction; /**< The reaction emoji. */
+        QVariantList authors; /**< The list of authors who sent the given reaction. */
+    };
+
+    /**
+     * @brief Defines the model roles.
+     */
+    enum Roles {
+        TextRole = Qt::DisplayRole, /**< The text to show in the reaction. */
+        ReactionRole, /**< The reaction emoji. */
+        ToolTipRole, /**< The tool tip to show for the reaction. */
+        AuthorsRole, /**< The list of authors who sent the given reaction. */
+        HasLocalUser, /**< Whether the local user is in the list of authors. */
+    };
+
+    ReactionModel(QObject *parent = nullptr, QList<Reaction> reactions = {}, NeoChatUser *localUser = nullptr);
+
+    /**
+     * @brief Get the given role value at the given index.
+     *
+     * @sa QAbstractItemModel::data
+     */
+    [[nodiscard]] QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override;
+
+    /**
+     * @brief Number of rows in the model.
+     *
+     * @sa QAbstractItemModel::rowCount
+     */
+    [[nodiscard]] int rowCount(const QModelIndex &parent = QModelIndex()) const override;
+
+    /**
+     * @brief Returns a mapping from Role enum values to role names.
+     *
+     * @sa Roles, QAbstractItemModel::roleNames()
+     */
+    [[nodiscard]] QHash<int, QByteArray> roleNames() const override;
+
+    /**
+     * @brief Set the reactions data in the model.
+     */
+    void setReactions(QList<Reaction> reactions);
+
+private:
+    QList<Reaction> m_reactions;
+
+    NeoChatUser *m_localUser;
+};
+Q_DECLARE_METATYPE(ReactionModel *)