feat: add playlist, recent files and MPRIS backends

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/models/recentfilesmodel.cpp

@@ -0,0 +1,122 @@
+// SPDX-FileCopyrightText: 2026 Tri Vo Khac
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "recentfilesmodel.h"
+
+#include <KConfigGroup>
+#include <KSharedConfig>
+
+#include <algorithm>
+
+using namespace Qt::Literals::StringLiterals;
+
+namespace
+{
+// Stored even when fewer are shown, so raising the limit brings old entries back.
+constexpr int StoredFiles = 50;
+
+KConfigGroup configGroup()
+{
+    return KSharedConfig::openStateConfig()->group(u"RecentFiles"_s);
+}
+}
+
+RecentFilesModel::RecentFilesModel(QObject *parent)
+    : QAbstractListModel(parent)
+{
+    const QStringList urls = configGroup().readEntry(u"Urls"_s, QStringList());
+    for (const QString &url : urls) {
+        m_urls.append(QUrl(url));
+    }
+}
+
+int RecentFilesModel::rowCount(const QModelIndex &parent) const
+{
+    return parent.isValid() ? 0 : count();
+}
+
+QVariant RecentFilesModel::data(const QModelIndex &index, int role) const
+{
+    if (!checkIndex(index, CheckIndexOption::IndexIsValid)) {
+        return {};
+    }
+    const QUrl &url = m_urls.at(index.row());
+    switch (role) {
+    case UrlRole:
+        return url;
+    case Qt::DisplayRole:
+    case NameRole:
+        return url.isLocalFile() ? url.fileName() : url.toDisplayString();
+    case PathRole:
+        return url.isLocalFile() ? url.toLocalFile() : url.toDisplayString();
+    }
+    return {};
+}
+
+QHash<int, QByteArray> RecentFilesModel::roleNames() const
+{
+    return {
+        {UrlRole, "url"},
+        {NameRole, "name"},
+        {PathRole, "path"},
+    };
+}
+
+int RecentFilesModel::count() const
+{
+    return int(std::min<qsizetype>(m_urls.size(), m_maxCount));
+}
+
+int RecentFilesModel::maxCount() const
+{
+    return m_maxCount;
+}
+
+void RecentFilesModel::setMaxCount(int maxCount)
+{
+    maxCount = std::clamp(maxCount, 0, StoredFiles);
+    if (maxCount == m_maxCount) {
+        return;
+    }
+    beginResetModel();
+    m_maxCount = maxCount;
+    endResetModel();
+    Q_EMIT maxCountChanged();
+    Q_EMIT countChanged();
+}
+
+void RecentFilesModel::add(const QUrl &url)
+{
+    if (!url.isValid()) {
+        return;
+    }
+    beginResetModel();
+    m_urls.removeAll(url);
+    m_urls.prepend(url);
+    if (m_urls.size() > StoredFiles) {
+        m_urls.resize(StoredFiles);
+    }
+    endResetModel();
+    Q_EMIT countChanged();
+    save();
+}
+
+void RecentFilesModel::clear()
+{
+    beginResetModel();
+    m_urls.clear();
+    endResetModel();
+    Q_EMIT countChanged();
+    save();
+}
+
+void RecentFilesModel::save() const
+{
+    QStringList urls;
+    for (const QUrl &url : m_urls) {
+        urls.append(url.toString());
+    }
+    KConfigGroup group = configGroup();
+    group.writeEntry(u"Urls"_s, urls);
+    group.sync();
+}

src/models/recentfilesmodel.h

@@ -0,0 +1,53 @@
+// SPDX-FileCopyrightText: 2026 Tri Vo Khac
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+#include <QAbstractListModel>
+#include <QList>
+#include <QUrl>
+#include <QtQml/qqmlregistration.h>
+
+// Recently opened files, newest first, kept in the application's state file.
+class RecentFilesModel : public QAbstractListModel
+{
+    Q_OBJECT
+    QML_ELEMENT
+    QML_SINGLETON
+
+    Q_PROPERTY(int count READ count NOTIFY countChanged)
+    // Rows beyond this are hidden (but kept, in case it is raised again).
+    Q_PROPERTY(int maxCount READ maxCount WRITE setMaxCount NOTIFY maxCountChanged)
+
+public:
+    enum Roles {
+        UrlRole = Qt::UserRole + 1,
+        NameRole,
+        PathRole,
+    };
+    Q_ENUM(Roles)
+
+    explicit RecentFilesModel(QObject *parent = nullptr);
+
+    int rowCount(const QModelIndex &parent = {}) const override;
+    QVariant data(const QModelIndex &index, int role) const override;
+    QHash<int, QByteArray> roleNames() const override;
+
+    int count() const;
+    int maxCount() const;
+    void setMaxCount(int maxCount);
+
+    // Moves \a url to the top, adding it if needed.
+    Q_INVOKABLE void add(const QUrl &url);
+    Q_INVOKABLE void clear();
+
+Q_SIGNALS:
+    void countChanged();
+    void maxCountChanged();
+
+private:
+    void save() const;
+
+    QList<QUrl> m_urls;
+    int m_maxCount = 10;
+};