Merge pull request #590 from GriffinRichards/update-promoter

Add update promoter

include/core/network.h

@@ -0,0 +1,87 @@
+#ifndef NETWORK_H
+#define NETWORK_H
+
+/*
+    The two classes defined here provide a simplified interface for Qt's network classes QNetworkAccessManager and QNetworkReply.
+
+    With the Qt classes, the workflow for a GET is roughly: generate a QNetworkRequest, give this request to QNetworkAccessManager::get,
+    connect the returned object to QNetworkReply::finished, and in the slot of that connection handle the various HTTP headers and attributes,
+    then manage errors or process the webpage's body.
+
+    These classes handle generating the QNetworkRequest with a given URL and manage the HTTP headers in the reply. They will automatically
+    respect rate limits and return cached data if the webpage hasn't changed since previous requests. Instead of interacting with a QNetworkReply,
+    callers interact with a simplified NetworkReplyData.
+    Example that logs Porymap's description on GitHub:
+
+    NetworkAccessManager * manager = new NetworkAccessManager(this);
+    NetworkReplyData * reply = manager->get("https://api.github.com/repos/huderlem/porymap");
+    connect(reply, &NetworkReplyData::finished, [reply] () {
+        if (!reply->errorString().isEmpty()) {
+            logError(QString("Failed to read description: %1").arg(reply->errorString()));
+        } else {
+            auto webpage = QJsonDocument::fromJson(reply->body());
+            logInfo(QString("Porymap: %1").arg(webpage["description"].toString()));
+        }
+        reply->deleteLater();
+    });
+*/
+
+#include <QNetworkAccessManager>
+#include <QNetworkRequest>
+#include <QNetworkReply>
+#include <QDateTime>
+
+class NetworkReplyData : public QObject
+{
+    Q_OBJECT
+
+public:
+    QUrl url() const { return m_url; }
+    QUrl nextUrl() const { return m_nextUrl; }
+    QByteArray body() const { return m_body; }
+    QString errorString() const { return m_error; }
+    QDateTime retryAfter() const { return m_retryAfter; }
+    bool isFinished() const { return m_finished; }
+
+    friend class NetworkAccessManager;
+
+private:
+    QUrl m_url;
+    QUrl m_nextUrl;
+    QByteArray m_body;
+    QString m_error;
+    QDateTime m_retryAfter;
+    bool m_finished;
+
+    void finish() {
+        m_finished = true;
+        emit finished();
+    };
+
+signals:
+    void finished();
+};
+
+class NetworkAccessManager : public QNetworkAccessManager
+{
+    Q_OBJECT
+
+public:
+    NetworkAccessManager(QObject * parent = nullptr);
+    ~NetworkAccessManager();
+    NetworkReplyData * get(const QString &url);
+    NetworkReplyData * get(const QUrl &url);
+
+private:
+    // For a more complex cache we could implement a QAbstractCache for the manager
+    struct CacheEntry {
+        QString eTag;
+        QByteArray data;
+    };
+    QMap<QUrl, CacheEntry*> cache;
+    QMap<QUrl, QDateTime> rateLimitTimes;
+    void processReply(QNetworkReply * reply, NetworkReplyData * data);
+    const QNetworkRequest getRequest(const QUrl &url);
+};
+
+#endif // NETWORK_H