First handshake with pica

API/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(HEADERS
+    api.h
+)
+
+set(SOURCES
+    api.cpp
+)
+
+target_sources(megpie PRIVATE ${SOURCES})

API/api.cpp

@@ -0,0 +1,93 @@
+#include "api.h"
+#include <QDebug>
+#include <QJsonDocument>
+#include <QJsonObject>
+
+constexpr const char* json = "application/json";
+
+struct NetworkReplyDeleter {
+    void operator () (QNetworkReply* reply) {
+        reply->deleteLater();
+    }
+};
+
+API::API(const QUrl& address, QObject* parent):
+    QObject(parent),
+    address(address),
+    network()
+{
+
+}
+
+void API::test(const QString& path, const QJSValue& finished) {
+    qDebug() << "Testing" << path;
+    QNetworkRequest request(path + "/info");
+    request.setHeader(QNetworkRequest::ContentTypeHeader, json);
+
+    QNetworkReply* reply = network.get(request);
+    connect(reply, &QNetworkReply::finished,
+        std::bind(&API::onTestSuccess, this, reply, finished)
+    );
+}
+
+void API::onTestSuccess(QNetworkReply* reply, const QJSValue& finished) const {
+    std::unique_ptr<QNetworkReply, NetworkReplyDeleter> rpl(reply);
+    QNetworkReply::NetworkError error = reply->error();
+    if (error != QNetworkReply::NoError) {
+        QString err = reply->errorString();
+        qDebug() << "Test for" << reply->url() << "failed:" << err;
+        callCallback(finished, err);
+        return;
+    }
+
+    QVariant contentType = reply->header(QNetworkRequest::ContentTypeHeader);
+    if (!
+        contentType.isValid() ||
+        !contentType.canConvert<QString>() ||
+        contentType.toString() != json
+    ) {
+        QString err("wrong response content type");
+        qDebug() << "Test for" << reply->url() << "failed:" << err;
+        callCallback(finished, err);
+        return;
+    }
+
+    QByteArray data = reply->readAll();
+    QJsonDocument document = QJsonDocument::fromJson(data);
+    QJsonObject rootObj = document.object();
+
+    QJsonValue type = rootObj.value("type");
+    QJsonValue version = rootObj.value("version");
+    if (!type.isString() || !version.isString()) {
+        QString err("malformed json");
+        qDebug() << "Test for" << reply->url() << "failed:" << err;
+        callCallback(finished, err);
+        return;
+    }
+
+    if (type.toString() != "Pica") {
+        QString err("server of this type (" + type.toString() + ") is not supported");
+        qDebug() << "Test for" << reply->url() << "failed:" << err;
+        callCallback(finished, err);
+        return;
+    }
+
+    if (version.toString() != "0.0.1") {
+        QString err("server of this version (" + version.toString() + ") is not supported");
+        qDebug() << "Test for" << reply->url() << "failed:" << err;
+        callCallback(finished, err);
+        return;
+    }
+
+    callCallback(finished, QString(), {QJSValue(true)});
+}
+
+void API::callCallback(const QJSValue& callback, const QString& error, const QJSValueList& arguments) const {
+    if (callback.isCallable()) {
+        if (error.isEmpty())
+            callback.call(QJSValueList({QJSValue(QJSValue::NullValue)}) + arguments);
+        else
+            callback.call({QJSValue(error)});
+    }
+}
+

API/api.h

@@ -0,0 +1,28 @@
+#pragma once
+
+#include <memory>
+
+#include <QObject>
+#include <QString>
+#include <QUrl>
+#include <QJSValue>
+#include <QNetworkAccessManager>
+#include <QNetworkReply>
+
+class API : public QObject {
+    Q_OBJECT
+public:
+    explicit API(const QUrl& path = QString(), QObject* parent = nullptr);
+
+    Q_INVOKABLE void test(const QString& path, const QJSValue& finished = QJSValue());
+
+private slots:
+    void onTestSuccess(QNetworkReply* reply, const QJSValue& finished) const;
+
+private:
+    void callCallback(const QJSValue& callback, const QString& error = QString(), const QJSValueList& arguments = QJSValueList()) const;
+
+private:
+    QUrl address;
+    QNetworkAccessManager network;
+};