Implementation without Proxy Pattern.

Qt/Qt.pro

@@ -1,8 +1,8 @@
-QT       += core gui
+QT       += core gui network
 
 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
 
-CONFIG += c++11
+CONFIG += c++17
 
 # The following define makes your compiler emit warnings if you use
 # any Qt feature that has been marked deprecated (the exact warnings
@@ -16,10 +16,12 @@ DEFINES += QT_DEPRECATED_WARNINGS
 #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0
 
 SOURCES += \
+    api_handler.cpp \
     main.cpp \
     mainwindow.cpp
 
 HEADERS += \
+    api_handler.h \
     mainwindow.h
 
 FORMS += \

Qt/api_handler.cpp

@@ -0,0 +1,26 @@
+// local
+#include "api_handler.h"
+
+namespace constants
+{
+    const QString FILES_ENDPOINT = "/api/files";
+    const QString DOWNLOAD_FILE_ENDPOINT = "/api/download/file/";
+}   // constants namespace
+
+APIHandler::APIHandler(const QString &hostUrl)
+    : m_hostUrl(hostUrl)
+{
+    m_networkManager = std::make_unique<QNetworkAccessManager>();
+}
+
+QNetworkReply *APIHandler::GetFilesList()
+{
+    const QString url = m_hostUrl + constants::FILES_ENDPOINT;
+    return m_networkManager->get(QNetworkRequest(url));
+}
+
+QNetworkReply *APIHandler::DownloadFile(const QString &fileName)
+{
+    const QString url = m_hostUrl + constants::DOWNLOAD_FILE_ENDPOINT + fileName;
+    return m_networkManager->get(QNetworkRequest(url));
+}

Qt/api_handler.h

@@ -0,0 +1,38 @@
+//---------------------------------------------------------------------------------------------------------------------
+/// @file
+///
+/// @brief      API Handler Class
+///
+/// @author     Ali Ibrahim (ali103575@gmail.com)
+///
+/// @version    1.0
+/// @date       01-15-2023
+//---------------------------------------------------------------------------------------------------------------------
+
+#ifndef API_HANDLER_H
+#define API_HANDLER_H
+
+// local
+
+// qt
+#include <QNetworkAccessManager>
+#include <QNetworkReply>
+#include <QString>
+
+// stdlib
+#include <memory>
+
+class APIHandler
+{
+public:
+    APIHandler(const QString &hostUrl);
+    virtual ~APIHandler() = default;
+    QNetworkReply *GetFilesList();
+    QNetworkReply *DownloadFile(const QString &fileName);
+
+private:
+    QString m_hostUrl;
+    std::unique_ptr<QNetworkAccessManager> m_networkManager;
+};
+
+#endif // API_HANDLER_H

Qt/mainwindow.cpp

@@ -1,11 +1,81 @@
+// local
 #include "mainwindow.h"
 #include "ui_mainwindow.h"
 
+// qt
+#include <QJsonArray>
+#include <QJsonDocument>
+#include <QJsonObject>
+
+namespace constants
+{
+    const QString BASE_URL = "http://127.0.0.1:3000";
+    int STATUS_BAR_TIMEOUT = 5000;
+    int MAX_CONTENT_LENGTH = 1000;
+    namespace json_keys
+    {
+        const QString SUMMARY_KEY = "summary";
+    }   // json_keys namespace
+} // constants namespace
 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent)
     , ui(new Ui::MainWindow)
+    , m_apiHandler(std::make_unique<APIHandler>(constants::BASE_URL))
 {
     ui->setupUi(this);
+    // Get Files
+    auto reply = m_apiHandler->GetFilesList();
+    connect(reply, &QNetworkReply::finished, this, [reply, this]
+    {
+        if(reply->error() == QNetworkReply::NoError)
+        {
+            auto data = reply->readAll();
+            QJsonDocument doc = QJsonDocument::fromJson(data);
+            QJsonObject obj = doc.object();
+            for(auto &&key: obj.keys()) {
+                auto summary = obj.value(key).toObject()[constants::json_keys::SUMMARY_KEY].toString().toStdString();
+                ui->filesComboBox->addItem(key);
+                m_summaries.push_back(summary);
+            }
+            connect(ui->filesComboBox, QOverload<int>::of(&QComboBox::currentIndexChanged), [=](int index)
+            {
+                ui->fileSummaryLabel->setText(QString::fromStdString(m_summaries[index]));
+            });
+        }
+        else
+        {
+            ui->statusbar->showMessage(reply->errorString(), constants::STATUS_BAR_TIMEOUT);
+        }
+        if(!m_summaries.empty())
+        {
+            ui->fileSummaryLabel->setText(QString::fromStdString(m_summaries[0]));
+        }
+        reply->deleteLater();
+    });
+    connect(ui->downloadButton, &QPushButton::clicked, this, [this]()
+    {
+        auto fileName = ui->filesComboBox->currentText();
+        auto reply = m_apiHandler->DownloadFile(fileName);
+        connect(reply, &QNetworkReply::finished, this, [this, reply]()
+        {
+            if(reply->error() == QNetworkReply::NoError)
+            {
+                auto data = reply->readAll();
+                // Do What ever you want with data now.
+                auto dataToDisplay = QString(data).left(std::min(constants::MAX_CONTENT_LENGTH, data.length()));
+                if(data.length() > constants::MAX_CONTENT_LENGTH)
+                {
+                    dataToDisplay += "...";
+                }
+                ui->fileContent->setText(dataToDisplay);
+            }
+            else
+            {
+                ui->statusbar->showMessage(reply->errorString(), constants::STATUS_BAR_TIMEOUT);
+            }
+            reply->deleteLater();
+        });
+    });
 }
 
 MainWindow::~MainWindow()

Qt/mainwindow.h

@@ -1,8 +1,17 @@
 #ifndef MAINWINDOW_H
 #define MAINWINDOW_H
 
+// local
+#include "api_handler.h"
+
+// qt
 #include <QMainWindow>
 
+// stdlib
+#include <memory>
+#include <string>
+#include <vector>
+
 QT_BEGIN_NAMESPACE
 namespace Ui { class MainWindow; }
 QT_END_NAMESPACE
@@ -17,5 +26,7 @@ class MainWindow : public QMainWindow
 
 private:
     Ui::MainWindow *ui;
+    std::unique_ptr<APIHandler> m_apiHandler;
+    std::vector<std::string> m_summaries;
 };
 #endif // MAINWINDOW_H