// Copyright (C) 2023 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GFDL-1.3-no-invariants-only

/*!
\ingroup qtquickdemos
\example demos/colorpaletteclient
\examplecategory {Networking}
\meta tags {quick, network, http}
\title Qt Quick Demo - RESTful Color Palette API client
\brief Example of how to create a RESTful API QML client.
\image colorpalette_listing.png

This example shows how to create a basic QML RESTful application with an imaginary color palette
service. The application uses RESTful communication with the selected server to request and send
data. The REST service is provided as a QML element whose child elements wrap the individual
JSON data APIs provided by the server.

\section1 Application functionality

The example provides the following basic functionalities:
\list
    \li Select the server to communicate with
    \li List users and colors
    \li Login and logout users
    \li Modify and create new colors
\endlist

\section2 Server selection

At start the application presents the options for the color palette server to communicate
with. The predefined options are:
\list
    \li \l {https://reqres.in}{reqres.in}, a publicly available REST API test service
    \li \l {RESTful Color Palette Server} {Qt-based REST API server example} in QtHttpServer
\endlist
Once selected, the application issues a test HTTP GET to the color API to check if the service is
accessible.

\image colorpalette_urlselection.png

One major difference between the two predefined API options is that the
\l {RESTful Color Palette Server}{Qt-based REST API server example} is a stateful
application which allows modifying colors, whereas the \e reqres.in is a stateless API testing
service. In other words, when using the \e reqres.in backend, modifying the colors has no impact on
the UI.

\section2 List users and colors

The users and colors are paginated resources on the server-side. This means that the server
provides the data in chunks called \e pages. The UI listing reflects this pagination and views the
data on pages.

Viewing the data on UI is done with standard QML views:
\snippet demos/colorpaletteclient/MainWindow.qml View and model
Where the model is a list of JSON data received from the server.

\section2 Logging in

Logging in happens via the login function provided by the login QML element:
\snippet demos/colorpaletteclient/MainWindow.qml Login
Under the hood the login sends a HTTP POST request. Upon receiving a successful
response the authorization token is extracted from the response, which in turn is then used in
subsequent HTTP requests which require the token.

\section2 Editing colors

Editing and adding new colors is done in a popup:
\image colorpalette_editing.png
Note that uploading the color changes to the server requires that a user has logged in.

\section1 REST implementation

The example illustrates one way to compose a REST service from individual resource elements. In
this example the resources are the paginated \e user and \e color resources plus the login service.
The resource elements are bound together by the base URL (server URL) and the shared network access
manager.

The basis of the REST service is the \e RestService element whose children items compose the actual
service:
\snippet demos/colorpaletteclient/MainWindow.qml RestService QML element

Upon instantiation the \e RestService element loops its children elements and sets them up
to use the same network access manager. This way the individual resources share the same access
details such as the server URL and authorization token.

The actual communication is done with a rest access manager which implements some
convenience functionality to deal specifically with HTTP REST APIs and effectively deals
with sending and receiving the QNetworkRequest and QNetworkReply as needed.

\include examples-run.qdocinc

*/
