qgsarcgisrestquery.cpp

Go to the documentation of this file.

/***************************************************************************
    qgsarcgisrestquery.cpp
    ----------------------
    begin                : December 2020
    copyright            : (C) 2020 by Nyall Dawson
    email                : nyall dot dawson at gmail dot com
 ***************************************************************************
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 ***************************************************************************/
 
#include "qgsarcgisrestquery.h"
#include "qgsarcgisrestutils.h"
#include "qgsblockingnetworkrequest.h"
#include "qgsnetworkaccessmanager.h"
#include "qgslogger.h"
#include "qgsapplication.h"
#include "qgsmessagelog.h"
#include "qgsauthmanager.h"
#include "qgscoordinatetransform.h"
 
#include <QUrl>
#include <QUrlQuery>
#include <QImageReader>
#include <QRegularExpression>
 
QVariantMap QgsArcGisRestQueryUtils::getServiceInfo( const QString &baseurl, const QString &authcfg, QString &errorTitle, QString &errorText, const QgsStringMap &requestHeaders )
{
  // http://sampleserver5.arcgisonline.com/arcgis/rest/services/Energy/Geology/FeatureServer?f=json
  QUrl queryUrl( baseurl );
  QUrlQuery query( queryUrl );
  query.addQueryItem( QStringLiteral( "f" ), QStringLiteral( "json" ) );
  queryUrl.setQuery( query );
  return queryServiceJSON( queryUrl, authcfg, errorTitle, errorText, requestHeaders );
}
 
QVariantMap QgsArcGisRestQueryUtils::getLayerInfo( const QString &layerurl, const QString &authcfg, QString &errorTitle, QString &errorText, const QgsStringMap &requestHeaders )
{
  // http://sampleserver5.arcgisonline.com/arcgis/rest/services/Energy/Geology/FeatureServer/1?f=json
  QUrl queryUrl( layerurl );
  QUrlQuery query( queryUrl );
  query.addQueryItem( QStringLiteral( "f" ), QStringLiteral( "json" ) );
  queryUrl.setQuery( query );
  return queryServiceJSON( queryUrl, authcfg, errorTitle, errorText, requestHeaders );
}
 
QVariantMap QgsArcGisRestQueryUtils::getObjectIds( const QString &layerurl, const QString &authcfg, QString &errorTitle, QString &errorText, const QgsStringMap &requestHeaders, const QgsRectangle &bbox )
{
  // http://sampleserver5.arcgisonline.com/arcgis/rest/services/Energy/Geology/FeatureServer/1/query?where=1%3D1&returnIdsOnly=true&f=json
  QUrl queryUrl( layerurl + "/query" );
  QUrlQuery query( queryUrl );
  query.addQueryItem( QStringLiteral( "f" ), QStringLiteral( "json" ) );
  query.addQueryItem( QStringLiteral( "where" ), QStringLiteral( "1=1" ) );
  query.addQueryItem( QStringLiteral( "returnIdsOnly" ), QStringLiteral( "true" ) );
  if ( !bbox.isNull() )
  {
    query.addQueryItem( QStringLiteral( "geometry" ), QStringLiteral( "%1,%2,%3,%4" )
                        .arg( bbox.xMinimum(), 0, 'f', -1 ).arg( bbox.yMinimum(), 0, 'f', -1 )
                        .arg( bbox.xMaximum(), 0, 'f', -1 ).arg( bbox.yMaximum(), 0, 'f', -1 ) );
    query.addQueryItem( QStringLiteral( "geometryType" ), QStringLiteral( "esriGeometryEnvelope" ) );
    query.addQueryItem( QStringLiteral( "spatialRel" ), QStringLiteral( "esriSpatialRelEnvelopeIntersects" ) );
  }
  queryUrl.setQuery( query );
  return queryServiceJSON( queryUrl, authcfg, errorTitle, errorText, requestHeaders );
}
 
QVariantMap QgsArcGisRestQueryUtils::getObjects( const QString &layerurl, const QString &authcfg, const QList<quint32> &objectIds, const QString &crs,
    bool fetchGeometry, const QStringList &fetchAttributes,
    bool fetchM, bool fetchZ,
    const QgsRectangle &filterRect,
    QString &errorTitle, QString &errorText, const QgsStringMap &requestHeaders, QgsFeedback *feedback )
{
  QStringList ids;
  for ( const int id : objectIds )
  {
    ids.append( QString::number( id ) );
  }
  QUrl queryUrl( layerurl + "/query" );
  QUrlQuery query( queryUrl );
  query.addQueryItem( QStringLiteral( "f" ), QStringLiteral( "json" ) );
  query.addQueryItem( QStringLiteral( "objectIds" ), ids.join( QLatin1Char( ',' ) ) );
  const QString wkid = crs.indexOf( QLatin1Char( ':' ) ) >= 0 ? crs.split( ':' )[1] : QString();
  query.addQueryItem( QStringLiteral( "inSR" ), wkid );
  query.addQueryItem( QStringLiteral( "outSR" ), wkid );
 
  query.addQueryItem( QStringLiteral( "returnGeometry" ), fetchGeometry ? QStringLiteral( "true" ) : QStringLiteral( "false" ) );
 
  QString outFields;
  if ( fetchAttributes.isEmpty() )
    outFields = QStringLiteral( "*" );
  else
    outFields = fetchAttributes.join( ',' );
  query.addQueryItem( QStringLiteral( "outFields" ), outFields );
 
  query.addQueryItem( QStringLiteral( "returnM" ), fetchM ? QStringLiteral( "true" ) : QStringLiteral( "false" ) );
  query.addQueryItem( QStringLiteral( "returnZ" ), fetchZ ? QStringLiteral( "true" ) : QStringLiteral( "false" ) );
  if ( !filterRect.isNull() )
  {
    query.addQueryItem( QStringLiteral( "geometry" ), QStringLiteral( "%1,%2,%3,%4" )
                        .arg( filterRect.xMinimum(), 0, 'f', -1 ).arg( filterRect.yMinimum(), 0, 'f', -1 )
                        .arg( filterRect.xMaximum(), 0, 'f', -1 ).arg( filterRect.yMaximum(), 0, 'f', -1 ) );
    query.addQueryItem( QStringLiteral( "geometryType" ), QStringLiteral( "esriGeometryEnvelope" ) );
    query.addQueryItem( QStringLiteral( "spatialRel" ), QStringLiteral( "esriSpatialRelEnvelopeIntersects" ) );
  }
  queryUrl.setQuery( query );
  return queryServiceJSON( queryUrl,  authcfg, errorTitle, errorText, requestHeaders, feedback );
}
 
QList<quint32> QgsArcGisRestQueryUtils::getObjectIdsByExtent( const QString &layerurl, const QgsRectangle &filterRect, QString &errorTitle, QString &errorText, const QString &authcfg, const QgsStringMap &requestHeaders, QgsFeedback *feedback )
{
  QUrl queryUrl( layerurl + "/query" );
  QUrlQuery query( queryUrl );
  query.addQueryItem( QStringLiteral( "f" ), QStringLiteral( "json" ) );
  query.addQueryItem( QStringLiteral( "where" ), QStringLiteral( "1=1" ) );
  query.addQueryItem( QStringLiteral( "returnIdsOnly" ), QStringLiteral( "true" ) );
  query.addQueryItem( QStringLiteral( "geometry" ), QStringLiteral( "%1,%2,%3,%4" )
                      .arg( filterRect.xMinimum(), 0, 'f', -1 ).arg( filterRect.yMinimum(), 0, 'f', -1 )
                      .arg( filterRect.xMaximum(), 0, 'f', -1 ).arg( filterRect.yMaximum(), 0, 'f', -1 ) );
  query.addQueryItem( QStringLiteral( "geometryType" ), QStringLiteral( "esriGeometryEnvelope" ) );
  query.addQueryItem( QStringLiteral( "spatialRel" ), QStringLiteral( "esriSpatialRelEnvelopeIntersects" ) );
  queryUrl.setQuery( query );
  const QVariantMap objectIdData = queryServiceJSON( queryUrl, authcfg, errorTitle, errorText, requestHeaders, feedback );
 
  if ( objectIdData.isEmpty() )
  {
    return QList<quint32>();
  }
 
  QList<quint32> ids;
  const QVariantList objectIdsList = objectIdData[QStringLiteral( "objectIds" )].toList();
  ids.reserve( objectIdsList.size() );
  for ( const QVariant &objectId : objectIdsList )
  {
    ids << objectId.toInt();
  }
  return ids;
}
 
QByteArray QgsArcGisRestQueryUtils::queryService( const QUrl &u, const QString &authcfg, QString &errorTitle, QString &errorText, const QgsStringMap &requestHeaders, QgsFeedback *feedback, QString *contentType )
{
  const QUrl url = parseUrl( u );
 
  QNetworkRequest request( url );
  QgsSetRequestInitiatorClass( request, QStringLiteral( "QgsArcGisRestUtils" ) );
  for ( auto it = requestHeaders.constBegin(); it != requestHeaders.constEnd(); ++it )
  {
    request.setRawHeader( it.key().toUtf8(), it.value().toUtf8() );
  }
 
  QgsBlockingNetworkRequest networkRequest;
  networkRequest.setAuthCfg( authcfg );
  const QgsBlockingNetworkRequest::ErrorCode error = networkRequest.get( request, false, feedback );
 
  if ( feedback && feedback->isCanceled() )
    return QByteArray();
 
  // Handle network errors
  if ( error != QgsBlockingNetworkRequest::NoError )
  {
    QgsDebugMsg( QStringLiteral( "Network error: %1" ).arg( networkRequest.errorMessage() ) );
    errorTitle = QStringLiteral( "Network error" );
    errorText = networkRequest.errorMessage();
    return QByteArray();
  }
 
  const QgsNetworkReplyContent content = networkRequest.reply();
  if ( contentType )
    *contentType = content.rawHeader( "Content-Type" );
  return content.content();
}
 
QVariantMap QgsArcGisRestQueryUtils::queryServiceJSON( const QUrl &url, const QString &authcfg, QString &errorTitle, QString &errorText, const QgsStringMap &requestHeaders, QgsFeedback *feedback )
{
  const QByteArray reply = queryService( url, authcfg, errorTitle, errorText, requestHeaders, feedback );
  if ( !errorTitle.isEmpty() )
  {
    return QVariantMap();
  }
  if ( feedback && feedback->isCanceled() )
    return QVariantMap();
 
  // Parse data
  QJsonParseError err;
  const QJsonDocument doc = QJsonDocument::fromJson( reply, &err );
  if ( doc.isNull() )
  {
    errorTitle = QStringLiteral( "Parsing error" );
    errorText = err.errorString();
    QgsDebugMsg( QStringLiteral( "Parsing error: %1" ).arg( err.errorString() ) );
    return QVariantMap();
  }
  const QVariantMap res = doc.object().toVariantMap();
  if ( res.contains( QStringLiteral( "error" ) ) )
  {
    const QVariantMap error = res.value( QStringLiteral( "error" ) ).toMap();
    errorText = error.value( QStringLiteral( "message" ) ).toString();
    errorTitle = QObject::tr( "Error %1" ).arg( error.value( QStringLiteral( "code" ) ).toString() );
    return QVariantMap();
  }
  return res;
}
 
QUrl QgsArcGisRestQueryUtils::parseUrl( const QUrl &url )
{
  QUrl modifiedUrl( url );
  if ( modifiedUrl.toString().contains( QLatin1String( "fake_qgis_http_endpoint" ) ) )
  {
    // Just for testing with local files instead of http:// resources
    QString modifiedUrlString = modifiedUrl.toString();
    // Qt5 does URL encoding from some reason (of the FILTER parameter for example)
    modifiedUrlString = QUrl::fromPercentEncoding( modifiedUrlString.toUtf8() );
    modifiedUrlString.replace( QLatin1String( "fake_qgis_http_endpoint/" ), QLatin1String( "fake_qgis_http_endpoint_" ) );
    QgsDebugMsg( QStringLiteral( "Get %1" ).arg( modifiedUrlString ) );
    modifiedUrlString = modifiedUrlString.mid( QStringLiteral( "http://" ).size() );
    QString args = modifiedUrlString.mid( modifiedUrlString.indexOf( '?' ) );
    if ( modifiedUrlString.size() > 150 )
    {
      args = QCryptographicHash::hash( args.toUtf8(), QCryptographicHash::Md5 ).toHex();
    }
    else
    {
      args.replace( QLatin1String( "?" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( "&" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( "<" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( ">" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( "'" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( "\"" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( " " ), QLatin1String( "_" ) );
      args.replace( QLatin1String( ":" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( "/" ), QLatin1String( "_" ) );
      args.replace( QLatin1String( "\n" ), QLatin1String( "_" ) );
    }
#ifdef Q_OS_WIN
    // Passing "urls" like "http://c:/path" to QUrl 'eats' the : after c,
    // so we must restore it
    if ( modifiedUrlString[1] == '/' )
    {
      modifiedUrlString = modifiedUrlString[0] + ":/" + modifiedUrlString.mid( 2 );
    }
#endif
    modifiedUrlString = modifiedUrlString.mid( 0, modifiedUrlString.indexOf( '?' ) ) + args;
    QgsDebugMsg( QStringLiteral( "Get %1 (after laundering)" ).arg( modifiedUrlString ) );
    modifiedUrl = QUrl::fromLocalFile( modifiedUrlString );
  }
 
  return modifiedUrl;
}
 
void QgsArcGisRestQueryUtils::adjustBaseUrl( QString &baseUrl, const QString &name )
{
  const QStringList parts = name.split( '/' );
  QString checkString;
  for ( const QString &part : parts )
  {
    if ( !checkString.isEmpty() )
      checkString += QString( '/' );
 
    checkString += part;
    if ( baseUrl.indexOf( QRegularExpression( checkString.replace( '/', QLatin1String( "\\/" ) ) + QStringLiteral( "\\/?$" ) ) ) > -1 )
    {
      baseUrl = baseUrl.left( baseUrl.length() - checkString.length() - 1 );
      break;
    }
  }
}
 
void QgsArcGisRestQueryUtils::visitFolderItems( const std::function< void( const QString &, const QString & ) > &visitor, const QVariantMap &serviceData, const QString &baseUrl )
{
  QString base( baseUrl );
  bool baseChecked = false;
  if ( !base.endsWith( '/' ) )
    base += QLatin1Char( '/' );
 
  const QStringList folderList = serviceData.value( QStringLiteral( "folders" ) ).toStringList();
  for ( const QString &folder : folderList )
  {
    if ( !baseChecked )
    {
      adjustBaseUrl( base, folder );
      baseChecked = true;
    }
    visitor( folder, base + folder );
  }
}
 
void QgsArcGisRestQueryUtils::visitServiceItems( const std::function<void ( const QString &, const QString &, const QString &, const ServiceTypeFilter )> &visitor, const QVariantMap &serviceData, const QString &baseUrl )
{
  QString base( baseUrl );
  bool baseChecked = false;
  if ( !base.endsWith( '/' ) )
    base += QLatin1Char( '/' );
 
  const QVariantList serviceList = serviceData.value( QStringLiteral( "services" ) ).toList();
  for ( const QVariant &service : serviceList )
  {
    const QVariantMap serviceMap = service.toMap();
    const QString serviceType = serviceMap.value( QStringLiteral( "type" ) ).toString();
    if ( serviceType != QLatin1String( "MapServer" ) && serviceType != QLatin1String( "ImageServer" ) && serviceType != QLatin1String( "FeatureServer" ) )
      continue;
 
    const ServiceTypeFilter type = serviceType == QLatin1String( "FeatureServer" ) ? Vector : Raster;
 
    const QString serviceName = serviceMap.value( QStringLiteral( "name" ) ).toString();
    const QString displayName = serviceName.split( '/' ).last();
    if ( !baseChecked )
    {
      adjustBaseUrl( base, serviceName );
      baseChecked = true;
    }
 
    visitor( displayName, base + serviceName + '/' + serviceType, serviceType, type );
  }
}
 
void QgsArcGisRestQueryUtils::addLayerItems( const std::function<void ( const QString &, ServiceTypeFilter, QgsWkbTypes::GeometryType, const QString &, const QString &, const QString &, const QString &, bool, const QString &, const QString & )> &visitor, const QVariantMap &serviceData, const QString &parentUrl, const QString &parentSupportedFormats, const ServiceTypeFilter filter )
{
  const QString authid = QgsArcGisRestUtils::convertSpatialReference( serviceData.value( QStringLiteral( "spatialReference" ) ).toMap() ).authid();
 
  bool found = false;
  const QList<QByteArray> supportedFormats = QImageReader::supportedImageFormats();
  const QStringList supportedImageFormatTypes = serviceData.value( QStringLiteral( "supportedImageFormatTypes" ) ).toString().isEmpty() ? parentSupportedFormats.split( ',' ) : serviceData.value( QStringLiteral( "supportedImageFormatTypes" ) ).toString().split( ',' );
  QString format = supportedImageFormatTypes.value( 0 );
  for ( const QString &encoding : supportedImageFormatTypes )
  {
    for ( const QByteArray &fmt : supportedFormats )
    {
      if ( encoding.startsWith( fmt, Qt::CaseInsensitive ) )
      {
        format = encoding;
        found = true;
        break;
      }
    }
    if ( found )
      break;
  }
  const QStringList capabilities = serviceData.value( QStringLiteral( "capabilities" ) ).toString().split( ',' );
 
  // If the requested layer type is vector, do not show raster-only layers (i.e. non query-able layers)
  const bool serviceMayHaveQueryCapability = capabilities.contains( QStringLiteral( "Query" ) ) ||
      serviceData.value( QStringLiteral( "serviceDataType" ) ).toString().startsWith( QLatin1String( "esriImageService" ) );
 
  const bool serviceMayRenderMaps = capabilities.contains( QStringLiteral( "Map" ) ) ||
                                    serviceData.value( QStringLiteral( "serviceDataType" ) ).toString().startsWith( QLatin1String( "esriImageService" ) );
 
  const QVariantList layerInfoList = serviceData.value( QStringLiteral( "layers" ) ).toList();
  for ( const QVariant &layerInfo : layerInfoList )
  {
    const QVariantMap layerInfoMap = layerInfo.toMap();
    const QString id = layerInfoMap.value( QStringLiteral( "id" ) ).toString();
    const QString parentLayerId = layerInfoMap.value( QStringLiteral( "parentLayerId" ) ).toString();
    const QString name = layerInfoMap.value( QStringLiteral( "name" ) ).toString();
    const QString description = layerInfoMap.value( QStringLiteral( "description" ) ).toString();
 
    // Yes, potentially we may visit twice, once as as a raster (if applicable), and once as a vector (if applicable)!
    if ( serviceMayRenderMaps && ( filter == Raster || filter == AllTypes ) )
    {
      if ( !layerInfoMap.value( QStringLiteral( "subLayerIds" ) ).toList().empty() )
      {
        visitor( parentLayerId, Raster, QgsWkbTypes::UnknownGeometry, id, name, description, parentUrl + '/' + id, true, QString(), format );
      }
      else
      {
        visitor( parentLayerId, Raster, QgsWkbTypes::UnknownGeometry, id, name, description, parentUrl + '/' + id, false, authid, format );
      }
    }
 
    if ( serviceMayHaveQueryCapability && ( filter == Vector || filter == AllTypes ) )
    {
      const QString geometryType = layerInfoMap.value( QStringLiteral( "geometryType" ) ).toString();
#if 0
      // we have a choice here -- if geometryType is unknown and the service reflects that it supports Map capabilities,
      // then we can't be sure whether or not the individual sublayers support Query or Map requests only. So we either:
      // 1. Send off additional requests for each individual layer's capabilities (too expensive)
      // 2. Err on the side of only showing services we KNOW will work for layer -- but this has the side effect that layers
      //    which ARE available as feature services will only show as raster mapserver layers, which is VERY bad/restrictive
      // 3. Err on the side of showing services we THINK may work, even though some of them may or may not work depending on the actual
      //    server configuration
      // We opt for 3, because otherwise we're making it impossible for users to load valid vector layers into QGIS
 
      if ( serviceMayRenderMaps )
      {
        if ( geometryType.isEmpty() )
          continue;
      }
#endif
 
      const QgsWkbTypes::Type wkbType = QgsArcGisRestUtils::convertGeometryType( geometryType );
 
 
      if ( !layerInfoMap.value( QStringLiteral( "subLayerIds" ) ).toList().empty() )
      {
        visitor( parentLayerId, Vector, QgsWkbTypes::geometryType( wkbType ), id, name, description, parentUrl + '/' + id, true, QString(), format );
      }
      else
      {
        visitor( parentLayerId, Vector, QgsWkbTypes::geometryType( wkbType ), id, name, description, parentUrl + '/' + id, false, authid, format );
      }
    }
  }
 
  // Add root MapServer as raster layer when multiple layers are listed
  if ( filter != Vector && layerInfoList.count() > 1 && serviceData.contains( QStringLiteral( "supportedImageFormatTypes" ) ) )
  {
    const QString name = QStringLiteral( "(%1)" ).arg( QObject::tr( "All layers" ) );
    const QString description = serviceData.value( QStringLiteral( "Comments" ) ).toString();
    visitor( nullptr, Raster, QgsWkbTypes::UnknownGeometry, nullptr, name, description, parentUrl, false, authid, format );
  }
 
  // Add root ImageServer as layer
  if ( serviceData.value( QStringLiteral( "serviceDataType" ) ).toString().startsWith( QLatin1String( "esriImageService" ) ) )
  {
    const QString name = serviceData.value( QStringLiteral( "name" ) ).toString();
    const QString description = serviceData.value( QStringLiteral( "description" ) ).toString();
    visitor( nullptr, Raster, QgsWkbTypes::UnknownGeometry, nullptr, name, description, parentUrl, false, authid, format );
  }
}
 
 
 
//
// QgsArcGisAsyncQuery
//
 
QgsArcGisAsyncQuery::QgsArcGisAsyncQuery( QObject *parent )
  : QObject( parent )
{
}
 
QgsArcGisAsyncQuery::~QgsArcGisAsyncQuery()
{
  if ( mReply )
    mReply->deleteLater();
}
 
void QgsArcGisAsyncQuery::start( const QUrl &url, const QString &authCfg, QByteArray *result, bool allowCache, const QgsStringMap &headers )
{
  mResult = result;
  QNetworkRequest request( url );
 
  for ( auto it = headers.constBegin(); it != headers.constEnd(); ++it )
  {
    request.setRawHeader( it.key().toUtf8(), it.value().toUtf8() );
  }
 
  if ( !authCfg.isEmpty() &&  !QgsApplication::authManager()->updateNetworkRequest( request, authCfg ) )
  {
    const QString error = tr( "network request update failed for authentication config" );
    emit failed( QStringLiteral( "Network" ), error );
    return;
  }
 
  QgsSetRequestInitiatorClass( request, QStringLiteral( "QgsArcGisAsyncQuery" ) );
  if ( allowCache )
  {
    request.setAttribute( QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferCache );
    request.setAttribute( QNetworkRequest::CacheSaveControlAttribute, true );
  }
  mReply = QgsNetworkAccessManager::instance()->get( request );
  connect( mReply, &QNetworkReply::finished, this, &QgsArcGisAsyncQuery::handleReply );
}
 
void QgsArcGisAsyncQuery::handleReply()
{
  mReply->deleteLater();
  // Handle network errors
  if ( mReply->error() != QNetworkReply::NoError )
  {
    QgsDebugMsg( QStringLiteral( "Network error: %1" ).arg( mReply->errorString() ) );
    emit failed( QStringLiteral( "Network error" ), mReply->errorString() );
    return;
  }
 
  // Handle HTTP redirects
  const QVariant redirect = mReply->attribute( QNetworkRequest::RedirectionTargetAttribute );
  if ( !redirect.isNull() )
  {
    QNetworkRequest request = mReply->request();
    QgsSetRequestInitiatorClass( request, QStringLiteral( "QgsArcGisAsyncQuery" ) );
    QgsDebugMsg( "redirecting to " + redirect.toUrl().toString() );
    request.setUrl( redirect.toUrl() );
    mReply = QgsNetworkAccessManager::instance()->get( request );
    connect( mReply, &QNetworkReply::finished, this, &QgsArcGisAsyncQuery::handleReply );
    return;
  }
 
  *mResult = mReply->readAll();
  mResult = nullptr;
  emit finished();
}
 
//
// QgsArcGisAsyncParallelQuery
//
 
QgsArcGisAsyncParallelQuery::QgsArcGisAsyncParallelQuery( const QString &authcfg, const QgsStringMap &requestHeaders, QObject *parent )
  : QObject( parent )
  , mAuthCfg( authcfg )
  , mRequestHeaders( requestHeaders )
{
}
 
void QgsArcGisAsyncParallelQuery::start( const QVector<QUrl> &urls, QVector<QByteArray> *results, bool allowCache )
{
  Q_ASSERT( results->size() == urls.size() );
  mResults = results;
  mPendingRequests = mResults->size();
  for ( int i = 0, n = urls.size(); i < n; ++i )
  {
    QNetworkRequest request( urls[i] );
    QgsSetRequestInitiatorClass( request, QStringLiteral( "QgsArcGisAsyncParallelQuery" ) );
    QgsSetRequestInitiatorId( request, QString::number( i ) );
 
    for ( auto it = mRequestHeaders.constBegin(); it != mRequestHeaders.constEnd(); ++it )
    {
      request.setRawHeader( it.key().toUtf8(), it.value().toUtf8() );
    }
    if ( !mAuthCfg.isEmpty() && !QgsApplication::authManager()->updateNetworkRequest( request, mAuthCfg ) )
    {
      const QString error = tr( "network request update failed for authentication config" );
      mErrors.append( error );
      QgsMessageLog::logMessage( error, tr( "Network" ) );
      continue;
    }
 
    request.setAttribute( QNetworkRequest::HttpPipeliningAllowedAttribute, true );
    if ( allowCache )
    {
      request.setAttribute( QNetworkRequest::CacheLoadControlAttribute, QNetworkRequest::PreferCache );
      request.setAttribute( QNetworkRequest::CacheSaveControlAttribute, true );
      request.setRawHeader( "Connection", "keep-alive" );
    }
    QNetworkReply *reply = QgsNetworkAccessManager::instance()->get( request );
    reply->setProperty( "idx", i );
    connect( reply, &QNetworkReply::finished, this, &QgsArcGisAsyncParallelQuery::handleReply );
  }
}
 
void QgsArcGisAsyncParallelQuery::handleReply()
{
  QNetworkReply *reply = qobject_cast<QNetworkReply *>( QObject::sender() );
  const QVariant redirect = reply->attribute( QNetworkRequest::RedirectionTargetAttribute );
  const int idx = reply->property( "idx" ).toInt();
  reply->deleteLater();
  if ( reply->error() != QNetworkReply::NoError )
  {
    // Handle network errors
    mErrors.append( reply->errorString() );
    --mPendingRequests;
  }
  else if ( !redirect.isNull() )
  {
    // Handle HTTP redirects
    QNetworkRequest request = reply->request();
    QgsSetRequestInitiatorClass( request, QStringLiteral( "QgsArcGisAsyncParallelQuery" ) );
    QgsDebugMsg( "redirecting to " + redirect.toUrl().toString() );
    request.setUrl( redirect.toUrl() );
    reply = QgsNetworkAccessManager::instance()->get( request );
    reply->setProperty( "idx", idx );
    connect( reply, &QNetworkReply::finished, this, &QgsArcGisAsyncParallelQuery::handleReply );
  }
  else
  {
    // All OK
    ( *mResults )[idx] = reply->readAll();
    --mPendingRequests;
  }
  if ( mPendingRequests == 0 )
  {
    emit finished( mErrors );
    mResults = nullptr;
    mErrors.clear();
  }
}