Add pause and unpause functions for aria2

This functions enable to stop and resume download with aria2.

The Downloader's constructor now checks the paused downloads with the
function "tellWaiting()" to get them at the start of kiwix-desktop.

include/downloader.h

@@ -54,6 +54,8 @@ class Download {
       m_status(K_UNKNOWN),
       m_did(did) {};
   void updateStatus(bool follow=false);
+  void pauseDownload();
+  void resumeDownload();
   StatusResult getStatus()          { return m_status; }
   std::string  getDid()             { return m_did; }
   std::string  getFollowedBy()      { return m_followedBy; }

src/aria2.cpp

@@ -171,7 +171,6 @@ std::vector<std::string> Aria2::tellActive()
   MethodCall methodCall("aria2.tellActive", m_secret);
   auto statusArray = methodCall.newParamValue().getArray();
   statusArray.addValue().set(std::string("gid"));
-  statusArray.addValue().set(std::string("following"));
   auto responseContent = doRequest(methodCall);
   MethodResponse response(responseContent);
   std::vector<std::string> activeGID;
@@ -186,6 +185,27 @@ std::vector<std::string> Aria2::tellActive()
   return activeGID;
 }
 
+std::vector<std::string> Aria2::tellWaiting()
+{
+  MethodCall methodCall("aria2.tellWaiting", m_secret);
+  methodCall.newParamValue().set(0);
+  methodCall.newParamValue().set(99); // max number of downloads to be returned, don't know how to set this properly assumed that there will not be more than 99 paused downloads.
+  auto statusArray = methodCall.newParamValue().getArray();
+  statusArray.addValue().set(std::string("gid"));
+  auto responseContent = doRequest(methodCall);
+  MethodResponse response(responseContent);
+  std::vector<std::string> waitingGID;
+  int index = 0;
+  while(true) {
+    try {
+      auto structNode = response.getParamValue(0).getArray().getValue(index++).getStruct();
+      auto gidNode = structNode.getMember("gid");
+      waitingGID.push_back(gidNode.getValue().getAsS());
+    } catch (InvalidRPCNode& e) { break; }
+  }
+  return waitingGID;
+}
+
 void Aria2::saveSession()
 {
   MethodCall methodCall("aria2.saveSession", m_secret);
@@ -199,5 +219,18 @@ void Aria2::shutdown()
   doRequest(methodCall);
 }
 
+void Aria2::pause(const std::string& gid)
+{
+    MethodCall methodCall("aria2.pause", m_secret);
+    methodCall.newParamValue().set(gid);
+    doRequest(methodCall);
+}
+
+void Aria2::unpause(const std::string& gid)
+{
+    MethodCall methodCall("aria2.unpause", m_secret);
+    methodCall.newParamValue().set(gid);
+    doRequest(methodCall);
+}
 
 } // end namespace kiwix

src/aria2.h

@@ -37,8 +37,11 @@ class Aria2
     std::string addUri(const std::vector<std::string>& uri);
     std::string tellStatus(const std::string& gid, const std::vector<std::string>& statusKey);
     std::vector<std::string> tellActive();
+    std::vector<std::string> tellWaiting();
     void saveSession();
     void shutdown();
+    void pause(const std::string& gid);
+    void unpause(const std::string& gid);
 };
 
 }; //end namespace kiwix

src/downloader.cpp

@@ -93,6 +93,24 @@ void Download::updateStatus(bool follow)
   }
 }
 
+void Download::resumeDownload()
+{
+    if (!m_followedBy.empty())
+        mp_aria->unpause(m_followedBy);
+    else
+        mp_aria->unpause(m_did);
+    updateStatus(true);
+}
+
+void Download::pauseDownload()
+{
+    if (!m_followedBy.empty())
+        mp_aria->pause(m_followedBy);
+    else
+        mp_aria->pause(m_did);
+    updateStatus(true);
+}
+
 /* Constructor */
 Downloader::Downloader() :
   mp_aria(new Aria2())
@@ -101,6 +119,10 @@ Downloader::Downloader() :
     m_knownDownloads[gid] = std::unique_ptr<Download>(new Download(mp_aria, gid));
     m_knownDownloads[gid]->updateStatus();
   }
+  for (auto gid : mp_aria->tellWaiting()) {
+    m_knownDownloads[gid] = std::unique_ptr<Download>(new Download(mp_aria, gid));
+    m_knownDownloads[gid]->updateStatus();
+  }
 }
 
 
@@ -148,6 +170,13 @@ Download* Downloader::getDownload(const std::string& did)
         m_knownDownloads.at(gid).get()->updateStatus(true);
         return m_knownDownloads[gid].get();
       }
+    }
+    for (auto gid : mp_aria->tellWaiting()) {
+      if (gid == did) {
+        m_knownDownloads[gid] = std::unique_ptr<Download>(new Download(mp_aria, gid));
+        m_knownDownloads.at(gid).get()->updateStatus(true);
+        return m_knownDownloads[gid].get();
+      }
   }
     throw e;
   }