From a539c9aacdb1cb252780aa8dc13142a1af31e5a9 Mon Sep 17 00:00:00 2001
From: Martin Rotter <rotter.martinos@gmail.com>
Date: Tue, 28 Oct 2014 17:45:37 +0100
Subject: [PATCH] Fixed #91.

---
 resources/text/CHANGELOG         |   1 +
 src/core/feedsmodel.cpp          | 119 +++++++++++++++++++++++++++++--
 src/core/feedsmodel.h            |   5 ++
 src/definitions/definitions.h.in |   2 +
 src/gui/feedsview.cpp            |   6 +-
 5 files changed, 126 insertions(+), 7 deletions(-)

diff --git a/resources/text/CHANGELOG b/resources/text/CHANGELOG
index a099e12ac..f7d5a5f1c 100644
--- a/resources/text/CHANGELOG
+++ b/resources/text/CHANGELOG
@@ -9,6 +9,7 @@ Fixed:
 
 Added:
 <ul>
+<li>Items in feed list (categories and feeds) now can be re-arranged via drag-drop functionality (issue report #91).</li>
 <li>Tray icon now displays blue number of unread messages if any of those messages is newly downloaded from online feed (enhancement #87).</li>
 <li>Fixed issue request #95: items are now permanently hidden (not deleted from database) when "deleted" from recycle bin.</li>
 <li>Issue request #95: moreover custom incremental ability to update database schema was added to keep RSS Guard 2.0.0.4+ fully compatible with previous releases. Incremental algorithm supports both database backends.</li>
diff --git a/src/core/feedsmodel.cpp b/src/core/feedsmodel.cpp
index f188c4c76..4c6ad2a2b 100755
--- a/src/core/feedsmodel.cpp
+++ b/src/core/feedsmodel.cpp
@@ -25,12 +25,14 @@
 #include "miscellaneous/textfactory.h"
 #include "miscellaneous/databasefactory.h"
 #include "miscellaneous/iconfactory.h"
+#include "gui/messagebox.h"
 
 #include <QSqlError>
 #include <QSqlQuery>
 #include <QSqlRecord>
 #include <QPair>
 #include <QStack>
+#include <QMimeData>
 
 #include <algorithm>
 
@@ -66,6 +68,117 @@ FeedsModel::~FeedsModel() {
   delete m_rootItem;
 }
 
+QMimeData *FeedsModel::mimeData(const QModelIndexList &indexes) const {
+  QMimeData *mime_data = new QMimeData();
+  QByteArray encoded_data;
+  QDataStream stream(&encoded_data, QIODevice::WriteOnly);
+
+  foreach (const QModelIndex &index, indexes) {
+    if (index.column() != 0) {
+      continue;
+    }
+
+    FeedsModelRootItem *item_for_index = itemForIndex(index);
+
+    if (item_for_index->kind() != FeedsModelRootItem::RootItem) {
+      stream << (quintptr) item_for_index;
+    }
+  }
+
+  mime_data->setData(MIME_TYPE_ITEM_POINTER, encoded_data);
+  return mime_data;
+}
+
+QStringList FeedsModel::mimeTypes() const {
+  return QStringList() << MIME_TYPE_ITEM_POINTER;
+}
+
+bool FeedsModel::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) {
+  Q_UNUSED(row)
+  Q_UNUSED(column)
+
+
+  if (action == Qt::IgnoreAction) {
+    return true;
+  }
+  else if (action != Qt::MoveAction) {
+    return false;
+  }
+
+  QByteArray dragged_items_data = data->data(MIME_TYPE_ITEM_POINTER);
+
+  if (dragged_items_data.isEmpty()) {
+    return false;
+  }
+  else {
+    QDataStream stream(&dragged_items_data, QIODevice::ReadOnly);
+
+    while (!stream.atEnd()) {
+      quintptr pointer_to_item;
+      stream >> pointer_to_item;
+
+      // We have item we want to drag, we also determine the target item.
+      FeedsModelRootItem *dragged_item = (FeedsModelRootItem*) pointer_to_item;
+      FeedsModelRootItem *target_item = itemForIndex(parent);
+
+      if (dragged_item == target_item || dragged_item->parent() == target_item) {
+        qDebug("Dragged item is equal to target item or its parent is equal to target item. Cancelling drag-drop action.");
+        return false;
+      }
+
+      if (dragged_item->kind() == FeedsModelRootItem::Feed) {
+        qDebug("Drag-drop action for feed '%s' detected, editing the feed.", qPrintable(dragged_item->title()));
+
+        FeedsModelFeed *actual_feed = static_cast<FeedsModelFeed*>(dragged_item);
+        FeedsModelFeed *feed_new = new FeedsModelFeed(*actual_feed);
+
+        feed_new->setParent(target_item);
+        editFeed(actual_feed, feed_new);
+      }
+      else if (dragged_item->kind() == FeedsModelRootItem::Category) {
+        qDebug("Drag-drop action for category '%s' detected, editing the feed.", qPrintable(dragged_item->title()));
+
+        FeedsModelCategory *actual_category = static_cast<FeedsModelCategory*>(dragged_item);
+        FeedsModelCategory *category_new = new FeedsModelCategory(*actual_category);
+
+        category_new->clearChildren();
+        category_new->setParent(target_item);
+        editCategory(actual_category, category_new);
+      }
+    }
+
+    return true;
+  }
+}
+
+Qt::DropActions FeedsModel::supportedDropActions() const {
+  return Qt::MoveAction;
+}
+
+Qt::ItemFlags FeedsModel::flags(const QModelIndex &index) const { 
+  Qt::ItemFlags base_flags = QAbstractItemModel::flags(index);
+  FeedsModelRootItem *item_for_index = itemForIndex(index);
+
+  switch (item_for_index->kind()) {
+    case FeedsModelRootItem::RecycleBin:
+      return base_flags;
+
+    case FeedsModelRootItem::Category:
+      return base_flags | Qt::ItemIsDragEnabled | Qt::ItemIsDropEnabled;
+
+    case FeedsModelRootItem::Feed:
+      return base_flags | Qt::ItemIsDragEnabled;
+
+    case FeedsModelRootItem::RootItem:
+    default:
+      return base_flags | Qt::ItemIsDropEnabled;
+  }
+
+
+  // TODO: Pokračovat tady: http://qt-project.org/doc/qt-4.8/model-view-programming.html#using-drag-and-drop-with-item-views
+  // neumožnit drag ani drop nad odpadkovým košem
+}
+
 QVariant FeedsModel::headerData(int section, Qt::Orientation orientation, int role) const {
   if (orientation != Qt::Horizontal) {
     return QVariant();
@@ -210,8 +323,7 @@ bool FeedsModel::addCategory(FeedsModelCategory *category, FeedsModelRootItem *p
 }
 
 bool FeedsModel::editCategory(FeedsModelCategory *original_category, FeedsModelCategory *new_category) {
-  QSqlDatabase database = qApp->database()->connection(objectName(),
-                                                       DatabaseFactory::FromSettings);
+  QSqlDatabase database = qApp->database()->connection(objectName(), DatabaseFactory::FromSettings);
   QSqlQuery query_update_category(database);
   FeedsModelRootItem *original_parent = original_category->parent();
   FeedsModelRootItem *new_parent = new_category->parent();
@@ -313,8 +425,7 @@ bool FeedsModel::addFeed(FeedsModelFeed *feed, FeedsModelRootItem *parent) {
 }
 
 bool FeedsModel::editFeed(FeedsModelFeed *original_feed, FeedsModelFeed *new_feed) {
-  QSqlDatabase database = qApp->database()->connection(objectName(),
-                                                       DatabaseFactory::FromSettings);
+  QSqlDatabase database = qApp->database()->connection(objectName(), DatabaseFactory::FromSettings);
   QSqlQuery query_update_feed(database);
   FeedsModelRootItem *original_parent = original_feed->parent();
   FeedsModelRootItem *new_parent = new_feed->parent();
diff --git a/src/core/feedsmodel.h b/src/core/feedsmodel.h
index 9f71fbf3e..19beb0eac 100644
--- a/src/core/feedsmodel.h
+++ b/src/core/feedsmodel.h
@@ -51,6 +51,11 @@ class FeedsModel : public QAbstractItemModel {
       return itemForIndex(index)->data(index.column(), role);
     }
 
+    QMimeData *mimeData(const QModelIndexList &indexes) const;
+    QStringList mimeTypes() const;
+    bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent);
+    Qt::DropActions supportedDropActions() const;
+    Qt::ItemFlags flags(const QModelIndex &index) const;
     QVariant headerData(int section, Qt::Orientation orientation, int role) const;
     QModelIndex index(int row, int column, const QModelIndex &parent) const;
     QModelIndex parent(const QModelIndex &child) const;
diff --git a/src/definitions/definitions.h.in b/src/definitions/definitions.h.in
index d1eb4b23d..81d91305c 100755
--- a/src/definitions/definitions.h.in
+++ b/src/definitions/definitions.h.in
@@ -75,6 +75,8 @@
 #define FEEDS_VIEW_INDENTATION                10
 #define ACCEPT_HEADER_FOR_FEED_DOWNLOADER     "application/atom+xml,application/xml;q=0.9,text/xml;q=0.8,*/*;q=0.7"
 
+#define MIME_TYPE_ITEM_POINTER    "rssguard/itempointer"
+
 #define BACKUP_NAME_SETTINGS    "config"
 #define BACKUP_SUFFIX_SETTINGS  ".ini.backup"
 #define BACKUP_NAME_DATABASE    "database"
diff --git a/src/gui/feedsview.cpp b/src/gui/feedsview.cpp
index 56bc75cb2..b0e084997 100755
--- a/src/gui/feedsview.cpp
+++ b/src/gui/feedsview.cpp
@@ -603,9 +603,9 @@ void FeedsView::setupAppearance() {
   setEditTriggers(QAbstractItemView::NoEditTriggers);
   setIndentation(FEEDS_VIEW_INDENTATION);
   setAcceptDrops(false);
-  setDragEnabled(false);
-  setDropIndicatorShown(false);
-  setDragDropMode(QAbstractItemView::NoDragDrop);
+  setDragEnabled(true);
+  setDropIndicatorShown(true);
+  setDragDropMode(QAbstractItemView::InternalMove);
   setAllColumnsShowFocus(false);
   setRootIsDecorated(false);
   setSelectionMode(QAbstractItemView::SingleSelection);