// For license of this file, see <project-root-folder>/LICENSE.md.

#include "core/feedsproxymodel.h"

#include "core/feedsmodel.h"
#include "definitions/definitions.h"
#include "miscellaneous/application.h"
#include "miscellaneous/regexfactory.h"
#include "services/abstract/rootitem.h"

#include <QTimer>

FeedsProxyModel::FeedsProxyModel(FeedsModel* source_model, QObject* parent)
  : QSortFilterProxyModel(parent), m_sourceModel(source_model), m_selectedItem(nullptr), m_showUnreadOnly(false) {
  setObjectName(QSL("FeedsProxyModel"));
  setSortRole(Qt::EditRole);
  setSortCaseSensitivity(Qt::CaseInsensitive);
  setFilterCaseSensitivity(Qt::CaseInsensitive);
  setFilterKeyColumn(-1);
  setFilterRole(Qt::EditRole);
  setDynamicSortFilter(true);
  setSourceModel(m_sourceModel);

  // Describes priorities of node types for sorting.
  // Smaller index means that item is "smaller" which
  // means it should be more on top when sorting
  // in ascending order.
  m_priorities = {
    RootItemKind::Kind::Category,
    RootItemKind::Kind::Feed,
    RootItemKind::Kind::Labels,
    RootItemKind::Kind::Important,
    RootItemKind::Kind::Bin
  };
}

FeedsProxyModel::~FeedsProxyModel() {
  qDebug("Destroying FeedsProxyModel instance");
}

QModelIndexList FeedsProxyModel::match(const QModelIndex& start, int role, const QVariant& value, int hits, Qt::MatchFlags flags) const {
  QModelIndexList result;
  const int match_type = flags & 0x0F;
  const Qt::CaseSensitivity cs = Qt::CaseInsensitive;
  const bool recurse = (flags& Qt::MatchRecursive) > 0;
  const bool wrap = (flags& Qt::MatchWrap) > 0;
  const bool all_hits = (hits == -1);
  QString entered_text;
  const QModelIndex p = parent(start);
  int from = start.row();
  int to = rowCount(p);

  for (int i = 0; (wrap && i < 2) || (!wrap && i < 1); ++i) {
    for (int r = from; (r < to) && (all_hits || result.count() < hits); ++r) {
      QModelIndex idx = index(r, start.column(), p);

      if (!idx.isValid()) {
        continue;
      }

      QModelIndex mapped_idx = mapToSource(idx);
      QVariant item_value = m_sourceModel->itemForIndex(mapped_idx)->title();

      // QVariant based matching.
      if (match_type == Qt::MatchExactly) {
        if (value == item_value) {
          result.append(idx);
        }
      }

      // QString based matching.
      else {
        if (entered_text.isEmpty()) {
          entered_text = value.toString();
        }

        QString item_text = item_value.toString();

        switch (match_type) {
#if QT_VERSION >= 0x050F00 // Qt >= 5.15.0
          case Qt::MatchRegularExpression:
#else
          case Qt::MatchRegExp:
#endif
            if (QRegularExpression(entered_text,
                                   QRegularExpression::PatternOption::CaseInsensitiveOption |
                                   QRegularExpression::PatternOption::UseUnicodePropertiesOption).match(item_text).hasMatch()) {
              result.append(idx);
            }

            break;

          case Qt::MatchWildcard:
            if (QRegularExpression(RegexFactory::wildcardToRegularExpression(entered_text),
                                   QRegularExpression::PatternOption::CaseInsensitiveOption |
                                   QRegularExpression::PatternOption::UseUnicodePropertiesOption).match(item_text).hasMatch()) {
              result.append(idx);
            }

            break;

          case Qt::MatchStartsWith:
            if (item_text.startsWith(entered_text, cs)) {
              result.append(idx);
            }

            break;

          case Qt::MatchEndsWith:
            if (item_text.endsWith(entered_text, cs)) {
              result.append(idx);
            }

            break;

          case Qt::MatchFixedString:
            if (item_text.compare(entered_text, cs) == 0) {
              result.append(idx);
            }

            break;

          case Qt::MatchContains:
          default:
            if (item_text.contains(entered_text, cs)) {
              result.append(idx);
            }

            break;
        }
      }

      if (recurse && hasChildren(idx)) {
        result +=
          match(index(0, idx.column(), idx), role, (entered_text.isEmpty() ? value : entered_text),
                (all_hits ? -1 : hits - result.count()), flags);
      }
    }

    from = 0;
    to = start.row();
  }

  return result;
}

bool FeedsProxyModel::lessThan(const QModelIndex& left, const QModelIndex& right) const {
  if (left.isValid() && right.isValid()) {
    // Make necessary castings.
    const RootItem* left_item = m_sourceModel->itemForIndex(left);
    const RootItem* right_item = m_sourceModel->itemForIndex(right);

    // NOTE: Here we want to accomplish that ALL
    // categories are queued one after another and all
    // feeds are queued one after another too.
    // Moreover, sort everything alphabetically or
    // by item counts, depending on the sort column.

    if (left_item->keepOnTop()) {
      return sortOrder() == Qt::SortOrder::AscendingOrder;
    }
    else if (right_item->keepOnTop()) {
      return sortOrder() == Qt::SortOrder::DescendingOrder;
    }
    else if (left_item->kind() == right_item->kind()) {
      // Both items are of the same type.
      if (left.column() == FDS_MODEL_COUNTS_INDEX) {
        // User wants to sort according to counts.
        return left_item->countOfUnreadMessages() < right_item->countOfUnreadMessages();
      }
      else {
        // In other cases, sort by title.
        return QString::localeAwareCompare(left_item->title(), right_item->title()) < 0;
      }
    }
    else {
      // We sort using priorities.
      auto left_priority = m_priorities.indexOf(left_item->kind());
      auto right_priority = m_priorities.indexOf(right_item->kind());

      return sortOrder() == Qt::SortOrder::AscendingOrder
          ? left_priority < right_priority
          : right_priority < left_priority;
    }
  }
  else {
    return false;
  }
}

bool FeedsProxyModel::filterAcceptsRow(int source_row, const QModelIndex& source_parent) const {
  bool should_show = filterAcceptsRowInternal(source_row, source_parent);

  if (should_show && m_hiddenIndices.contains(QPair<int, QModelIndex>(source_row, source_parent))) {
    const_cast<FeedsProxyModel*>(this)->m_hiddenIndices.removeAll(QPair<int, QModelIndex>(source_row, source_parent));

    // Load status.
    emit expandAfterFilterIn(m_sourceModel->index(source_row, 0, source_parent));
  }

  if (!should_show) {
    const_cast<FeedsProxyModel*>(this)->m_hiddenIndices.append(QPair<int, QModelIndex>(source_row, source_parent));
  }

  return should_show;
}

bool FeedsProxyModel::filterAcceptsRowInternal(int source_row, const QModelIndex& source_parent) const {
  if (!m_showUnreadOnly) {
    return QSortFilterProxyModel::filterAcceptsRow(source_row, source_parent);
  }

  const QModelIndex idx = m_sourceModel->index(source_row, 0, source_parent);

  if (!idx.isValid()) {
    return false;
  }

  const RootItem* item = m_sourceModel->itemForIndex(idx);

  if (item->kind() != RootItemKind::Category && item->kind() != RootItemKind::Feed) {
    // Some items are always visible.
    return true;
  }
  else if (item->isParentOf(m_selectedItem) /* || item->isChildOf(m_selectedItem)*/ || m_selectedItem == item) {
    // Currently selected item and all its parents and children must be displayed.
    return true;
  }
  else {
    // NOTE: If item has < 0 of unread message it may mean, that the count
    // of unread messages is not (yet) known, display that item too.
    return item->countOfUnreadMessages() != 0;
  }
}

const RootItem* FeedsProxyModel::selectedItem() const {
  return m_selectedItem;
}

void FeedsProxyModel::setSelectedItem(const RootItem* selected_item) {
  m_selectedItem = selected_item;
}

bool FeedsProxyModel::showUnreadOnly() const {
  return m_showUnreadOnly;
}

void FeedsProxyModel::invalidateReadFeedsFilter(bool set_new_value, bool show_unread_only) {
  if (set_new_value) {
    setShowUnreadOnly(show_unread_only);
  }

  QTimer::singleShot(0, this, &FeedsProxyModel::invalidateFilter);
}

void FeedsProxyModel::setShowUnreadOnly(bool show_unread_only) {
  m_showUnreadOnly = show_unread_only;
  qApp->settings()->setValue(GROUP(Feeds), Feeds::ShowOnlyUnreadFeeds, show_unread_only);
}

QModelIndexList FeedsProxyModel::mapListToSource(const QModelIndexList& indexes) const {
  QModelIndexList source_indexes;

  for (const QModelIndex& index : indexes) {
    source_indexes << mapToSource(index);
  }

  return source_indexes;
}

void FeedsProxyModel::invalidateFilter() {
  QSortFilterProxyModel::invalidateFilter();
}