/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*
  This file provides the implementation for the sort service manager.
 */

#include "nsXULSortService.h"

#include "mozilla/dom/Element.h"
#include "mozilla/intl/AppCollator.h"
#include "nsWhitespaceTokenizer.h"
#include "nsXULContentUtils.h"

using mozilla::dom::Element;
const unsigned long SORT_COMPARECASE = 0x0001;
const unsigned long SORT_INTEGER = 0x0100;

enum nsSortState_direction {
  nsSortState_descending,
  nsSortState_ascending,
  nsSortState_natural
};

// the sort state holds info about the current sort
struct MOZ_STACK_CLASS nsSortState final {
  bool initialized;
  MOZ_INIT_OUTSIDE_CTOR bool invertSort;

  uint32_t sortHints;

  MOZ_INIT_OUTSIDE_CTOR nsSortState_direction direction;
  nsAutoString sort;
  nsTArray<RefPtr<nsAtom>> sortKeys;

  nsCOMPtr<nsIContent> lastContainer;
  MOZ_INIT_OUTSIDE_CTOR bool lastWasFirst, lastWasLast;

  nsSortState() : initialized(false), sortHints(0) {}
};

// Information about a particular item to be sorted.
// Its lifecycle is bound to the 'SortContainer' function scope,
// so we can use raw pointers to avoid refcount noise during sorting.
struct contentSortInfo {
  nsIContent* content;
  nsIContent* parent;
};

/**
 * Set sortActive and sortDirection attributes on a tree column when a sort
 * is done. The column to change is the one with a sort attribute that
 * matches the sort key. The sort attributes are removed from the other
 * columns.
 */
static void SetSortColumnHints(nsIContent* content,
                               const nsAString& sortResource,
                               const nsAString& sortDirection) {
  // set sort info on current column. This ensures that the
  // column header sort indicator is updated properly.
  for (nsIContent* child = content->GetFirstChild(); child;
       child = child->GetNextSibling()) {
    if (child->IsXULElement(nsGkAtoms::treecols)) {
      SetSortColumnHints(child, sortResource, sortDirection);
    } else if (child->IsXULElement(nsGkAtoms::treecol)) {
      nsAutoString value;
      child->AsElement()->GetAttr(nsGkAtoms::sort, value);
      if (value == sortResource) {
        child->AsElement()->SetAttr(kNameSpaceID_None, nsGkAtoms::sortActive,
                                    u"true"_ns, true);

        child->AsElement()->SetAttr(kNameSpaceID_None, nsGkAtoms::sortDirection,
                                    sortDirection, true);
        // Note: don't break out of loop; want to set/unset
        // attribs on ALL sort columns
      } else if (!value.IsEmpty()) {
        child->AsElement()->UnsetAttr(kNameSpaceID_None, nsGkAtoms::sortActive,
                                      true);
        child->AsElement()->UnsetAttr(kNameSpaceID_None,
                                      nsGkAtoms::sortDirection, true);
      }
    }
  }
}

/**
 * Set sort and sortDirection attributes when a sort is done.
 */
static void SetSortHints(Element* aElement, nsSortState* aSortState) {
  // set sort and sortDirection attributes when is sort is done
  aElement->SetAttr(kNameSpaceID_None, nsGkAtoms::sort, aSortState->sort, true);

  nsAutoString direction;
  if (aSortState->direction == nsSortState_descending)
    direction.AssignLiteral("descending");
  else if (aSortState->direction == nsSortState_ascending)
    direction.AssignLiteral("ascending");
  aElement->SetAttr(kNameSpaceID_None, nsGkAtoms::sortDirection, direction,
                    true);

  // for trees, also set the sort info on the currently sorted column
  if (aElement->IsXULElement(nsGkAtoms::tree)) {
    if (aSortState->sortKeys.Length() >= 1) {
      nsAutoString sortkey;
      aSortState->sortKeys[0]->ToString(sortkey);
      SetSortColumnHints(aElement, sortkey, direction);
    }
  }
}

/**
 * Determine the list of items which need to be sorted. This is determined
 * in the following way:
 *   - for elements that have a content builder, get its list of generated
 *     results
 *   - otherwise, for trees, get the child treeitems
 *   - otherwise, get the direct children
 */
static nsresult GetItemsToSort(nsIContent* aContainer,
                               nsTArray<contentSortInfo>& aSortItems) {
  // Get the children. For trees, get the treechildren element and
  // use that as the parent
  RefPtr<Element> treechildren;
  if (aContainer->IsXULElement(nsGkAtoms::tree)) {
    nsXULContentUtils::FindChildByTag(aContainer, kNameSpaceID_XUL,
                                      nsGkAtoms::treechildren,
                                      getter_AddRefs(treechildren));
    if (!treechildren) return NS_OK;

    aContainer = treechildren;
  }

  for (nsIContent* child = aContainer->GetFirstChild(); child;
       child = child->GetNextSibling()) {
    contentSortInfo* cinfo = aSortItems.AppendElement();
    if (!cinfo) return NS_ERROR_OUT_OF_MEMORY;

    cinfo->content = child;
  }

  return NS_OK;
}

/**
 * Compares aLeft and aRight and returns < 0, 0, or > 0. The sort
 * hints are checked for case matching and integer sorting.
 */
static int32_t CompareValues(const nsAString& aLeft, const nsAString& aRight,
                             uint32_t aSortHints) {
  if (aSortHints & SORT_INTEGER) {
    nsresult err;
    int32_t leftint = PromiseFlatString(aLeft).ToInteger(&err);
    if (NS_SUCCEEDED(err)) {
      int32_t rightint = PromiseFlatString(aRight).ToInteger(&err);
      if (NS_SUCCEEDED(err)) {
        return leftint - rightint;
      }
    }
    // if they aren't integers, just fall through and compare strings
  }

  if (aSortHints & SORT_COMPARECASE) {
    // XXX why does this not use a real collator?
    return ::Compare(aLeft, aRight);
  }

  return mozilla::intl::AppCollator::CompareBase(aLeft, aRight);
}

static int testSortCallback(const contentSortInfo& left,
                            const contentSortInfo& right,
                            nsSortState& sortState) {
  int32_t sortOrder = 0;

  size_t length = sortState.sortKeys.Length();
  for (size_t t = 0; t < length; t++) {
    // compare attributes. Ignore namespaces for now.
    nsAutoString leftstr, rightstr;
    if (left.content->IsElement()) {
      left.content->AsElement()->GetAttr(sortState.sortKeys[t], leftstr);
    }
    if (right.content->IsElement()) {
      right.content->AsElement()->GetAttr(sortState.sortKeys[t], rightstr);
    }

    sortOrder = CompareValues(leftstr, rightstr, sortState.sortHints);
  }

  if (sortState.direction == nsSortState_descending) sortOrder = -sortOrder;

  return sortOrder;
}

/**
 * Given a list of sortable items, reverse the list. This is done
 * when simply changing the sort direction for the same key.
 */
static nsresult InvertSortInfo(nsTArray<contentSortInfo>& aData, int32_t aStart,
                               int32_t aNumItems) {
  if (aNumItems > 1) {
    // reverse the items in the array starting from aStart
    int32_t upPoint = (aNumItems + 1) / 2 + aStart;
    int32_t downPoint = (aNumItems - 2) / 2 + aStart;
    int32_t half = aNumItems / 2;
    while (half-- > 0) {
      std::swap(aData[downPoint--], aData[upPoint++]);
    }
  }
  return NS_OK;
}

/**
 * Sort a container using the supplied sort state details.
 */
static nsresult SortContainer(nsIContent* aContainer, nsSortState& aSortState) {
  nsTArray<contentSortInfo> items;
  nsresult rv = GetItemsToSort(aContainer, items);
  NS_ENSURE_SUCCESS(rv, rv);

  uint32_t numResults = items.Length();
  if (!numResults) return NS_OK;

  uint32_t i;

  // if the items are just being inverted, that is, just switching between
  // ascending and descending, just reverse the list.
  if (aSortState.invertSort) {
    InvertSortInfo(items, 0, numResults);
  } else {
    items.Sort([&aSortState](auto left, auto right) {
      return testSortCallback(left, right, aSortState);
    });
  }

  // first remove the items from the old positions
  for (i = 0; i < numResults; i++) {
    nsIContent* child = items[i].content;
    nsIContent* parent = child->GetParent();

    if (parent) {
      // remember the parent so that it can be reinserted back
      // into the same parent. This is necessary as multiple rules
      // may generate results which get placed in different locations.
      items[i].parent = parent;
      parent->RemoveChildNode(child, true);
    }
  }

  // now add the items back in sorted order
  for (i = 0; i < numResults; i++) {
    nsIContent* child = items[i].content;
    nsIContent* parent = items[i].parent;
    if (parent) {
      parent->AppendChildTo(child, true, mozilla::IgnoreErrors());

      // if it's a container in a tree or menu, find its children,
      // and sort those also
      if (!child->IsElement() || !child->AsElement()->AttrValueIs(
                                     kNameSpaceID_None, nsGkAtoms::container,
                                     nsGkAtoms::_true, eCaseMatters))
        continue;

      for (nsIContent* grandchild = child->GetFirstChild(); grandchild;
           grandchild = grandchild->GetNextSibling()) {
        mozilla::dom::NodeInfo* ni = grandchild->NodeInfo();
        nsAtom* localName = ni->NameAtom();
        if (ni->NamespaceID() == kNameSpaceID_XUL &&
            (localName == nsGkAtoms::treechildren ||
             localName == nsGkAtoms::menupopup)) {
          SortContainer(grandchild, aSortState);
        }
      }
    }
  }

  return NS_OK;
}

/**
 * Initialize sort information from attributes specified on the container,
 * the sort key and sort direction.
 *
 * @param aRootElement the element that contains sort attributes
 * @param aContainer the container to sort, usually equal to aRootElement
 * @param aSortKey space separated list of sort keys
 * @param aSortDirection direction to sort in
 * @param aSortState structure filled in with sort data
 */
static nsresult InitializeSortState(Element* aRootElement, Element* aContainer,
                                    const nsAString& aSortKey,
                                    const nsAString& aSortHints,
                                    nsSortState* aSortState) {
  // used as an optimization for the content builder
  if (aContainer != aSortState->lastContainer.get()) {
    aSortState->lastContainer = aContainer;
    aSortState->lastWasFirst = false;
    aSortState->lastWasLast = false;
  }

  // The sort attribute is of the form: sort="key1 key2 ..."
  nsAutoString sort(aSortKey);
  aSortState->sortKeys.Clear();
  nsWhitespaceTokenizer tokenizer(sort);
  while (tokenizer.hasMoreTokens()) {
    RefPtr<nsAtom> keyatom = NS_Atomize(tokenizer.nextToken());
    NS_ENSURE_TRUE(keyatom, NS_ERROR_OUT_OF_MEMORY);
    aSortState->sortKeys.AppendElement(keyatom);
  }

  aSortState->sort.Assign(sort);
  aSortState->direction = nsSortState_natural;

  bool noNaturalState = false;
  nsWhitespaceTokenizer hintsTokenizer(aSortHints);
  while (hintsTokenizer.hasMoreTokens()) {
    const nsDependentSubstring& token(hintsTokenizer.nextToken());
    if (token.EqualsLiteral("comparecase"))
      aSortState->sortHints |= SORT_COMPARECASE;
    else if (token.EqualsLiteral("integer"))
      aSortState->sortHints |= SORT_INTEGER;
    else if (token.EqualsLiteral("descending"))
      aSortState->direction = nsSortState_descending;
    else if (token.EqualsLiteral("ascending"))
      aSortState->direction = nsSortState_ascending;
    else if (token.EqualsLiteral("twostate"))
      noNaturalState = true;
  }

  // if the twostate flag was set, the natural order is skipped and only
  // ascending and descending are allowed
  if (aSortState->direction == nsSortState_natural && noNaturalState) {
    aSortState->direction = nsSortState_ascending;
  }

  // set up sort order info
  aSortState->invertSort = false;

  nsAutoString existingsort;
  aRootElement->GetAttr(nsGkAtoms::sort, existingsort);
  nsAutoString existingsortDirection;
  aRootElement->GetAttr(nsGkAtoms::sortDirection, existingsortDirection);

  // if just switching direction, set the invertSort flag
  if (sort.Equals(existingsort)) {
    if (aSortState->direction == nsSortState_descending) {
      if (existingsortDirection.EqualsLiteral("ascending"))
        aSortState->invertSort = true;
    } else if (aSortState->direction == nsSortState_ascending &&
               existingsortDirection.EqualsLiteral("descending")) {
      aSortState->invertSort = true;
    }
  }

  aSortState->initialized = true;

  return NS_OK;
}

nsresult mozilla::XULWidgetSort(Element* aNode, const nsAString& aSortKey,
                                const nsAString& aSortHints) {
  nsSortState sortState;
  nsresult rv =
      InitializeSortState(aNode, aNode, aSortKey, aSortHints, &sortState);
  NS_ENSURE_SUCCESS(rv, rv);

  // store sort info in attributes on content
  SetSortHints(aNode, &sortState);
  rv = SortContainer(aNode, sortState);

  return rv;
}