/*

* Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).

* All rights reserved.

*

* Redistribution and use in source and binary forms, with or without

* modification, are permitted provided that the following conditions are met:

*

* - Redistributions of source code must retain the above copyright notice,

*   this list of conditions and the following disclaimer.

* - Redistributions in binary form must reproduce the above copyright notice,

*   this list of conditions and the following disclaimer in the documentation

*   and/or other materials provided with the distribution.

* - Neither the name of Nokia Corporation nor the names of its contributors

*   may be used to endorse or promote products derived from this software

*   without specific prior written permission.

*

* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE

* POSSIBILITY OF SUCH DAMAGE.

* 

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description: 

*

*/

using System;

using System.Collections;

using System.Collections.Generic;

using HeapLib.Cells;

using HeapLib.Array;

using HeapLib.Statistics;

using SymbianUtils.RawItems;

using SymbianUtils.TextUtilities.Readers.Types.Array;

namespace HeapLib.Relationships

{

    internal class RelationshipInspector : AsyncEnumerableReader<HeapCell>

	{

		#region Constructors & destructor

		public RelationshipInspector( HeapCellArray aEntries, HeapStatistics aStats )

            : base( null )

		{

			iEntries = aEntries;

            iStats = aStats;

		}

		#endregion

		#region API

		public void InspectLater( HeapCell aCell )

		{

            iDictionary.Add( aCell );

		}

		public void Inspect()

		{

            iResultCache.Clear();

            base.Setup( iDictionary.Count, iDictionary.GetEnumerator() );

            base.AsyncRead();

		}

		#endregion

        #region From AsyncEnumerableReader

        protected override void HandleObject( HeapCell aObject, long aIndex, long aCount )

        {

            CheckForCrossReferences( aObject );

        }

        protected override void HandleReadCompleted()

        {

            iResultCache.Clear();

            iDictionary.Clear();

            base.HandleReadCompleted();

        }

        #endregion

        #region Internal methods

        private void CheckForCrossReferences( HeapCell aCell )

		{

            // If we're dealing with a free cell, then set up the free cell 

            // linked list.

            if ( aCell.Type == HeapCell.TType.EFree && aCell.HeaderRawItems.Count == 2 )

            {

                uint length = aCell.HeaderRawItems[ 0 ].Data;

                uint address = aCell.HeaderRawItems[ 1 ].Data;

                //

                LocateMatch( aCell, aCell.HeaderRawItems[ 1 ], 0 );

            }

            // For all other cells, identify other links

			foreach( RawItem rawItem in aCell )

			{

                uint headerOffset = HeapCell.CellHeaderSize( aCell.Type );

                LocateMatch( aCell, rawItem, headerOffset );

			}

        }

        private void LocateMatch( HeapCell aCell, RawItem aItem, uint aHeaderOffset )

        {

            RelationshipManager linkManager = aCell.RelationshipManager;

            // Now check if this address exactly matches a heap cell

            if ( iStats.WithinHeapBounds( aItem.Data ) )

            {

                // The address of another object within the heap

                // is always the address of the object within the payload

                // section of a heap cell. Therefore in order to find the

                // corresponding heap cell address, we must subtract the

                // heap cell header length from the starting address.

                //

                // In other words, the rawItem.Data value points to a payload address.

                // However, our cell search function (CellByExactAddress) works in 

                // terms of a heap cell address. The heap cell includes [header + payload].

                //

                // In order to convert the object address into a heap cell address,

                // we must subtract the allocated heap cell header size from the 

                // raw address.

                uint exactMatchAddress = aItem.Data - aHeaderOffset;

                HeapCell cell = iEntries.CellByExactAddress( exactMatchAddress );

                if ( cell != null && cell.Address != aCell.Address )

                {

                    linkManager.AddEmbeddedReferenceTo( aItem, cell );

                }

                else if ( cell == null )

                {

                    uint partialMatchAddress = aItem.Data;

                    // Didn't find an exact match, but we might find that this address

                    // points to part way through another heap cell.

                    cell = Lookup( partialMatchAddress );

                    if ( cell != null && cell.Address != aCell.Address )

                    {

                        // It also has to point to the payload

                        HeapCell.TRegion region = cell.RegionForAddress( partialMatchAddress );

                        if ( region == HeapCell.TRegion.EPayload )

                        {

                            linkManager.AddEmbeddedReferenceTo( aItem, cell );

                        }

                    }

                }

            }

        }

        private HeapCell Lookup( uint aAddress )

        {

            HeapCell ret = null;

            //

            if ( !iResultCache.TryGetValue( aAddress, out ret ) )

            {

                ret = iEntries.CellByAddress( aAddress );

                if ( ret != null )

                {

                    iResultCache.Add( aAddress, ret );

                }

            }

            //

            return ret;

        }

		#endregion

        #region Data members

        private readonly HeapCellArray iEntries;

        private readonly HeapStatistics iStats;

        private RelationshipDictionary iDictionary = new RelationshipDictionary();

        private Dictionary<uint, HeapCell> iResultCache = new Dictionary<uint, HeapCell>();

		#endregion

    }

}