/*
 * Copyright 2011, Haiku Inc. All rights reserved.
 * This file may be used under the terms of the MIT License.
 *
 * Authors:
 *              Jérôme Duval
 */


#include "DataStream.h"

#include "Volume.h"


//#define TRACE_EXFAT
#ifdef TRACE_EXFAT
#       define TRACE(x...) dprintf("\33[34mexfat:\33[0m " x)
#else
#       define TRACE(x...) ;
#endif
#define ERROR(x...)     dprintf("\33[34mexfat:\33[0m " x)


DataStream::DataStream(Volume* volume, Inode* inode, off_t size)
        :
        kBlockSize(volume->BlockSize()),
        kClusterSize(volume->ClusterSize()),
        fVolume(volume),
        fInode(inode),
        fSize(size)
{
        fNumBlocks = size == 0 ? 0 : ((size - 1) / kBlockSize) + 1;
}


DataStream::~DataStream()
{
}


status_t
DataStream::FindBlock(off_t pos, off_t& physical, off_t *_length)
{
        if (pos >= fSize) {
                TRACE("FindBlock: offset larger than size\n");
                return B_ENTRY_NOT_FOUND;
        }
        cluster_t clusterIndex = pos / kClusterSize;
        uint32 offset = pos % kClusterSize;

        cluster_t cluster = fInode->StartCluster();
        for (uint32 i = 0; i < clusterIndex; i++)
                cluster = fInode->NextCluster(cluster);
        fsblock_t block;
        if (fVolume->ClusterToBlock(cluster, block) != B_OK)
                return B_BAD_DATA;
        physical = block * kBlockSize + offset;
        for (uint32 i = 0; i < 64; i++) {
                cluster_t extentEnd = fInode->NextCluster(cluster);
                if (extentEnd == EXFAT_CLUSTER_END || extentEnd == cluster + 1)
                        break;
                cluster = extentEnd;
        }
        *_length = min_c((cluster - clusterIndex + 1) * kClusterSize - offset,
                fSize - pos);
        TRACE("inode %" B_PRIdINO ": cluster %" B_PRIu32 ", pos %" B_PRIdOFF ", %"
                B_PRIdOFF "\n", fInode->ID(), clusterIndex, pos, physical);
        return B_OK;
}