/*
 * Copyright 2013-2014, Ingo Weinhold, ingo_weinhold@gmx.de.
 * Distributed under the terms of the MIT License.
 */


#include <package/hpkg/PackageFileHeapAccessorBase.h>

#include <stdlib.h>
#include <string.h>

#include <algorithm>
#include <new>
#ifdef _KERNEL_MODE
#include <slab/Slab.h>
#endif

#include <ByteOrder.h>
#include <DataIO.h>
#include <package/hpkg/ErrorOutput.h>

#include <AutoDeleter.h>
#include <CompressionAlgorithm.h>


namespace BPackageKit {

namespace BHPKG {

namespace BPrivate {


#if defined(_KERNEL_MODE)
void* PackageFileHeapAccessorBase::sChunkCache = NULL;
#endif


// #pragma mark - OffsetArray


PackageFileHeapAccessorBase::OffsetArray::OffsetArray()
	:
	fOffsets(NULL)
{
}


PackageFileHeapAccessorBase::OffsetArray::~OffsetArray()
{
	delete[] fOffsets;
}


bool
PackageFileHeapAccessorBase::OffsetArray::InitUncompressedChunksOffsets(
	size_t totalChunkCount)
{
	if (totalChunkCount <= 1)
		return true;

	const size_t max32BitChunks = (uint64(1) << 32) / kChunkSize;
	size_t actual32BitChunks = totalChunkCount;
	if (totalChunkCount - 1 > max32BitChunks) {
		actual32BitChunks = max32BitChunks;
		fOffsets = _AllocateOffsetArray(totalChunkCount, max32BitChunks);
	} else
		fOffsets = _AllocateOffsetArray(totalChunkCount, 0);

	if (fOffsets == NULL)
		return false;

	{
		uint32 offset = kChunkSize;
		for (size_t i = 1; i < actual32BitChunks; i++, offset += kChunkSize)
			fOffsets[i] = offset;

	}

	if (actual32BitChunks < totalChunkCount) {
		uint64 offset = actual32BitChunks * kChunkSize;
		uint32* offsets = fOffsets + actual32BitChunks;
		for (size_t i = actual32BitChunks; i < totalChunkCount;
				i++, offset += kChunkSize) {
			*offsets++ = (uint32)offset;
			*offsets++ = uint32(offset >> 32);
		}
	}

	return true;
}


bool
PackageFileHeapAccessorBase::OffsetArray::InitChunksOffsets(
	size_t totalChunkCount, size_t baseIndex, const uint16* chunkSizes,
	size_t chunkCount)
{
	if (totalChunkCount <= 1)
		return true;

	if (fOffsets == NULL) {
		fOffsets = _AllocateOffsetArray(totalChunkCount, totalChunkCount);
		if (fOffsets == NULL)
			return false;
	}

	uint64 offset = (*this)[baseIndex];
	for (size_t i = 0; i < chunkCount; i++) {
		offset += (uint64)B_BENDIAN_TO_HOST_INT16(chunkSizes[i]) + 1;
			// the stored value is chunkSize - 1
		size_t index = baseIndex + i + 1;
			// (baseIndex + i) is the index of the chunk whose size is stored in
			// chunkSizes[i]. We compute the offset of the following element
			// which we store at index (baseIndex + i + 1).

		if (offset <= ~(uint32)0) {
			fOffsets[index] = (uint32)offset;
		} else {
			if (fOffsets[0] == 0) {
				// Not scaled to allow for 64 bit offsets yet. Do that.
				uint32* newOffsets = _AllocateOffsetArray(totalChunkCount,
					index);
				if (newOffsets == NULL)
					return false;

				fOffsets[0] = index;
				memcpy(newOffsets, fOffsets, sizeof(newOffsets[0]) * index);

				delete[] fOffsets;
				fOffsets = newOffsets;
			}

			index += index - fOffsets[0];
			fOffsets[index] = (uint32)offset;
			fOffsets[index + 1] = uint32(offset >> 32);
		}
	}

	return true;
}


bool
PackageFileHeapAccessorBase::OffsetArray::Init(size_t totalChunkCount,
	const OffsetArray& other)
{
	if (other.fOffsets == NULL)
		return true;

	size_t elementCount = other.fOffsets[0] == 0
		? totalChunkCount
		: 2 * totalChunkCount - other.fOffsets[0];

	fOffsets = new(std::nothrow) uint32[elementCount];
	if (fOffsets == NULL)
		return false;

	memcpy(fOffsets, other.fOffsets, elementCount * sizeof(fOffsets[0]));
	return true;
}


/*static*/ uint32*
PackageFileHeapAccessorBase::OffsetArray::_AllocateOffsetArray(
	size_t totalChunkCount, size_t offset32BitChunkCount)
{
	uint32* offsets = new(std::nothrow) uint32[
		2 * totalChunkCount - offset32BitChunkCount];

	if (offsets != NULL) {
		offsets[0] = offset32BitChunkCount == totalChunkCount
			? 0 : offset32BitChunkCount;
			// 0 means that all offsets are 32 bit. Otherwise it's the index of
			// the first 64 bit offset.
	}

	return offsets;
}


// #pragma mark - PackageFileHeapAccessorBase


PackageFileHeapAccessorBase::PackageFileHeapAccessorBase(
	BErrorOutput* errorOutput, BPositionIO* file, off_t heapOffset,
	DecompressionAlgorithmOwner* decompressionAlgorithm)
	:
	fErrorOutput(errorOutput),
	fFile(file),
	fHeapOffset(heapOffset),
	fCompressedHeapSize(0),
	fUncompressedHeapSize(0),
	fDecompressionAlgorithm(decompressionAlgorithm)
{
	if (fDecompressionAlgorithm != NULL)
		fDecompressionAlgorithm->AcquireReference();
}


PackageFileHeapAccessorBase::~PackageFileHeapAccessorBase()
{
	if (fDecompressionAlgorithm != NULL)
		fDecompressionAlgorithm->ReleaseReference();
}


status_t
PackageFileHeapAccessorBase::ReadDataToOutput(off_t offset, size_t size,
	BDataIO* output)
{
	if (size == 0)
		return B_OK;

	if (offset < 0 || (uint64)offset > fUncompressedHeapSize
		|| size > fUncompressedHeapSize - offset) {
		return B_BAD_VALUE;
	}

	// allocate buffers for compressed and uncompressed data
	uint16* compressedDataBuffer, *uncompressedDataBuffer;
	MemoryDeleter compressedMemoryDeleter, uncompressedMemoryDeleter;

#if defined(_KERNEL_MODE) && !defined(_BOOT_MODE)
	struct ObjectCacheDeleter {
		object_cache* cache;
		void* object;

		ObjectCacheDeleter(object_cache* c)
			: cache(c)
			, object(NULL)
		{
		}

		~ObjectCacheDeleter()
		{
			if (cache != NULL && object != NULL)
				object_cache_free(cache, object, 0);
		}
	};

	ObjectCacheDeleter compressedCacheDeleter((object_cache*)sChunkCache),
		uncompressedCacheDeleter((object_cache*)sChunkCache);
	if (sChunkCache != NULL) {
		compressedDataBuffer = (uint16*)object_cache_alloc((object_cache*)sChunkCache, 0);
		uncompressedDataBuffer = (uint16*)object_cache_alloc((object_cache*)sChunkCache, 0);
		compressedCacheDeleter.object = compressedDataBuffer;
		uncompressedCacheDeleter.object = uncompressedDataBuffer;
	} else
#endif
	{
		compressedDataBuffer = (uint16*)malloc(kChunkSize);
		uncompressedDataBuffer = (uint16*)malloc(kChunkSize);
		compressedMemoryDeleter.SetTo(compressedDataBuffer);
		uncompressedMemoryDeleter.SetTo(uncompressedDataBuffer);
	}

	if (compressedDataBuffer == NULL || uncompressedDataBuffer == NULL)
		return B_NO_MEMORY;

	// read the data
	size_t chunkIndex = size_t(offset / kChunkSize);
	size_t inChunkOffset = (uint64)offset - (uint64)chunkIndex * kChunkSize;
	size_t remainingBytes = size;

	while (remainingBytes > 0) {
		status_t error = ReadAndDecompressChunk(chunkIndex,
			compressedDataBuffer, uncompressedDataBuffer);
		if (error != B_OK)
			return error;

		size_t toWrite = std::min((size_t)kChunkSize - inChunkOffset,
			remainingBytes);
			// The last chunk may be shorter than kChunkSize, but since
			// size (and thus remainingSize) had been clamped, that doesn't
			// harm.
		error = output->WriteExactly(
			(char*)uncompressedDataBuffer + inChunkOffset, toWrite);
		if (error != B_OK)
			return error;

		remainingBytes -= toWrite;
		chunkIndex++;
		inChunkOffset = 0;
	}

	return B_OK;
}


status_t
PackageFileHeapAccessorBase::ReadAndDecompressChunkData(uint64 offset,
	size_t compressedSize, size_t uncompressedSize, void* compressedDataBuffer,
	void* uncompressedDataBuffer)
{
	// if uncompressed, read directly into the uncompressed data buffer
	if (compressedSize == uncompressedSize)
		return ReadFileData(offset, uncompressedDataBuffer, compressedSize);

	// otherwise read into the other buffer and decompress
	status_t error = ReadFileData(offset, compressedDataBuffer, compressedSize);
	if (error != B_OK)
		return error;

	return DecompressChunkData(compressedDataBuffer, compressedSize,
		uncompressedDataBuffer, uncompressedSize);
}


status_t
PackageFileHeapAccessorBase::DecompressChunkData(void* compressedDataBuffer,
	size_t compressedSize, void* uncompressedDataBuffer,
	size_t uncompressedSize)
{
	size_t actualSize;
	status_t error = fDecompressionAlgorithm->algorithm->DecompressBuffer(
		compressedDataBuffer, compressedSize, uncompressedDataBuffer,
		uncompressedSize, actualSize, fDecompressionAlgorithm->parameters);
	if (error != B_OK) {
		fErrorOutput->PrintError("Failed to decompress chunk data: %s\n",
			strerror(error));
		return error;
	}

	if (actualSize != uncompressedSize) {
		fErrorOutput->PrintError("Failed to decompress chunk data: size "
			"mismatch\n");
		return B_ERROR;
	}

	return B_OK;
}


status_t
PackageFileHeapAccessorBase::ReadFileData(uint64 offset, void* buffer,
	size_t size)
{
	status_t error = fFile->ReadAtExactly(fHeapOffset + (off_t)offset, buffer,
		size);
	if (error != B_OK) {
		fErrorOutput->PrintError("ReadFileData(%" B_PRIu64 ", %p, %zu) failed "
			"to read data: %s\n", offset, buffer, size, strerror(error));
		return error;
	}

	return B_OK;
}


}	// namespace BPrivate

}	// namespace BHPKG

}	// namespace BPackageKit