/*******************************************************************************
* The MIT License (MIT)
*
* Copyright (c) 2015 David Williams and Matthew Williams
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in all
* copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*******************************************************************************/

#ifndef __PolyVox_FilePager_H__
#define __PolyVox_FilePager_H__

#include "Impl/PlatformDefinitions.h"

#include "PagedVolume.h"
#include "Region.h"

#include <cstdlib>
#include <ctime>
#include <fstream>
#include <stdexcept>
#include <string>
#include <vector>

namespace PolyVox
{
	/**
	 * An implementation of Pager which stores voxels to files on disk. Each chunk is written
	 * to a seperate file and you can specify the name of a folder where these will be stored.
	 *
	 * Note that no compression is performed (mostly to avoid dependancies) so for large
	 * volumes you may want to consider this class as an example and create a custom version
	 * with compression.
	 */
	template <typename VoxelType>
	class FilePager : public PagedVolume<VoxelType>::Pager
	{
	public:
		/// Constructor
		FilePager(const std::string& strFolderName = ".")
			:PagedVolume<VoxelType>::Pager()
			, m_strFolderName(strFolderName)
		{
				// Add the trailing slash, assuming the user dind't already do it.
				if ((m_strFolderName.back() != '/') && (m_strFolderName.back() != '\\'))
				{
					m_strFolderName.append("/");
				}

				// Build a unique postfix to avoid filename conflicts between multiple pagers/runs.
				// Not a very robust solution but this class is meant as an example for testing really.
				std::stringstream ss;
				ss << time(0) << "--"; // Avoid multiple runs using the same filenames.
				ss << this; // Avoid multiple FilePagers using the same filenames.
				m_strPostfix = ss.str();
		}

		/// Destructor
		virtual ~FilePager()
		{
			for (std::vector<std::string>::iterator iter = m_vecCreatedFiles.begin(); iter < m_vecCreatedFiles.end(); iter++)
			{
				POLYVOX_LOG_WARNING_IF(std::remove(iter->c_str()) != 0, "Failed to delete '", *iter, "' when destroying FilePager");
			}

			m_vecCreatedFiles.clear();
		}

		virtual void pageIn(const Region& region, typename PagedVolume<VoxelType>::Chunk* pChunk)
		{
			POLYVOX_ASSERT(pChunk, "Attempting to page in NULL chunk");
			POLYVOX_ASSERT(pChunk->getData(), "Chunk must have valid data");

			std::stringstream ssFilename;
			ssFilename << m_strFolderName << "/"
				<< region.getLowerX() << "_" << region.getLowerY() << "_" << region.getLowerZ() << "_"
				<< region.getUpperX() << "_" << region.getUpperY() << "_" << region.getUpperZ()
				<< "--" << m_strPostfix;

			std::string filename = ssFilename.str();

			// FIXME - This should be replaced by C++ style IO, but currently this causes problems with
			// the gameplay-cubiquity integration. See: https://github.com/blackberry/GamePlay/issues/919

			FILE* pFile = fopen(filename.c_str(), "rb");
			if (pFile)
			{
				POLYVOX_LOG_TRACE("Paging in data for ", region);

				/*fseek(pFile, 0L, SEEK_END);
				size_t fileSizeInBytes = ftell(pFile);
				fseek(pFile, 0L, SEEK_SET);

				uint8_t* buffer = new uint8_t[fileSizeInBytes];
				fread(buffer, sizeof(uint8_t), fileSizeInBytes, pFile);
				pChunk->setData(buffer, fileSizeInBytes);
				delete[] buffer;*/

				fread(pChunk->getData(), sizeof(uint8_t), pChunk->getDataSizeInBytes(), pFile);

				if (ferror(pFile))
				{
					POLYVOX_THROW(std::runtime_error, "Error reading in chunk data, even though a file exists.");
				}

				fclose(pFile);
			}
			else
			{
				POLYVOX_LOG_TRACE("No data found for ", region, " during paging in.");

				// Just fill with zeros. This feels hacky... perhaps we should just throw
				// an exception and let the calling code handle it and fill with zeros.
				uint32_t noOfVoxels = region.getWidthInVoxels() * region.getHeightInVoxels() * region.getDepthInVoxels();
				std::fill(pChunk->getData(), pChunk->getData() + noOfVoxels, VoxelType());
			}
		}

		virtual void pageOut(const Region& region, typename PagedVolume<VoxelType>::Chunk* pChunk)
		{
			POLYVOX_ASSERT(pChunk, "Attempting to page out NULL chunk");
			POLYVOX_ASSERT(pChunk->getData(), "Chunk must have valid data");

			POLYVOX_LOG_TRACE("Paging out data for ", region);

			std::stringstream ssFilename;
			ssFilename << m_strFolderName << "/"
				<< region.getLowerX() << "_" << region.getLowerY() << "_" << region.getLowerZ() << "_"
				<< region.getUpperX() << "_" << region.getUpperY() << "_" << region.getUpperZ()
				<< "--" << m_strPostfix;

			std::string filename = ssFilename.str();

			// FIXME - This should be replaced by C++ style IO, but currently this causes problems with
			// the gameplay-cubiquity integration. See: https://github.com/blackberry/GamePlay/issues/919

			FILE* pFile = fopen(filename.c_str(), "wb");
			if (!pFile)
			{
				POLYVOX_THROW(std::runtime_error, "Unable to open file to write out chunk data.");
			}

			//The file has been created, so add it to the list to delete on shutdown.
			m_vecCreatedFiles.push_back(filename);

			fwrite(pChunk->getData(), sizeof(uint8_t), pChunk->getDataSizeInBytes(), pFile);

			if (ferror(pFile))
			{
				POLYVOX_THROW(std::runtime_error, "Error writing out chunk data.");
			}

			fclose(pFile);
		}

	protected:
		std::string m_strFolderName;
		std::string m_strPostfix;

		std::vector<std::string> m_vecCreatedFiles;
	};
}

#endif //__PolyVox_FilePager_H__