/*	EQEmu: EQEmulator

	Copyright (C) 2001-2026 EQEmu Development Team

	This program is free software; you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation; either version 3 of the License, or
	(at your option) any later version.

	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "memory_mapped_file.h"

#include "common/eqemu_exception.h"

#include <filesystem>

#ifdef _WINDOWS
#include <windows.h>
#else
#include <sys/types.h>
#include <sys/mman.h>
#include <err.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#endif
#ifdef FREEBSD
#include <sys/stat.h>
#endif

namespace fs = std::filesystem;

namespace EQ {

	struct MemoryMappedFile::Implementation {
#ifdef _WINDOWS
		HANDLE mapped_object_;
#else
		int fd_;
#endif
	};

	MemoryMappedFile::MemoryMappedFile(std::string filename, uint32 size)
		: filename_(filename), size_(size) {
		imp_ = new Implementation;

#ifdef _WINDOWS
		DWORD total_size = size + sizeof(shared_memory_struct);
		HANDLE file = CreateFile(filename.c_str(),
			GENERIC_READ | GENERIC_WRITE,
			FILE_SHARE_READ | FILE_SHARE_WRITE,
			nullptr,
			OPEN_ALWAYS,
			0,
			nullptr);

		if(file == INVALID_HANDLE_VALUE) {
			EQ_EXCEPT("Shared Memory", "Could not open a file for this shared memory segment.");
		}

		imp_->mapped_object_ = CreateFileMapping(file,
			nullptr,
			PAGE_READWRITE,
			0,
			total_size,
			filename.c_str());

		if(!imp_->mapped_object_) {
			EQ_EXCEPT("Shared Memory", "Could not create a file mapping for this shared memory file.");
		}

		memory_ = reinterpret_cast<shared_memory_struct*>(MapViewOfFile(imp_->mapped_object_,
			FILE_MAP_ALL_ACCESS,
			0,
			0,
			total_size));

		if(!memory_) {
			EQ_EXCEPT("Shared Memory", "Could not map a view of the shared memory file.");
		}

#else
		size_t total_size = size + sizeof(shared_memory_struct);
		imp_->fd_ = open(filename.c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
		if(imp_->fd_ == -1) {
			EQ_EXCEPT("Shared Memory", "Could not open a file for this shared memory segment.");
		}

		if(ftruncate(imp_->fd_, total_size) == -1) {
			EQ_EXCEPT("Shared Memory", "Could not set file size for this shared memory segment.");
		}

		memory_ = reinterpret_cast<shared_memory_struct*>(
			mmap(nullptr, total_size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, imp_->fd_, 0));

		if(memory_ == MAP_FAILED) {
			EQ_EXCEPT("Shared Memory", "Could not create a file mapping for this shared memory file.");
		}
#endif
	}

	MemoryMappedFile::MemoryMappedFile(std::string filename)
		: filename_(filename) {
		imp_ = new Implementation;

		//get existing size
		FILE *f = fopen(filename.c_str(), "rb");
		if(!f) {
			EQ_EXCEPT("Shared Memory", "Could not open the file to find the existing file size.");
		}
		fseek(f, 0U, SEEK_END);
		uint32 size = static_cast<uint32>(ftell(f)) - sizeof(shared_memory_struct);
		size_ = size;
		fclose(f);

#ifdef _WINDOWS
		DWORD total_size = size + sizeof(shared_memory_struct);
		HANDLE file = CreateFile(filename.c_str(),
			GENERIC_READ | GENERIC_WRITE,
			FILE_SHARE_READ | FILE_SHARE_WRITE,
			nullptr,
			OPEN_ALWAYS,
			0,
			nullptr);

		if(file == INVALID_HANDLE_VALUE) {
			EQ_EXCEPT("Shared Memory", "Could not open a file for this shared memory segment.");
		}

		imp_->mapped_object_ = CreateFileMapping(file,
			nullptr,
			PAGE_READWRITE,
			0,
			total_size,
			filename.c_str());

		if(!imp_->mapped_object_) {
			EQ_EXCEPT("Shared Memory", "Could not create a file mapping for this shared memory file.");
		}

		memory_ = reinterpret_cast<shared_memory_struct*>(MapViewOfFile(imp_->mapped_object_,
			FILE_MAP_ALL_ACCESS,
			0,
			0,
			total_size));

		if(!memory_) {
			EQ_EXCEPT("Shared Memory", "Could not map a view of the shared memory file.");
		}

#else
		size_t total_size = size + sizeof(shared_memory_struct);
		imp_->fd_ = open(filename.c_str(), O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
		if(imp_->fd_ == -1) {
			EQ_EXCEPT("Shared Memory", "Could not open a file for this shared memory segment.");
		}

		if(ftruncate(imp_->fd_, total_size) == -1) {
			EQ_EXCEPT("Shared Memory", "Could not set file size for this shared memory segment.");
		}

		memory_ = reinterpret_cast<shared_memory_struct*>(
			mmap(nullptr, total_size, PROT_READ | PROT_WRITE, MAP_FILE | MAP_SHARED, imp_->fd_, 0));

		if(memory_ == MAP_FAILED) {
			EQ_EXCEPT("Shared Memory", "Could not create a file mapping for this shared memory file.");
		}
#endif
	}

	MemoryMappedFile::~MemoryMappedFile() {
#ifdef _WINDOWS
		if(imp_->mapped_object_) {
			CloseHandle(imp_->mapped_object_);
		}
#else
		if(memory_) {
			size_t total_size = size_ + sizeof(shared_memory_struct);
			munmap(reinterpret_cast<void*>(memory_), total_size);
			close(imp_->fd_);
		}
#endif
		delete imp_;
	}

	void MemoryMappedFile::ZeroFile() {
		memset(reinterpret_cast<void*>(memory_), 0, sizeof(shared_memory_struct));
		memset(memory_->data, 0, size_);
		memory_->size = size_;
	}
} // EQEmu