#include "Memory.h"
#include <psapi.h>
#include <tlhelp32.h>
#include <iostream>

#undef PROCESSENTRY32
#undef Process32Next

Memory::Memory(const std::string& processName) {
	// First, get the handle of the process
	PROCESSENTRY32 entry;
	entry.dwSize = sizeof(entry);
	HANDLE snapshot = CreateToolhelp32Snapshot(TH32CS_SNAPPROCESS, 0);
	while (Process32Next(snapshot, &entry)) {
		if (processName == entry.szExeFile) {
			_handle = OpenProcess(PROCESS_ALL_ACCESS, FALSE, entry.th32ProcessID);
			break;
		}
	}
	if (!_handle) {
		std::cout << "Couldn't find " << processName.c_str() << ", is it open?" << std::endl;
		exit(EXIT_FAILURE);
	}

	// Next, get the process base address
	DWORD numModules;
	std::vector<HMODULE> moduleList(1024);
	EnumProcessModulesEx(_handle, &moduleList[0], static_cast<DWORD>(moduleList.size()), &numModules, 3);

	std::string name(64, 0);
	for (DWORD i = 0; i < numModules / sizeof(HMODULE); i++) {
		GetModuleBaseNameA(_handle, moduleList[i], &name[0], sizeof(name));

		// TODO: Filling with 0s still yeilds name.size() == 64...
		if (strcmp(processName.c_str(), name.c_str()) == 0) {
			_baseAddress = (uintptr_t)moduleList[i];
			break;
		}
	}
	if (_baseAddress == 0) {
		std::cout << "Couldn't find the base process address!" << std::endl;
		exit(EXIT_FAILURE);
	}
}

Memory::~Memory() {
	CloseHandle(_handle);
}

void Memory::ThrowError() {
	std::string message(256, '\0');
	FormatMessageA(4096, nullptr, GetLastError(), 1024, &message[0], static_cast<DWORD>(message.length()), nullptr);
	std::cout << message.c_str() << std::endl;
	exit(EXIT_FAILURE);
}

void* Memory::ComputeOffset(std::vector<int> offsets)
{
	// Leave off the last offset, since it will be either read/write, and may not be of type unitptr_t.
	int final_offset = offsets.back();
	offsets.pop_back();

	uintptr_t cumulativeAddress = _baseAddress;
	for (const int offset : offsets) {
		cumulativeAddress += offset;

		const auto search = _computedAddresses.find(cumulativeAddress);
		if (search == std::end(_computedAddresses)) {
			// If the address is not yet computed, then compute it.
			uintptr_t computedAddress = 0;
			if (!ReadProcessMemory(_handle, reinterpret_cast<LPVOID>(cumulativeAddress), &computedAddress, sizeof(uintptr_t), NULL)) {
				ThrowError();
			}
			_computedAddresses[cumulativeAddress] = computedAddress;
		}

		cumulativeAddress = _computedAddresses[cumulativeAddress];
	}
	return reinterpret_cast<void*>(cumulativeAddress + final_offset);
}