/*************************************************************************/
/*  crash_handler_windows.cpp                                            */
/*************************************************************************/
/*                       This file is part of:                           */
/*                           GODOT ENGINE                                */
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/* Copyright (c) 2007-2020 Juan Linietsky, Ariel Manzur.                 */
/* Copyright (c) 2014-2020 Godot Engine contributors (cf. AUTHORS.md).   */
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/*************************************************************************/

#include "crash_handler_windows.h"

#include "core/config/project_settings.h"
#include "core/os/os.h"
#include "main/main.h"

#ifdef CRASH_HANDLER_EXCEPTION

// Backtrace code code based on: https://stackoverflow.com/questions/6205981/windows-c-stack-trace-from-a-running-app

#include <algorithm>
#include <iterator>
#include <string>
#include <vector>

#include <psapi.h>

#pragma comment(lib, "psapi.lib")
#pragma comment(lib, "dbghelp.lib")

// Some versions of imagehlp.dll lack the proper packing directives themselves
// so we need to do it.
#pragma pack(push, before_imagehlp, 8)
#include <imagehlp.h>
#pragma pack(pop, before_imagehlp)

struct module_data {
	std::string image_name;
	std::string module_name;
	void *base_address = nullptr;
	DWORD load_size;
};

class symbol {
	typedef IMAGEHLP_SYMBOL64 sym_type;
	sym_type *sym;
	static const int max_name_len = 1024;

public:
	symbol(HANDLE process, DWORD64 address) :
			sym((sym_type *)::operator new(sizeof(*sym) + max_name_len)) {
		memset(sym, '\0', sizeof(*sym) + max_name_len);
		sym->SizeOfStruct = sizeof(*sym);
		sym->MaxNameLength = max_name_len;
		DWORD64 displacement;

		SymGetSymFromAddr64(process, address, &displacement, sym);
	}

	std::string name() { return std::string(sym->Name); }
	std::string undecorated_name() {
		if (*sym->Name == '\0')
			return "<couldn't map PC to fn name>";
		std::vector<char> und_name(max_name_len);
		UnDecorateSymbolName(sym->Name, &und_name[0], max_name_len, UNDNAME_COMPLETE);
		return std::string(&und_name[0], strlen(&und_name[0]));
	}
};

class get_mod_info {
	HANDLE process;

public:
	get_mod_info(HANDLE h) :
			process(h) {}

	module_data operator()(HMODULE module) {
		module_data ret;
		char temp[4096];
		MODULEINFO mi;

		GetModuleInformation(process, module, &mi, sizeof(mi));
		ret.base_address = mi.lpBaseOfDll;
		ret.load_size = mi.SizeOfImage;

		GetModuleFileNameEx(process, module, temp, sizeof(temp));
		ret.image_name = temp;
		GetModuleBaseName(process, module, temp, sizeof(temp));
		ret.module_name = temp;
		std::vector<char> img(ret.image_name.begin(), ret.image_name.end());
		std::vector<char> mod(ret.module_name.begin(), ret.module_name.end());
		SymLoadModule64(process, 0, &img[0], &mod[0], (DWORD64)ret.base_address, ret.load_size);
		return ret;
	}
};

DWORD CrashHandlerException(EXCEPTION_POINTERS *ep) {
	HANDLE process = GetCurrentProcess();
	HANDLE hThread = GetCurrentThread();
	DWORD offset_from_symbol = 0;
	IMAGEHLP_LINE64 line = { 0 };
	std::vector<module_data> modules;
	DWORD cbNeeded;
	std::vector<HMODULE> module_handles(1);

	if (OS::get_singleton() == nullptr || OS::get_singleton()->is_disable_crash_handler() || IsDebuggerPresent()) {
		return EXCEPTION_CONTINUE_SEARCH;
	}

	fprintf(stderr, "%s: Program crashed\n", __FUNCTION__);

	if (OS::get_singleton()->get_main_loop())
		OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_CRASH);

	// Load the symbols:
	if (!SymInitialize(process, nullptr, false))
		return EXCEPTION_CONTINUE_SEARCH;

	SymSetOptions(SymGetOptions() | SYMOPT_LOAD_LINES | SYMOPT_UNDNAME);
	EnumProcessModules(process, &module_handles[0], module_handles.size() * sizeof(HMODULE), &cbNeeded);
	module_handles.resize(cbNeeded / sizeof(HMODULE));
	EnumProcessModules(process, &module_handles[0], module_handles.size() * sizeof(HMODULE), &cbNeeded);
	std::transform(module_handles.begin(), module_handles.end(), std::back_inserter(modules), get_mod_info(process));
	void *base = modules[0].base_address;

	// Setup stuff:
	CONTEXT *context = ep->ContextRecord;
	STACKFRAME64 frame;
	bool skip_first = false;

	frame.AddrPC.Mode = AddrModeFlat;
	frame.AddrStack.Mode = AddrModeFlat;
	frame.AddrFrame.Mode = AddrModeFlat;

#ifdef _M_X64
	frame.AddrPC.Offset = context->Rip;
	frame.AddrStack.Offset = context->Rsp;
	frame.AddrFrame.Offset = context->Rbp;
#else
	frame.AddrPC.Offset = context->Eip;
	frame.AddrStack.Offset = context->Esp;
	frame.AddrFrame.Offset = context->Ebp;

	// Skip the first one to avoid a duplicate on 32-bit mode
	skip_first = true;
#endif

	line.SizeOfStruct = sizeof(line);
	IMAGE_NT_HEADERS *h = ImageNtHeader(base);
	DWORD image_type = h->FileHeader.Machine;

	String msg;
	const ProjectSettings *proj_settings = ProjectSettings::get_singleton();
	if (proj_settings) {
		msg = proj_settings->get("debug/settings/crash_handler/message");
	}

	fprintf(stderr, "Dumping the backtrace. %s\n", msg.utf8().get_data());

	int n = 0;
	do {
		if (skip_first) {
			skip_first = false;
		} else {
			if (frame.AddrPC.Offset != 0) {
				std::string fnName = symbol(process, frame.AddrPC.Offset).undecorated_name();

				if (SymGetLineFromAddr64(process, frame.AddrPC.Offset, &offset_from_symbol, &line))
					fprintf(stderr, "[%d] %s (%s:%d)\n", n, fnName.c_str(), line.FileName, line.LineNumber);
				else
					fprintf(stderr, "[%d] %s\n", n, fnName.c_str());
			} else
				fprintf(stderr, "[%d] ???\n", n);

			n++;
		}

		if (!StackWalk64(image_type, process, hThread, &frame, context, nullptr, SymFunctionTableAccess64, SymGetModuleBase64, nullptr))
			break;
	} while (frame.AddrReturn.Offset != 0 && n < 256);

	fprintf(stderr, "-- END OF BACKTRACE --\n");

	SymCleanup(process);

	// Pass the exception to the OS
	return EXCEPTION_CONTINUE_SEARCH;
}
#endif

CrashHandler::CrashHandler() {
	disabled = false;
}

CrashHandler::~CrashHandler() {
}

void CrashHandler::disable() {
	if (disabled)
		return;

	disabled = true;
}

void CrashHandler::initialize() {
}