/*
	This file is part of Fennix Kernel.

	Fennix Kernel 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.

	Fennix Kernel 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 Fennix Kernel. If not, see <https://www.gnu.org/licenses/>.
*/

#include <kexcept/cxxabi.h>

#include <memory.hpp>
#include <debug.h>
#include <smp.hpp>

#include "../../kernel.h"

extern "C" _Unwind_Reason_Code _Unwind_RaiseException(_Unwind_Exception *Exception);

using namespace __cxxabiv1;

atexit_func_entry_t __atexit_funcs[ATEXIT_MAX_FUNCS];
uarch_t __atexit_func_count = 0;

__cxa_eh_globals *__cxa_get_globals() noexcept
{
	return &GetCurrentCPU()->Exception.globals;
}

/**
 * @param f The destructor
 * @param objptr The object to be destructed
 * @param dso The DSO from which the object was obtained (unused in our case)
 * @return Zero on success, non-zero on failure
 */
extern "C" int __cxa_atexit(void (*f)(void *), void *objptr, void *dso)
{
	if (KernelSymbolTable)
	{
		debug("Registering atexit function for \"%s\" with destructor \"%s\"",
			  KernelSymbolTable->GetSymbol((uintptr_t)objptr),
			  KernelSymbolTable->GetSymbol((uintptr_t)f));
	}
	else
	{
		debug("Registering atexit function for %p with destructor %p",
			  objptr, f);
	}

	if (__atexit_func_count >= ATEXIT_MAX_FUNCS)
		return -1;
	__atexit_funcs[__atexit_func_count].destructor_func = f;
	__atexit_funcs[__atexit_func_count].obj_ptr = objptr;
	__atexit_funcs[__atexit_func_count].dso_handle = dso;
	__atexit_func_count++;
	return 0;
}

extern "C" void __cxa_finalize(void *f)
{
	func("%p", f);
	uarch_t i = __atexit_func_count;
	if (f == nullptr)
	{
		while (i--)
		{
			if (__atexit_funcs[i].destructor_func)
			{
				if (KernelSymbolTable)
				{
					debug("Calling atexit function \"%s\"",
						  KernelSymbolTable->GetSymbol((uintptr_t)__atexit_funcs[i].destructor_func));
				}
				else
				{
					debug("Calling atexit function %p",
						  __atexit_funcs[i].destructor_func);
				}
				(*__atexit_funcs[i].destructor_func)(__atexit_funcs[i].obj_ptr);
			}
		}
		return;
	}

	while (i--)
	{
		if (__atexit_funcs[i].destructor_func == f)
		{
			(*__atexit_funcs[i].destructor_func)(__atexit_funcs[i].obj_ptr);
			__atexit_funcs[i].destructor_func = 0;
		}
	}
}

extern "C" _Unwind_Reason_Code __gxx_personality_v0(int version, _Unwind_Action actions, _Unwind_Exception_Class exception_class, _Unwind_Exception *ue_header, _Unwind_Context *context)
{
	fixme("__gxx_personality_v0( %d %p %p %p %p ) called.", version, actions, exception_class, ue_header, context);
	return _URC_NO_REASON;
}

extern "C" void *__cxa_begin_catch(void *thrown_object) noexcept
{
	func("%p", thrown_object);

	__cxa_exception *Exception = (__cxa_exception *)thrown_object - 1;
	__cxa_eh_globals *Globals = __cxa_get_globals();

	Exception->handlerCount++;
	Globals->uncaughtExceptions--;

	Exception->nextException = Globals->caughtExceptions;
	Globals->caughtExceptions = Exception;
	return Exception + 1;
}

extern "C" void __cxa_end_catch()
{
	fixme("__cxa_end_catch() called.");
}

static __always_inline inline size_t align_exception_allocation_size(size_t a, size_t b)
{
	return (a + b - 1) & ~(b - 1);
}

static __always_inline inline void INIT_EXCEPTION_CLASS(_Unwind_Exception_Class *c)
{
	char *ptr = (char *)c;
	ptr[0] = 'G';
	ptr[1] = 'N';
	ptr[2] = 'U';
	ptr[3] = 'C';
	ptr[4] = 'C';
	ptr[5] = '+';
	ptr[6] = '+';
	ptr[7] = '\0';
}

void unexpected_header_stub() { fixme("unexpected() called."); }

void terminate_header_stub()
{
	if (TaskManager && !TaskManager->IsPanic())
	{
		TaskManager->KillThread(thisThread, Tasking::KILL_CXXABI_EXCEPTION);
		TaskManager->Yield();
	}

	error("No task manager to kill thread!");
	CPU::Stop(); /* FIXME: Panic */
}

void exception_cleanup_stub(_Unwind_Reason_Code Code,
							_Unwind_Exception *Exception)
{
	fixme("exception_cleanup( %d %p ) called.",
		  Code, Exception);
}

extern "C" void *__cxa_allocate_exception(size_t thrown_size) throw()
{
	debug("Allocating exception of size %d.", thrown_size);

	size_t alloc_size = align_exception_allocation_size(thrown_size + sizeof(__cxa_exception), alignof(__cxa_exception));
	__cxa_exception *Exception = (__cxa_exception *)kmalloc(alloc_size);
	memset(Exception, 0, alloc_size);
	return Exception + 1;
}

extern "C" __noreturn void __cxa_throw(void *thrown_object,
									   std::type_info *tinfo,
									   void (*dest)(void *))
{
	trace("Throwing exception of type \"%s\". ( object: %p, destructor: %p )",
		  tinfo->name(), thrown_object, dest);

	__cxa_eh_globals *Globals = __cxa_get_globals();
	Globals->uncaughtExceptions++;

	__cxa_exception *Exception = (__cxa_exception *)thrown_object - 1;
	Exception->exceptionType = (std::type_info *)tinfo;
	Exception->exceptionDestructor = dest;
	Exception->unexpectedHandler = &unexpected_header_stub;
	Exception->terminateHandler = &terminate_header_stub;
	Exception->unwindHeader.exception_cleanup = &exception_cleanup_stub;
	INIT_EXCEPTION_CLASS(&Exception->unwindHeader.exception_class);
	Exception->adjustedPtr = thrown_object;

	_Unwind_RaiseException(&Exception->unwindHeader);
	__cxa_begin_catch(&Exception->unwindHeader);

	error("Uncaught exception!");
	CPU::Stop(); /* FIXME: Panic */
}

extern "C" void __cxa_rethrow()
{
	fixme("__cxa_rethrow() called.");
}

extern "C" void __cxa_pure_virtual()
{
	fixme("__cxa_pure_virtual() called.");
}

extern "C" void __cxa_throw_bad_array_new_length()
{
	fixme("__cxa_throw_bad_array_new_length() called.");
}

extern "C" void __cxa_free_exception(void *thrown_exception)
{
	fixme("__cxa_free_exception( %p ) called.",
		  thrown_exception);
}

__extension__ typedef int __guard __attribute__((mode(__DI__)));

extern "C" int __cxa_guard_acquire(__guard *g)
{
	fixme("__cxa_guard_acquire( %p ) called.", g);
	return !*(char *)(g);
}

extern "C" void __cxa_guard_release(__guard *g)
{
	fixme("__cxa_guard_release( %p ) called.", g);
	*(char *)g = 1;
}

extern "C" void __cxa_guard_abort(__guard *g)
{
	fixme("__cxa_guard_abort( %p ) called.", g);
}

extern "C" __noreturn void __cxa_bad_typeid()
{
	fixme("__cxa_bad_typeid() called.");
	CPU::Stop(); /* FIXME: Crash the system */
}

extern "C" void *__cxa_get_exception_ptr(void *exceptionObject)
{
	stub;
	return nullptr;
}