/**
 * Copyright (c) 2020 Paul-Louis Ageneau
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at https://mozilla.org/MPL/2.0/.
 */

#ifndef JUICE_THREAD_H
#define JUICE_THREAD_H

#ifdef _WIN32

#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0601 // Windows 7
#endif
#ifndef __MSVCRT_VERSION__
#define __MSVCRT_VERSION__ 0x0601
#endif

#include <windows.h>

typedef HRESULT(WINAPI *pfnSetThreadDescription)(HANDLE, PCWSTR); // for thread_set_name_self()

typedef HANDLE mutex_t;
typedef HANDLE thread_t;
typedef DWORD thread_return_t;
#define THREAD_CALL __stdcall

#define MUTEX_INITIALIZER NULL

#define MUTEX_PLAIN 0x0
#define MUTEX_RECURSIVE 0x0 // mutexes are recursive on Windows

static inline int mutex_init_impl(mutex_t *m) {
	return ((*(m) = CreateMutex(NULL, FALSE, NULL)) != NULL ? 0 : (int)GetLastError());
}

static inline int mutex_lock_impl(volatile mutex_t *m) {
	// Atomically initialize the mutex on first lock
	if (*(m) == NULL) {
		HANDLE cm = CreateMutex(NULL, FALSE, NULL);
		if (cm == NULL)
			return (int)GetLastError();
		if (InterlockedCompareExchangePointer(m, cm, NULL) != NULL)
			CloseHandle(cm);
	}
	return WaitForSingleObject(*m, INFINITE) != WAIT_FAILED ? 0 : (int)GetLastError();
}

#define mutex_init(m, flags) mutex_init_impl(m)
#define mutex_lock(m) mutex_lock_impl(m)
#define mutex_unlock(m) (void)ReleaseMutex(*(m))
#define mutex_destroy(m) (void)CloseHandle(*(m))

static inline void thread_join_impl(thread_t t, thread_return_t *res) {
	WaitForSingleObject(t, INFINITE);
	if (res)
		GetExitCodeThread(t, res);
	CloseHandle(t);
}

#define thread_init(t, func, arg)                                                                  \
	((*(t) = CreateThread(NULL, 0, func, arg, 0, NULL)) != NULL ? 0 : (int)GetLastError())
#define thread_join(t, res) thread_join_impl(t, res)

#else // POSIX

#include <pthread.h>

#if defined(__linux__)
#include <sys/prctl.h> // for prctl(PR_SET_NAME)
#endif
#if defined(__FreeBSD__)
#include <pthread_np.h> // for pthread_set_name_np
#endif

typedef pthread_mutex_t mutex_t;
typedef pthread_t thread_t;
typedef void *thread_return_t;
#define THREAD_CALL

#define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER

#define MUTEX_PLAIN PTHREAD_MUTEX_NORMAL
#define MUTEX_RECURSIVE PTHREAD_MUTEX_RECURSIVE

static inline int mutex_init_impl(mutex_t *m, int flags) {
	pthread_mutexattr_t mutexattr;
	pthread_mutexattr_init(&mutexattr);
	pthread_mutexattr_settype(&mutexattr, flags);
	int ret = pthread_mutex_init(m, &mutexattr);
	pthread_mutexattr_destroy(&mutexattr);
	return ret;
}

#define mutex_init(m, flags) mutex_init_impl(m, flags)
#define mutex_lock(m) pthread_mutex_lock(m)
#define mutex_unlock(m) (void)pthread_mutex_unlock(m)
#define mutex_destroy(m) (void)pthread_mutex_destroy(m)

#define thread_init(t, func, arg) pthread_create(t, NULL, func, arg)
#define thread_join(t, res) (void)pthread_join(t, res)

#endif // ifdef _WIN32

static inline void thread_set_name_self(const char *name) {
#if defined(_WIN32)
	wchar_t wname[256];
	if (MultiByteToWideChar(CP_UTF8, MB_ERR_INVALID_CHARS, name, -1, wname, 256) > 0) {
		HMODULE kernel32 = GetModuleHandleW(L"kernel32.dll");
		if (kernel32) {
			pfnSetThreadDescription pSetThreadDescription =
			    (pfnSetThreadDescription)GetProcAddress(kernel32, "SetThreadDescription");
			if (pSetThreadDescription) {
				pSetThreadDescription(GetCurrentThread(), wname);
			}
		}
	}
#elif defined(__linux__)
	prctl(PR_SET_NAME, name);
#elif defined(__APPLE__)
	pthread_setname_np(name);
#elif defined(__FreeBSD__)
	pthread_set_name_np(pthread_self(), name);
#else
	(void)name;
#endif
}

#if __STDC_VERSION__ >= 201112L && !defined(__STDC_NO_ATOMICS__)

#include <stdatomic.h>
#define atomic(T) _Atomic(T)
#define atomic_ptr(T) _Atomic(T *)

#else // no atomics

// Since we don't need compare-and-swap, just assume store and load are atomic
#define atomic(T) volatile T
#define atomic_ptr(T) T *volatile
#define atomic_store(a, v) (void)(*(a) = (v))
#define atomic_load(a) (*(a))
#define ATOMIC_VAR_INIT(v) (v)

#endif // if atomics

#endif // JUICE_THREAD_H