#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <pthread.h>
#include <emscripten.h>
#include <emscripten/threading.h>
#include <assert.h>

#if !defined(__EMSCRIPTEN_PTHREADS__) || __EMSCRIPTEN_PTHREADS__ != 1
#error __EMSCRIPTEN_PTHREADS__ should have been defined to be equal to 1 when building with pthreads support enabled!
#endif

#define NUM_THREADS 8

volatile unsigned char globalUchar = 0;
volatile unsigned short globalUshort = 0;
volatile unsigned int globalUint = 0;
volatile float globalFloat = 0.0f;
volatile double globalDouble = 0.0;
volatile uint64_t globalU64 = 0;

const int N = 10;
int sharedData[N] = {};

struct Test
{
	int op;
	int threadId;
};

uint64_t threadCasAccumulatedWrittenData[NUM_THREADS] = {};
uint64_t threadCasAccumulatedReadData[NUM_THREADS] = {};

int rand_32()
{
	return (int)(emscripten_random() * 0x3FFFFFFF);
}

void *ThreadMain(void *arg)
{
	assert(pthread_self() != 0);
	assert(globalUchar == 5);
	assert(globalUshort == 5);
	assert(globalUint == 5);
	assert(globalFloat == 5.0f);
	assert(globalDouble == 5.0);
	assert(globalU64 == 5);
	struct Test *t = (struct Test*)arg;
	EM_ASM(Module['print']('Thread ' + $0 + ' for test ' + $1 + ': starting computation.'), t->threadId, t->op);

	for(int i = 0; i < 99999; ++i)
		for(int j = 0; j < N; ++j)
		{
			switch(t->op)
			{
				case 0: emscripten_atomic_add_u32(&sharedData[j], 1); break;
				case 1: emscripten_atomic_sub_u32(&sharedData[j], 1); break;
				case 2: emscripten_atomic_and_u32(&sharedData[j], ~(1UL << t->threadId)); break;
				case 3: emscripten_atomic_or_u32(&sharedData[j], 1UL << t->threadId); break;
				case 4: emscripten_atomic_xor_u32(&sharedData[j], 1UL << t->threadId); break;
				case 5:
				{
					// Atomically load and store data, and test that each individual u8 is the same.
					int data = emscripten_atomic_load_u32(&sharedData[j]);
					uint8_t dataU8[4];
					memcpy(dataU8, &data, 4);
					assert(dataU8[0] >= 10 && dataU8[0] < 10+NUM_THREADS);
					assert(dataU8[0] == dataU8[1] && dataU8[0] == dataU8[2] && dataU8[0] == dataU8[3]);
					dataU8[0] = dataU8[1] = dataU8[2] = dataU8[3] = 10 + t->threadId;
					memcpy(&data, dataU8, 4);
					emscripten_atomic_store_u32(&sharedData[j], data);
				}
				break;
				case 6:
				{
					int newData = rand_32();
					int data;
					int prevData;
					do {
						data = emscripten_atomic_load_u32(&sharedData[j]);
						prevData = emscripten_atomic_cas_u32(&sharedData[j], data, newData);
					} while(prevData != data);
					threadCasAccumulatedReadData[t->threadId] += data;
					threadCasAccumulatedWrittenData[t->threadId] += newData;
				}
				break;
			}
		}
	EM_ASM(Module['print']('Thread ' + $0 + ' for test ' + $1 + ': finished, exit()ing.'), t->threadId, t->op);
	pthread_exit(0);
}

struct Test t[NUM_THREADS] = {};
pthread_t thread[NUM_THREADS];

void RunTest(int test)
{	
	pthread_attr_t attr;
	pthread_attr_init(&attr);
	pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);
	pthread_attr_setstacksize(&attr, 4*1024);

	printf("Main thread has thread ID %d\n", (int)pthread_self());
	assert(pthread_self() != 0);

	switch(test)
	{
		case 2: memset(sharedData, 0xFF, sizeof(sharedData)); break;
		case 5: memset(sharedData, 0x10, sizeof(sharedData)); break;
		default: memset(sharedData, 0, sizeof(sharedData)); break;
	}

	EM_ASM(Module['print']('Main: Starting test ' + $0), test);

	for(int i = 0; i < NUM_THREADS; ++i)
	{
		t[i].op = test;
		t[i].threadId = i;
		int rc = pthread_create(&thread[i], &attr, ThreadMain, &t[i]);
		assert(rc == 0);
	}

	pthread_attr_destroy(&attr);

	for(int i = 0; i < NUM_THREADS; ++i)
	{
		int status = 1;
		int rc = pthread_join(thread[i], (void**)&status);
		assert(rc == 0);
		assert(status == 0);
	}

	int val = sharedData[0];
	EM_ASM(Module['print']('Main: Test ' + $0 + ' finished. Result: ' + $1), test, val);
	if (test != 6)
	{
		for(int i = 1; i < N; ++i)
			assert(sharedData[i] == sharedData[0]);
	}
}

int main()
{
	globalUchar = 5;
	globalUshort = 5;
	globalUint = 5;
	globalFloat = 5.0f;
	globalDouble = 5.0;
	globalU64 = 5;

	emscripten_atomic_fence();
	__sync_synchronize();

	if (!emscripten_has_threading_support())
	{
#ifdef REPORT_RESULT
		REPORT_RESULT(0);
#endif
		printf("Skipped: Threading is not supported.\n");
		return 0;
	}

	for(int i = 0; i < 7; ++i)
		RunTest(i);

	uint64_t totalRead = 0;
	uint64_t totalWritten = 0;
	for(int i = 0; i < NUM_THREADS; ++i)
	{
		totalRead += threadCasAccumulatedReadData[i];
		totalWritten += threadCasAccumulatedWrittenData[i];
	}
	for(int i = 0; i < N; ++i)
		totalRead += sharedData[i];
	if (totalRead == totalWritten)
		printf("totalRead: %llu, totalWritten: %llu\n", totalRead, totalWritten);
	else
		printf("32-bit CAS test failed! totalRead != totalWritten (%llu != %llu)\n", totalRead, totalWritten);
#ifdef REPORT_RESULT
	int result = (totalRead != totalWritten) ? 1 : 0;
	REPORT_RESULT(result);
#else
	EM_ASM(Module['print']('Main: Test successfully finished.'));
#endif
}
