/**
 * Copyright (c) 2026 Dominic Masters
 *
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "dusktest.h"
#include "thread/thread.h"
#include "util/memory.h"

// --- Helpers ---

static void helper_noop(thread_t *thread) {
  // intentionally empty: one-shot thread that exits immediately
}

static void helper_loop(thread_t *thread) {
  while(!threadShouldStop(thread)) {}
}

static void helper_write_data(thread_t *thread) {
  int32_t *value = (int32_t *)thread->data;
  *value = 42;
}

// --- thread_t tests ---

static void test_threadInit(void **state) {
  thread_t thread;
  threadInit(&thread, helper_noop);

  assert_int_equal(thread.state, THREAD_STATE_STOPPED);
  assert_ptr_equal(thread.callback, helper_noop);
  assert_null(thread.data);
}

static void test_thread_start_stop(void **state) {
  thread_t thread;
  threadInit(&thread, helper_noop);
  threadStart(&thread);
  threadStop(&thread);

  assert_int_equal(thread.state, THREAD_STATE_STOPPED);
}

static void test_thread_should_stop(void **state) {
  // threadStop blocks until STOPPED — if threadShouldStop is broken the
  // looping callback never exits and this test hangs / times out.
  thread_t thread;
  threadInit(&thread, helper_loop);
  threadStart(&thread);
  threadStop(&thread);

  assert_int_equal(thread.state, THREAD_STATE_STOPPED);
}

static void test_thread_data(void **state) {
  int32_t value = 0;

  thread_t thread;
  threadInit(&thread, helper_write_data);
  thread.data = &value;
  threadStart(&thread);
  threadStop(&thread);

  // After threadStop the callback has definitely run.
  assert_int_equal(value, 42);
}

static void test_thread_restart(void **state) {
  // A thread can be started, stopped, and started again.
  thread_t thread;
  threadInit(&thread, helper_noop);

  threadStart(&thread);
  threadStop(&thread);
  assert_int_equal(thread.state, THREAD_STATE_STOPPED);

  // Re-initialise so threadId / state are reset, then start again.
  threadInit(&thread, helper_noop);
  threadStart(&thread);
  threadStop(&thread);
  assert_int_equal(thread.state, THREAD_STATE_STOPPED);
}

// --- threadmutex_t tests ---

static void test_threadMutex_lock_unlock(void **state) {
  threadmutex_t mutex;
  threadMutexInit(&mutex);

  threadMutexLock(&mutex);
  threadMutexUnlock(&mutex);

  threadMutexDispose(&mutex);
}

// Shared data for try-lock test. Uses volatile phase to coordinate the two
// threads without introducing a second mutex.
typedef struct {
  threadmutex_t *target;
  volatile int32_t phase;
  bool_t resultWhileLocked;
  bool_t resultAfterUnlock;
} trylock_data_t;

static void helper_trylock(thread_t *thread) {
  trylock_data_t *data = (trylock_data_t *)thread->data;

  // Phase 1: main holds the lock — trylock must fail.
  while(data->phase != 1) {}
  data->resultWhileLocked = threadMutexTryLock(data->target);
  data->phase = 2;

  // Phase 3: main released the lock — trylock must succeed.
  while(data->phase != 3) {}
  data->resultAfterUnlock = threadMutexTryLock(data->target);
  if(data->resultAfterUnlock) {
    threadMutexUnlock(data->target);
  }
  data->phase = 4;
}

static void test_threadMutex_try_lock(void **state) {
  threadmutex_t mutex;
  threadMutexInit(&mutex);

  trylock_data_t data = {
    .target = &mutex,
    .phase = 0,
    .resultWhileLocked = false,
    .resultAfterUnlock = false
  };

  thread_t thread;
  threadInit(&thread, helper_trylock);
  thread.data = &data;
  threadStart(&thread);

  // Hold the lock, then let the helper try.
  threadMutexLock(&mutex);
  data.phase = 1;
  while(data.phase != 2) {}
  assert_false(data.resultWhileLocked);

  // Release, then let the helper try again.
  threadMutexUnlock(&mutex);
  data.phase = 3;
  while(data.phase != 4) {}
  assert_true(data.resultAfterUnlock);

  threadStop(&thread);
  threadMutexDispose(&mutex);
}

// Mutual-exclusion test: N threads each increment a shared counter M times
// under a mutex. The final value must be exactly N*M.
#define MUTEX_THREADS     4
#define MUTEX_ITERATIONS  10000

typedef struct {
  threadmutex_t *mutex;
  int32_t *counter;
} counter_data_t;

static counter_data_t counter_thread_data[MUTEX_THREADS];
static thread_t counter_threads[MUTEX_THREADS];

static void helper_increment(thread_t *thread) {
  counter_data_t *data = (counter_data_t *)thread->data;
  for(int32_t i = 0; i < MUTEX_ITERATIONS; i++) {
    threadMutexLock(data->mutex);
    (*data->counter)++;
    threadMutexUnlock(data->mutex);
  }
}

static void test_threadMutex_mutual_exclusion(void **state) {
  threadmutex_t mutex;
  threadMutexInit(&mutex);
  int32_t counter = 0;

  for(int32_t i = 0; i < MUTEX_THREADS; i++) {
    counter_thread_data[i].mutex = &mutex;
    counter_thread_data[i].counter = &counter;
    threadInit(&counter_threads[i], helper_increment);
    counter_threads[i].data = &counter_thread_data[i];
  }

  for(int32_t i = 0; i < MUTEX_THREADS; i++) {
    threadStart(&counter_threads[i]);
  }

  for(int32_t i = 0; i < MUTEX_THREADS; i++) {
    threadStop(&counter_threads[i]);
  }

  assert_int_equal(counter, MUTEX_THREADS * MUTEX_ITERATIONS);

  threadMutexDispose(&mutex);
}

int main(void) {
  const struct CMUnitTest tests[] = {
    cmocka_unit_test(test_threadInit),
    cmocka_unit_test(test_thread_start_stop),
    cmocka_unit_test(test_thread_should_stop),
    cmocka_unit_test(test_thread_data),
    cmocka_unit_test(test_thread_restart),
    cmocka_unit_test(test_threadMutex_lock_unlock),
    cmocka_unit_test(test_threadMutex_try_lock),
    cmocka_unit_test(test_threadMutex_mutual_exclusion),
  };
  return cmocka_run_group_tests(tests, NULL, NULL);
}