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

#include "dusktest.h"
#include "asset/asset.h"
#include "asset/assetbatch.h"
#include "asset/loader/assetloader.h"
#include "asset/loader/assetentry.h"
#include "util/memory.h"

// ============================================================
// Stub loader callbacks
// ============================================================

static errorret_t stub_load_success(assetloading_t *loading) {
  loading->entry->state = ASSET_ENTRY_STATE_LOADED;
  errorOk();
}

static errorret_t stub_load_fail(assetloading_t *loading) {
  loading->entry->state = ASSET_ENTRY_STATE_ERROR;
  errorThrow("Stub loader failed");
}

static errorret_t stub_dispose(assetentry_t *entry) {
  errorOk();
}

// ============================================================
// Per-test setup / teardown
// ============================================================

static assetloadercallbacks_t saved_callbacks[ASSET_LOADER_TYPE_COUNT];

static int batch_setup(void **state) {
  memoryCopy(saved_callbacks, ASSET_LOADER_CALLBACKS, sizeof(saved_callbacks));

  memoryZero(&ASSET, sizeof(ASSET));
  for(size_t i = 0; i < ASSET_LOADING_COUNT_MAX; i++) {
    threadMutexInit(&ASSET.loading[i].mutex);
  }

  for(int i = 0; i < ASSET_LOADER_TYPE_COUNT; i++) {
    ASSET_LOADER_CALLBACKS[i].loadSync = stub_load_success;
    ASSET_LOADER_CALLBACKS[i].dispose = stub_dispose;
  }

  return 0;
}

static int batch_teardown(void **state) {
  for(int i = 0; i < ASSET_ENTRY_COUNT_MAX; i++) {
    if(ASSET.entries[i].type != ASSET_LOADER_TYPE_NULL) {
      errorret_t ret = assetEntryDispose(&ASSET.entries[i]);
      if(errorIsNotOk(ret)) errorCatch(ret);
    }
  }

  for(size_t i = 0; i < ASSET_LOADING_COUNT_MAX; i++) {
    threadMutexDispose(&ASSET.loading[i].mutex);
  }

  memoryCopy(ASSET_LOADER_CALLBACKS, saved_callbacks, sizeof(saved_callbacks));
  memoryZero(&ASSET, sizeof(ASSET));
  return 0;
}

// ============================================================
// Event counters
// ============================================================

static int32_t g_onLoadedCount;
static int32_t g_onErrorCount;
static int32_t g_onEntryLoadedCount;
static int32_t g_onEntryErrorCount;

static void resetCounters(void) {
  g_onLoadedCount = 0;
  g_onErrorCount = 0;
  g_onEntryLoadedCount = 0;
  g_onEntryErrorCount = 0;
}

static void onLoadedCb(void *params, void *user) { g_onLoadedCount++; }
static void onErrorCb(void *params, void *user) { g_onErrorCount++; }
static void onEntryLoadedCb(void *params, void *user) { g_onEntryLoadedCount++; }
static void onEntryErrorCb(void *params, void *user) { g_onEntryErrorCount++; }

// ============================================================
// Basic lifecycle
// ============================================================

static void test_batch_single_entry_loads_and_fires_events(void **state) {
  resetCounters();
  assetbatchdesc_t descs[1] = {
    { .path = "a.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatch_t batch;
  assetBatchInit(&batch, 1, descs);
  eventSubscribe(&batch.onLoaded, onLoadedCb, NULL);
  eventSubscribe(&batch.onEntryLoaded, onEntryLoadedCb, NULL);

  assert_false(assetBatchIsLoaded(&batch));

  errorret_t ret = assetUpdate();
  assert_true(errorIsOk(ret));

  assert_true(assetBatchIsLoaded(&batch));
  assert_int_equal(g_onLoadedCount, 1);
  assert_int_equal(g_onEntryLoadedCount, 1);

  assetBatchDispose(&batch);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

static void test_batch_multiple_entries_fire_onLoaded_once(void **state) {
  resetCounters();
  assetbatchdesc_t descs[3] = {
    { .path = "a.locale", .type = ASSET_LOADER_TYPE_LOCALE },
    { .path = "b.locale", .type = ASSET_LOADER_TYPE_LOCALE },
    { .path = "c.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatch_t batch;
  assetBatchInit(&batch, 3, descs);
  eventSubscribe(&batch.onLoaded, onLoadedCb, NULL);
  eventSubscribe(&batch.onEntryLoaded, onEntryLoadedCb, NULL);

  errorret_t ret = assetUpdate();
  assert_true(errorIsOk(ret));

  assert_true(assetBatchIsLoaded(&batch));
  assert_int_equal(g_onEntryLoadedCount, 3);
  assert_int_equal(g_onLoadedCount, 1);  // batch-level: fires once, not per-entry

  assetBatchDispose(&batch);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

static void test_batch_already_loaded_entry_counts_immediately(void **state) {
  // Pre-load an entry directly before the batch ever sees it.
  assetentry_t *preloaded = assetGetEntry(
    "preloaded.locale", ASSET_LOADER_TYPE_LOCALE, NULL
  );
  assetEntryLock(preloaded);
  assetUpdate();
  assert_int_equal(preloaded->state, ASSET_ENTRY_STATE_LOADED);

  assetbatchdesc_t descs[1] = {
    { .path = "preloaded.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatch_t batch;
  assetBatchInit(&batch, 1, descs);

  // assetBatchInit must recognize the already-LOADED entry synchronously,
  // without waiting on an assetUpdate to discover it.
  assert_true(assetBatchIsLoaded(&batch));

  assetEntryUnlock(preloaded);
  assetBatchDispose(&batch);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

// ============================================================
// Error handling
// ============================================================

static void test_batch_error_entry_sets_hasError_and_fires_events(
  void **state
) {
  resetCounters();
  ASSET_LOADER_CALLBACKS[ASSET_LOADER_TYPE_LOCALE].loadSync = stub_load_fail;

  assetbatchdesc_t descs[1] = {
    { .path = "fail.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatch_t batch;
  assetBatchInit(&batch, 1, descs);
  eventSubscribe(&batch.onError, onErrorCb, NULL);
  eventSubscribe(&batch.onEntryError, onEntryErrorCb, NULL);

  // First update: the sync loader fails and sets ERROR, but the loading
  // slot isn't cleared (and the entry's onError doesn't fire) until the
  // NEXT update sees the already-errored slot -- matches assetUpdate's
  // documented two-step error handling (see test_asset.c).
  errorret_t ret = assetUpdate();
  assert_true(errorIsOk(ret));
  assert_int_equal(g_onErrorCount, 0);

  ret = assetUpdate();
  assert_true(errorIsNotOk(ret));
  errorCatch(ret);

  assert_true(assetBatchHasError(&batch));
  assert_int_equal(g_onErrorCount, 1);
  assert_int_equal(g_onEntryErrorCount, 1);

  assetBatchDispose(&batch);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

// ============================================================
// assetBatchRequireLoaded
// ============================================================

static void test_batch_requireLoaded_blocks_until_loaded(void **state) {
  assetbatchdesc_t descs[2] = {
    { .path = "a.locale", .type = ASSET_LOADER_TYPE_LOCALE },
    { .path = "b.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatch_t batch;
  assetBatchInit(&batch, 2, descs);

  errorret_t ret = assetBatchRequireLoaded(&batch);
  assert_true(errorIsOk(ret));
  assert_true(assetBatchIsLoaded(&batch));

  assetBatchDispose(&batch);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

static void test_batch_requireLoaded_returns_error_on_failed_entry(
  void **state
) {
  ASSET_LOADER_CALLBACKS[ASSET_LOADER_TYPE_LOCALE].loadSync = stub_load_fail;

  assetbatchdesc_t descs[1] = {
    { .path = "fail.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatch_t batch;
  assetBatchInit(&batch, 1, descs);

  errorret_t ret = assetBatchRequireLoaded(&batch);
  assert_true(errorIsNotOk(ret));
  errorCatch(ret);

  assetBatchDispose(&batch);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

// ============================================================
// assetBatchLock / assetBatchUnlock
// ============================================================

static void test_batch_lock_unlock_adjust_ref_counts(void **state) {
  assetbatchdesc_t descs[1] = {
    { .path = "a.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatch_t batch;
  assetBatchInit(&batch, 1, descs);
  assert_int_equal((int)batch.entries[0]->refs.count, 1);

  assetBatchLock(&batch);
  assert_int_equal((int)batch.entries[0]->refs.count, 2);

  assetBatchUnlock(&batch);
  assert_int_equal((int)batch.entries[0]->refs.count, 1);

  assetBatchDispose(&batch);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

// ============================================================
// Caching: sharing a single cached entry across independent consumers
// ============================================================

// Regression coverage for a real bug found while writing these tests:
// eventSubscribe/eventUnsubscribe used to match on `callback` alone, so two
// independent assetbatch_t's both waiting on the same cached asset entry
// (identical assetBatchEntryOnLoadedCb function pointer, different `batch`
// as the `user`) would hit assertUnreachable() inside assetBatchInit. Now
// fixed to match on the (callback, user) pair.
static void test_two_batches_share_one_cached_entry(void **state) {
  resetCounters();
  assetbatchdesc_t descsA[1] = {
    { .path = "shared.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };
  assetbatchdesc_t descsB[1] = {
    { .path = "shared.locale", .type = ASSET_LOADER_TYPE_LOCALE },
  };

  assetbatch_t batchA, batchB;
  assetBatchInit(&batchA, 1, descsA);
  assetBatchInit(&batchB, 1, descsB);  // must not abort

  // Cache hit: the second batch must resolve to the exact same entry
  // rather than triggering a second, independent load.
  assert_ptr_equal(batchA.entries[0], batchB.entries[0]);
  assert_int_equal((int)batchA.entries[0]->refs.count, 2);

  eventSubscribe(&batchA.onLoaded, onLoadedCb, NULL);
  eventSubscribe(&batchB.onLoaded, onLoadedCb, NULL);

  errorret_t ret = assetUpdate();
  assert_true(errorIsOk(ret));

  // Both batches observe completion of the single underlying load.
  assert_true(assetBatchIsLoaded(&batchA));
  assert_true(assetBatchIsLoaded(&batchB));
  assert_int_equal(g_onLoadedCount, 2);

  assetBatchDispose(&batchA);
  // Still referenced by batchB -- must survive batchA's dispose untouched.
  assert_int_equal((int)batchB.entries[0]->type, (int)ASSET_LOADER_TYPE_LOCALE);
  assert_int_equal((int)batchB.entries[0]->refs.count, 1);

  assetBatchDispose(&batchB);

  errorret_t reapRet = assetReapUnused();
  assert_true(errorIsOk(reapRet));
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

// ============================================================
// main
// ============================================================

int main(void) {
  assertInit();
  const struct CMUnitTest tests[] = {
    cmocka_unit_test_setup_teardown(test_batch_single_entry_loads_and_fires_events, batch_setup, batch_teardown),
    cmocka_unit_test_setup_teardown(test_batch_multiple_entries_fire_onLoaded_once, batch_setup, batch_teardown),
    cmocka_unit_test_setup_teardown(test_batch_already_loaded_entry_counts_immediately, batch_setup, batch_teardown),

    cmocka_unit_test_setup_teardown(test_batch_error_entry_sets_hasError_and_fires_events, batch_setup, batch_teardown),

    cmocka_unit_test_setup_teardown(test_batch_requireLoaded_blocks_until_loaded, batch_setup, batch_teardown),
    cmocka_unit_test_setup_teardown(test_batch_requireLoaded_returns_error_on_failed_entry, batch_setup, batch_teardown),

    cmocka_unit_test_setup_teardown(test_batch_lock_unlock_adjust_ref_counts, batch_setup, batch_teardown),

    cmocka_unit_test_setup_teardown(test_two_batches_share_one_cached_entry, batch_setup, batch_teardown),
  };
  return cmocka_run_group_tests(tests, NULL, NULL);
}