/**
 * 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/loader/assetloader.h"
#include "asset/loader/assetentry.h"
#include "asset/loader/dmf/assetmeshloader.h"
#include "display/mesh/meshvertex.h"
#include "thread/thread.h"
#include "util/memory.h"
#include <zip.h>
#include <string.h>

// ============================================================
// DMF binary fixtures
// DMF layout:
//   [0-2]  magic "DMF"
//   [3]    pad
//   [4-7]  version   (uint32 LE)
//   [8-11] vertCount (uint32 LE)
//   [12..] vertCount * meshvertex_t {uv[2], pos[3]} (float LE each)
//
// meshvertex_t is already {float uv[2]; float pos[3];} in wire order, and
// this test host is little-endian, so a plain memcpy of real meshvertex_t
// values reproduces the exact on-disk format -- no manual byte encoding.
// ============================================================

typedef struct {
  uint8_t magic[3];
  uint8_t pad;
  uint32_t version;
  uint32_t vertCount;
} dmfheader_t;

static size_t buildMeshFixture(
  uint8_t *out,
  const uint8_t magic[3],
  uint32_t version,
  uint32_t vertCount,
  const meshvertex_t *verts
) {
  dmfheader_t header;
  header.magic[0] = magic[0];
  header.magic[1] = magic[1];
  header.magic[2] = magic[2];
  header.pad = 0;
  header.version = version;
  header.vertCount = vertCount;

  memcpy(out, &header, sizeof(header));
  if(vertCount > 0) {
    memcpy(out + sizeof(header), verts, vertCount * sizeof(meshvertex_t));
  }
  return sizeof(header) + (size_t)vertCount * sizeof(meshvertex_t);
}

static const uint8_t MAGIC_DMF[3] = { 'D', 'M', 'F' };
static const uint8_t MAGIC_BAD[3] = { 'X', 'Y', 'Z' };

static const meshvertex_t TWO_VERTS[2] = {
  { .uv = { 0.25f, 0.75f }, .pos = { 1.0f, 2.0f, 3.0f } },
  { .uv = { 0.5f, 0.5f }, .pos = { -1.0f, 0.0f, 4.0f } },
};

// ============================================================
// Async thread helper
// ============================================================

typedef struct {
  assetloading_t *loading;
  bool_t ok;
} mesh_async_run_t;

static void mesh_async_thread_cb(thread_t *thread) {
  mesh_async_run_t *run = (mesh_async_run_t *)thread->data;
  errorret_t ret = assetMeshLoaderAsync(run->loading);
  run->ok = errorIsOk(ret);
  if(errorIsNotOk(ret)) errorCatch(ret);
}

static bool_t run_mesh_async(assetloading_t *loading) {
  mesh_async_run_t run = { .loading = loading, .ok = false };
  thread_t thread;
  threadInit(&thread, mesh_async_thread_cb);
  thread.data = &run;
  threadStart(&thread);
  threadStop(&thread);
  return run.ok;
}

// ============================================================
// In-memory ZIP
// ============================================================

static zip_t *g_zip = NULL;

static int mesh_zip_add(
  zip_t *za, const char_t *name, const void *data, size_t len
) {
  zip_source_t *s = zip_source_buffer(za, data, len, 0);
  return (int)zip_file_add(za, name, s, ZIP_FL_OVERWRITE);
}

static int zip_setup(void **state) {
  zip_error_t err;
  zip_error_init(&err);

  zip_source_t *write_src = zip_source_buffer_create(NULL, 0, 1, &err);
  if(!write_src) return -1;

  zip_t *za = zip_open_from_source(write_src, ZIP_TRUNCATE, &err);
  if(!za) { zip_source_free(write_src); return -1; }

  // zip_source_buffer defers reading until zip_close(), so each fixture
  // needs its own backing buffer -- reusing one scratch buffer across
  // multiple calls would make every entry read back whatever was written
  // into it last.
  static uint8_t bufEmpty[512], bufBadMagic[512], bufBadVersion[512],
    bufVerts[512];
  size_t len;

  len = buildMeshFixture(bufEmpty, MAGIC_DMF, ASSET_MESH_FILE_VERSION, 0, NULL);
  if(mesh_zip_add(za, "empty.mesh", bufEmpty, len) < 0) { zip_close(za); return -1; }

  len = buildMeshFixture(bufBadMagic, MAGIC_BAD, ASSET_MESH_FILE_VERSION, 0, NULL);
  if(mesh_zip_add(za, "badmagic.mesh", bufBadMagic, len) < 0) { zip_close(za); return -1; }

  len = buildMeshFixture(bufBadVersion, MAGIC_DMF, ASSET_MESH_FILE_VERSION + 1, 0, NULL);
  if(mesh_zip_add(za, "badversion.mesh", bufBadVersion, len) < 0) { zip_close(za); return -1; }

  len = buildMeshFixture(bufVerts, MAGIC_DMF, ASSET_MESH_FILE_VERSION, 2, TWO_VERTS);
  if(mesh_zip_add(za, "verts.mesh", bufVerts, len) < 0) { zip_close(za); return -1; }

  zip_source_keep(write_src);
  if(zip_close(za) != 0) { zip_source_free(write_src); return -1; }

  zip_stat_t zs;
  memset(&zs, 0, sizeof(zs));
  if(zip_source_stat(write_src, &zs) != 0 || !(zs.valid & ZIP_STAT_SIZE)) {
    zip_source_free(write_src); return -1;
  }

  void *zipbuf = malloc((size_t)zs.size);
  if(!zipbuf) { zip_source_free(write_src); return -1; }

  if(zip_source_open(write_src) != 0) {
    free(zipbuf); zip_source_free(write_src); return -1;
  }
  zip_source_read(write_src, zipbuf, (zip_uint64_t)zs.size);
  zip_source_close(write_src);
  zip_source_free(write_src);

  zip_error_init(&err);
  zip_source_t *read_src = zip_source_buffer_create(
    zipbuf, (zip_uint64_t)zs.size, 1, &err
  );
  if(!read_src) { free(zipbuf); return -1; }

  g_zip = zip_open_from_source(read_src, 0, &err);
  if(!g_zip) { zip_source_free(read_src); return -1; }

  ASSET.zip = g_zip;
  return 0;
}

static int zip_teardown(void **state) {
  if(g_zip) { zip_close(g_zip); g_zip = NULL; }
  ASSET.zip = NULL;
  return 0;
}

// ============================================================
// Loader pipeline helper
// ============================================================

typedef struct {
  assetentry_t entry;
  assetloading_t loading;
} loader_ctx_t;

static void loader_ctx_init(loader_ctx_t *ctx, const char_t *name) {
  assetEntryInit(&ctx->entry, name, ASSET_LOADER_TYPE_MESH, NULL);
  threadMutexInit(&ctx->loading.mutex);
  memoryZero(&ctx->loading.loading, sizeof(ctx->loading.loading));
  ctx->loading.type = ASSET_LOADER_TYPE_MESH;
  ctx->loading.entry = &ctx->entry;
  ctx->entry.state = ASSET_ENTRY_STATE_PENDING_SYNC;
}

// Drives sync(INITIAL) -> async(READ_FILE) -> sync(CREATE_MESH). Only safe
// to call for a fixture with vertCount == 0: any vertCount > 0 would reach
// the GPU-touching mesh upload in the sync phase, which this headless test
// binary has no GL context for.
static errorret_t loader_ctx_run_empty(loader_ctx_t *ctx) {
  errorret_t ret = assetMeshLoaderSync(&ctx->loading);
  if(errorIsNotOk(ret)) return ret;

  if(!run_mesh_async(&ctx->loading)) {
    ctx->entry.state = ASSET_ENTRY_STATE_ERROR;
    errorThrow("Async mesh load failed");
  }

  return assetMeshLoaderSync(&ctx->loading);
}

static void loader_ctx_dispose(loader_ctx_t *ctx) {
  if(ctx->entry.type != ASSET_LOADER_TYPE_NULL) {
    errorret_t ret = assetEntryDispose(&ctx->entry);
    if(errorIsNotOk(ret)) errorCatch(ret);
  }
  threadMutexDispose(&ctx->loading.mutex);
}

// ============================================================
// Tests
// ============================================================

static void test_mesh_zero_vertices_full_roundtrip_skips_gpu(void **state) {
  loader_ctx_t ctx;
  loader_ctx_init(&ctx, "empty.mesh");

  errorret_t ret = loader_ctx_run_empty(&ctx);
  assert_true(errorIsOk(ret));
  assert_int_equal(ctx.entry.state, ASSET_ENTRY_STATE_LOADED);

  assetmeshoutput_t *out = &ctx.entry.data.mesh;
  assert_false(out->meshInitialized);
  assert_null(out->vertices);

  loader_ctx_dispose(&ctx);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

static void test_mesh_bad_magic_errors(void **state) {
  loader_ctx_t ctx;
  loader_ctx_init(&ctx, "badmagic.mesh");

  errorret_t ret = assetMeshLoaderSync(&ctx.loading);
  assert_true(errorIsOk(ret));
  assert_false(run_mesh_async(&ctx.loading));

  assert_int_equal(ctx.entry.state, ASSET_ENTRY_STATE_ERROR);
  loader_ctx_dispose(&ctx);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

static void test_mesh_bad_version_errors(void **state) {
  loader_ctx_t ctx;
  loader_ctx_init(&ctx, "badversion.mesh");

  errorret_t ret = assetMeshLoaderSync(&ctx.loading);
  assert_true(errorIsOk(ret));
  assert_false(run_mesh_async(&ctx.loading));

  assert_int_equal(ctx.entry.state, ASSET_ENTRY_STATE_ERROR);
  loader_ctx_dispose(&ctx);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

static void test_mesh_missing_file_errors(void **state) {
  loader_ctx_t ctx;
  loader_ctx_init(&ctx, "nonexistent.mesh");

  errorret_t ret = assetMeshLoaderSync(&ctx.loading);
  assert_true(errorIsOk(ret));
  assert_false(run_mesh_async(&ctx.loading));

  assert_int_equal(ctx.entry.state, ASSET_ENTRY_STATE_ERROR);
  loader_ctx_dispose(&ctx);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

static void test_mesh_async_parses_vertices_and_endian(void **state) {
  // Only drives the async (file-read/parse) phase -- the sync phase for a
  // non-zero vertex count would upload to the GPU, which this headless
  // test binary can't do.
  loader_ctx_t ctx;
  loader_ctx_init(&ctx, "verts.mesh");

  errorret_t ret = assetMeshLoaderSync(&ctx.loading);  // arms READ_FILE state
  assert_true(errorIsOk(ret));

  assert_true(run_mesh_async(&ctx.loading));

  assert_int_equal((int)ctx.loading.loading.mesh.vertCount, 2);
  assert_int_equal(ctx.entry.state, ASSET_ENTRY_STATE_PENDING_SYNC);
  assert_int_equal(
    ctx.loading.loading.mesh.state, ASSET_MESH_LOADING_STATE_CREATE_MESH
  );

  meshvertex_t *parsed = (meshvertex_t *)ctx.loading.loading.mesh.data;
  assert_non_null(parsed);
  assert_float_equal(parsed[0].uv[0], 0.25f, 0.0001f);
  assert_float_equal(parsed[0].uv[1], 0.75f, 0.0001f);
  assert_float_equal(parsed[0].pos[0], 1.0f, 0.0001f);
  assert_float_equal(parsed[0].pos[1], 2.0f, 0.0001f);
  assert_float_equal(parsed[0].pos[2], 3.0f, 0.0001f);
  assert_float_equal(parsed[1].uv[0], 0.5f, 0.0001f);
  assert_float_equal(parsed[1].pos[2], 4.0f, 0.0001f);

  // Never reached the sync/GPU phase, so the parsed buffer is still owned
  // by the loading slot (entry->data.mesh.vertices is still NULL) -- free
  // it manually before disposing, since assetMeshDispose only knows about
  // the entry-owned copy.
  memoryFree(ctx.loading.loading.mesh.data);
  ctx.loading.loading.mesh.data = NULL;

  loader_ctx_dispose(&ctx);
  assert_int_equal(memoryGetAllocatedCount(), 0);
}

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

int main(void) {
  assertInit();
  const struct CMUnitTest tests[] = {
    cmocka_unit_test_setup_teardown(test_mesh_zero_vertices_full_roundtrip_skips_gpu, zip_setup, zip_teardown),
    cmocka_unit_test_setup_teardown(test_mesh_bad_magic_errors, zip_setup, zip_teardown),
    cmocka_unit_test_setup_teardown(test_mesh_bad_version_errors, zip_setup, zip_teardown),
    cmocka_unit_test_setup_teardown(test_mesh_missing_file_errors, zip_setup, zip_teardown),
    cmocka_unit_test_setup_teardown(test_mesh_async_parses_vertices_and_endian, zip_setup, zip_teardown),
  };
  return cmocka_run_group_tests(tests, NULL, NULL);
}