// Copyright 2021 DeepMind Technologies Limited
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include "test/fixture.h"

#include <filesystem>
#include <fstream>
#include <memory>
#include <string_view>

#include <gmock/gmock.h>
#include <gtest/gtest.h>
#include <absl/base/const_init.h>
#include <absl/strings/str_cat.h>
#include <absl/synchronization/mutex.h>
#include <mujoco/mjmodel.h>
#include <mujoco/mujoco.h>

namespace mujoco {
namespace {

using ::testing::NotNull;

ABSL_CONST_INIT static absl::Mutex handlers_mutex(absl::kConstInit);
static int guard_count ABSL_GUARDED_BY(handlers_mutex) = 0;

void default_mj_error_handler(const char* msg) {
  FAIL() << "mju_user_error: " << msg;
}

void default_mj_warning_handler(const char* msg) {
  ADD_FAILURE() << "mju_user_warning: " << msg;
}
}  // namespace

MujocoErrorTestGuard::MujocoErrorTestGuard() {
  absl::MutexLock lock(&handlers_mutex);
  if (++guard_count == 1) {
    mju_user_error = default_mj_error_handler;
    mju_user_warning = default_mj_warning_handler;
  }
}

MujocoErrorTestGuard::~MujocoErrorTestGuard() {
  absl::MutexLock lock(&handlers_mutex);
  if (--guard_count == 0) {
    mju_user_error = nullptr;
    mju_user_warning = nullptr;
  }
}

const std::string GetTestDataFilePath(std::string_view path) {
  return std::string(path);
}

const std::string GetModelPath(std::string_view path) {
  return absl::StrCat("../model/", path);
}

mjModel* LoadModelFromString(std::string_view xml, char* error,
                             int error_size, mjVFS* vfs) {
  // register string resource provider if not registered before
  if (mjp_getResourceProvider("LoadModelFromString:") == nullptr) {
    mjpResourceProvider resourceProvider;
    mjp_defaultResourceProvider(&resourceProvider);
    resourceProvider.prefix = "LoadModelFromString";
    resourceProvider.open = +[](mjResource* resource) {
      resource->data = &(resource->name[strlen("LoadModelFromString:")]);
      return 1;
    };
    resourceProvider.read = +[](mjResource* resource, const void** buffer) {
      *buffer = resource->data;
      return (int) strlen((const char*) resource->data);
    };
    resourceProvider.close = +[](mjResource* resource) {};
    mjp_registerResourceProvider(&resourceProvider);
  }
  std::string xml2 = {xml.begin(), xml.end()};
  std::string str = "LoadModelFromString:" +  xml2;
  return mj_loadXML(str.c_str(), vfs, error, error_size);
}

static void AssertModelNotNull(mjModel* model,
                                  const std::array<char, 1024>& error) {
  ASSERT_THAT(model, NotNull()) << "Failed to load model: " << error.data();
}

mjModel* LoadModelFromPath(const char* model_path) {
  const std::string xml_path = GetModelPath(model_path);
  std::array<char, 1024> error;
  mjModel* model = mj_loadXML(
    xml_path.c_str(), nullptr, error.data(), error.size());
  AssertModelNotNull(model, error);
  return model;
}

const std::string GetFileContents(const char* path) {
  std::ifstream ifs;
  ifs.open(path, std::ifstream::in);
  EXPECT_FALSE(ifs.fail());
  std::ostringstream sstream;
  sstream << ifs.rdbuf();
  return sstream.str();
}

const std::string SaveAndReadXml(const mjModel* model) {
  EXPECT_THAT(model, testing::NotNull());

  constexpr int kMaxPathLen = 1024;
  std::string path_template =
      std::filesystem::temp_directory_path().append("tmp.XXXXXX").string();
  EXPECT_LT(path_template.size(), kMaxPathLen);

  char filepath[kMaxPathLen];
  mju_strncpy(filepath, path_template.c_str(), path_template.size() + 1);

#if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
  int fd = mkstemp(filepath);
  EXPECT_NE(fd, -1) << std::strerror(errno);
#elif defined(_WIN32)
  EXPECT_NE(_mktemp_s(filepath), EINVAL);
#endif

  mj_saveLastXML(filepath, model, nullptr, 0);
  std::string contents = GetFileContents(filepath);

#if defined(_POSIX_VERSION) && _POSIX_VERSION >= 200112L
  close(fd);
#endif
  std::remove(filepath);

  return contents;
}

std::vector<mjtNum> GetCtrlNoise(const mjModel* m, int nsteps,
                                 mjtNum ctrlnoise) {
  std::vector<mjtNum> ctrl;
  for (int step=0; step < nsteps; step++) {
    for (int i = 0; i < m->nu; i++) {
      mjtNum center = 0.0;
      mjtNum radius = 1.0;
      mjtNum* range = m->actuator_ctrlrange + 2 * i;
      if (m->actuator_ctrllimited[i]) {
        center = (range[1] + range[0]) / 2;
        radius = (range[1] - range[0]) / 2;
      }
      radius *= ctrlnoise;
      ctrl.push_back(center + radius * (2 * mju_Halton(step, i+2) - 1));
    }
  }
  return ctrl;
}

}  // namespace mujoco