//*****************************************************************************
// Copyright 2017-2020 Intel Corporation
//
// 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.
//*****************************************************************************

#ifdef _WIN32
#include <windows.h>
#if defined(WINAPI_FAMILY) && !WINAPI_PARTITION_DESKTOP
#error "Only WINAPI_PARTITION_DESKTOP is supported, because of LoadLibrary[A|W]"
#endif
#elif defined(__linux) || defined(__APPLE__)
#include <dlfcn.h>
#endif

#include <sstream>

#include "backend.hpp"
#include "backend_manager.hpp"
#include "dynamic/dynamic_backend.hpp"
#include "ngraph/file_util.hpp"
#include "ngraph/util.hpp"

using namespace std;
using namespace ngraph;

std::mutex runtime::Backend::m_mtx;
std::string runtime::Backend::s_backend_shared_library_search_directory;

// This finds the full path of the containing shared library
static string find_my_pathname()
{
#ifdef NGRAPH_DYNAMIC_COMPONENTS_ENABLE
#ifdef _WIN32
    HMODULE hModule = GetModuleHandleW(L"ngraph.dll");
    WCHAR wpath[MAX_PATH];
    GetModuleFileNameW(hModule, wpath, MAX_PATH);
    wstring ws(wpath);
    string path(ws.begin(), ws.end());
    replace(path.begin(), path.end(), '\\', '/');
    path = file_util::get_directory(path);
    path += "/";
    return path;
#elif defined(__linux) || defined(__APPLE__)
    Dl_info dl_info;
    dladdr(reinterpret_cast<void*>(ngraph::to_lower), &dl_info);
    return dl_info.dli_fname;
#else
#error "Unsupported OS"
#endif
#else
    return {};
#endif
}

runtime::Backend::~Backend()
{
}

std::shared_ptr<runtime::Backend> runtime::Backend::create(const string& t,
                                                           bool must_support_dynamic)
{
    // Rewrite backend name BACKEND_OPTION to BACKEND:OPTION
    string type = t;
    auto pos = type.find('_');
    if (pos != string::npos)
    {
        type = type.replace(pos, 1, ":");
    }

    auto inner_backend = BackendManager::create_backend(type);

    if (!must_support_dynamic || inner_backend->supports_dynamic_tensors())
    {
        return inner_backend;
    }
    else
    {
        return make_shared<runtime::dynamic::DynamicBackend>(inner_backend);
    }
}

vector<string> runtime::Backend::get_registered_devices()
{
    return BackendManager::get_registered_backends();
}

std::shared_ptr<ngraph::runtime::Tensor>
    runtime::Backend::create_dynamic_tensor(const ngraph::element::Type& /* element_type */,
                                            const PartialShape& /* shape */)
{
    throw std::invalid_argument("This backend does not support dynamic tensors");
}

bool runtime::Backend::is_supported(const Node& /* node */) const
{
    // The default behavior is that a backend does not support any ops. If this is not the case
    // then override this method and enhance.
    return false;
}

std::shared_ptr<runtime::Executable> runtime::Backend::load(istream& /* input_stream */)
{
    throw runtime_error("load operation unimplemented.");
}

void runtime::Backend::set_backend_shared_library_search_directory(const string& path)
{
    std::lock_guard<std::mutex> lock(runtime::Backend::m_mtx);
    s_backend_shared_library_search_directory = path;
}

const string& runtime::Backend::get_backend_shared_library_search_directory()
{
    if (s_backend_shared_library_search_directory.empty())
    {
        s_backend_shared_library_search_directory = find_my_pathname();
    }
    return s_backend_shared_library_search_directory;
}

bool runtime::Backend::set_config(const map<string, string>& /* config */, string& error)
{
    error = "set_config not supported";
    return false;
}