// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "flutter/shell/platform/windows/public/flutter_windows.h"

#include <assert.h>
#include <io.h>

#include <algorithm>
#include <chrono>
#include <cstdlib>
#include <filesystem>
#include <iostream>
#include <memory>
#include <vector>

#include "flutter/shell/platform/common/cpp/client_wrapper/include/flutter/plugin_registrar.h"
#include "flutter/shell/platform/common/cpp/incoming_message_dispatcher.h"
#include "flutter/shell/platform/common/cpp/path_utils.h"
#include "flutter/shell/platform/embedder/embedder.h"
#include "flutter/shell/platform/windows/flutter_windows_view.h"
#include "flutter/shell/platform/windows/win32_dpi_utils.h"
#include "flutter/shell/platform/windows/win32_flutter_window.h"
#include "flutter/shell/platform/windows/win32_platform_handler.h"
#include "flutter/shell/platform/windows/win32_task_runner.h"
#include "flutter/shell/platform/windows/window_binding_handler.h"
#include "flutter/shell/platform/windows/window_state.h"

static_assert(FLUTTER_ENGINE_VERSION == 1, "");

// Attempts to load AOT data from the given path, which must be absolute and
// non-empty. Logs and returns nullptr on failure.
UniqueAotDataPtr LoadAotData(std::filesystem::path aot_data_path) {
  if (aot_data_path.empty()) {
    std::cerr
        << "Attempted to load AOT data, but no aot_library_path was provided."
        << std::endl;
    return nullptr;
  }
  if (!std::filesystem::exists(aot_data_path)) {
    std::cerr << "Can't load AOT data from " << aot_data_path.u8string()
              << "; no such file." << std::endl;
    return nullptr;
  }
  std::string path_string = aot_data_path.u8string();
  FlutterEngineAOTDataSource source = {};
  source.type = kFlutterEngineAOTDataSourceTypeElfPath;
  source.elf_path = path_string.c_str();
  FlutterEngineAOTData data = nullptr;
  auto result = FlutterEngineCreateAOTData(&source, &data);
  if (result != kSuccess) {
    std::cerr << "Failed to load AOT data from: " << path_string << std::endl;
    return nullptr;
  }
  return UniqueAotDataPtr(data);
}

// Spins up an instance of the Flutter Engine.
//
// This function launches the Flutter Engine in a background thread, supplying
// the necessary callbacks for rendering within a win32window (if one is
// provided).
//
// Returns the state object for the engine, or null on failure to start the
// engine.
static std::unique_ptr<FlutterDesktopEngineState> RunFlutterEngine(
    flutter::FlutterWindowsView* view,
    const FlutterDesktopEngineProperties& engine_properties) {
  auto state = std::make_unique<FlutterDesktopEngineState>();

  // FlutterProjectArgs is expecting a full argv, so when processing it for
  // flags the first item is treated as the executable and ignored. Add a dummy
  // value so that all provided arguments are used.
  std::vector<const char*> argv = {"placeholder"};
  if (engine_properties.switches_count > 0) {
    argv.insert(argv.end(), &engine_properties.switches[0],
                &engine_properties.switches[engine_properties.switches_count]);
  }

  view->CreateRenderSurface();

  // Provide the necessary callbacks for rendering within a win32 child window.
  FlutterRendererConfig config = {};
  config.type = kOpenGL;
  config.open_gl.struct_size = sizeof(config.open_gl);
  config.open_gl.make_current = [](void* user_data) -> bool {
    auto host = static_cast<flutter::FlutterWindowsView*>(user_data);
    return host->MakeCurrent();
  };
  config.open_gl.clear_current = [](void* user_data) -> bool {
    auto host = static_cast<flutter::FlutterWindowsView*>(user_data);
    return host->ClearContext();
  };
  config.open_gl.present = [](void* user_data) -> bool {
    auto host = static_cast<flutter::FlutterWindowsView*>(user_data);
    return host->SwapBuffers();
  };
  config.open_gl.fbo_callback = [](void* user_data) -> uint32_t { return 0; };
  config.open_gl.gl_proc_resolver = [](void* user_data,
                                       const char* what) -> void* {
    return reinterpret_cast<void*>(eglGetProcAddress(what));
  };
  config.open_gl.make_resource_current = [](void* user_data) -> bool {
    auto host = static_cast<flutter::FlutterWindowsView*>(user_data);
    return host->MakeResourceCurrent();
  };

  // Configure task runner interop.
  auto state_ptr = state.get();
  state->task_runner = std::make_unique<flutter::Win32TaskRunner>(
      GetCurrentThreadId(), [state_ptr](const auto* task) {
        if (FlutterEngineRunTask(state_ptr->engine, task) != kSuccess) {
          std::cerr << "Could not post an engine task." << std::endl;
        }
      });
  FlutterTaskRunnerDescription platform_task_runner = {};
  platform_task_runner.struct_size = sizeof(FlutterTaskRunnerDescription);
  platform_task_runner.user_data = state->task_runner.get();
  platform_task_runner.runs_task_on_current_thread_callback =
      [](void* user_data) -> bool {
    return reinterpret_cast<flutter::Win32TaskRunner*>(user_data)
        ->RunsTasksOnCurrentThread();
  };
  platform_task_runner.post_task_callback = [](FlutterTask task,
                                               uint64_t target_time_nanos,
                                               void* user_data) -> void {
    reinterpret_cast<flutter::Win32TaskRunner*>(user_data)->PostTask(
        task, target_time_nanos);
  };

  FlutterCustomTaskRunners custom_task_runners = {};
  custom_task_runners.struct_size = sizeof(FlutterCustomTaskRunners);
  custom_task_runners.platform_task_runner = &platform_task_runner;

  std::filesystem::path assets_path(engine_properties.assets_path);
  std::filesystem::path icu_path(engine_properties.icu_data_path);
  std::filesystem::path aot_library_path =
      engine_properties.aot_library_path == nullptr
          ? std::filesystem::path()
          : std::filesystem::path(engine_properties.aot_library_path);
  if (assets_path.is_relative() || icu_path.is_relative() ||
      (!aot_library_path.empty() && aot_library_path.is_relative())) {
    // Treat relative paths as relative to the directory of this executable.
    std::filesystem::path executable_location =
        flutter::GetExecutableDirectory();
    if (executable_location.empty()) {
      std::cerr
          << "Unable to find executable location to resolve resource paths."
          << std::endl;
      return nullptr;
    }
    assets_path = std::filesystem::path(executable_location) / assets_path;
    icu_path = std::filesystem::path(executable_location) / icu_path;
    if (!aot_library_path.empty()) {
      aot_library_path =
          std::filesystem::path(executable_location) / aot_library_path;
    }
  }
  std::string assets_path_string = assets_path.u8string();
  std::string icu_path_string = icu_path.u8string();

  if (FlutterEngineRunsAOTCompiledDartCode()) {
    state->aot_data = LoadAotData(aot_library_path);
    if (!state->aot_data) {
      std::cerr << "Unable to start engine without AOT data." << std::endl;
      return nullptr;
    }
  }

  FlutterProjectArgs args = {};
  args.struct_size = sizeof(FlutterProjectArgs);
  args.assets_path = assets_path_string.c_str();
  args.icu_data_path = icu_path_string.c_str();
  args.command_line_argc = static_cast<int>(argv.size());
  args.command_line_argv = &argv[0];
  args.platform_message_callback =
      [](const FlutterPlatformMessage* engine_message,
         void* user_data) -> void {
    auto window = reinterpret_cast<flutter::FlutterWindowsView*>(user_data);
    return window->HandlePlatformMessage(engine_message);
  };
  args.custom_task_runners = &custom_task_runners;
  if (state->aot_data) {
    args.aot_data = state->aot_data.get();
  }

  FLUTTER_API_SYMBOL(FlutterEngine) engine = nullptr;
  auto result =
      FlutterEngineRun(FLUTTER_ENGINE_VERSION, &config, &args, view, &engine);
  if (result != kSuccess || engine == nullptr) {
    std::cerr << "Failed to start Flutter engine: error " << result
              << std::endl;
    return nullptr;
  }
  state->engine = engine;
  return state;
}

FlutterDesktopViewControllerRef FlutterDesktopCreateViewController(
    int width,
    int height,
    const FlutterDesktopEngineProperties& engine_properties) {
  std::unique_ptr<flutter::WindowBindingHandler> window_wrapper =
      std::make_unique<flutter::Win32FlutterWindow>(width, height);

  FlutterDesktopViewControllerRef state =
      flutter::FlutterWindowsView::CreateFlutterWindowsView(
          std::move(window_wrapper));

  auto engine_state = RunFlutterEngine(state->view.get(), engine_properties);

  if (!engine_state) {
    return nullptr;
  }
  state->view->SetState(engine_state->engine);
  state->engine_state = std::move(engine_state);
  return state;
}

FlutterDesktopViewControllerRef FlutterDesktopCreateViewControllerLegacy(
    int initial_width,
    int initial_height,
    const char* assets_path,
    const char* icu_data_path,
    const char** arguments,
    size_t argument_count) {
  std::filesystem::path assets_path_fs = std::filesystem::u8path(assets_path);
  std::filesystem::path icu_data_path_fs =
      std::filesystem::u8path(icu_data_path);
  FlutterDesktopEngineProperties engine_properties = {};
  engine_properties.assets_path = assets_path_fs.c_str();
  engine_properties.icu_data_path = icu_data_path_fs.c_str();
  engine_properties.switches = arguments;
  engine_properties.switches_count = argument_count;

  return FlutterDesktopCreateViewController(initial_width, initial_height,
                                            engine_properties);
}

uint64_t FlutterDesktopProcessMessages(
    FlutterDesktopViewControllerRef controller) {
  return controller->engine_state->task_runner->ProcessTasks().count();
}

void FlutterDesktopDestroyViewController(
    FlutterDesktopViewControllerRef controller) {
  FlutterEngineShutdown(controller->engine_state->engine);
  delete controller;
}

FlutterDesktopPluginRegistrarRef FlutterDesktopGetPluginRegistrar(
    FlutterDesktopViewControllerRef controller,
    const char* plugin_name) {
  // Currently, one registrar acts as the registrar for all plugins, so the
  // name is ignored. It is part of the API to reduce churn in the future when
  // aligning more closely with the Flutter registrar system.

  return controller->view->GetRegistrar();
}

FlutterDesktopViewRef FlutterDesktopGetView(
    FlutterDesktopViewControllerRef controller) {
  return controller->view_wrapper.get();
}

HWND FlutterDesktopViewGetHWND(FlutterDesktopViewRef view_ref) {
  return std::get<HWND>(*view_ref->view->GetRenderTarget());
}

UINT FlutterDesktopGetDpiForHWND(HWND hwnd) {
  return flutter::GetDpiForHWND(hwnd);
}

UINT FlutterDesktopGetDpiForMonitor(HMONITOR monitor) {
  return flutter::GetDpiForMonitor(monitor);
}

void FlutterDesktopResyncOutputStreams() {
  FILE* unused;
  if (freopen_s(&unused, "CONOUT$", "w", stdout)) {
    _dup2(_fileno(stdout), 1);
  }
  if (freopen_s(&unused, "CONOUT$", "w", stderr)) {
    _dup2(_fileno(stdout), 2);
  }
  std::ios::sync_with_stdio();
}

FlutterDesktopEngineRef FlutterDesktopRunEngine(
    const FlutterDesktopEngineProperties& engine_properties) {
  auto engine = RunFlutterEngine(nullptr, engine_properties);
  return engine.release();
}

bool FlutterDesktopShutDownEngine(FlutterDesktopEngineRef engine_ref) {
  std::cout << "Shutting down flutter engine process." << std::endl;
  auto result = FlutterEngineShutdown(engine_ref->engine);
  delete engine_ref;
  return (result == kSuccess);
}

void FlutterDesktopRegistrarEnableInputBlocking(
    FlutterDesktopPluginRegistrarRef registrar,
    const char* channel) {
  registrar->messenger->dispatcher->EnableInputBlockingForChannel(channel);
}

FlutterDesktopMessengerRef FlutterDesktopRegistrarGetMessenger(
    FlutterDesktopPluginRegistrarRef registrar) {
  return registrar->messenger.get();
}

void FlutterDesktopRegistrarSetDestructionHandler(
    FlutterDesktopPluginRegistrarRef registrar,
    FlutterDesktopOnRegistrarDestroyed callback) {
  registrar->destruction_handler = callback;
}

FlutterDesktopViewRef FlutterDesktopRegistrarGetView(
    FlutterDesktopPluginRegistrarRef registrar) {
  return registrar->view;
}

bool FlutterDesktopMessengerSendWithReply(FlutterDesktopMessengerRef messenger,
                                          const char* channel,
                                          const uint8_t* message,
                                          const size_t message_size,
                                          const FlutterDesktopBinaryReply reply,
                                          void* user_data) {
  FlutterPlatformMessageResponseHandle* response_handle = nullptr;
  if (reply != nullptr && user_data != nullptr) {
    FlutterEngineResult result = FlutterPlatformMessageCreateResponseHandle(
        messenger->engine, reply, user_data, &response_handle);
    if (result != kSuccess) {
      std::cout << "Failed to create response handle\n";
      return false;
    }
  }

  FlutterPlatformMessage platform_message = {
      sizeof(FlutterPlatformMessage),
      channel,
      message,
      message_size,
      response_handle,
  };

  FlutterEngineResult message_result =
      FlutterEngineSendPlatformMessage(messenger->engine, &platform_message);

  if (response_handle != nullptr) {
    FlutterPlatformMessageReleaseResponseHandle(messenger->engine,
                                                response_handle);
  }

  return message_result == kSuccess;
}

bool FlutterDesktopMessengerSend(FlutterDesktopMessengerRef messenger,
                                 const char* channel,
                                 const uint8_t* message,
                                 const size_t message_size) {
  return FlutterDesktopMessengerSendWithReply(messenger, channel, message,
                                              message_size, nullptr, nullptr);
}

void FlutterDesktopMessengerSendResponse(
    FlutterDesktopMessengerRef messenger,
    const FlutterDesktopMessageResponseHandle* handle,
    const uint8_t* data,
    size_t data_length) {
  FlutterEngineSendPlatformMessageResponse(messenger->engine, handle, data,
                                           data_length);
}

void FlutterDesktopMessengerSetCallback(FlutterDesktopMessengerRef messenger,
                                        const char* channel,
                                        FlutterDesktopMessageCallback callback,
                                        void* user_data) {
  messenger->dispatcher->SetMessageCallback(channel, callback, user_data);
}