#include "loader.h"

#include <cerrno>
#include <cstdint>
#include <filesystem>

#include <imgui/backends/imgui_impl_opengl3.h>
#include <imgui/backends/imgui_impl_sdl3.h>

#include <SDL3_mixer/SDL_mixer.h>

#ifdef _WIN32
  #include "util/path_.h"
  #include <format>
  #include <windows.h>
#endif

#include "log.h"
#include "sdl.h"

#include "imgui_.h"

#include "snapshots.h"
#include "socket.h"

#include "util/math_.h"

using namespace anm2ed::types;
using namespace anm2ed::util;

namespace anm2ed
{
  constexpr auto WINDOW_4K_SIZE = glm::ivec2(3840, 2160);
  constexpr auto UI_SCALE_4K_DEFAULT = 1.5f;
  constexpr auto WINDOW_DEFAULT_SIZE_MULTIPLIER = 0.90f;

  constexpr auto SOCKET_ADDRESS = "127.0.0.1";
  constexpr auto SOCKET_PORT = 11414;

#ifdef _WIN32
  constexpr int SOCKET_ERROR_ADDRESS_IN_USE = WSAEADDRINUSE;
#else
  constexpr int SOCKET_ERROR_ADDRESS_IN_USE = EADDRINUSE;
#endif

  namespace
  {
#ifdef _WIN32
    void windows_wer_localdumps_configure()
    {
  #ifndef DEBUG
      return;
  #endif

      auto prefDir = sdl::preferences_directory_get();
      if (prefDir.empty()) return;

      std::error_code ec{};
      auto dumpDir = prefDir / "crash";
      std::filesystem::create_directories(dumpDir, ec);
      if (ec)
      {
        logger.warning(std::format("Failed to create dump directory {}: {}", path::to_utf8(dumpDir), ec.message()));
        return;
      }

      wchar_t modulePath[MAX_PATH]{};
      auto charsWritten = GetModuleFileNameW(nullptr, modulePath, MAX_PATH);
      if (charsWritten == 0 || charsWritten >= MAX_PATH)
      {
        logger.warning(std::format("Failed to get module filename for WER LocalDumps (error {}).", GetLastError()));
        return;
      }

      auto exeName = std::filesystem::path(modulePath).filename().wstring();
      if (exeName.empty())
      {
        logger.warning("Failed to determine executable name for WER LocalDumps.");
        return;
      }

      auto subkey = std::wstring(L"Software\\Microsoft\\Windows Error Reporting\\LocalDumps\\") + exeName;

      HKEY key{};
      auto status =
          RegCreateKeyExW(HKEY_CURRENT_USER, subkey.c_str(), 0, nullptr, 0, KEY_SET_VALUE, nullptr, &key, nullptr);
      if (status != ERROR_SUCCESS)
      {
        logger.warning(std::format("Failed to create/open WER LocalDumps key (status {}).", (int)status));
        return;
      }

      auto closeKey = [&]()
      {
        if (key) RegCloseKey(key);
        key = nullptr;
      };

      auto dumpDirW = dumpDir.wstring();
      const DWORD dumpType = 2; // full dump
      const DWORD dumpCount = 10;

      status = RegSetValueExW(key, L"DumpFolder", 0, REG_EXPAND_SZ, (const BYTE*)dumpDirW.c_str(),
                              (DWORD)((dumpDirW.size() + 1) * sizeof(wchar_t)));
      if (status != ERROR_SUCCESS)
      {
        logger.warning(std::format("Failed to set WER DumpFolder (status {}).", (int)status));
        closeKey();
        return;
      }

      status = RegSetValueExW(key, L"DumpType", 0, REG_DWORD, (const BYTE*)&dumpType, sizeof(dumpType));
      if (status != ERROR_SUCCESS) logger.warning(std::format("Failed to set WER DumpType (status {}).", (int)status));

      status = RegSetValueExW(key, L"DumpCount", 0, REG_DWORD, (const BYTE*)&dumpCount, sizeof(dumpCount));
      if (status != ERROR_SUCCESS) logger.warning(std::format("Failed to set WER DumpCount (status {}).", (int)status));

      closeKey();
      logger.info(std::format("Crash dumps enabled: {}", path::to_utf8(dumpDir)));
    }
#endif

    bool socket_paths_send(Socket& socket, const std::vector<std::string>& paths)
    {
      uint32_t count = htonl(static_cast<uint32_t>(paths.size()));
      if (!socket.send(&count, sizeof(count))) return false;

      for (const auto& path : paths)
      {
        uint32_t length = htonl(static_cast<uint32_t>(path.size()));
        if (!socket.send(&length, sizeof(length))) return false;
        if (!path.empty() && !socket.send(path.data(), path.size())) return false;
      }

      return true;
    }

    std::vector<std::string> socket_paths_receive(Socket& socket)
    {
      uint32_t count{};
      if (!socket.receive(&count, sizeof(count))) return {};
      count = ntohl(count);

      std::vector<std::string> paths;
      paths.reserve(count);

      for (uint32_t i = 0; i < count; ++i)
      {
        uint32_t length{};
        if (!socket.receive(&length, sizeof(length))) return {};
        length = ntohl(length);

        std::string path(length, '\0');
        if (length > 0 && !socket.receive(path.data(), length)) return {};
        paths.emplace_back(std::move(path));
      }

      return paths;
    }
  }

  std::filesystem::path Loader::settings_path() { return sdl::preferences_directory_get() / "settings.ini"; }

  Loader::Loader(int argc, const char** argv)
  {
    for (int i = 1; i < argc; i++)
      arguments.emplace_back(argv[i]);

    Socket testSocket;
    if (!testSocket.open(SERVER))
      logger.warning(std::format("Failed to open socket; single instancing will not work."));

    if (testSocket.bind({SOCKET_ADDRESS, SOCKET_PORT}))
    {
      socket = std::move(testSocket);

      if (!socket.listen())
        logger.warning("Could not listen on socket; single instancing disabled.");
      else
      {
        isSocketThread = true;
        logger.info(std::format("Opened socket at {}:{}", SOCKET_ADDRESS, SOCKET_PORT));
      }
    }
    else
    {
      if (testSocket.last_error() != SOCKET_ERROR_ADDRESS_IN_USE)
      {
        logger.fatal(std::format("Failed to bind single-instance socket (error {}).", testSocket.last_error()));
        isError = true;
        return;
      }

      logger.info(std::format("Existing instance of program exists; passing arguments..."));
      Socket clientSocket;
      if (!clientSocket.open(CLIENT))
        logger.warning("Could not open client socket to forward arguments.");
      else if (!clientSocket.connect({SOCKET_ADDRESS, SOCKET_PORT}))
        logger.warning("Could not connect to existing instance.");
      else if (!socket_paths_send(clientSocket, arguments))
        logger.warning("Failed to transfer arguments to existing instance.");
      else
        logger.info("Sent arguments to existing instance. Exiting.");

      isError = true;
      return;
    }

    settings = Settings(settings_path());
    SnapshotStack::max_size_set(settings.fileSnapshotStackSize);
    localize.language = (Language)settings.language;

    if (!SDL_Init(SDL_INIT_VIDEO))
    {
      logger.fatal(std::format("Could not initialize SDL! {}", SDL_GetError()));
      isError = true;
      return;
    }

    logger.info("Initialized SDL");

#ifdef _WIN32
    windows_wer_localdumps_configure();
#endif

    auto windowProperties = SDL_CreateProperties();

    if (windowProperties == 0)
    {
      logger.fatal(std::format("Could not initialize window properties! {}", SDL_GetError()));
      isError = true;
      return;
    }

    if (settings.isDefault)
    {
      if (auto display = SDL_GetPrimaryDisplay(); display != 0)
      {
        if (auto mode = SDL_GetCurrentDisplayMode(display))
        {
          if (mode->w >= WINDOW_4K_SIZE.x || mode->h >= WINDOW_4K_SIZE.y) settings.uiScale = UI_SCALE_4K_DEFAULT;
          settings.windowSize.x = mode->w * WINDOW_DEFAULT_SIZE_MULTIPLIER;
          settings.windowSize.y = mode->h * WINDOW_DEFAULT_SIZE_MULTIPLIER;
        }
        else
          logger.warning(std::format("Failed to query primary display mode: {}", SDL_GetError()));
      }
      else
        logger.warning("Failed to detect primary display for UI scaling.");
    }

    if (!MIX_Init())
      logger.warning(std::format("Could not initialize SDL_mixer! {}", SDL_GetError()));
    else
      logger.info("Initialized SDL_mixer");

    SDL_SetStringProperty(windowProperties, SDL_PROP_WINDOW_CREATE_TITLE_STRING, "Anm2Ed");
    SDL_SetNumberProperty(windowProperties, SDL_PROP_WINDOW_CREATE_WIDTH_NUMBER, settings.windowSize.x);
    SDL_SetNumberProperty(windowProperties, SDL_PROP_WINDOW_CREATE_HEIGHT_NUMBER, settings.windowSize.y);

    SDL_SetNumberProperty(windowProperties, SDL_PROP_WINDOW_CREATE_X_NUMBER,
                          settings.isDefault ? SDL_WINDOWPOS_CENTERED : settings.windowPosition.x);
    SDL_SetNumberProperty(windowProperties, SDL_PROP_WINDOW_CREATE_Y_NUMBER,
                          settings.isDefault ? SDL_WINDOWPOS_CENTERED : settings.windowPosition.y);

    SDL_SetBooleanProperty(windowProperties, SDL_PROP_WINDOW_CREATE_RESIZABLE_BOOLEAN, true);
    SDL_SetBooleanProperty(windowProperties, SDL_PROP_WINDOW_CREATE_OPENGL_BOOLEAN, true);
    SDL_SetBooleanProperty(windowProperties, SDL_PROP_WINDOW_CREATE_HIGH_PIXEL_DENSITY_BOOLEAN, true);

    window = SDL_CreateWindowWithProperties(windowProperties);

    if (!window)
    {
      logger.fatal(std::format("Could not initialize window! {}", SDL_GetError()));
      isError = true;
      return;
    }

    SDL_GL_SetAttribute(SDL_GL_CONTEXT_PROFILE_MASK, SDL_GL_CONTEXT_PROFILE_CORE);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MAJOR_VERSION, 3);
    SDL_GL_SetAttribute(SDL_GL_CONTEXT_MINOR_VERSION, 3);

    glContext = SDL_GL_CreateContext(window);

    if (!glContext)
    {
      logger.fatal(std::format("Could not initialize OpenGL context! {}", SDL_GetError()));
      isError = true;
      return;
    }

    if (!gladLoadGLLoader((GLADloadproc)(SDL_GL_GetProcAddress)))
    {
      logger.fatal(std::format("Could not initialize OpenGL!"));
      isError = true;
      return;
    }

    logger.info(std::format("Initialized OpenGL {}", (const char*)glGetString(GL_VERSION)));

    glEnable(GL_BLEND);
    glBlendFuncSeparate(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA, GL_ONE, GL_ONE_MINUS_SRC_ALPHA);
    glLineWidth(2.0f);
    glDisable(GL_DEPTH_TEST);
    glDisable(GL_LINE_SMOOTH);

    math::random_seed_set();

    IMGUI_CHECKVERSION();
    if (!ImGui::CreateContext())
    {
      logger.fatal("Could not initialize Dear ImGui!");
      isError = true;
      return;
    }

    logger.info("Initialized Dear ImGui");

    imgui::theme_set((theme::Type)settings.theme);

    ImGui_ImplSDL3_InitForOpenGL(window, glContext);
    ImGui_ImplOpenGL3_Init("#version 330");

    ImGuiIO& io = ImGui::GetIO();
    io.IniFilename = nullptr;
    io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
    io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
    io.KeyRepeatDelay = settings.keyboardRepeatDelay;
    io.KeyRepeatRate = settings.keyboardRepeatRate;
    ImGui::GetStyle().FontScaleMain = settings.uiScale;
    io.ConfigWindowsMoveFromTitleBarOnly = true;

    if (auto imguiData = Settings::imgui_data_load(settings_path()); !imguiData.empty())
      ImGui::LoadIniSettingsFromMemory(imguiData.c_str(), imguiData.size());

    if (isSocketThread)
    {
      isSocketRunning = true;
      socketThread = std::thread(
          [this]()
          {
            while (isSocketRunning)
            {
              auto client = socket.accept();
              if (!client.is_valid())
              {
                if (!isSocketRunning) break;
                continue;
              }

              SDL_FlashWindow(window, SDL_FLASH_UNTIL_FOCUSED);

              auto paths = socket_paths_receive(client);
              for (auto& path : paths)
              {
                if (path.empty()) continue;
                SDL_Event event{};
                event.type = SDL_EVENT_USER;
                event.drop.data = SDL_strdup(path.c_str());
                event.drop.windowID = window ? SDL_GetWindowID(window) : 0;
                SDL_PushEvent(&event);
              }
            }
          });
    }
  }

  Loader::~Loader()
  {
    if (isSocketThread)
    {
      isSocketRunning = false;

      if (socket.is_valid())
      {
        Socket wakeSocket;
        if (wakeSocket.open(CLIENT) && wakeSocket.connect({SOCKET_ADDRESS, SOCKET_PORT}))
          socket_paths_send(wakeSocket, {});
      }

      socket.close();
      if (socketThread.joinable()) socketThread.join();
    }

    if (ImGui::GetCurrentContext())
    {
      settings.save(settings_path(), ImGui::SaveIniSettingsToMemory(nullptr));

      ImGui_ImplSDL3_Shutdown();
      ImGui_ImplOpenGL3_Shutdown();
      ImGui::DestroyContext();
    }

    MIX_Quit();

    if (SDL_WasInit(0))
    {
      SDL_GL_DestroyContext(glContext);
      SDL_DestroyWindow(window);
      SDL_Quit();
    }
  }
}