#include "flutter_window.h"

#include <optional>

#include <flutter/generated_plugin_registrant.h>
#include <flutter/method_channel.h>
#include <flutter/standard_method_codec.h>

#include <windows.h>
#include <iostream>

static HHOOK g_hHook = nullptr;

constexpr wchar_t kFlutterTitleName[] = L"Desktop";

FlutterWindow* g_flutter_window = nullptr;

enum KeyState {
  kNone,
  kWinPressed,
  kOtherKeyPressed
};

KeyState g_keyState = kNone;

bool g_isLeftShiftPressed = false;
bool g_isRightShiftPressed = false;

void UpdateShiftState(UINT vkCode, bool isKeyDown) {
  if (vkCode == VK_LSHIFT) {
    g_isLeftShiftPressed = isKeyDown;
  } else if (vkCode == VK_RSHIFT) {
    g_isRightShiftPressed = isKeyDown;
  }
}

bool IsShiftPressed() {
  return g_isLeftShiftPressed || g_isRightShiftPressed;
}

int GetFlutterKeyId(UINT vkCode) {
  bool shiftPressed = IsShiftPressed();
//  std::wcout << L"[GetFlutterKeyId] shiftPressed=" << shiftPressed
//                   << L", vkCode=" << vkCode
//                   << L"\n" << std::flush;

  if(shiftPressed) {
    if (vkCode >= 0x41 && vkCode <= 0x5A) {
        return vkCode + 0x20; // 'A' = 0x0041
    }

    if (vkCode >= 0x61 && vkCode <= 0x7A) {
        return vkCode - 0x20; // 'a' ~ 'z'
    }
  } else {
    if (vkCode >= 0x41 && vkCode <= 0x5A) {
        return vkCode; // 'A' ~ 'Z' = 0x0041
    }

    if (vkCode >= 0x61 && vkCode <= 0x7A) {
        return vkCode; // 'a' ~ 'z'
    }
  }

  if (vkCode >= 0x30 && vkCode <= 0x39) return vkCode; // '0'~'9'


  if (vkCode >= 0x60 && vkCode <= 0x69) {
    return 0xFFB0 + (vkCode - 0x60);
  }

  if (vkCode >= 0x70 && vkCode <= 0x7B) {
    return 0xFFBE + (vkCode - 0x70);
  }

  switch (vkCode) {
    // Modifier Keys
      case 0x25: return 0xFF51; // Left
      case 0x26: return 0xFF52; // Up
      case 0x27: return 0xFF53; // Right
      case 0x28: return 0xFF54; // Down

      case 0x08: return 0xFF08; // Backspace
      case 0x09: return 0xFF09; // Tab
      case 0x0D: return 0xFF0D; // Enter
      case 0x1B: return 0xFF1B; // Escape
      case 0x20: return 0x0020; // Space
      case 0x2D: return 0xFF63; // Insert
      case 0x2E: return 0xFFFF; // Delete
      case 0x24: return 0xFF50; // Home
      case 0x23: return 0xFF57; // End
      case 0x21: return 0xFF55; // Page Up
      case 0x22: return 0xFF56; // Page Down

      case 0xBA: return 0x003B; // Semicolon (;)
      case 0xBB: return 0x003D; // Equal (=)
      case 0xBC: return 0x002C; // Comma (,)
      case 0xBD: return 0x002D; // Minus (-)
      case 0xBE: return 0x002E; // Period (.)
      case 0xBF: return 0x002F; // Slash (/)
      case 0xC0: return 0x0060; // Backquote (`) or ~
      case 0xDB: return 0x005B; // Open Bracket ([)
      case 0xDC: return 0x005C; // Backslash (\)
      case 0xDD: return 0x005D; // Close Bracket (])
      case 0xDE: return 0x0027; // Quote (')

      case 0xA0: return 0xFFE1; // Left Shift
      case 0xA1: return 0xFFE2; // Right Shift
      case 0xA2: return 0xFFE3; // Left Control
      case 0xA3: return 0xFFE4; // Right Control
      case 0xA4: return 0xFFE9; // Left Alt
      case 0xA5: return 0xFFEA; // Right Alt
      case 0x5B: return 0xFFEB; // Left Meta (Win)
      case 0x5C: return 0xFFEC; // Right Meta (Win)
      case 0x5D: return 0xFF67; // Context Menu

      case 0x90: return 0xFF7F; // Num Lock
      case 0x91: return 0xFF14; // Scroll Lock
      case 0x14: return 0xFFE5; // Caps Lock

      case 0xAD: return 0xFF12; // Mute
      case 0xAE: return 0xFF11; // Volume Down
      case 0xAF: return 0xFF13; // Volume Up
      case 0xB0: return 0xFF16; // Media Previous
      case 0xB1: return 0xFF17; // Media Next
      case 0xB2: return 0xFF14; // Play/Pause
      case 0xB3: return 0xFF15; // Stop
      default:
        return 0x0000; // Unknown
  }
}

void SendKeyEventToDart(UINT vkCode, bool down) {
  if (g_flutter_window) {
    auto messenger = g_flutter_window->GetMessenger();
    if (messenger) {
      int flutterKeyId = GetFlutterKeyId(vkCode);
      if (flutterKeyId == 0) return;
      auto channel = std::make_unique<flutter::MethodChannel<flutter::EncodableValue>>(
          messenger,
          "com.example.vnc_viewer/keyboard",
          &flutter::StandardMethodCodec::GetInstance());

      auto args = std::make_unique<flutter::EncodableValue>(
          flutter::EncodableMap{
              {"key", flutter::EncodableValue(flutterKeyId)},
              {"vkCode", flutter::EncodableValue(vkCode)},
              {"down", flutter::EncodableValue(down)},
          }
      );

//      std::wcout << L"[send] Pressed=" << g_keyState
//                     << L", args=" << args
//                     << L"\n" << std::flush;
      channel->InvokeMethod("onPhysicalKeyEvent", std::move(args));
    }
  }
}

static LRESULT CALLBACK LLKeyProc(int nCode, WPARAM w, LPARAM l) {
  if (nCode == HC_ACTION) {
    std::string type = "";
    auto* kbd = reinterpret_cast<KBDLLHOOKSTRUCT*>(l);

    HWND hwndFore = GetForegroundWindow();
    if (hwndFore == nullptr) return CallNextHookEx(nullptr, nCode, w, l);

    wchar_t titleName[256] = {0};
    GetWindowText(hwndFore, titleName, 256);

//    std::wcout << L"[g_keyState] Pressed=" << g_keyState
//                     << L", kFlutterTitleName=" << kFlutterTitleName
//                     << L", titleName=" << titleName
//                     << L", compare=" << wcscmp(titleName, kFlutterTitleName)
//                     << L"\n" << std::flush;

    if (wcscmp(titleName, kFlutterTitleName) == 0) {
      bool isKeyDown = (w == WM_KEYDOWN || w == WM_SYSKEYDOWN);
      if (kbd->vkCode == VK_LSHIFT || kbd->vkCode == VK_RSHIFT) {
        UpdateShiftState(kbd->vkCode, isKeyDown);
      }
//      std::wcout << L"[g_keyState] Pressed=" << g_keyState
//                 << L", kWinPressed=" << kWinPressed
//                 << L", vkCode=" << kbd->vkCode
//                 << L"\n" << std::flush;

      if(kbd->vkCode == 20 && !isKeyDown) {
        return 1;
      }
      SendKeyEventToDart(kbd->vkCode, isKeyDown);
      return 1;
    } else {
      return CallNextHookEx(nullptr, nCode, w, l);
    }
  }
  return CallNextHookEx(nullptr, nCode, w, l);
}

static void InstallLLHook() {
  if (!g_hHook) {
    g_hHook = SetWindowsHookEx(
      WH_KEYBOARD_LL,
      LLKeyProc,
      GetModuleHandle(nullptr),
      0
    );
  }
}

static void RemoveLLHook() {
  if (g_hHook) {
    UnhookWindowsHookEx(g_hHook);
    g_hHook = nullptr;
  }
}


void FlutterWindow::CreateMessageChannel() {
  if (!flutter_controller_ || !flutter_controller_->engine()) {
      return;
    }

    message_channel_ =
        std::make_unique<flutter::MethodChannel<flutter::EncodableValue>>(
            flutter_controller_->engine()->messenger(),
            "com.example.vnc_viewer/keyboard",
            &flutter::StandardMethodCodec::GetInstance());

    message_channel_->SetMethodCallHandler(&FlutterWindow::HandleMethodCall);
}

void FlutterWindow::HandleMethodCall(
    const flutter::MethodCall<flutter::EncodableValue>& method_call,
    std::unique_ptr<flutter::MethodResult<flutter::EncodableValue>> result) {
  result->NotImplemented();
}

// ----------------------------------------------------

FlutterWindow::FlutterWindow(const flutter::DartProject& project)
    : project_(project) {
    g_flutter_window = this;
}

FlutterWindow::~FlutterWindow() {
//  RemoveLLHook();
}

bool FlutterWindow::OnCreate() {
  if (!Win32Window::OnCreate()) {
    return false;
  }

  RECT frame = GetClientArea();

  // The size here must match the window dimensions to avoid unnecessary surface
  // creation / destruction in the startup path.
  flutter_controller_ = std::make_unique<flutter::FlutterViewController>(
      frame.right - frame.left, frame.bottom - frame.top, project_);
  // Ensure that basic setup of the controller was successful.
  if (!flutter_controller_->engine() || !flutter_controller_->view()) {
    return false;
  }
  RegisterPlugins(flutter_controller_->engine());
  SetChildContent(flutter_controller_->view()->GetNativeWindow());

  flutter_controller_->engine()->SetNextFrameCallback([&]() {
    this->Show();
  });


  CreateMessageChannel();

  // Flutter can complete the first frame before the "show window" callback is
  // registered. The following call ensures a frame is pending to ensure the
  // window is shown. It is a no-op if the first frame hasn't completed yet.
  flutter_controller_->ForceRedraw();

  InstallLLHook();
  return true;
}

void FlutterWindow::OnDestroy() {
  RemoveLLHook();
  if (flutter_controller_) {
    flutter_controller_ = nullptr;
  }

  Win32Window::OnDestroy();
}

LRESULT
FlutterWindow::MessageHandler(HWND hwnd, UINT const message,
                              WPARAM const wparam,
                              LPARAM const lparam) noexcept {
  // Give Flutter, including plugins, an opportunity to handle window messages.
  if (flutter_controller_) {
    std::optional<LRESULT> result =
        flutter_controller_->HandleTopLevelWindowProc(hwnd, message, wparam,
                                                      lparam);
    if (result) {
      return *result;
    }
  }

  switch (message) {
    case WM_FONTCHANGE:
      flutter_controller_->engine()->ReloadSystemFonts();
      break;
  }

  return Win32Window::MessageHandler(hwnd, message, wparam, lparam);
}