/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsColorPicker.h"

#include <shlwapi.h>

#include "mozilla/ArrayUtils.h"
#include "mozilla/AutoRestore.h"
#include "nsIWidget.h"
#include "nsString.h"
#include "WidgetUtils.h"
#include "nsPIDOMWindow.h"

using namespace mozilla::widget;

namespace {
// Manages NS_NATIVE_TMP_WINDOW child windows. NS_NATIVE_TMP_WINDOWs are
// temporary child windows of mParentWidget created to address RTL issues
// in picker dialogs. We are responsible for destroying these.
class AutoDestroyTmpWindow {
 public:
  explicit AutoDestroyTmpWindow(HWND aTmpWnd) : mWnd(aTmpWnd) {}

  ~AutoDestroyTmpWindow() {
    if (mWnd) DestroyWindow(mWnd);
  }

  inline HWND get() const { return mWnd; }

 private:
  HWND mWnd;
};

static DWORD ColorStringToRGB(const nsAString& aColor) {
  DWORD result = 0;

  for (uint32_t i = 1; i < aColor.Length(); ++i) {
    result *= 16;

    char16_t c = aColor[i];
    if (c >= '0' && c <= '9') {
      result += c - '0';
    } else if (c >= 'a' && c <= 'f') {
      result += 10 + (c - 'a');
    } else {
      result += 10 + (c - 'A');
    }
  }

  DWORD r = result & 0x00FF0000;
  DWORD g = result & 0x0000FF00;
  DWORD b = result & 0x000000FF;

  r = r >> 16;
  b = b << 16;

  result = r | g | b;

  return result;
}

static nsString ToHexString(BYTE n) {
  nsString result;
  if (n <= 0x0F) {
    result.Append('0');
  }
  result.AppendInt(n, 16);
  return result;
}

static void BGRIntToRGBString(DWORD color, nsAString& aResult) {
  BYTE r = GetRValue(color);
  BYTE g = GetGValue(color);
  BYTE b = GetBValue(color);

  aResult.Assign('#');
  aResult.Append(ToHexString(r));
  aResult.Append(ToHexString(g));
  aResult.Append(ToHexString(b));
}
}  // namespace

static AsyncColorChooser* gColorChooser;

AsyncColorChooser::AsyncColorChooser(COLORREF aInitialColor,
                                     const nsTArray<nsString>& aDefaultColors,
                                     nsIWidget* aParentWidget,
                                     nsIColorPickerShownCallback* aCallback)
    : mozilla::Runnable("AsyncColorChooser"),
      mInitialColor(aInitialColor),
      mDefaultColors(aDefaultColors.Clone()),
      mColor(aInitialColor),
      mParentWidget(aParentWidget),
      mCallback(aCallback) {}

NS_IMETHODIMP
AsyncColorChooser::Run() {
  MOZ_ASSERT(NS_IsMainThread(),
             "Color pickers can only be opened from main thread currently");

  // Allow only one color picker to be opened at a time, to workaround bug
  // 944737
  if (!gColorChooser) {
    mozilla::AutoRestore<AsyncColorChooser*> restoreColorChooser(gColorChooser);
    gColorChooser = this;

    AutoDestroyTmpWindow adtw(
        (HWND)(mParentWidget.get()
                   ? mParentWidget->GetNativeData(NS_NATIVE_TMP_WINDOW)
                   : nullptr));

    COLORREF customColors[16];
    for (size_t i = 0; i < mozilla::ArrayLength(customColors); i++) {
      if (i < mDefaultColors.Length()) {
        customColors[i] = ColorStringToRGB(mDefaultColors[i]);
      } else {
        customColors[i] = 0x00FFFFFF;
      }
    }

    CHOOSECOLOR options;
    options.lStructSize = sizeof(options);
    options.hwndOwner = adtw.get();
    options.Flags = CC_RGBINIT | CC_FULLOPEN | CC_ENABLEHOOK;
    options.rgbResult = mInitialColor;
    options.lpCustColors = customColors;
    options.lpfnHook = HookProc;

    mColor = ChooseColor(&options) ? options.rgbResult : mInitialColor;
  } else {
    NS_WARNING(
        "Currently, it's not possible to open more than one color "
        "picker at a time");
    mColor = mInitialColor;
  }

  if (mCallback) {
    nsAutoString colorStr;
    BGRIntToRGBString(mColor, colorStr);
    mCallback->Done(colorStr);
  }

  return NS_OK;
}

void AsyncColorChooser::Update(COLORREF aColor) {
  if (mColor != aColor) {
    mColor = aColor;

    nsAutoString colorStr;
    BGRIntToRGBString(mColor, colorStr);
    mCallback->Update(colorStr);
  }
}

/* static */ UINT_PTR CALLBACK AsyncColorChooser::HookProc(HWND aDialog,
                                                           UINT aMsg,
                                                           WPARAM aWParam,
                                                           LPARAM aLParam) {
  if (!gColorChooser) {
    return 0;
  }

  if (aMsg == WM_INITDIALOG) {
    // "The default dialog box procedure processes the WM_INITDIALOG message
    // before passing it to the hook procedure.
    // For all other messages, the hook procedure receives the message first."
    // https://docs.microsoft.com/en-us/windows/win32/api/commdlg/nc-commdlg-lpcchookproc
    // "The dialog box procedure should return TRUE to direct the system to
    // set the keyboard focus to the control specified by wParam."
    // https://docs.microsoft.com/en-us/windows/win32/dlgbox/wm-initdialog
    return 1;
  }

  if (aMsg == WM_CTLCOLORSTATIC) {
    // The color picker does not expose a proper way to retrieve the current
    // color, so we need to obtain it from the static control displaying the
    // current color instead.
    const int kCurrentColorBoxID = 709;
    if ((HWND)aLParam == GetDlgItem(aDialog, kCurrentColorBoxID)) {
      gColorChooser->Update(GetPixel((HDC)aWParam, 0, 0));
    }
  }

  // Let the default dialog box procedure processes the message.
  return 0;
}

///////////////////////////////////////////////////////////////////////////////
// nsIColorPicker

nsColorPicker::nsColorPicker() {}

nsColorPicker::~nsColorPicker() {}

NS_IMPL_ISUPPORTS(nsColorPicker, nsIColorPicker)

NS_IMETHODIMP
nsColorPicker::Init(mozIDOMWindowProxy* parent, const nsAString& title,
                    const nsAString& aInitialColor,
                    const nsTArray<nsString>& aDefaultColors) {
  MOZ_ASSERT(parent,
             "Null parent passed to colorpicker, no color picker for you!");
  mParentWidget =
      WidgetUtils::DOMWindowToWidget(nsPIDOMWindowOuter::From(parent));
  mInitialColor = ColorStringToRGB(aInitialColor);
  mDefaultColors.Assign(aDefaultColors);
  return NS_OK;
}

NS_IMETHODIMP
nsColorPicker::Open(nsIColorPickerShownCallback* aCallback) {
  NS_ENSURE_ARG(aCallback);
  nsCOMPtr<nsIRunnable> event = new AsyncColorChooser(
      mInitialColor, mDefaultColors, mParentWidget, aCallback);
  return NS_DispatchToMainThread(event);
}