/*******************************************************************************
 * Copyright (c) 2000, 2008 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwt.widgets.Scrollable;

import dwt.DWT;
import dwt.DWTException;

import dwt.graphics.Rectangle;

import dwt.internal.win32.OS;

import dwt.widgets.Composite;
import dwt.widgets.Control;
import dwt.widgets.Decorations;
import dwt.widgets.Event;
import dwt.widgets.ScrollBar;
import dwt.widgets.Widget;

import dwt.dwthelper.utils;

/**
 * This class is the abstract superclass of all classes which
 * represent controls that have standard scroll bars.
 * <dl>
 * <dt><b>Styles:</b></dt>
 * <dd>H_SCROLL, V_SCROLL</dd>
 * <dt><b>Events:</b>
 * <dd>(none)</dd>
 * </dl>
 * <p>
 * IMPORTANT: This class is intended to be subclassed <em>only</em>
 * within the DWT implementation.
 * </p>
 *
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */

public abstract class Scrollable : Control {

    alias Control.windowProc windowProc;

    ScrollBar horizontalBar, verticalBar;

/**
 * Prevents uninitialized instances from being created outside the package.
 */
this () {
}

/**
 * Constructs a new instance of this class given its parent
 * and a style value describing its behavior and appearance.
 * <p>
 * The style value is either one of the style constants defined in
 * class <code>DWT</code> which is applicable to instances of this
 * class, or must be built by <em>bitwise OR</em>'ing together
 * (that is, using the <code>int</code> "|" operator) two or more
 * of those <code>DWT</code> style constants. The class description
 * lists the style constants that are applicable to the class.
 * Style bits are also inherited from superclasses.
 * </p>
 *
 * @param parent a composite control which will be the parent of the new instance (cannot be null)
 * @param style the style of control to construct
 *
 * @exception IllegalArgumentException <ul>
 *    <li>ERROR_NULL_ARGUMENT - if the parent is null</li>
 * </ul>
 * @exception DWTException <ul>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent</li>
 *    <li>ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass</li>
 * </ul>
 *
 * @see DWT#H_SCROLL
 * @see DWT#V_SCROLL
 * @see Widget#checkSubclass
 * @see Widget#getStyle
 */
public this (Composite parent, int style) {
    super (parent, style);
}

override int callWindowProc (HWND hwnd, int msg, int wParam, int lParam) {
    if (handle is null) return 0;
    return OS.DefWindowProc (hwnd, msg, wParam, lParam);
}

/**
 * Given a desired <em>client area</em> for the receiver
 * (as described by the arguments), returns the bounding
 * rectangle which would be required to produce that client
 * area.
 * <p>
 * In other words, it returns a rectangle such that, if the
 * receiver's bounds were set to that rectangle, the area
 * of the receiver which is capable of displaying data
 * (that is, not covered by the "trimmings") would be the
 * rectangle described by the arguments (relative to the
 * receiver's parent).
 * </p>
 *
 * @param x the desired x coordinate of the client area
 * @param y the desired y coordinate of the client area
 * @param width the desired width of the client area
 * @param height the desired height of the client area
 * @return the required bounds to produce the given client area
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #getClientArea
 */
public Rectangle computeTrim (int x, int y, int width, int height) {
    checkWidget ();
    auto scrolledHandle_ = scrolledHandle ();
    RECT rect;
    OS.SetRect (&rect, x, y, x + width, y + height);
    int bits1 = OS.GetWindowLong (scrolledHandle_, OS.GWL_STYLE);
    int bits2 = OS.GetWindowLong (scrolledHandle_, OS.GWL_EXSTYLE);
    OS.AdjustWindowRectEx (&rect, bits1, false, bits2);
    if (horizontalBar !is null) rect.bottom += OS.GetSystemMetrics (OS.SM_CYHSCROLL);
    if (verticalBar !is null) rect.right += OS.GetSystemMetrics (OS.SM_CXVSCROLL);
    int nWidth = rect.right - rect.left, nHeight = rect.bottom - rect.top;
    return new Rectangle (rect.left, rect.top, nWidth, nHeight);
}

ScrollBar createScrollBar (int type) {
    ScrollBar bar = new ScrollBar (this, type);
    if ((state & CANVAS) !is 0) {
        bar.setMaximum (100);
        bar.setThumb (10);
    }
    return bar;
}

override void createWidget () {
    super.createWidget ();
    if ((style & DWT.H_SCROLL) !is 0) horizontalBar = createScrollBar (DWT.H_SCROLL);
    if ((style & DWT.V_SCROLL) !is 0) verticalBar = createScrollBar (DWT.V_SCROLL);
}

void destroyScrollBar (int type) {
    auto hwnd = scrolledHandle ();
    int bits = OS.GetWindowLong (hwnd, OS.GWL_STYLE);
    if ((type & DWT.HORIZONTAL) !is 0) {
        style &= ~DWT.H_SCROLL;
        bits &= ~OS.WS_HSCROLL;
    }
    if ((type & DWT.VERTICAL) !is 0) {
        style &= ~DWT.V_SCROLL;
        bits &= ~OS.WS_VSCROLL;
    }
    OS.SetWindowLong (hwnd, OS.GWL_STYLE, bits);
}

/**
 * Returns a rectangle which describes the area of the
 * receiver which is capable of displaying data (that is,
 * not covered by the "trimmings").
 *
 * @return the client area
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 *
 * @see #computeTrim
 */
public Rectangle getClientArea () {
    checkWidget ();
    forceResize ();
    RECT rect;
    auto scrolledHandle_ = scrolledHandle ();
    OS.GetClientRect (scrolledHandle_, &rect);
    int x = rect.left, y = rect.top;
    int width = rect.right - rect.left;
    int height = rect.bottom - rect.top;
    if (scrolledHandle_ !is handle) {
        OS.GetClientRect (handle, &rect);
        OS.MapWindowPoints(handle, scrolledHandle_, cast(POINT*)&rect, 2);
        x = -rect.left;
        y = -rect.top;
    }
    return new Rectangle (x, y, width, height);
}

/**
 * Returns the receiver's horizontal scroll bar if it has
 * one, and null if it does not.
 *
 * @return the horizontal scroll bar (or null)
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public ScrollBar getHorizontalBar () {
    checkWidget ();
    return horizontalBar;
}

/**
 * Returns the receiver's vertical scroll bar if it has
 * one, and null if it does not.
 *
 * @return the vertical scroll bar (or null)
 *
 * @exception DWTException <ul>
 *    <li>ERROR_WIDGET_DISPOSED - if the receiver has been disposed</li>
 *    <li>ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver</li>
 * </ul>
 */
public ScrollBar getVerticalBar () {
    checkWidget ();
    return verticalBar;
}

override void releaseChildren (bool destroy) {
    if (horizontalBar !is null) {
        horizontalBar.release (false);
        horizontalBar = null;
    }
    if (verticalBar !is null) {
        verticalBar.release (false);
        verticalBar = null;
    }
    super.releaseChildren (destroy);
}

HANDLE scrolledHandle () {
    return handle;
}

override int widgetExtStyle () {
    return super.widgetExtStyle ();
    /*
    * This code is intentionally commented.  In future,
    * we may wish to support different standard Windows
    * edge styles.  The issue here is that not all of
    * these styles are available on the other platforms
    * this would need to be a hint.
    */
//  if ((style & DWT.BORDER) !is 0) return OS.WS_EX_CLIENTEDGE;
//  if ((style & DWT.SHADOW_IN) !is 0) return OS.WS_EX_STATICEDGE;
//  return super.widgetExtStyle ();
}

override int widgetStyle () {
    int bits = super.widgetStyle () | OS.WS_TABSTOP;
    if ((style & DWT.H_SCROLL) !is 0) bits |= OS.WS_HSCROLL;
    if ((style & DWT.V_SCROLL) !is 0) bits |= OS.WS_VSCROLL;
    return bits;
}

override String windowClass () {
    return display.windowClass();
}

override int windowProc () {
    return display.windowProc;
}

override LRESULT WM_HSCROLL (int wParam, int lParam) {
    LRESULT result = super.WM_HSCROLL (wParam, lParam);
    if (result !is null) return result;

    /*
    * Bug on WinCE.  lParam should be NULL when the message is not sent
    * by a scroll bar control, but it contains the handle to the window.
    * When the message is sent by a scroll bar control, it correctly
    * contains the handle to the scroll bar.  The fix is to check for
    * both.
    */
    if (horizontalBar !is null && (lParam is 0 || lParam is cast(int)handle)) {
        return wmScroll (horizontalBar, (state & CANVAS) !is 0, handle, OS.WM_HSCROLL, wParam, lParam);
    }
    return result;
}

override LRESULT WM_MOUSEWHEEL (int wParam, int lParam) {
    int scrollRemainder = display.scrollRemainder;
    LRESULT result = super.WM_MOUSEWHEEL (wParam, lParam);
    if (result !is null) return result;
    /*
    * Translate WM_MOUSEWHEEL to WM_VSCROLL or WM_HSCROLL.
    */
    if ((state & CANVAS) !is 0) {
        if ((wParam & (OS.MK_SHIFT | OS.MK_CONTROL)) !is 0) return result;
        bool vertical = verticalBar !is null && verticalBar.getEnabled ();
        bool horizontal = horizontalBar !is null && horizontalBar.getEnabled ();
        int msg = vertical ? OS.WM_VSCROLL : horizontal ? OS.WM_HSCROLL : 0;
        if (msg is 0) return result;
        int linesToScroll;
        OS.SystemParametersInfo (OS.SPI_GETWHEELSCROLLLINES, 0, &linesToScroll, 0);
        int delta = OS.GET_WHEEL_DELTA_WPARAM (wParam);
        bool pageScroll = linesToScroll is OS.WHEEL_PAGESCROLL;
        if (!OS.IsWinCE && OS.WIN32_VERSION >= OS.VERSION (6, 0)) {
            ScrollBar bar = vertical ? verticalBar : horizontalBar;
            SCROLLINFO info;
            info.cbSize = SCROLLINFO.sizeof;
            info.fMask = OS.SIF_POS;
            OS.GetScrollInfo (handle, bar.scrollBarType (), &info);
            if (vertical && !pageScroll) delta *= linesToScroll;
            int increment = pageScroll ? bar.getPageIncrement () : bar.getIncrement ();
            info.nPos -=  increment * delta / OS.WHEEL_DELTA;
            OS.SetScrollInfo (handle, bar.scrollBarType (), &info, true);
            OS.SendMessage (handle, msg, OS.SB_THUMBPOSITION, 0);
        } else {
            int code = 0;
            if (pageScroll) {
                code = delta < 0 ? OS.SB_PAGEDOWN : OS.SB_PAGEUP;
            } else {
                code = delta < 0 ? OS.SB_LINEDOWN : OS.SB_LINEUP;
                if (msg is OS.WM_VSCROLL) delta *= linesToScroll;
            }
            /* Check if the delta and the remainder have the same direction (sign) */
            if ((delta ^ scrollRemainder) >= 0) delta += scrollRemainder;
            int count = Math.abs (delta) / OS.WHEEL_DELTA;
            for (int i=0; i<count; i++) {
                OS.SendMessage (handle, msg, code, 0);
            }
        }
        return LRESULT.ZERO;
    }

    /*
    * When the native widget scrolls inside WM_MOUSEWHEEL, it
    * may or may not send a WM_VSCROLL or WM_HSCROLL to do the
    * actual scrolling.  This depends on the implementation of
    * each native widget.  In order to ensure that application
    * code is notified when the scroll bar moves, compare the
    * scroll bar position before and after the WM_MOUSEWHEEL.
    * If the native control sends a WM_VSCROLL or WM_HSCROLL,
    * then the application has already been notified.  If not
    * explicitly send the event.
    */
    int vPosition = verticalBar is null ? 0 : verticalBar.getSelection ();
    int hPosition = horizontalBar is null ? 0 : horizontalBar.getSelection ();
    int /*long*/ code = callWindowProc (handle, OS.WM_MOUSEWHEEL, wParam, lParam);
    if (verticalBar !is null) {
        int position = verticalBar.getSelection ();
        if (position !is vPosition) {
            Event event = new Event ();
            event.detail = position < vPosition ? DWT.PAGE_UP : DWT.PAGE_DOWN;
            verticalBar.sendEvent (DWT.Selection, event);
        }
    }
    if (horizontalBar !is null) {
        int position = horizontalBar.getSelection ();
        if (position !is hPosition) {
            Event event = new Event ();
            event.detail = position < hPosition ? DWT.PAGE_UP : DWT.PAGE_DOWN;
            horizontalBar.sendEvent (DWT.Selection, event);
        }
    }
    return new LRESULT (code);
}

override LRESULT WM_SIZE (int wParam, int lParam) {
    int /*long*/ code = callWindowProc (handle, OS.WM_SIZE, wParam, lParam);
    super.WM_SIZE (wParam, lParam);
    // widget may be disposed at this point
    if (code is 0) return LRESULT.ZERO;
    return new LRESULT (code);
}

override LRESULT WM_VSCROLL (int wParam, int lParam) {
    LRESULT result = super.WM_VSCROLL (wParam, lParam);
    if (result !is null) return result;
    /*
    * Bug on WinCE.  lParam should be NULL when the message is not sent
    * by a scroll bar control, but it contains the handle to the window.
    * When the message is sent by a scroll bar control, it correctly
    * contains the handle to the scroll bar.  The fix is to check for
    * both.
    */
    if (verticalBar !is null && (lParam is 0 || lParam is cast(int)handle)) {
        return wmScroll (verticalBar, (state & CANVAS) !is 0, handle, OS.WM_VSCROLL, wParam, lParam);
    }
    return result;
}

override LRESULT wmNCPaint (HWND hwnd, int /*long*/ wParam, int /*long*/ lParam) {
    LRESULT result = super.wmNCPaint (hwnd, wParam, lParam);
    if (result !is null) return result;
    /*
    * Bug in Windows.  On XP only (not Vista), Windows sometimes
    * does not redraw the bottom right corner of a window that
    * has scroll bars, causing pixel corruption.  The fix is to
    * always draw the corner.
    */
    if (OS.COMCTL32_MAJOR >= 6 && OS.IsAppThemed ()) {
        if (!OS.IsWinCE && OS.WIN32_VERSION < OS.VERSION (6, 0)) {
            int bits1 = OS.GetWindowLong (hwnd, OS.GWL_STYLE);
            if ((bits1 & (OS.WS_HSCROLL | OS.WS_VSCROLL)) !is 0) {
                RECT windowRect;
                OS.GetWindowRect (hwnd, &windowRect);
                RECT trimRect;
                int bits2 = OS.GetWindowLong (hwnd, OS.GWL_EXSTYLE);
                OS.AdjustWindowRectEx (&trimRect, bits1, false, bits2);
                bool hVisible = false, vVisible = false;
                SCROLLBARINFO psbi;
                psbi.cbSize = SCROLLBARINFO.sizeof;
                if (OS.GetScrollBarInfo (hwnd, OS.OBJID_HSCROLL, &psbi)) {
                    hVisible = (psbi.rgstate [0] & OS.STATE_SYSTEM_INVISIBLE) is 0;
                }
                if (OS.GetScrollBarInfo (hwnd, OS.OBJID_VSCROLL, &psbi)) {
                    vVisible = (psbi.rgstate [0] & OS.STATE_SYSTEM_INVISIBLE) is 0;
                }
                RECT cornerRect;
                cornerRect.right = windowRect.right - windowRect.left - trimRect.right;
                cornerRect.bottom = windowRect.bottom - windowRect.top - trimRect.bottom;
                cornerRect.left = cornerRect.right - (hVisible ? OS.GetSystemMetrics (OS.SM_CXVSCROLL) : 0);
                cornerRect.top = cornerRect.bottom - (vVisible ? OS.GetSystemMetrics (OS.SM_CYHSCROLL) : 0);
                if (cornerRect.left !is cornerRect.right && cornerRect.top !is cornerRect.bottom) {
                    auto hDC = OS.GetWindowDC (hwnd);
                    OS.FillRect (hDC, &cornerRect, cast(HANDLE)( OS.COLOR_BTNFACE + 1));
                    Decorations shell = menuShell ();
                    if ((shell.style & DWT.RESIZE) !is 0) {
                        auto hwndScroll = shell.scrolledHandle ();
                        bool drawGripper = hwnd is hwndScroll;
                        if (!drawGripper) {
                            RECT shellRect;
                            OS.GetClientRect (hwndScroll, &shellRect);
                            OS.MapWindowPoints (hwndScroll, null, cast(POINT*)&shellRect, 2);
                            drawGripper = shellRect.right is windowRect.right && shellRect.bottom is windowRect.bottom;
                        }
                        if (drawGripper) {
                            OS.DrawThemeBackground (display.hScrollBarTheme(), hDC, OS.SBP_SIZEBOX, 0, &cornerRect, null);
                        }
                    }
                    OS.ReleaseDC (hwnd, hDC);
                }
            }
        }
    }
    return result;
}

LRESULT wmScroll (ScrollBar bar, bool update, HWND hwnd, int msg, int /*long*/ wParam, int /*long*/ lParam) {
    LRESULT result = null;
    if (update) {
        int type = msg is OS.WM_HSCROLL ? OS.SB_HORZ : OS.SB_VERT;
        SCROLLINFO info;
        info.cbSize = SCROLLINFO.sizeof;
        info.fMask = OS.SIF_TRACKPOS | OS.SIF_POS | OS.SIF_RANGE;
        OS.GetScrollInfo (hwnd, type, &info);
        info.fMask = OS.SIF_POS;
        int code = OS.LOWORD (wParam);
        switch (code) {
            case OS.SB_ENDSCROLL:  return null;
            case OS.SB_THUMBPOSITION:
            case OS.SB_THUMBTRACK:
                /*
                * Note: On WinCE, the value in SB_THUMBPOSITION is relative to nMin.
                * Same for SB_THUMBPOSITION 'except' for the very first thumb track
                * message which has the actual value of nMin. This is a problem when
                * nMin is not zero.
                */
                info.nPos = info.nTrackPos;
                break;
            case OS.SB_TOP:
                info.nPos = info.nMin;
                break;
            case OS.SB_BOTTOM:
                info.nPos = info.nMax;
                break;
            case OS.SB_LINEDOWN:
                info.nPos += bar.getIncrement ();
                break;
            case OS.SB_LINEUP:
                int increment = bar.getIncrement ();
                info.nPos = Math.max (info.nMin, info.nPos - increment);
                break;
            case OS.SB_PAGEDOWN:
                info.nPos += bar.getPageIncrement ();
                break;
            case OS.SB_PAGEUP:
                int pageIncrement = bar.getPageIncrement ();
                info.nPos = Math.max (info.nMin, info.nPos - pageIncrement);
                break;
            default:
        }
        OS.SetScrollInfo (hwnd, type, &info, true);
    } else {
        int /*long*/ code = callWindowProc (hwnd, msg, wParam, lParam);
        result = code is 0 ? LRESULT.ZERO : new LRESULT (code);
    }
    bar.wmScrollChild (wParam, lParam);
    return result;
}

}