/*******************************************************************************
 * Copyright (c) 2000, 2007 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.widgets.Widget;
import dwt.widgets.Event;
import dwt.widgets.Control;
import dwt.widgets.ScrollBar;
import dwt.widgets.Composite;
import dwt.DWT;
import dwt.DWTException;
import dwt.graphics.Rectangle;
import dwt.internal.win32.OS;

import dwt.dwthelper.utils;
import tango.util.log.Trace;
void trc( long line ){
    //Trace.formatln( "Scrollable {}", line );
}

/**
 * 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>
 */

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);
}

/**
 * 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) {
trc(__LINE__);
    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) {
trc(__LINE__);
    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 value;
        OS.SystemParametersInfo (OS.SPI_GETWHEELSCROLLLINES, 0, &value, 0);
        int delta = cast(short) (wParam >> 16);
        int code = 0, count = 0;
        if (value  is OS.WHEEL_PAGESCROLL) {
            code = delta < 0 ? OS.SB_PAGEDOWN : OS.SB_PAGEUP;
            count = Math.abs (delta / OS.WHEEL_DELTA);
        } else {
            code = delta < 0 ? OS.SB_LINEDOWN : OS.SB_LINEUP;
            delta = Math.abs (delta);
            if (delta < OS.WHEEL_DELTA) return result;
            if (msg is OS.WM_VSCROLL) {
                count = value  * delta / OS.WHEEL_DELTA;
            } else {
                count = 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 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) {
trc(__LINE__);
    int 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) {
trc(__LINE__);
    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;
}

LRESULT wmScroll (ScrollBar bar, bool update, HWND hwnd, int msg, int wParam, int lParam) {
trc(__LINE__);
    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 = wParam & 0xFFFF;
        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 code = callWindowProc (hwnd, msg, wParam, lParam);
        result = code is 0 ? LRESULT.ZERO : new LRESULT (code);
    }
    bar.wmScrollChild (wParam, lParam);
    return result;
}

}