/*
 * Copyright 2010-2011, Haiku, Inc.
 * Distributed under the terms of the MIT license.
 *
 * Authors:
 *              Stephan Aßmus <superstippi@gmx.de>
 *              Ingo Weinhold <ingo_weinhold@gmx.de>
 *              Clemens Zeidler <haiku@clemens-zeidler.de>
 */


#include "MagneticBorder.h"

#include "Decorator.h"
#include "Window.h"
#include "Screen.h"


MagneticBorder::MagneticBorder()
        :
        fLastSnapTime(0)
{

}


bool
MagneticBorder::AlterDeltaForSnap(Window* window, BPoint& delta, bigtime_t now)
{
        BRect frame = window->Frame();
        Decorator* decorator = window->Decorator();
        if (decorator)
                frame = decorator->GetFootprint().Frame();

        return AlterDeltaForSnap(window->Screen(), frame, delta, now);
}


bool
MagneticBorder::AlterDeltaForSnap(const Screen* screen, BRect& frame,
        BPoint& delta, bigtime_t now)
{
        // Alter the delta (which is a proposed offset used while dragging a
        // window) so that the frame of the window 'snaps' to the edges of the
        // screen.

        const bigtime_t kSnappingDuration = 1500000LL;
        const bigtime_t kSnappingPause = 3000000LL;
        const float kSnapDistance = 8.0f;

        if (now - fLastSnapTime > kSnappingDuration
                && now - fLastSnapTime < kSnappingPause) {
                // Maintain a pause between snapping.
                return false;
        }

        // TODO: Perhaps obtain the usable area (not covered by the Deskbar)?
        BRect screenFrame = screen->Frame();
        BRect originalFrame = frame;
        frame.OffsetBy(delta);

        float leftDist = fabs(frame.left - screenFrame.left);
        float topDist = fabs(frame.top - screenFrame.top);
        float rightDist = fabs(frame.right - screenFrame.right);
        float bottomDist = fabs(frame.bottom - screenFrame.bottom);

        bool snapped = false;
        if (leftDist < kSnapDistance || rightDist < kSnapDistance) {
                snapped = true;
                if (leftDist < rightDist)
                        delta.x = screenFrame.left - originalFrame.left;
                else
                        delta.x = screenFrame.right - originalFrame.right;
        }

        if (topDist < kSnapDistance || bottomDist < kSnapDistance) {
                snapped = true;
                if (topDist < bottomDist)
                        delta.y = screenFrame.top - originalFrame.top;
                else
                        delta.y = screenFrame.bottom - originalFrame.bottom;
        }
        if (snapped && now - fLastSnapTime > kSnappingPause)
                fLastSnapTime = now;

        return snapped;
}