#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <glibmm/i18n.h>
#include "sp-item.h"
#include "desktop.h"
#include "message-context.h"
#include "message-stack.h"
#include "context-fns.h"
#include "snap.h"
#include "event-context.h"
#include "sp-namedview.h"
#include "display/snap-indicator.h"

static const double midpt_1_goldenratio = (1 + goldenratio) / 2;
static const double midpt_goldenratio_2 = (goldenratio + 2) / 2;

/* FIXME: could probably use a template here */

/**
 *  Check to see if the current layer is both unhidden and unlocked.  If not,
 *  set a message about it on the given context.
 *
 *  \param desktop Desktop.
 *  \param message Message context to put messages on.
 *  \return true if the current layer is both unhidden and unlocked, otherwise false.
 */

bool Inkscape::have_viable_layer(SPDesktop *desktop, MessageContext *message)
{
    SPItem const *layer = SP_ITEM(desktop->currentLayer());

    if ( !layer || desktop->itemIsHidden(layer) ) {
            message->flash(Inkscape::ERROR_MESSAGE,
                         _("<b>Current layer is hidden</b>. Unhide it to be able to draw on it."));
            return false;
    }

    if ( !layer || layer->isLocked() ) {
            message->flash(Inkscape::ERROR_MESSAGE,
                         _("<b>Current layer is locked</b>. Unlock it to be able to draw on it."));
            return false;
    }

    return true;
}


/**
 *  Check to see if the current layer is both unhidden and unlocked.  If not,
 *  set a message about it on the given context.
 *
 *  \param desktop Desktop.
 *  \param message Message context to put messages on.
 *  \return true if the current layer is both unhidden and unlocked, otherwise false.
 */

bool Inkscape::have_viable_layer(SPDesktop *desktop, MessageStack *message)
{
    SPItem const *layer = SP_ITEM(desktop->currentLayer());

    if ( !layer || desktop->itemIsHidden(layer) ) {
            message->flash(Inkscape::WARNING_MESSAGE,
                         _("<b>Current layer is hidden</b>. Unhide it to be able to draw on it."));
            return false;
    }

    if ( !layer || layer->isLocked() ) {
            message->flash(Inkscape::WARNING_MESSAGE,
                         _("<b>Current layer is locked</b>. Unlock it to be able to draw on it."));
            return false;
    }

    return true;
}


Geom::Rect Inkscape::snap_rectangular_box(SPDesktop const *desktop, SPItem *item,
                                        Geom::Point const &pt, Geom::Point const &center, int state)
{
    Geom::Point p[2];

    bool const shift = state & GDK_SHIFT_MASK;
    bool const control = state & GDK_CONTROL_MASK;

    SnapManager &m = desktop->namedview->snap_manager;
    m.setup(desktop, false, item);
    Inkscape::SnappedPoint snappoint;

    if (control) {

        /* Control is down: we are constrained to producing integer-ratio rectangles */

        /* Vector from the centre of the box to the point we are dragging to */
        Geom::Point delta = pt - center;

        /* Round it so that we have an integer-ratio (or golden ratio) box */
        if (fabs(delta[Geom::X]) > fabs(delta[Geom::Y]) && (delta[Geom::Y] != 0.0)) {
            double ratio = delta[Geom::X] / delta[Geom::Y];
            double ratioabs = fabs (ratio);
            double sign = (ratio < 0 ? -1 : 1);
            if (midpt_1_goldenratio < ratioabs && ratioabs < midpt_goldenratio_2) {
                delta[Geom::X] = sign * goldenratio * delta[Geom::Y];
            } else {
                delta[Geom::X] = floor(ratio + 0.5) * delta[Geom::Y];
            }
        } else if (delta[Geom::X] != 0.0) {
            double ratio = delta[Geom::Y] / delta[Geom::X];
            double ratioabs = fabs (ratio);
            double sign = (ratio < 0 ? -1 : 1);
            if (midpt_1_goldenratio < ratioabs && ratioabs < midpt_goldenratio_2) {
                delta[Geom::Y] = sign * goldenratio * delta[Geom::X];
            } else {
                delta[Geom::Y] = floor(delta[Geom::Y] / delta[Geom::X] + 0.5) * delta[Geom::X];
            }
        }

        /* p[1] is the dragged point with the integer-ratio constraint */
        p[1] = center + delta;

        if (shift) {

            /* Shift is down, so our origin is the centre point rather than the corner
            ** point; this means that corner-point movements are bound to each other.
            */

            /* p[0] is the opposite corner of our box */
            p[0] = center - delta;

            Inkscape::SnappedPoint s[2];

            /* Try to snap p[0] (the opposite corner) along the constraint vector */
            s[0] = m.constrainedSnap(Inkscape::SnapCandidatePoint(p[0], Inkscape::SNAPSOURCE_NODE_HANDLE),
                                     Inkscape::Snapper::ConstraintLine(p[0] - p[1]));

            /* Try to snap p[1] (the dragged corner) along the constraint vector */
            s[1] = m.constrainedSnap(Inkscape::SnapCandidatePoint(p[1], Inkscape::SNAPSOURCE_NODE_HANDLE),
                                     Inkscape::Snapper::ConstraintLine(p[1] - p[0]));

            /* Choose the best snap and update points accordingly */
            if (s[0].getSnapDistance() < s[1].getSnapDistance()) {
                if (s[0].getSnapped()) {
                    p[0] = s[0].getPoint();
                    p[1] = 2 * center - s[0].getPoint();
                    snappoint = s[0];
                }
            } else {
                if (s[1].getSnapped()) {
                    p[0] = 2 * center - s[1].getPoint();
                    p[1] = s[1].getPoint();
                    snappoint = s[1];
                }
            }
        } else {

            /* Our origin is the opposite corner.  Snap the drag point along the constraint vector */
            p[0] = center;
            snappoint = m.constrainedSnap(Inkscape::SnapCandidatePoint(p[1], Inkscape::SNAPSOURCE_NODE_HANDLE),
                                          Inkscape::Snapper::ConstraintLine(p[1] - p[0]));
            if (snappoint.getSnapped()) {
                p[1] = snappoint.getPoint();
            }
        }

    } else if (shift) {

        /* Shift is down, so our origin is the centre point rather than the corner point;
        ** this means that corner-point movements are bound to each other.
        */

        p[1] = pt;
        p[0] = 2 * center - p[1];

        Inkscape::SnappedPoint s[2];

        s[0] = m.freeSnap(Inkscape::SnapCandidatePoint(p[0], Inkscape::SNAPSOURCE_NODE_HANDLE));
        s[1] = m.freeSnap(Inkscape::SnapCandidatePoint(p[1], Inkscape::SNAPSOURCE_NODE_HANDLE));

        if (s[0].getSnapDistance() < s[1].getSnapDistance()) {
            if (s[0].getSnapped()) {
                p[0] = s[0].getPoint();
                p[1] = 2 * center - s[0].getPoint();
                snappoint = s[0];
            }
        } else {
            if (s[1].getSnapped()) {
                p[0] = 2 * center - s[1].getPoint();
                p[1] = s[1].getPoint();
                snappoint = s[1];
            }
        }

    } else {

        /* There's no constraint on the corner point, so just snap it to anything */
        p[0] = center;
        p[1] = pt;
        snappoint = m.freeSnap(Inkscape::SnapCandidatePoint(pt, Inkscape::SNAPSOURCE_NODE_HANDLE));
        if (snappoint.getSnapped()) {
            p[1] = snappoint.getPoint();
        }
    }

    if (snappoint.getSnapped()) {
        desktop->snapindicator->set_new_snaptarget(snappoint);
    }

    p[0] *= desktop->dt2doc();
    p[1] *= desktop->dt2doc();

    return Geom::Rect(Geom::Point(MIN(p[0][Geom::X], p[1][Geom::X]), MIN(p[0][Geom::Y], p[1][Geom::Y])),
                    Geom::Point(MAX(p[0][Geom::X], p[1][Geom::X]), MAX(p[0][Geom::Y], p[1][Geom::Y])));
}



Geom::Point Inkscape::setup_for_drag_start(SPDesktop *desktop, SPEventContext* ec, GdkEvent *ev)
{
    ec->xp = static_cast<gint>(ev->button.x);
    ec->yp = static_cast<gint>(ev->button.y);
    ec->within_tolerance = true;

    Geom::Point const p(ev->button.x, ev->button.y);
    ec->item_to_select = sp_event_context_find_item(desktop, p, ev->button.state & GDK_MOD1_MASK, TRUE);
    return ec->desktop->w2d(p);
}


/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
