/********************************************************************
 KWin - the KDE window manager
 This file is part of the KDE project.

 Copyright (C) 2015 Thomas Lübking <thomas.luebking@gmail.com>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*********************************************************************/
/*global effect, effects, animate, animationTime, Effect, QEasingCurve */

"use strict";

var badBadWindowsEffect = {
    duration: animationTime(250),
    loadConfig: function () {
        badBadWindowsEffect.duration = animationTime(250);
    },
    offToCorners: function (showing) {
        var stackingOrder = effects.stackingOrder;
        var screenGeo = effects.virtualScreenGeometry;
        var xOffset = screenGeo.width / 16;
        var yOffset = screenGeo.height / 16;
        if (showing) {
            var closestWindows = [ undefined, undefined, undefined, undefined ];
            var movedWindowsCount = 0;
            for (var i = 0; i < stackingOrder.length; ++i) {
                var w = stackingOrder[i];

                // ignore windows above the desktop
                // (when not showing, pretty much everything would be)
                if (w.desktopWindow)
                    break;

                // ignore invisible windows and such that do not have to be restored
                if (!w.visible)
                    continue;

                // we just fade out docks - moving panels into edges looks dull
                if (w.dock) {
                    w.offToCornerId = set({
                        window: w,
                        duration: badBadWindowsEffect.duration,
                        animations: [{
                            type: Effect.Opacity,
                            to: 0.0
                        }]
                    });
                    continue;
                }

                // calculate the corner distances
                var geo = w.geometry;
                var dl = geo.x + geo.width - screenGeo.x;
                var dr = screenGeo.x + screenGeo.width - geo.x;
                var dt = geo.y + geo.height - screenGeo.y;
                var db = screenGeo.y + screenGeo.height - geo.y;
                w.apertureDistances = [ dl + dt, dr + dt, dr + db, dl + db ];
                movedWindowsCount += 1;

                // if this window is the closest one to any corner, set it as preferred there
                var nearest = 0;
                for (var j = 1; j < 4; ++j) {
                    if (w.apertureDistances[j] < w.apertureDistances[nearest] ||
                        (w.apertureDistances[j] == w.apertureDistances[nearest] && closestWindows[j] === undefined)) {
                        nearest = j;
                    }
                }
                if (closestWindows[nearest] === undefined ||
                    closestWindows[nearest].apertureDistances[nearest] > w.apertureDistances[nearest])
                    closestWindows[nearest] = w;
            }

            // second pass, select corners

            // 1st off, move the nearest windows to their nearest corners
            // this will ensure that if there's only on window in the lower right
            // it won't be moved out to the upper left
            var movedWindowsDec = [ 0, 0, 0, 0 ];
            for (var i = 0; i < 4; ++i) {
                if (closestWindows[i] === undefined)
                    continue;
                closestWindows[i].apertureCorner = i;
                delete closestWindows[i].apertureDistances;
                movedWindowsDec[i] = 1;
            }

            // 2nd, distribute the remainders according to their preferences
            // this doesn't exactly have heapsort performance ;-)
            movedWindowsCount = Math.floor((movedWindowsCount + 3) / 4);
            for (var i = 0; i < 4; ++i) {
                for (var j = 0; j < movedWindowsCount - movedWindowsDec[i]; ++j) {
                    var bestWindow = undefined;
                    for (var k = 0; k < stackingOrder.length; ++k) {
                        if (stackingOrder[k].apertureDistances === undefined)
                            continue;
                        if (bestWindow === undefined ||
                            stackingOrder[k].apertureDistances[i] < bestWindow.apertureDistances[i])
                            bestWindow = stackingOrder[k];
                    }
                    if (bestWindow === undefined)
                        break;
                    bestWindow.apertureCorner = i;
                    delete bestWindow.apertureDistances;
                }
            }

        }

        // actually re/move windows from/to assigned corners
        for (var i = 0; i < stackingOrder.length; ++i) {
            var w = stackingOrder[i];
            if (w.apertureCorner === undefined && w.offToCornerId === undefined)
                continue;

            // keep windows above the desktop visually
            effects.setElevatedWindow(w, showing);

            if (!showing && w.dock) {
                cancel(w.offToCornerId);
                delete w.offToCornerId;
                delete w.apertureCorner; // should not exist, but better safe than sorry.
                animate({
                    window: w,
                    duration: badBadWindowsEffect.duration,
                    animations: [{
                        type: Effect.Opacity,
                        from: 0.0
                    }]
                });
                continue;
            }

            var anchor, tx, ty;
            var geo = w.geometry;
            if (w.apertureCorner == 1 || w.apertureCorner == 2) {
                tx = screenGeo.x + screenGeo.width - xOffset;
                anchor = Effect.Left;
            } else {
                tx = xOffset;
                anchor = Effect.Right;
            }
            if (w.apertureCorner > 1) {
                ty = screenGeo.y + screenGeo.height - yOffset;
                anchor |= Effect.Top;
            } else {
                ty = yOffset;
                anchor |= Effect.Bottom;
            }

            if (showing) {
                w.offToCornerId = set({
                    window: w,
                    duration: badBadWindowsEffect.duration,
                    curve: QEasingCurve.InOutQuad,
                    animations: [{
                        type: Effect.Position,
                        targetAnchor: anchor,
                        to: { value1: tx, value2: ty }
                    },{
                        type: Effect.Opacity,
                        to: 0.2
                    }]
                });
            } else {
                cancel(w.offToCornerId);
                delete w.offToCornerId;
                delete w.apertureCorner;
                if (w.visible) { // could meanwhile have been hidden
                    animate({
                        window: w,
                        duration: badBadWindowsEffect.duration,
                        curve: QEasingCurve.InOutQuad,
                        animations: [{
                            type: Effect.Position,
                            sourceAnchor: anchor,
                            from: { value1: tx, value2: ty }
                        },{
                            type: Effect.Opacity,
                            from: 0.2
                        }]
                    });
                }
            }
        }
    },
    init: function () {
        badBadWindowsEffect.loadConfig();
        effects.showingDesktopChanged.connect(badBadWindowsEffect.offToCorners);
    }
};

badBadWindowsEffect.init();