/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */

const Clutter = imports.gi.Clutter;
const Signals = imports.signals;
const Lang = imports.lang;
const Meta = imports.gi.Meta;
const Shell = imports.gi.Shell;
const St = imports.gi.St;
const Gettext = imports.gettext.domain('gnome-shell');
const _ = Gettext.gettext;

const AppDisplay = imports.ui.appDisplay;
const AppFavorites = imports.ui.appFavorites;
const DND = imports.ui.dnd;
const IconGrid = imports.ui.iconGrid;
const Main = imports.ui.main;
const Tweener = imports.ui.tweener;
const Workspace = imports.ui.workspace;

const DASH_ANIMATION_TIME = 0.2;

// A container like StBin, but taking the child's scale into account
// when requesting a size
function DashItemContainer() {
    this._init();
}

DashItemContainer.prototype = {
    _init: function() {
        this.actor = new Shell.GenericContainer({ style_class: 'dash-item-container' });
        this.actor.connect('get-preferred-width',
                           Lang.bind(this, this._getPreferredWidth));
        this.actor.connect('get-preferred-height',
                           Lang.bind(this, this._getPreferredHeight));
        this.actor.connect('allocate',
                           Lang.bind(this, this._allocate));
        this.actor._delegate = this;

        this.child = null;
        this._childScale = 1;
        this._childOpacity = 255;
    },

    _allocate: function(actor, box, flags) {
        if (this.child == null)
            return;

        let availWidth = box.x2 - box.x1;
        let availHeight = box.y2 - box.y1;
        let [minChildWidth, minChildHeight, natChildWidth, natChildHeight] =
            this.child.get_preferred_size();
        let [childScaleX, childScaleY] = this.child.get_scale();

        let childWidth = Math.min(natChildWidth * childScaleX, availWidth);
        let childHeight = Math.min(natChildHeight * childScaleY, availHeight);

        let childBox = new Clutter.ActorBox();
        childBox.x1 = (availWidth - childWidth) / 2;
        childBox.y1 = (availHeight - childHeight) / 2;
        childBox.x2 = childBox.x1 + childWidth;
        childBox.y2 = childBox.y1 + childHeight;

        this.child.allocate(childBox, flags);
    },

    _getPreferredHeight: function(actor, forWidth, alloc) {
        alloc.min_size = 0;
        alloc.natural_size = 0;

        if (this.child == null)
            return;

        let [minHeight, natHeight] = this.child.get_preferred_height(forWidth);
        alloc.min_size += minHeight * this.child.scale_y;
        alloc.natural_size += natHeight * this.child.scale_y;
    },

    _getPreferredWidth: function(actor, forHeight, alloc) {
        alloc.min_size = 0;
        alloc.natural_size = 0;

        if (this.child == null)
            return;

        let [minWidth, natWidth] = this.child.get_preferred_width(forHeight);
        alloc.min_size = minWidth * this.child.scale_y;
        alloc.natural_size = natWidth * this.child.scale_y;
    },

    setChild: function(actor) {
        if (this.child == actor)
            return;

        this.actor.destroy_children();

        this.child = actor;
        this.actor.add_actor(this.child);
    },

    animateIn: function() {
        if (this.child == null)
            return;

        this.childScale = 0;
        this.childOpacity = 0;
        Tweener.addTween(this,
                         { childScale: 1.0,
                           childOpacity: 255,
                           time: DASH_ANIMATION_TIME,
                           transition: 'easeOutQuad'
                         });
    },

    animateOutAndDestroy: function() {
        if (this.child == null) {
            this.actor.destroy();
            return;
        }

        this.childScale = 1.0;
        Tweener.addTween(this,
                         { childScale: 0.0,
                           childOpacity: 0,
                           time: DASH_ANIMATION_TIME,
                           transition: 'easeOutQuad',
                           onComplete: Lang.bind(this, function() {
                               this.actor.destroy();
                           })
                         });
    },

    set childScale(scale) {
        this._childScale = scale;

        if (this.child == null)
            return;

        this.child.set_scale_with_gravity(scale, scale,
                                          Clutter.Gravity.CENTER);
        this.actor.queue_relayout();
    },

    get childScale() {
        return this._childScale;
    },

    set childOpacity(opacity) {
        this._childOpacity = opacity;

        if (this.child == null)
            return;

        this.child.set_opacity(opacity);
        this.actor.queue_redraw();
    },

    get childOpacity() {
        return this._childOpacity;
    }
};

function RemoveFavoriteIcon() {
    this._init();
}

RemoveFavoriteIcon.prototype = {
    __proto__: DashItemContainer.prototype,

    _init: function() {
        DashItemContainer.prototype._init.call(this);

        this._iconBin = new St.Bin({ style_class: 'remove-favorite' });
        this._iconActor = null;
        this.icon = new IconGrid.BaseIcon(_("Remove"),
                                           { setSizeManually: true,
                                             showLabel: false,
                                             createIcon: Lang.bind(this, this._createIcon) });
        this._iconBin.set_child(this.icon.actor);
        this._iconBin._delegate = this;

        this.setChild(this._iconBin);
        this.hiding = false;
    },

    animateOutAndDestroy: function() {
        DashItemContainer.prototype.animateOutAndDestroy.call(this);
        this.hiding = true;
    },

    _createIcon: function(size) {
        this._iconActor = new St.Icon({ icon_name: 'user-trash',
                                        style_class: 'remove-favorite-icon',
                                        icon_size: size });
        return this._iconActor;
    },

    setHover: function(hovered) {
        this._iconBin.set_hover(hovered);
        if (this._iconActor)
            this._iconActor.set_hover(hovered);
    },

    // Rely on the dragged item being a favorite
    handleDragOver: function(source, actor, x, y, time) {
        return DND.DragMotionResult.MOVE_DROP;
    },

    acceptDrop: function(source, actor, x, y, time) {
        let app = null;
        if (source instanceof AppDisplay.AppWellIcon) {
            let appSystem = Shell.AppSystem.get_default();
            app = appSystem.get_app(source.getId());
        } else if (source.metaWindow) {
            let tracker = Shell.WindowTracker.get_default();
            app = tracker.get_window_app(source.metaWindow);
        }

        let id = app.get_id();

        Meta.later_add(Meta.LaterType.BEFORE_REDRAW, Lang.bind(this,
            function () {
                AppFavorites.getAppFavorites().removeFavorite(id);
                return false;
            }));

        return true;
    }
};


function DragPlaceholderItem() {
    this._init();
}

DragPlaceholderItem.prototype = {
    __proto__: DashItemContainer.prototype,

    _init: function() {
        DashItemContainer.prototype._init.call(this);
        this.setChild(new St.Bin({ style_class: 'dash-placeholder' }));
    }
};


function Dash() {
    this._init();
}

Dash.prototype = {
    _init : function() {
        this._maxHeight = -1;
        this.iconSize = 64;
        this._shownInitially = false;

        this._dragPlaceholder = null;
        this._dragPlaceholderPos = -1;
        this._animatingPlaceholdersCount = 0;
        this._favRemoveTarget = null;

        this._box = new St.BoxLayout({ name: 'dash',
                                       vertical: true,
                                       clip_to_allocation: true });
        this._box._delegate = this;

        this.actor = new St.Bin({ y_align: St.Align.START, child: this._box });
        this.actor.connect('notify::height', Lang.bind(this,
            function() {
                if (this._maxHeight != this.actor.height)
                    this._queueRedisplay();
                this._maxHeight = this.actor.height;
            }));

        this._workId = Main.initializeDeferredWork(this._box, Lang.bind(this, this._redisplay));

        this._tracker = Shell.WindowTracker.get_default();
        this._appSystem = Shell.AppSystem.get_default();

        this._appSystem.connect('installed-changed', Lang.bind(this, this._queueRedisplay));
        AppFavorites.getAppFavorites().connect('changed', Lang.bind(this, this._queueRedisplay));
        this._tracker.connect('app-state-changed', Lang.bind(this, this._queueRedisplay));

        Main.overview.connect('item-drag-begin',
                              Lang.bind(this, this._onDragBegin));
        Main.overview.connect('item-drag-end',
                              Lang.bind(this, this._onDragEnd));
        Main.overview.connect('item-drag-cancelled',
                              Lang.bind(this, this._onDragCancelled));
        Main.overview.connect('window-drag-begin',
                              Lang.bind(this, this._onDragBegin));
        Main.overview.connect('window-drag-cancelled',
                              Lang.bind(this, this._onDragCancelled));
        Main.overview.connect('window-drag-end',
                              Lang.bind(this, this._onDragEnd));
    },

    _onDragBegin: function() {
        this._dragCancelled = false;
        this._dragMonitor = {
            dragMotion: Lang.bind(this, this._onDragMotion)
        };
        DND.addDragMonitor(this._dragMonitor);
    },

    _onDragCancelled: function() {
        this._dragCancelled = true;
        this._endDrag();
    },

    _onDragEnd: function() {
        if (this._dragCancelled)
            return;

        this._endDrag();
    },

    _endDrag: function() {
        this._clearDragPlaceholder();
        if (this._favRemoveTarget) {
            this._favRemoveTarget.actor.hide();
            this._adjustIconSize();
            this._favRemoveTarget.actor.show();

            this._favRemoveTarget.animateOutAndDestroy();
            this._favRemoveTarget.actor.connect('destroy', Lang.bind(this,
                function() {
                    this._favRemoveTarget = null;
                }));
        }
        DND.removeMonitor(this._dragMonitor);
    },

    _onDragMotion: function(dragEvent) {
        let app = null;
        if (dragEvent.source instanceof AppDisplay.AppWellIcon)
            app = this._appSystem.get_app(dragEvent.source.getId());
        else if (dragEvent.source.metaWindow)
            app = this._tracker.get_window_app(dragEvent.source.metaWindow);
        else
            return DND.DragMotionResult.CONTINUE;

        let id = app.get_id();

        let favorites = AppFavorites.getAppFavorites().getFavoriteMap();

        let srcIsFavorite = (id in favorites);

        if (srcIsFavorite && this._favRemoveTarget == null) {
                this._favRemoveTarget = new RemoveFavoriteIcon();
                this._favRemoveTarget.icon.setIconSize(this.iconSize);
                this._box.add(this._favRemoveTarget.actor);
                this._adjustIconSize();
                this._favRemoveTarget.animateIn();
        }

        let favRemoveHovered = false;
        if (this._favRemoveTarget)
            favRemoveHovered =
                this._favRemoveTarget.actor.contains(dragEvent.targetActor);

        if (!this._box.contains(dragEvent.targetActor) || favRemoveHovered)
            this._clearDragPlaceholder();

        if (this._favRemoveTarget)
            this._favRemoveTarget.setHover(favRemoveHovered);

        return DND.DragMotionResult.CONTINUE;
    },

    _appIdListToHash: function(apps) {
        let ids = {};
        for (let i = 0; i < apps.length; i++)
            ids[apps[i].get_id()] = apps[i];
        return ids;
    },

    _queueRedisplay: function () {
        Main.queueDeferredWork(this._workId);
    },

    _createAppItem: function(app) {
        let display = new AppDisplay.AppWellIcon(app,
                                                 { setSizeManually: true,
                                                   showLabel: false });
        display._draggable.connect('drag-begin',
                                   Lang.bind(this, function() {
                                       display.actor.opacity = 50;
                                   }));
        display._draggable.connect('drag-end',
                                   Lang.bind(this, function() {
                                       display.actor.opacity = 255;
                                   }));
        let item = new DashItemContainer();
        item.setChild(display.actor);

        display.icon.setIconSize(this.iconSize);

        return item;
    },

    _adjustIconSize: function() {
        let children = this._box.get_children();
        if (children.length == 0) {
            this._box.add_style_pseudo_class('empty');
            return;
        }

        this._box.remove_style_pseudo_class('empty');

        if (this._maxHeight == -1)
            return;

        let iconChildren = children.filter(function(actor) {
            return actor.visible &&
                   actor._delegate.child &&
                   actor._delegate.child._delegate &&
                   actor._delegate.child._delegate.icon;
        });

        // Compute the amount of extra space (or missing space) we have
        // per icon with the current icon size
        let [minHeight, natHeight] = this.actor.get_preferred_height(-1);
        let diff = (this._maxHeight - natHeight) / iconChildren.length;

        let iconSizes = [ 16, 22, 24, 32, 48, 64 ];

        let newIconSize = 16;
        for (let i = 0; i < iconSizes.length; i++) {
            if (iconSizes[i] < this.iconSize + diff)
                newIconSize = iconSizes[i];
        }

        if (newIconSize == this.iconSize)
            return;

        let oldIconSize = this.iconSize;
        this.iconSize = newIconSize;

        let scale = oldIconSize / newIconSize;
        for (let i = 0; i < iconChildren.length; i++) {
            let icon = iconChildren[i]._delegate.child._delegate.icon;

            // Set the new size immediately, to keep the icons' sizes
            // in sync with this.iconSize
            icon.setIconSize(this.iconSize);

            // Don't animate the icon size change when the overview
            // is not visible or when initially filling the dash
            if (!Main.overview.visible || !this._shownInitially)
                continue;

            let [targetWidth, targetHeight] = icon.icon.get_size();

            // Scale the icon's texture to the previous size and
            // tween to the new size
            icon.icon.set_size(icon.icon.width * scale,
                               icon.icon.height * scale);

            Tweener.addTween(icon.icon,
                             { width: targetWidth,
                               height: targetHeight,
                               time: DASH_ANIMATION_TIME,
                               transition: 'easeOutQuad'
                             });
        }
    },

    _redisplay: function () {
        let favorites = AppFavorites.getAppFavorites().getFavoriteMap();

        /* hardcode here pending some design about how exactly desktop contexts behave */
        let contextId = '';

        let running = this._tracker.get_running_apps(contextId);

        let children = this._box.get_children().filter(function(actor) {
                return actor._delegate.child &&
                       actor._delegate.child._delegate &&
                       actor._delegate.child._delegate.app;
            });
        // Apps currently in the dash
        let oldApps = children.map(function(actor) {
                return actor._delegate.child._delegate.app;
            });
        // Apps supposed to be in the dash
        let newApps = [];

        for (let id in favorites)
            newApps.push(favorites[id]);

        for (let i = 0; i < running.length; i++) {
            let app = running[i];
            if (app.get_id() in favorites)
                continue;
            newApps.push(app);
        }

        // Figure out the actual changes to the list of items; we iterate
        // over both the list of items currently in the dash and the list
        // of items expected there, and collect additions and removals.
        // Moves are both an addition and a removal, where the order of
        // the operations depends on whether we encounter the position
        // where the item has been added first or the one from where it
        // was removed.
        // There is an assumption that only one item is moved at a given
        // time; when moving several items at once, everything will still
        // end up at the right position, but there might be additional
        // additions/removals (e.g. it might remove all the launchers
        // and add them back in the new order even if a smaller set of
        // additions and removals is possible).
        // If above assumptions turns out to be a problem, we might need
        // to use a more sophisticated algorithm, e.g. Longest Common
        // Subsequence as used by diff.
        let addedItems = [];
        let removedActors = [];

        let newIndex = 0;
        let oldIndex = 0;
        while (newIndex < newApps.length || oldIndex < oldApps.length) {
            // No change at oldIndex/newIndex
            if (oldApps[oldIndex] == newApps[newIndex]) {
                oldIndex++;
                newIndex++;
                continue;
            }

            // App removed at oldIndex
            if (oldApps[oldIndex] &&
                newApps.indexOf(oldApps[oldIndex]) == -1) {
                removedActors.push(children[oldIndex]);
                oldIndex++;
                continue;
            }

            // App added at newIndex
            if (newApps[newIndex] &&
                oldApps.indexOf(newApps[newIndex]) == -1) {
                addedItems.push({ app: newApps[newIndex],
                                  item: this._createAppItem(newApps[newIndex]),
                                  pos: newIndex });
                newIndex++;
                continue;
            }

            // App moved
            let insertHere = newApps[newIndex + 1] &&
                             newApps[newIndex + 1] == oldApps[oldIndex];
            let alreadyRemoved = removedActors.reduce(function(result, actor) {
                let removedApp = actor._delegate.child._delegate.app;
                return result || removedApp == newApps[newIndex];
            }, false);

            if (insertHere || alreadyRemoved) {
                let newItem = this._createAppItem(newApps[newIndex]);
                addedItems.push({ app: newApps[newIndex],
                                  item: newItem,
                                  pos: newIndex + removedActors.length });
                newIndex++;
            } else {
                removedActors.push(children[oldIndex]);
                oldIndex++;
            }
        }

        for (let i = 0; i < addedItems.length; i++)
            this._box.insert_actor(addedItems[i].item.actor,
                                   addedItems[i].pos);

        // Hide removed actors to not take them into account
        // when adjusting the icon size ...
        for (let i = 0; i < removedActors.length; i++)
            removedActors[i].hide();

        // ... and do the same for the remove target if necessary
        if (this._favRemoveTarget && this._favRemoveTarget.hiding)
            this._favRemoveTarget.actor.hide();

        this._adjustIconSize();

        if (this._favRemoveTarget && this._favRemoveTarget.hiding)
            this._favRemoveTarget.actor.show();

        // Skip animations on first run when adding the initial set
        // of items, to avoid all items zooming in at once
        if (!this._shownInitially) {
            this._shownInitially = true;
            return;
        }

        for (let i = 0; i < removedActors.length; i++) {
            removedActors[i].show();
            let item = removedActors[i]._delegate;

            // Don't animate item removal when the overview is hidden
            if (Main.overview.visible)
                item.animateOutAndDestroy();
            else
                item.actor.destroy();
        }

        // Don't animate item addition when the overview is hidden
        if (!Main.overview.visible)
            return;

        for (let i = 0; i < addedItems.length; i++)
            addedItems[i].item.animateIn();
    },

    _clearDragPlaceholder: function() {
        if (this._dragPlaceholder) {
            this._dragPlaceholder.animateOutAndDestroy();
            this._dragPlaceholder = null;
            this._dragPlaceholderPos = -1;
        }
    },

    handleDragOver : function(source, actor, x, y, time) {
        let app = null;
        if (source instanceof AppDisplay.AppWellIcon)
            app = this._appSystem.get_app(source.getId());
        else if (source.metaWindow)
            app = this._tracker.get_window_app(source.metaWindow);

        // Don't allow favoriting of transient apps
        if (app == null || app.is_transient())
            return DND.DragMotionResult.NO_DROP;

        let favorites = AppFavorites.getAppFavorites().getFavorites();
        let numFavorites = favorites.length;

        let favPos = favorites.indexOf(app);

        let children = this._box.get_children();
        let numChildren = children.length;
        let boxHeight = this._box.height;

        // Keep the placeholder out of the index calculation; assuming that
        // the remove target has the same size as "normal" items, we don't
        // need to do the same adjustment there.
        if (this._dragPlaceholder) {
            boxHeight -= this._dragPlaceholder.actor.height;
            numChildren--;
        }

        let pos = Math.round(y * numChildren / boxHeight);

        if (pos != this._dragPlaceholderPos && pos <= numFavorites) {
            if (this._animatingPlaceholdersCount > 0) {
                let appChildren = children.filter(function(actor) {
                    return actor._delegate &&
                           actor._delegate.child &&
                           actor._delegate.child._delegate &&
                           actor._delegate.child._delegate.app;
                });
                this._dragPlaceholderPos = children.indexOf(appChildren[pos]);
            } else {
                this._dragPlaceholderPos = pos;
            }

            // Don't allow positioning before or after self
            if (favPos != -1 && (pos == favPos || pos == favPos + 1)) {
                if (this._dragPlaceholder) {
                    this._dragPlaceholder.animateOutAndDestroy();
                    this._animatingPlaceholdersCount++;
                    this._dragPlaceholder.actor.connect('destroy',
                        Lang.bind(this, function() {
                            this._animatingPlaceholdersCount--;
                        }));
                }
                this._dragPlaceholder = null;

                return DND.DragMotionResult.CONTINUE;
            }

            // If the placeholder already exists, we just move
            // it, but if we are adding it, expand its size in
            // an animation
            let fadeIn;
            if (this._dragPlaceholder) {
                this._dragPlaceholder.actor.destroy();
                fadeIn = false;
            } else {
                fadeIn = true;
            }

            this._dragPlaceholder = new DragPlaceholderItem();
            this._box.insert_actor(this._dragPlaceholder.actor,
                                   this._dragPlaceholderPos);
            if (fadeIn)
                this._dragPlaceholder.animateIn();
        }

        let srcIsFavorite = (favPos != -1);

        if (srcIsFavorite)
            return DND.DragMotionResult.MOVE_DROP;

        return DND.DragMotionResult.COPY_DROP;
    },

    // Draggable target interface
    acceptDrop : function(source, actor, x, y, time) {
        let app = null;
        if (source instanceof AppDisplay.AppWellIcon) {
            app = this._appSystem.get_app(source.getId());
        } else if (source.metaWindow) {
            app = this._tracker.get_window_app(source.metaWindow);
        }

        // Don't allow favoriting of transient apps
        if (app == null || app.is_transient()) {
            return false;
        }

        let id = app.get_id();

        let favorites = AppFavorites.getAppFavorites().getFavoriteMap();

        let srcIsFavorite = (id in favorites);

        let favPos = 0;
        let children = this._box.get_children();
        for (let i = 0; i < this._dragPlaceholderPos; i++) {
            if (this._dragPlaceholder &&
                children[i] == this._dragPlaceholder.actor)
                continue;

            let childId = children[i]._delegate.child._delegate.app.get_id();
            if (childId == id)
                continue;
            if (childId in favorites)
                favPos++;
        }

        Meta.later_add(Meta.LaterType.BEFORE_REDRAW, Lang.bind(this,
            function () {
                let appFavorites = AppFavorites.getAppFavorites();
                if (srcIsFavorite)
                    appFavorites.moveFavoriteToPos(id, favPos);
                else
                    appFavorites.addFavoriteAtPos(id, favPos);
                return false;
            }));

        return true;
    }
};

Signals.addSignalMethods(Dash.prototype);