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

const Clutter = imports.gi.Clutter;
const Gio = imports.gi.Gio;
const Gdk = imports.gi.Gdk;
const Gtk = imports.gi.Gtk;
const Lang = imports.lang;
const Mainloop = imports.mainloop;
const Meta = imports.gi.Meta;
const Pango = imports.gi.Pango;
const Signals = imports.signals;
const Shell = imports.gi.Shell;
const St = imports.gi.St;

const DND = imports.ui.dnd;
const Main = imports.ui.main;

const RedisplayFlags = { NONE: 0,
                         FULL: 1 << 1,
                         SUBSEARCH: 1 << 2,
                         IMMEDIATE: 1 << 3 };

// Used by subclasses
const ITEM_DISPLAY_ICON_SIZE = 48;
const PREVIEW_ICON_SIZE = 96;

/* This is a virtual class that represents a single display item containing
 * a name, a description, and an icon. It allows selecting an item and represents
 * it by highlighting it with a different background color than the default.
 */
function GenericDisplayItem() {
    this._init();
}

GenericDisplayItem.prototype = {
    _init: function() {
        this.actor = new St.BoxLayout({ style_class: 'generic-display-item',
                                         reactive: true });

        this.actor._delegate = this;
        this.actor.connect('button-release-event',
                           Lang.bind(this,
                                     function() {
                                         // Activates the item by launching it
                                         this.emit('activate');
                                         return true;  
                                     }));

        let draggable = DND.makeDraggable(this.actor);

        this._iconBin = new St.Bin();
        this.actor.add(this._iconBin);

        this._infoText = new St.BoxLayout({ style_class: 'generic-display-item-text',
                                             vertical: true });
        this.actor.add(this._infoText, { expand: true, y_fill: false });

        this._name = null;
        this._description = null;
        this._icon = null;

        this._initialLoadComplete = false;

        // An array of details description actors that we create over time for the item.
        // It is used for updating the description text inside the details actor when
        // the description text for the item is updated.
        this._detailsDescriptions = [];
    },

    //// Draggable object interface ////

    // Returns a cloned texture of the item's icon to represent the item as it 
    // is being dragged. 
    getDragActor: function(stageX, stageY) {
        return this._createIcon();
    },

    // Returns the item icon, a separate copy of which is used to
    // represent the item as it is being dragged. This is used to
    // determine a snap-back location for the drag icon if it does
    // not get accepted by any drop target.
    getDragActorSource: function() {
        return this._icon;
    },

    //// Public methods ////

    // Highlights the item by setting a different background color than the default 
    // if isSelected is true, removes the highlighting otherwise.
    markSelected: function(isSelected) {
        if (isSelected)
            this.actor.add_style_pseudo_class('selected');
        else
            this.actor.remove_style_pseudo_class('selected');
    },

    /*
     * Returns an actor containing item details. In the future details can have more information than what
     * the preview pop-up has and be item-type specific.
     */
    createDetailsActor: function() {

        let details = new St.BoxLayout({ style_class: 'generic-display-container',
                                         vertical: true });

        let mainDetails = new St.BoxLayout({ style_class: 'generic-display-container' });

        // Inner box with name and description
        let textDetails = new St.BoxLayout({ style_class: 'generic-display-details',
                                             vertical: true });
        let detailsName = new St.Label({ style_class: 'generic-display-details-name',
                                          text: this._name.text });
        textDetails.add(detailsName);

        let detailsDescription = new St.Label({ text: this._description.text });
        textDetails.add(detailsDescription);

        this._detailsDescriptions.push(detailsDescription);

        mainDetails.add(textDetails, { expand: true });

        let previewIcon = this._createPreviewIcon();
        let largePreviewIcon = this._createLargePreviewIcon();

        if (previewIcon != null && largePreviewIcon == null) {
            mainDetails.insert_actor(previewIcon, 0);
        }

        details.add(mainDetails);

        if (largePreviewIcon != null) {
            details.add(largePreviewIcon);
        }
   
        return details;
    },

    // Destroys the item.
    destroy: function() {
        this.actor.destroy();
    },

    //// Pure virtual public methods ////

    // Performes an action associated with launching this item, such as opening a file or an application.
    launch: function() {
        throw new Error('Not implemented');
    },

    //// Protected methods ////

    /*
     * Creates the graphical elements for the item based on the item information.
     *
     * nameText - name of the item
     * descriptionText - short description of the item
     */
    _setItemInfo: function(nameText, descriptionText) {
        if (this._name != null) {
            // this also removes this._name from the parent container,
            // so we don't need to call this.actor.remove_actor(this._name) directly
            this._name.destroy();
            this._name = null;
        } 
        if (this._description != null) {
            this._description.destroy();
            this._description = null;
        } 
        if (this._icon != null) {
            // though we get the icon from elsewhere, we assume its ownership here,
            // and therefore should be responsible for distroying it
            this._icon.destroy();
            this._icon = null;
        }

        this._icon = this._createIcon();
        this._iconBin.set_child(this._icon);

        this._name = new St.Label({ style_class: 'generic-display-item-name',
                                     text: nameText });
        this._infoText.add(this._name);

        this._description = new St.Label({ style_class: 'generic-display-item-description',
                                            text: descriptionText ? descriptionText : '' });
        this._infoText.add(this._description);
    },

    // Sets the description text for the item, including the description text
    // in the details actors that have been created for the item.
    _setDescriptionText: function(text) {
        this._description.text = text;
        for (let i = 0; i < this._detailsDescriptions.length; i++) {
            let detailsDescription = this._detailsDescriptions[i];
            if (detailsDescription != null) {
                detailsDescription.text = text;
            }
        }
    },

    //// Virtual protected methods ////

    // Creates and returns a large preview icon, but only if we have a detailed image.
    _createLargePreviewIcon : function() {
        return null;
    },

    //// Pure virtual protected methods ////

    // Returns an icon for the item.
    _createIcon: function() {
        throw new Error('Not implemented');
    },

    // Returns a preview icon for the item.
    _createPreviewIcon: function() {
        throw new Error('Not implemented');
    }

    //// Private methods ////
};

Signals.addSignalMethods(GenericDisplayItem.prototype);

const GenericDisplayFlags = {
    DISABLE_VSCROLLING: 1 << 0
};

/* This is a virtual class that represents a display containing a collection of items
 * that can be filtered with a search string.
 */
function GenericDisplay(flags) {
    this._init(flags);
}

GenericDisplay.prototype = {
    _init : function(flags) {
        let disableVScrolling = (flags & GenericDisplayFlags.DISABLE_VSCROLLING) != 0;
        this._search = '';
        this._expanded = false;

        if (disableVScrolling) {
            this.actor = this._list = new Shell.OverflowList({ spacing: 6,
                                                               item_height: 50 });
        } else {
            this.actor = new St.ScrollView({ x_fill: true,
                                             y_fill: false,
                                             vshadows: true });
            this._list = new St.BoxLayout({ style_class: 'generic-display-container',
                                             vertical: true });
            this.actor.add_actor(this._list);
            this.actor.set_policy(Gtk.PolicyType.NEVER, Gtk.PolicyType.AUTOMATIC);
        }

        this._pendingRedisplay = RedisplayFlags.NONE;
        this.actor.connect('notify::mapped', Lang.bind(this, this._onMappedNotify));

        // map<itemId, Object> where Object represents the item info
        this._allItems = {};
        // set<itemId>
        this._matchedItems = {};
        // sorted array of items matched by search
        this._matchedItemKeys = [];
        // map<itemId, GenericDisplayItem>
        this._displayedItems = {};
        this._openDetailIndex = -1;
        this._selectedIndex = -1;
    },

    //// Public methods ////

    // Sets the search string and displays the matching items.
    setSearch: function(text) {
        let lowertext = text.toLowerCase();
        if (lowertext == this._search) {
            return;
        }
        let flags = RedisplayFlags.IMMEDIATE;
        if (this._search != '') {
            // Because we combine search terms with OR, we have to be sure that no new term
            // was introduced before deciding that the new search results will be a subset of
            // the existing search results.
            if (lowertext.indexOf(this._search) == 0 &&
                lowertext.split(/\s+/).length == this._search.split(/\s+/).length) {
                flags |= RedisplayFlags.SUBSEARCH;
            }
        }
        this._search = lowertext;
        this._redisplay(flags);
    },

    // Launches the item that is currently selected, closing the Overview
    activateSelected: function() {
        if (this._selectedIndex != -1) {
            let selected = this._findDisplayedByIndex(this._selectedIndex);
            selected.launch();
            this.unsetSelected();
            Main.overview.hide();
        }
    },

    // Moves the selection one up. If the selection was already on the top item, it's moved
    // to the bottom one. Returns true if the selection actually moved up, false if it wrapped 
    // around to the bottom.
    selectUp: function() {
        let count = this._getVisibleCount();
        let selectedUp = true;
        let prev = this._selectedIndex - 1;
        if (this._selectedIndex <= 0) {
            prev = count - 1;
            selectedUp = false; 
        }
        this._selectIndex(prev);
        return selectedUp;
    },

    // Moves the selection one down. If the selection was already on the bottom item, it's moved
    // to the top one. Returns true if the selection actually moved down, false if it wrapped 
    // around to the top.
    selectDown: function() {
        let count = this._getVisibleCount();
        let selectedDown = true;
        let next = this._selectedIndex + 1;
        if (this._selectedIndex == count - 1) {
            next = 0;
            selectedDown = false;
        }
        this._selectIndex(next);
        return selectedDown;
    },

    // Selects the first item among the displayed items.
    selectFirstItem: function() {
        if (this.hasItems())
            this._selectIndex(0);
    },

    // Selects the last item among the displayed items.
    selectLastItem: function() {
        let count = this._getVisibleCount();
        if (this.hasItems())
            this._selectIndex(count - 1);
    },

    // Returns true if the display has some item selected.
    hasSelected: function() {
        return this._selectedIndex != -1;
    },

    // Removes selection if some display item is selected.
    unsetSelected: function() {
        this._selectIndex(-1);
    },

    // Returns true if the display has any displayed items.
    hasItems: function() {
        // TODO: figure out why this._list.displayedCount is returning a
        // positive number when this._mathedItems.length is 0
        // This can be triggered if a search string is entered for which there are no matches.
        // log('this._mathedItems.length: ' + this._matchedItems.length + ' this._list.displayedCount ' + this._list.displayedCount);
        return this._matchedItemKeys.length > 0;
    },

    getMatchedItemsCount: function() {
        return this._matchedItemKeys.length;
    },

    // Load the initial state
    load: function() {
        this._redisplay(RedisplayFlags.FULL);
    },

    // Should be called when the display is closed
    resetState: function() {
        this._filterReset();
        this._openDetailIndex = -1;
        if (!(this.actor instanceof Shell.OverflowList))
            this.actor.get_vscroll_bar().get_adjustment().value = 0;
    },

    // Returns an actor which acts as a sidebar; this is used for
    // the applications category view
    getNavigationArea: function () {
        return null;
    },

    createDetailsForIndex: function(index) {
        let item = this._findDisplayedByIndex(index);
        return item.createDetailsActor();
    },

    //// Protected methods ////

    _recreateDisplayItems: function() {
        this._removeAllDisplayItems();
        this._setDefaultList();
        for (let itemId in this._allItems) {
            this._addDisplayItem(itemId);
        }
    },

    // Creates a display item based on the information associated with itemId
    // and adds it to the list of displayed items, but does not yet display it.
    _addDisplayItem : function(itemId) {
        if (this._displayedItems.hasOwnProperty(itemId)) {
            log('Tried adding a display item for ' + itemId + ', but an item with this item id is already among displayed items.');
            return;
        }

        let itemInfo = this._allItems[itemId];
        let displayItem = this._createDisplayItem(itemInfo);

        displayItem.connect('activate',
                            Lang.bind(this,
                                      function() {
                                          // update the selection
                                          this._selectIndex(this._list.get_children().indexOf(displayItem.actor));
                                          this.activateSelected();
                                      }));

        displayItem.connect('show-details',
                            Lang.bind(this,
                                      function() {
                                          let index = this._list.get_children().indexOf(displayItem.actor);
                                          /* Close the details pane if already open */
                                          if (index == this._openDetailIndex) {
                                              this._openDetailIndex = -1;
                                              this.emit('show-details', -1);
                                          } else {
                                              this._openDetailIndex = index;
                                              this.emit('show-details', index);
                                          }
                                      }));
        this._displayedItems[itemId] = displayItem;
    },

    // Removes an item identifed by the itemId from the displayed items.
    _removeDisplayItem: function(itemId) {
        let children = this._list.get_children();
        let count = children.length;
        let displayItem = this._displayedItems[itemId];
        let displayItemIndex = children.indexOf(displayItem.actor);

        if (this.hasSelected() && count == 1) {
            this.unsetSelected();
        } else if (this.hasSelected() && displayItemIndex < this._selectedIndex) {
            this.selectUp();
        }

        displayItem.destroy();

        delete this._displayedItems[itemId];
    },

    // Removes all displayed items.
    _removeAllDisplayItems: function() {
        this.unsetSelected();
        for (itemId in this._displayedItems)
            this._removeDisplayItem(itemId);
     },

    // Return true if there's an active search or other constraint
    // on the list
    _filterActive: function() {
        return this._search != '';
    },

    // Called when we are resetting state
    _filterReset: function() {
        this.unsetSelected();
    },

    _compareSearchMatch: function(a, b) {
        let countA = this._matchedItems[a];
        let countB = this._matchedItems[b];
        if (countA > countB)
            return -1;
        else if (countA < countB)
            return 1;
        else
            return this._compareItems(a, b);
    },

    _setMatches: function(matches) {
        this._matchedItems = matches;
        this._matchedItemKeys = [];
        for (let itemId in this._matchedItems) {
            this._matchedItemKeys.push(itemId);
        }
        this._matchedItemKeys.sort(Lang.bind(this, this._compareSearchMatch));
    },

    /**
     * _redisplaySubSearch:
     * A somewhat more optimized function called when we know
     * that we're going to be displaying a subset of the items
     * we already had, in the same order.  In that case, we can
     * just hide the actors that shouldn't be shown.
     */
    _redisplaySubSearch: function() {
        let matches = this._getSearchMatchedItems(true);

        // Just hide all from the old set,
        // we'll show the ones we want below
        for (let itemId in this._displayedItems) {
            let item = this._displayedItems[itemId];
            item.actor.hide();
        }

        this._setMatches(matches);

        for (let itemId in matches) {
            let item = this._displayedItems[itemId];
            item.actor.show();
        }
        this._list.queue_relayout();
    },

    _redisplayReordering: function() {
        if (!this._filterActive()) {
            this._setDefaultList();
        } else {
            this._setMatches(this._getSearchMatchedItems(false));
        }
        this._list.remove_all();
        for (let i = 0; i < this._matchedItemKeys.length; i++) {
            let itemId = this._matchedItemKeys[i];
            let item = this._displayedItems[itemId];
            item.actor.show();
            this._list.add_actor(item.actor);
       }
    },

    /*
     * Updates the displayed items, applying the search string if one exists.
     * @flags: Flags controlling redisplay behavior as follows:
     *  SUBSEARCH - Indicates that the current _search is a superstring of the previous
     *  one, which implies we only need to re-search through previous results.
     *  FULL - Indicates that we need recreate all displayed items.
     *  IMMEDIATE - Do the full redisplay even if we're not mapped.  This is useful
     *  if you want to get the number of matched items and show/hide a section based on
     *  that number.
     */
    _redisplay: function(flags) {
        let immediate = (flags & RedisplayFlags.IMMEDIATE) != 0;
        if (!immediate && !this.actor.mapped) {
            this._pendingRedisplay |= flags;
            return;
        }

        let isSubSearch = (flags & RedisplayFlags.SUBSEARCH) != 0;
        let fullReload = (flags & RedisplayFlags.FULL) != 0;

        let hadSelected = this.hasSelected();
        this.unsetSelected();

        if (!this._initialLoadComplete)
            fullReload = true;

        if (!this._refreshCache())
            fullReload = true;

        if (fullReload) {
            this._recreateDisplayItems();
            this._initialLoadComplete = true;
        }

        if (isSubSearch) {
            this._redisplaySubSearch();
        } else {
            this._redisplayReordering();
        }

        if (hadSelected) {
            this._selectedIndex = -1;
            this.selectFirstItem();
        }

        this.emit('redisplayed');
    },

    //// Pure virtual protected methods ////

    // Performs the steps needed to have the latest information about the items.
    // Implementation should return %true if we are up to date, and %false
    // if a full reload occurred.
    _refreshCache: function() {
        throw new Error('Not implemented');
    },

    // Sets the list of the displayed items based on the default sorting order.
    // The default sorting order is specific to each implementing class.
    _setDefaultList: function() {
        throw new Error('Not implemented');
    },

    // Compares items associated with the item ids based on the order in which the
    // items should be displayed.
    // Intended to be used as a compareFunction for array.sort().
    // Returns an integer value indicating the result of the comparison.
    _compareItems: function(itemIdA, itemIdB) {
        throw new Error('Not implemented');
    },

    // Checks if the item info can be a match for the search string. 
    // Returns a boolean flag indicating if that's the case.
    _isInfoMatching: function(itemInfo, search) {
        throw new Error('Not implemented');
    },

    // Creates a display item based on itemInfo.
    _createDisplayItem: function(itemInfo) {
        throw new Error('Not implemented');
    },

    //// Private methods ////

    _getItemSearchScore: function(itemId, terms) {
        let item = this._allItems[itemId];
        let score = 0;
        for (let i = 0; i < terms.length; i++) {
            let term = terms[i];
            if (this._isInfoMatching(item, term)) {
                score++;
            }
        }
        return score;
    },

    _getSearchMatchedItems: function(isSubSearch) {
        // Break the search up into terms, and search for each
        // individual term.  Keep track of the number of terms
        // each item matched.
        let terms = this._search.split(/\s+/);
        let matchScores = {};

        if (isSubSearch) {
            for (let i = 0; i < this._matchedItemKeys.length; i++) {
                let itemId = this._matchedItemKeys[i];
                let score = this._getItemSearchScore(itemId, terms);
                if (score > 0)
                    matchScores[itemId] = score;
            }
        } else {
            for (let itemId in this._displayedItems) {
                let score = this._getItemSearchScore(itemId, terms);
                if (score > 0)
                    matchScores[itemId] = score;
            }
        }
        return matchScores;
    },

    // Returns a display item based on its index in the ordering of the
    // display children.
    _findDisplayedByIndex: function(index) {
        let actor;
        if (this.actor instanceof Shell.OverflowList)
            actor = this.actor.get_displayed_actor(index);
        else
            actor = this._list.get_children()[index];
        return this._findDisplayedByActor(actor);
    },

    // Returns a display item based on the actor that represents it in 
    // the display.
    _findDisplayedByActor: function(actor) {
        for (itemId in this._displayedItems) {
            let item = this._displayedItems[itemId];
            if (item.actor == actor) {
                return item;
            }
        }
        return null;
    },

    // Selects (e.g. highlights) a display item at the provided index,
    // updates this.selectedItemDetails actor, and emits 'selected' signal.
    _selectIndex: function(index) {
        // Cleanup from the previous item
        if (this.hasSelected()) {
            this._findDisplayedByIndex(this._selectedIndex).markSelected(false);
        }

        this._selectedIndex = index;
        if (index < 0)
            return;

        // Mark the new item as selected and create its details pane
        let item = this._findDisplayedByIndex(index);
        item.markSelected(true);
        this.emit('selected');
    },

    _getVisibleCount: function() {
        if (this.actor instanceof Shell.OverflowList)
            return this._list.displayed_count;
        return this._list.get_n_children();
    },

    _onMappedNotify: function () {
        let mapped = this.actor.mapped;
        if (mapped && this._pendingRedisplay > RedisplayFlags.NONE)
            this._redisplay(this._pendingRedisplay);

        this._pendingRedisplay = RedisplayFlags.NONE;
    }
};

Signals.addSignalMethods(GenericDisplay.prototype);