/**
 * @docauthor Tommy Maintz <tommy@sencha.com>
 *
 * A mixin which allows a data component to be sorted. This is used by e.g. {@link Ext.data.Store} and {@link Ext.data.TreeStore}.
 *
 * **NOTE**: This mixin is mainly for internal use and most users should not need to use it directly. It
 * is more likely you will want to use one of the component classes that import this mixin, such as
 * {@link Ext.data.Store} or {@link Ext.data.TreeStore}.
 */
Ext.define("Ext.util.Sortable", {
    /**
     * @property {Boolean} isSortable
     * `true` in this class to identify an object as an instantiated Sortable, or subclass thereof.
     */
    isSortable: true,

    /**
     * @cfg {String} defaultSortDirection
     * The default sort direction to use if one is not specified.
     */
    defaultSortDirection: "ASC",

    requires: [
        'Ext.util.Sorter'
    ],

    statics: {
        /**
         * Creates a single comparator function which encapsulates the passed Sorter array.
         * @param {Ext.util.Sorter[]} sorters The sorter set for which to create a comparator function
         * @return {Function} a function, which when passed two comparable objects returns the result
         * of the whole sorter comparator functions.
         */
        createComparator: function(sorters) {
            return sorters && sorters.length ? function(r1, r2) {
                var result = sorters[0].sort(r1, r2),
                    length = sorters.length,
                    i = 1;

                // if we have more than one sorter, OR any additional sorter functions together
                for (; i < length; i++) {
                    result = result || sorters[i].sort.call(this, r1, r2);
                }
                return result;
            }: function() {
                return 0;
            };
        }
    },

    /**
     * @cfg {String} sortRoot
     * The property in each item that contains the data to sort.
     */

    /**
     * @cfg {Ext.util.Sorter[]/Object[]} sorters
     * The initial set of {@link Ext.util.Sorter Sorters}
     */

    /**
     * Performs initialization of this mixin. Component classes using this mixin should call this method during their
     * own initialization.
     */
    initSortable: function() {
        var me = this,
            sorters = me.sorters;

        /**
         * @property {Ext.util.MixedCollection} sorters
         * The collection of {@link Ext.util.Sorter Sorters} currently applied to this Store
         */
        me.sorters = new Ext.util.AbstractMixedCollection(false, function(item) {
            return item.id || item.property;
        });

        if (sorters) {
            me.sorters.addAll(me.decodeSorters(sorters));
        }
    },

    /**
     * Sorts the data in the Store by one or more of its properties. Example usage:
     *
     *     //sort by a single field
     *     myStore.sort('myField', 'DESC');
     *
     *     //sorting by multiple fields
     *     myStore.sort([
     *         {
     *             property : 'age',
     *             direction: 'ASC'
     *         },
     *         {
     *             property : 'name',
     *             direction: 'DESC'
     *         }
     *     ]);
     *
     * Internally, Store converts the passed arguments into an array of {@link Ext.util.Sorter} instances, and delegates
     * the actual sorting to its internal {@link Ext.util.MixedCollection}.
     *
     * When passing a single string argument to sort, Store maintains a ASC/DESC toggler per field, so this code:
     *
     *     store.sort('myField');
     *     store.sort('myField');
     *
     * Is equivalent to this code, because Store handles the toggling automatically:
     *
     *     store.sort('myField', 'ASC');
     *     store.sort('myField', 'DESC');
     *
     * @param {String/Ext.util.Sorter[]} [sorters] Either a string name of one of the fields in this Store's configured
     * {@link Ext.data.Model Model}, or an array of sorter configurations.
     * @param {String} [direction="ASC"] The overall direction to sort the data by.
     * @return {Ext.util.Sorter[]}
     */
    sort: function(sorters, direction, where, doSort) {
        var me = this,
            sorter, sorterFn,
            newSorters;

        if (Ext.isArray(sorters)) {
            doSort = where;
            where = direction;
            newSorters = sorters;
        }
        else if (Ext.isObject(sorters)) {
            doSort = where;
            where = direction;
            newSorters = [sorters];
        }
        else if (Ext.isString(sorters)) {
            sorter = me.sorters.get(sorters);

            if (!sorter) {
                sorter = {
                    property : sorters,
                    direction: direction
                };
                newSorters = [sorter];
            }
            else if (direction === undefined) {
                sorter.toggle();
            }
            else {
                sorter.setDirection(direction);
            }
        }

        if (newSorters && newSorters.length) {
            newSorters = me.decodeSorters(newSorters);
            if (Ext.isString(where)) {
                if (where === 'prepend') {
                    sorters = me.sorters.clone().items;

                    me.sorters.clear();
                    me.sorters.addAll(newSorters);
                    me.sorters.addAll(sorters);
                }
                else {
                    me.sorters.addAll(newSorters);
                }
            }
            else {
                me.sorters.clear();
                me.sorters.addAll(newSorters);
            }
        }

        if (doSort !== false) {
            me.fireEvent('beforesort', me, newSorters);
            me.onBeforeSort(newSorters);
            
            sorters = me.sorters.items;
            if (sorters.length) {
                // Sort using a generated sorter function which combines all of the Sorters passed
                me.doSort(me.generateComparator());
            }
        }

        return sorters;
    },

    /**
     * Returns a comparator function which compares two items and returns -1, 0, or 1 depending
     * on the currently defined set of {@link #cfg-sorters}.
     *
     * If there are no {@link #cfg-sorters} defined, it returns a function which returns `0` meaning
     * that no sorting will occur.
     */
    generateComparator: function() {
        var sorters = this.sorters.getRange();
        return sorters.length ? this.createComparator(sorters) : this.emptyComparator;
    },

    emptyComparator: function(){
        return 0;
    },

    onBeforeSort: Ext.emptyFn,

    /**
     * @private
     * Normalizes an array of sorter objects, ensuring that they are all Ext.util.Sorter instances
     * @param {Object[]} sorters The sorters array
     * @return {Ext.util.Sorter[]} Array of Ext.util.Sorter objects
     */
    decodeSorters: function(sorters) {
        if (!Ext.isArray(sorters)) {
            if (sorters === undefined) {
                sorters = [];
            } else {
                sorters = [sorters];
            }
        }

        var length = sorters.length,
            Sorter = Ext.util.Sorter,
            fields = this.model ? this.model.prototype.fields : null,
            field,
            config, i;

        for (i = 0; i < length; i++) {
            config = sorters[i];

            if (!(config instanceof Sorter)) {
                if (Ext.isString(config)) {
                    config = {
                        property: config
                    };
                }

                Ext.applyIf(config, {
                    root     : this.sortRoot,
                    direction: "ASC"
                });

                //support for 3.x style sorters where a function can be defined as 'fn'
                if (config.fn) {
                    config.sorterFn = config.fn;
                }

                //support a function to be passed as a sorter definition
                if (typeof config == 'function') {
                    config = {
                        sorterFn: config
                    };
                }

                // ensure sortType gets pushed on if necessary
                if (fields && !config.transform) {
                    field = fields.get(config.property);
                    config.transform = field ? field.sortType : undefined;
                }
                sorters[i] = new Ext.util.Sorter(config);
            }
        }

        return sorters;
    },

    getSorters: function() {
        return this.sorters.items;
    },
    
    /**
     * Gets the first sorter from the sorters collection, excluding
     * any groupers that may be in place
     * @protected
     * @return {Ext.util.Sorter} The sorter, null if none exist
     */
    getFirstSorter: function(){
        var sorters = this.sorters.items,
            len = sorters.length,
            i = 0,
            sorter;
            
        for (; i < len; ++i) {
            sorter = sorters[i];
            if (!sorter.isGrouper) {
                return sorter;    
            }
        }
        return null;
    }
}, function() {
    // Reference the static implementation in prototype
    this.prototype.createComparator = this.createComparator;
});