/**
 * Private record store class which takes the place of the view's data store to provide a grouped
 * view of the data when the Grouping feature is used.
 * 
 * Relays granular mutation events from the underlying store as refresh events to the view.
 * 
 * On mutation events from the underlying store, updates the summary rows by firing update events on the corresponding
 * summary records.
 * @private
 */
Ext.define('Ext.grid.feature.GroupStore', {
    extend: 'Ext.util.Observable',

    isStore: true,

    constructor: function(groupingFeature, store) {
        var me = this;

        me.superclass.constructor.apply(me, arguments);
        me.groupingFeature = groupingFeature;
        me.bindStore(store);
        me.processStore(store);
        me.view.dataSource = me;
    },

    bindStore: function(store) {
        var me = this;

        if (me.store) {
            Ext.destroy(me.storeListeners);
            me.store = null;
        }
        if (store) {
            me.storeListeners = store.on({
                bulkremove: me.onBulkRemove,
                add: me.onAdd,
                update: me.onUpdate,
                refresh: me.onRefresh,
                clear: me.onClear,
                scope: me,
                destroyable: true
            });
            me.store = store;
        }
    },

    processStore: function(store) {
        var me = this,
            groups = store.getGroups(),
            groupCount = groups.length,
            i,
            group,
            groupPlaceholder,
            data = me.data,
            oldGroupCache = me.groupingFeature.groupCache,
            groupCache = me.groupingFeature.clearGroupCache(),
            collapseAll = me.groupingFeature.startCollapsed;

        if (data) {
            data.clear();
        } else {
            data = me.data = new Ext.util.MixedCollection(false, Ext.data.Store.recordIdFn);
        }

        if (store.getCount()) {

            // Upon first process of a loaded store, clear the "always" collapse" flag
            me.groupingFeature.startCollapsed = false;

            for (i = 0; i < groupCount; i++) {

                // group contains eg
                // { children: [childRec0, childRec1...], name: <group field value for group> }
                group = groups[i];

                // Cache group information by group name
                groupCache[group.name] = group;
                group.isCollapsed = collapseAll || (oldGroupCache[group.name] && oldGroupCache[group.name].isCollapsed);

                // If group is collapsed, then represent it by one dummy row which is never visible, but which acts
                // as a start and end group trigger.
                if (group.isCollapsed) {
                    group.placeholder = groupPlaceholder = new store.model(null, 'group-' + group.name + '-placeholder');
                    groupPlaceholder.set(me.getGroupField(), group.name);
                    groupPlaceholder.rows = groupPlaceholder.children = group.children;
                    groupPlaceholder.isCollapsedPlaceholder = true;
                    data.add(groupPlaceholder);
                }

                // Expanded group - add the group's child records.
                else {
                    data.insert(me.data.length, group.children);
                }
            }
        }
    },

    isCollapsed: function(name) {
        return this.groupingFeature.groupCache[name].isCollapsed; 
    },

    isInCollapsedGroup: function(record) {
        var groupData;

        if (this.store.isGrouped() && (groupData = this.groupingFeature.groupCache[record.get(this.getGroupField())])) {
            return groupData.isCollapsed || false;
        }
        return false;
    },

    getCount: function() {
        return this.data.getCount();
    },

    getTotalCount: function() {
        return this.data.getCount();
    },

    // This class is only created for fully loaded, non-buffered stores
    rangeCached: function(start, end) {
        return end < this.getCount();
    },

    getRange: function(start, end, options) {
        var result = this.data.getRange(start, end);

        if (options && options.callback) {
            options.callback.call(options.scope || this, result, start, end, options);
        }
        return result;
    },

    getAt: function(index) {
        return this.getRange(index, index)[0];
    },

    getById: function(id) {
        return this.store.getById(id);
    },

    expandGroup: function(group) {
        var me = this,
            startIdx;

        if (typeof group === 'string') {
            group = me.groupingFeature.groupCache[group];
        }

        if (group && group.children.length && (startIdx = me.indexOf(group.children[0], true, true)) !== -1) {

            // Any event handlers must see the new state
            group.isCollapsed = false;
            me.isExpandingOrCollapsing = 1;
            
            // Remove the collapsed group placeholder record
            me.data.removeAt(startIdx);
            me.fireEvent('bulkremove', me, [me.getGroupPlaceholder(group)], [startIdx]);

            // Insert the child records in its place
            me.data.insert(startIdx, group.children);
            me.fireEvent('add', me, group.children, startIdx);

            me.fireEvent('groupexpand', me, group);
            me.isExpandingOrCollapsing = 0;
        }
    },

    collapseGroup: function(group) {
        var me = this,
            startIdx,
            placeholder,
            i, j, len,
            removeIndices;

        if (typeof group === 'string') {
            group = me.groupingFeature.groupCache[group];
        }

        if (group && (len = group.children.length) && (startIdx = me.indexOf(group.children[0], true)) !== -1) {

            // Any event handlers must see the new state
            group.isCollapsed = true;
            me.isExpandingOrCollapsing = 2;

            // Remove the group child records
            me.data.removeRange(startIdx, len);

            // Indices argument is mandatory and used by views - we MUST build it.
            removeIndices = new Array(len);
            for (i = 0, j = startIdx; i < len; i++, j++) {
                removeIndices[i] = j;
            }
            me.fireEvent('bulkremove', me, group.children, removeIndices);

            // Insert a placeholder record in their place
            me.data.insert(startIdx, placeholder = me.getGroupPlaceholder(group));
            me.fireEvent('add', me, [placeholder], startIdx);

            me.fireEvent('groupcollapse', me, group);
            me.isExpandingOrCollapsing = 0;
        }
    },

    getGroupPlaceholder: function(group) {
        if (!group.placeholder) {
            var groupPlaceholder = group.placeholder = new this.store.model(null, 'group-' + group.name + '-placeholder');
            groupPlaceholder.set(this.getGroupField(), group.name);
            groupPlaceholder.rows = groupPlaceholder.children = group.children;
            groupPlaceholder.isCollapsedPlaceholder = true;
        }
        return group.placeholder;
    },

    // Find index of record in group store.
    // If it's in a collapsed group, then it's -1, not present
    // Otherwise, loop through groups keeping tally of intervening records.
    indexOf: function(record, viewOnly, includeCollapsed) {
        var me = this,
            groups,
            groupCount,
            i,
            group,
            groupIndex,
            result = 0;

        if (record && (includeCollapsed || !me.isInCollapsedGroup(record))) {
            groups = me.store.getGroups();
            groupCount = groups.length;
            for (i = 0; i < groupCount; i++) {

                // group contains eg
                // { children: [childRec0, childRec1...], name: <group field value for group> }
                group = groups[i];
                if (group.name === this.store.getGroupString(record)) {
                    groupIndex = Ext.Array.indexOf(group.children, record);
                    return result + groupIndex;
                }

                result += (viewOnly && me.isCollapsed(group.name)) ? 1 : group.children.length;
            }
        }
        return -1;
    },

    /**
     * Get the index within the entire dataset. From 0 to the totalCount.
     *
     * Like #indexOf, this method is effected by filtering.
     *
     * @param {Ext.data.Model} record The Ext.data.Model object to find.
     * @return {Number} The index of the passed Record. Returns -1 if not found.
     */
    indexOfTotal: function(record) {
        var index = record.index;
        if (index || index === 0) {
            return index;
        }
        return this.istore.ndexOf(record);
    },

    onRefresh: function(store) {
        this.processStore(this.store);
        this.fireEvent('refresh', this);
    },

    onBulkRemove: function(store, records, indices) {
        this.processStore(this.store);
        this.fireEvent('refresh', this);
    },

    onClear: function(store, records, startIndex) {
        this.processStore(this.store);
        this.fireEvent('clear', this);
    },

    onAdd: function(store, records, startIndex) {
        this.processStore(this.store);
        this.fireEvent('refresh', this);
    },

    onUpdate: function(store, record, operation, modifiedFieldNames) {
        var me = this,
            groupInfo = me.groupingFeature.getRecordGroup(record),
            firstRec, lastRec;

        // The grouping field value has been modified.
        // This could either move a record from one group to another, or introduce a new group.
        // Either way, we have to refresh the grid
        if (store.isGrouped()) {
            if (modifiedFieldNames && Ext.Array.contains(modifiedFieldNames, me.groupingFeature.getGroupField())) {
                return me.onRefresh(me.store);
            }

            // Fire an update event on the collapsed group placeholder record
            if (groupInfo.isCollapsed) {
                me.fireEvent('update', me, groupInfo.placeholder);
            }

            // Not in a collapsed group, fire update event on the modified record
            // and, if in a grouped store, on the first and last records in the group.
            else {
                Ext.suspendLayouts();

                // Propagate the record's update event
                me.fireEvent('update', me, record, operation, modifiedFieldNames);

                // Fire update event on first and last record in group (only once if a single row group)
                // So that custom header TPL is applied, and the summary row is updated
                firstRec = groupInfo.children[0];
                lastRec = groupInfo.children[groupInfo.children.length - 1];

                // Do not pass modifiedFieldNames so that the TableView's shouldUpdateCell call always returns true.
                if (firstRec !== record) {
                    me.fireEvent('update', me, firstRec, 'edit');
                }
                if (lastRec !== record && lastRec !== firstRec) {
                    me.fireEvent('update', me, lastRec, 'edit');
                }
                Ext.resumeLayouts(true);
            }
        } else {
            // Propagate the record's update event
            me.fireEvent('update', me, record, operation, modifiedFieldNames);
        }
    }
});