(function($) {
    $.extend(true, window, {
        Slick: {
            Data: {
                DataView: DataView,
                Aggregators: {
                    Avg: AvgAggregator,
                    Min: MinAggregator,
                    Max: MaxAggregator
                }
            }
        }
    });


    /***
     * A sample Model implementation.
     * Provides a filtered view of the underlying data.
     *
     * Relies on the data item having an "id" property uniquely identifying it.
     */
    function DataView(options) {
        var self = this;

        var defaults = {
            groupItemMetadataProvider: null
        };


        // private
        var idProperty = "id";  // property holding a unique row id
        var items = [];         // data by index
        var rows = [];          // data by row
        var idxById = {};       // indexes by id
        var rowsById = null;    // rows by id; lazy-calculated
        var filter = null;      // filter function
        var updated = null;     // updated item ids
        var suspend = false;    // suspends the recalculation
        var sortAsc = true;
        var fastSortField;
        var sortComparer;
        var refreshHints = {};
        var prevRefreshHints = {};
        var filterArgs;
        var filteredItems = [];
        var compiledFilter;
        var compiledFilterWithCaching;
        var filterCache = [];

        // grouping
        var groupingGetter;
        var groupingGetterIsAFn;
        var groupingFormatter;
        var groupingComparer;
        var groups = [];
        var collapsedGroups = {};
        var aggregators;
        var aggregateCollapsed = false;
        var compiledAccumulators;

        var pagesize = 0;
        var pagenum = 0;
        var totalRows = 0;

        // events
        var onRowCountChanged = new Slick.Event();
        var onRowsChanged = new Slick.Event();
        var onPagingInfoChanged = new Slick.Event();

        options = $.extend(true, {}, defaults, options);


        function beginUpdate() {
            suspend = true;
        }

        function endUpdate() {
            suspend = false;
            refresh();
        }

        function setRefreshHints(hints){
            refreshHints = hints;
        }

        function setFilterArgs(args) {
            filterArgs = args;
        }

        function updateIdxById(startingIndex) {
            startingIndex = startingIndex || 0;
            var id;
            for (var i = startingIndex, l = items.length; i < l; i++) {
                id = items[i][idProperty];
                if (id === undefined) {
                    throw "Each data element must implement a unique 'id' property";
                }
                idxById[id] = i;
            }
        }

        function ensureIdUniqueness() {
            var id;
            for (var i = 0, l = items.length; i < l; i++) {
                id = items[i][idProperty];
                if (id === undefined || idxById[id] !== i) {
                    throw "Each data element must implement a unique 'id' property";
                }
            }
        }

        function getItems() {
            return items;
        }

        function setItems(data, objectIdProperty) {
            if (objectIdProperty !== undefined) idProperty = objectIdProperty;
            items = filteredItems = data;
            idxById = {};
            updateIdxById();
            ensureIdUniqueness();
            refresh();
        }

        function setPagingOptions(args) {
            if (args.pageSize != undefined)
                pagesize = args.pageSize;

            if (args.pageNum != undefined)
                pagenum = Math.min(args.pageNum, Math.ceil(totalRows / pagesize));

            onPagingInfoChanged.notify(getPagingInfo(), null, self);

            refresh();
        }

        function getPagingInfo() {
            return {pageSize:pagesize, pageNum:pagenum, totalRows:totalRows};
        }

        function sort(comparer, ascending) {
            sortAsc = ascending;
            sortComparer = comparer;
            fastSortField = null;
            if (ascending === false) items.reverse();
            items.sort(comparer);
            if (ascending === false) items.reverse();
            idxById = {};
            updateIdxById();
            refresh();
        }

        /***
        * Provides a workaround for the extremely slow sorting in IE.
        * Does a [lexicographic] sort on a give column by temporarily overriding Object.prototype.toString
        * to return the value of that field and then doing a native Array.sort().
        */
        function fastSort(field, ascending) {
            sortAsc = ascending;
            fastSortField = field;
            sortComparer = null;
            var oldToString = Object.prototype.toString;
            Object.prototype.toString = (typeof field == "function")?field:function() { return this[field] };
            // an extra reversal for descending sort keeps the sort stable
            // (assuming a stable native sort implementation, which isn't true in some cases)
            if (ascending === false) items.reverse();
            items.sort();
            Object.prototype.toString = oldToString;
            if (ascending === false) items.reverse();
            idxById = {};
            updateIdxById();
            refresh();
        }

        function reSort() {
            if (sortComparer) {
               sort(sortComparer, sortAsc);
            }
            else if (fastSortField) {
               fastSort(fastSortField, sortAsc);
            }
        }

        function setFilter(filterFn) {
            filter = filterFn;
            compiledFilter = compileFilter();
            compiledFilterWithCaching = compileFilterWithCaching();
            refresh();
        }

        function groupBy(valueGetter, valueFormatter, sortComparer) {
            if (!options.groupItemMetadataProvider) {
                options.groupItemMetadataProvider = new Slick.Data.GroupItemMetadataProvider();
            }

            groupingGetter = valueGetter;
            groupingGetterIsAFn = typeof groupingGetter === "function";
            groupingFormatter = valueFormatter;
            groupingComparer = sortComparer;
            collapsedGroups = {};
            groups = [];
            refresh();
        }

        function setAggregators(groupAggregators, includeCollapsed) {
            aggregators = groupAggregators;
            aggregateCollapsed = (includeCollapsed !== undefined)
                ? includeCollapsed : aggregateCollapsed;

            // pre-compile accumulator loops
            compiledAccumulators = [];
            var idx = aggregators.length;
            while (idx--) {
                compiledAccumulators[idx] = compileAccumulatorLoop(aggregators[idx]);
            }

            refresh();
        }

        function getItemByIdx(i) {
            return items[i];
        }

        function getIdxById(id) {
            return idxById[id];
        }

        function ensureRowsByIdCache() {
            if (!rowsById) {
                 rowsById = {};
                 for (var i = 0, l = rows.length; i < l; i++) {
                     rowsById[rows[i][idProperty]] = i;
                 }
             }
        }

        function getRowById(id) {
            ensureRowsByIdCache();
            return rowsById[id];
        }

        function getItemById(id) {
            return items[idxById[id]];
        }

        function updateItem(id, item) {
            if (idxById[id] === undefined || id !== item[idProperty])
                throw "Invalid or non-matching id";
            items[idxById[id]] = item;
            if (!updated) updated = {};
            updated[id] = true;
            refresh();
        }

        function insertItem(insertBefore, item) {
            items.splice(insertBefore, 0, item);
            updateIdxById(insertBefore);
            refresh();
        }

        function addItem(item) {
            items.push(item);
            updateIdxById(items.length - 1);
            refresh();
        }

        function deleteItem(id) {
            var idx = idxById[id];
            if (idx === undefined) {
                throw "Invalid id";
            }
            delete idxById[id];
            items.splice(idx, 1);
            updateIdxById(idx);
            refresh();
        }

        function getLength() {
            return rows.length;
        }

        function getItem(i) {
            return rows[i];
        }

        function getItemMetadata(i) {
            var item = rows[i];
            if (item === undefined) {
                return null;
            }

            // overrides for group rows
            if (item.__group) {
                return options.groupItemMetadataProvider.getGroupRowMetadata(item);
            }

            // overrides for totals rows
            if (item.__groupTotals) {
                return options.groupItemMetadataProvider.getTotalsRowMetadata(item);
            }

            return null;
        }

        function collapseGroup(groupingValue) {
            collapsedGroups[groupingValue] = true;
            refresh();
        }

        function expandGroup(groupingValue) {
            delete collapsedGroups[groupingValue];
            refresh();
        }

        function getGroups() {
            return groups;
        }

        function extractGroups(rows) {
            var group;
            var val;
            var groups = [];
            var groupsByVal = [];
            var r;

            for (var i = 0, l = rows.length; i < l; i++) {
                r = rows[i];
                val = (groupingGetterIsAFn) ? groupingGetter(r) : r[groupingGetter];
                val = val || 0;
                group = groupsByVal[val];
                if (!group) {
                    group = new Slick.Group();
                    group.count = 0;
                    group.value = val;
                    group.rows = [];
                    groups[groups.length] = group;
                    groupsByVal[val] = group;
                }

                group.rows[group.count++] = r;
            }

            return groups;
        }

        // TODO:  lazy totals calculation
        function calculateGroupTotals(group) {
            if (group.collapsed && !aggregateCollapsed) {
                return;
            }

            // TODO:  try moving iterating over groups into compiled accumulator
            var totals = new Slick.GroupTotals();
            var agg, idx = aggregators.length;
            while (idx--) {
                agg = aggregators[idx];
                agg.init();
                compiledAccumulators[idx].call(agg, group.rows);
                agg.storeResult(totals);
            }
            totals.group = group;
            group.totals = totals;
        }

        function calculateTotals(groups) {
            var idx = groups.length;
            while (idx--) {
                calculateGroupTotals(groups[idx]);
            }
        }

        function finalizeGroups(groups) {
            var idx = groups.length, g;
            while (idx--) {
                g = groups[idx];
                g.collapsed = (g.value in collapsedGroups);
                g.title = groupingFormatter ? groupingFormatter(g) : g.value;
            }
        }

        function flattenGroupedRows(groups) {
            var groupedRows = [], gl = 0, g;
            for (var i = 0, l = groups.length; i < l; i++) {
                g = groups[i];
                groupedRows[gl++] = g;

                if (!g.collapsed) {
                    for (var j = 0, jj = g.rows.length; j < jj; j++) {
                        groupedRows[gl++] = g.rows[j];
                    }
                }

                if (g.totals && (!g.collapsed || aggregateCollapsed)) {
                    groupedRows[gl++] = g.totals;
                }
            }
            return groupedRows;
        }

        function getFunctionInfo(fn) {
            var fnRegex = /^function[^(]*\(([^)]*)\)\s*{([\s\S]*)}$/;
            var matches = fn.toString().match(fnRegex);
            return {
                params: matches[1].split(","),
                body: matches[2]
            };
        }

        function compileAccumulatorLoop(aggregator) {
            var accumulatorInfo = getFunctionInfo(aggregator.accumulate);
            var fn = new Function(
                "_items",
                "for (var " + accumulatorInfo.params[0] + ", _i=0, _il=_items.length; _i<_il; _i++) {" +
                accumulatorInfo.params[0] + " = _items[_i]; " +
                accumulatorInfo.body +
                "}"
            );
            fn.displayName = fn.name = "compiledAccumulatorLoop";
            return fn;
        }
        
        function compileFilter() {
            var filterInfo = getFunctionInfo(filter);

            var filterBody = filterInfo.body
                .replace(/return false;/gi, "{ continue _coreloop; }")
                .replace(/return true;/gi, "{ _retval[_idx++] = $item$; continue _coreloop; }")
                .replace(/return ([^;]+?);/gi,
                    "{ if ($1) { _retval[_idx++] = $item$; }; continue _coreloop; }");

            // This preserves the function template code after JS compression,
            // so that replace() commands still work as expected.
            var tpl = [
                //"function(_items, _args) { ",
                    "var _retval = [], _idx = 0; ",
                    "var $item$, $args$ = _args; ",
                    "_coreloop: ",
                    "for (var _i = 0, _il = _items.length; _i < _il; _i++) { ",
                        "$item$ = _items[_i]; ",
                        "$filter$; ",
                    "} ",
                    "return _retval; "
                //"}"
            ].join("");
            tpl = tpl.replace(/\$filter\$/gi, filterBody);
            tpl = tpl.replace(/\$item\$/gi, filterInfo.params[0]);
            tpl = tpl.replace(/\$args\$/gi, filterInfo.params[1]);

            var fn = new Function("_items,_args", tpl);
            fn.displayName = fn.name = "compiledFilter";
            return fn;
        }

        function compileFilterWithCaching() {
            var filterInfo = getFunctionInfo(filter);
            
            var filterBody = filterInfo.body
                .replace(/return false;/gi, "{ continue _coreloop; }")
                .replace(/return true;/gi, "{ _cache[_i] = true;_retval[_idx++] = $item$; continue _coreloop; }")
                .replace(/return ([^;]+?);/gi,
                    "{ if ((_cache[_i] = $1)) { _retval[_idx++] = $item$; }; continue _coreloop; }");

            // This preserves the function template code after JS compression,
            // so that replace() commands still work as expected.
            var tpl = [
                //"function(_items, _args, _cache) { ",
                    "var _retval = [], _idx = 0; ",
                    "var $item$, $args$ = _args; ",
                    "_coreloop: ",
                    "for (var _i = 0, _il = _items.length; _i < _il; _i++) { ",
                        "$item$ = _items[_i]; ",
                        "if (_cache[_i]) { ",
                            "_retval[_idx++] = $item$; ",
                            "continue _coreloop; ",
                        "} ",
                        "$filter$; ",
                    "} ",
                    "return _retval; "
                //"}"
            ].join("");
            tpl = tpl.replace(/\$filter\$/gi, filterBody);
            tpl = tpl.replace(/\$item\$/gi, filterInfo.params[0]);
            tpl = tpl.replace(/\$args\$/gi, filterInfo.params[1]);

            var fn = new Function("_items,_args,_cache", tpl);
            fn.displayName = fn.name = "compiledFilterWithCaching";
            return fn;
        }

        function getFilteredAndPagedItems(items) {
            if (filter && !refreshHints.isFilterUnchanged) {
                if (refreshHints.isFilterNarrowing) {
                    filteredItems = compiledFilter(filteredItems, filterArgs);
                } else if (refreshHints.isFilterExpanding) {
                    filteredItems = compiledFilterWithCaching(items, filterArgs, filterCache);
                } else {
                    filteredItems = compiledFilter(items, filterArgs);
                }
            } else {
                // special case:  if not filtering and not paging, the resulting
                // rows collection needs to be a copy so that changes due to sort
                // can be caught
                filteredItems = pagesize ? items : items.concat();
            }

            // get the current page
            var paged;
            if (pagesize) {
                if (filteredItems.length < pagenum * pagesize) {
                    pagenum = Math.floor(filteredItems.length / pagesize);
                }
                paged = filteredItems.slice(pagesize * pagenum, pagesize * pagenum + pagesize);
            } else {
                paged = filteredItems;
            }

            return {totalRows:filteredItems.length, rows:paged};
        }

        function getRowDiffs(rows, newRows) {
            var item, r, eitherIsNonData, diff = [];
            var from = 0, to = newRows.length;

            if (refreshHints && refreshHints.ignoreDiffsBefore) {
                from = Math.max(0,
                    Math.min(newRows.length, refreshHints.ignoreDiffsBefore));
            }

            if (refreshHints && refreshHints.ignoreDiffsAfter) {
                to = Math.min(newRows.length,
                    Math.max(0, refreshHints.ignoreDiffsAfter));
            }

            for (var i = from, rl = rows.length; i < to; i++) {
                if (i >= rl) {
                    diff[diff.length] = i;
                }
                else {
                    item = newRows[i];
                    r = rows[i];

                    if ((groupingGetter && (eitherIsNonData = (item.__nonDataRow) || (r.__nonDataRow)) &&
                            item.__group !== r.__group ||
                            item.__updated ||
                            item.__group && !item.equals(r))
                        || (aggregators && eitherIsNonData &&
                            // no good way to compare totals since they are arbitrary DTOs
                            // deep object comparison is pretty expensive
                            // always considering them 'dirty' seems easier for the time being
                            (item.__groupTotals || r.__groupTotals))
                        || item[idProperty] != r[idProperty]
                        || (updated && updated[item[idProperty]])
                        ) {
                        diff[diff.length] = i;
                    }
                }
            }
            return diff;
        }

        function recalc(_items) {
            rowsById = null;

            if (refreshHints.isFilterNarrowing != prevRefreshHints.isFilterNarrowing ||
                refreshHints.isFilterExpanding != prevRefreshHints.isFilterExpanding) {
              filterCache = [];
            }

            var filteredItems = getFilteredAndPagedItems(_items);
            totalRows = filteredItems.totalRows;
            var newRows = filteredItems.rows;

            groups = [];
            if (groupingGetter != null) {
                groups = extractGroups(newRows);
                if (groups.length) {
                    finalizeGroups(groups);
                    if (aggregators) {
                        calculateTotals(groups);
                    }
                    groups.sort(groupingComparer);
                    newRows = flattenGroupedRows(groups);
                }
            }

            var diff = getRowDiffs(rows, newRows);

            rows = newRows;

            return diff;
        }

        function refresh() {
            if (suspend) return;

            var countBefore = rows.length;
            var totalRowsBefore = totalRows;

            var diff = recalc(items, filter); // pass as direct refs to avoid closure perf hit

            // if the current page is no longer valid, go to last page and recalc
            // we suffer a performance penalty here, but the main loop (recalc) remains highly optimized
            if (pagesize && totalRows < pagenum * pagesize) {
                pagenum = Math.floor(totalRows / pagesize);
                diff = recalc(items, filter);
            }

            updated = null;
            prevRefreshHints = refreshHints;
            refreshHints = {};

            if (totalRowsBefore != totalRows) onPagingInfoChanged.notify(getPagingInfo(), null, self);
            if (countBefore != rows.length) onRowCountChanged.notify({previous:countBefore, current:rows.length}, null, self);
            if (diff.length > 0) onRowsChanged.notify({rows:diff}, null, self);
        }


        return {
            // methods
            "beginUpdate":      beginUpdate,
            "endUpdate":        endUpdate,
            "setPagingOptions": setPagingOptions,
            "getPagingInfo":    getPagingInfo,
            "getItems":         getItems,
            "setItems":         setItems,
            "setFilter":        setFilter,
            "sort":             sort,
            "fastSort":         fastSort,
            "reSort":           reSort,
            "groupBy":          groupBy,
            "setAggregators":   setAggregators,
            "collapseGroup":    collapseGroup,
            "expandGroup":      expandGroup,
            "getGroups":        getGroups,
            "getIdxById":       getIdxById,
            "getRowById":       getRowById,
            "getItemById":      getItemById,
            "getItemByIdx":     getItemByIdx,
            "setRefreshHints":  setRefreshHints,
            "setFilterArgs":    setFilterArgs,
            "refresh":          refresh,
            "updateItem":       updateItem,
            "insertItem":       insertItem,
            "addItem":          addItem,
            "deleteItem":       deleteItem,

            // data provider methods
            "getLength":        getLength,
            "getItem":          getItem,
            "getItemMetadata":  getItemMetadata,

            // events
            "onRowCountChanged":    onRowCountChanged,
            "onRowsChanged":        onRowsChanged,
            "onPagingInfoChanged":  onPagingInfoChanged
        };
    }

    function AvgAggregator(field) {
        this.field_ = field;

        this.init = function() {
            this.count_ = 0;
            this.nonNullCount_ = 0;
            this.sum_ = 0;
        };

        this.accumulate = function(item) {
            var val = item[this.field_];
            this.count_++;
            if (val != null && val != NaN) {
                this.nonNullCount_++;
                this.sum_ += 1 * val;
            }
        };

        this.storeResult = function(groupTotals) {
            if (!groupTotals.avg) {
                groupTotals.avg = {};
            }
            if (this.nonNullCount_ != 0) {
                groupTotals.avg[this.field_] = this.sum_ / this.nonNullCount_;
            }
        };
    }

    function MinAggregator(field) {
        this.field_ = field;

        this.init = function() {
            this.min_ = null;
        };

        this.accumulate = function(item) {
            var val = item[this.field_];
            if (val != null && val != NaN) {
                if (this.min_ == null ||val < this.min_) {
                    this.min_ = val;
                }
            }
        };

        this.storeResult = function(groupTotals) {
            if (!groupTotals.min) {
                groupTotals.min = {};
            }
            groupTotals.min[this.field_] = this.min_;
        }
    }

    function MaxAggregator(field) {
        this.field_ = field;

        this.init = function() {
            this.max_ = null;
        };

        this.accumulate = function(item) {
            var val = item[this.field_];
            if (val != null && val != NaN) {
                if (this.max_ == null ||val > this.max_) {
                    this.max_ = val;
                }
            }
        };

        this.storeResult = function(groupTotals) {
            if (!groupTotals.max) {
                groupTotals.max = {};
            }
            groupTotals.max[this.field_] = this.max_;
        }
    }

    // TODO:  add more built-in aggregators
    // TODO:  merge common aggregators in one to prevent needles iterating

})(jQuery);