var Base64 = (function() {
    // Private property
    	var keyStr = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

    // Private method for UTF-8 encoding
	    function utf8Encode(string) {
	        string = string.replace(/\r\n/g,"\n");
	        var utftext = "";
	        for (var n = 0; n < string.length; n++) {
	            var c = string.charCodeAt(n);
	            if (c < 128) {
	                utftext += String.fromCharCode(c);
	            }
	            else if((c > 127) && (c < 2048)) {
	                utftext += String.fromCharCode((c >> 6) | 192);
	                utftext += String.fromCharCode((c & 63) | 128);
	            }
	            else {
	                utftext += String.fromCharCode((c >> 12) | 224);
	                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
	                utftext += String.fromCharCode((c & 63) | 128);
	            }
	        }
	        return utftext;
	    }

    // Public method for encoding
	    return {
	        encode : (typeof btoa == 'function') ? function(input) { return btoa(input); } : function (input) {
	            var output = "";
	            var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
	            var i = 0;
	            input = utf8Encode(input);
	            while (i < input.length) {
	                chr1 = input.charCodeAt(i++);
	                chr2 = input.charCodeAt(i++);
	                chr3 = input.charCodeAt(i++);
	                enc1 = chr1 >> 2;
	                enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
	                enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
	                enc4 = chr3 & 63;
	                if (isNaN(chr2)) {
	                    enc3 = enc4 = 64;
	                } else if (isNaN(chr3)) {
	                    enc4 = 64;
	                }
	                output = output +
	                keyStr.charAt(enc1) + keyStr.charAt(enc2) +
	                keyStr.charAt(enc3) + keyStr.charAt(enc4);
	            }
	            return output;
	        }
	    };
})();

Ext.override(Ext.grid.GridPanel, {
    getExcelXml: function(includeHidden) {
        var worksheet = this.createWorksheet(includeHidden);
        var totalWidth = this.getColumnModel().getTotalWidth(includeHidden);
        return '<xml version="1.0" encoding="utf-8">' +
            '<ss:Workbook xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:o="urn:schemas-microsoft-com:office:office">' +
            '<o:DocumentProperties><o:Title>' + this.title + '</o:Title></o:DocumentProperties>' +
            '<ss:ExcelWorkbook>' +
                '<ss:WindowHeight>' + worksheet.height + '</ss:WindowHeight>' +
                '<ss:WindowWidth>' + worksheet.width + '</ss:WindowWidth>' +
                '<ss:ProtectStructure>False</ss:ProtectStructure>' +
                '<ss:ProtectWindows>False</ss:ProtectWindows>' +
            '</ss:ExcelWorkbook>' +
            '<ss:Styles>' +
                '<ss:Style ss:ID="Default">' +
                    '<ss:Alignment ss:Vertical="Top" ss:WrapText="1" />' +
                    '<ss:Font ss:FontName="arial" ss:Size="10" />' +
                    '<ss:Borders>' +
                        '<ss:Border ss:Color="#e4e4e4" ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Top" />' +
                        '<ss:Border ss:Color="#e4e4e4" ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Bottom" />' +
                        '<ss:Border ss:Color="#e4e4e4" ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Left" />' +
                        '<ss:Border ss:Color="#e4e4e4" ss:Weight="1" ss:LineStyle="Continuous" ss:Position="Right" />' +
                    '</ss:Borders>' +
                    '<ss:Interior />' +
                    '<ss:NumberFormat />' +
                    '<ss:Protection />' +
                '</ss:Style>' +
                '<ss:Style ss:ID="title">' +
                    '<ss:Borders />' +
                    '<ss:Font />' +
                    '<ss:Alignment ss:WrapText="1" ss:Vertical="Center" ss:Horizontal="Center" />' +
                    '<ss:NumberFormat ss:Format="@" />' +
                '</ss:Style>' +
                '<ss:Style ss:ID="headercell">' +
                    '<ss:Font ss:Bold="1" ss:Size="10" />' +
                    '<ss:Alignment ss:WrapText="1" ss:Horizontal="Center" />' +
                    '<ss:Interior ss:Pattern="Solid" ss:Color="#A3C9F1" />' +
                '</ss:Style>' +
                '<ss:Style ss:ID="even">' +
                    '<ss:Interior ss:Pattern="Solid" ss:Color="#CCFFFF" />' +
                '</ss:Style>' +
                '<ss:Style ss:Parent="even" ss:ID="evendate">' +
                    '<ss:NumberFormat ss:Format="[ENG][$-409]dd\-mmm\-yyyy;@" />' +
                '</ss:Style>' +
                '<ss:Style ss:Parent="even" ss:ID="evenint">' +
                    '<ss:NumberFormat ss:Format="0" />' +
                '</ss:Style>' +
                '<ss:Style ss:Parent="even" ss:ID="evenfloat">' +
                    '<ss:NumberFormat ss:Format="0.00" />' +
                '</ss:Style>' +
                '<ss:Style ss:ID="odd">' +
                    '<ss:Interior ss:Pattern="Solid" ss:Color="#CCCCFF" />' +
                '</ss:Style>' +
                '<ss:Style ss:Parent="odd" ss:ID="odddate">' +
                    '<ss:NumberFormat ss:Format="[ENG][$-409]dd\-mmm\-yyyy;@" />' +
                '</ss:Style>' +
                '<ss:Style ss:Parent="odd" ss:ID="oddint">' +
                    '<ss:NumberFormat ss:Format="0" />' +
                '</ss:Style>' +
                '<ss:Style ss:Parent="odd" ss:ID="oddfloat">' +
                    '<ss:NumberFormat ss:Format="0.00" />' +
                '</ss:Style>' +
            '</ss:Styles>' +
            worksheet.xml +
            '</ss:Workbook>';
    },

    createWorksheet: function(includeHidden) {
	// Calculate cell data types and extra class names which affect formatting
        var cellType = [];
        var cellTypeClass = [];
        var cm = this.getColumnModel();
        var totalWidthInPixels = 0;
        var colXml = '';
        var headerXml = '';
        var visibleColumnCountReduction = 0;
        for (var i = 0; i < cm.getColumnCount(); i++) {
            if (includeHidden || !cm.isHidden(i)) {
                var w = cm.getColumnWidth(i)
                totalWidthInPixels += w;
                if (cm.getColumnHeader(i) === ""){
                	cellType.push("None");
                	cellTypeClass.push("");
                	++visibleColumnCountReduction;
                }
                else
                {
	                colXml += '<ss:Column ss:AutoFitWidth="1" ss:Width="' + w + '" />';
	                headerXml += '<ss:Cell ss:StyleID="headercell">' +
	                    '<ss:Data ss:Type="String">' + cm.getColumnHeader(i) + '</ss:Data>' +
	                    '<ss:NamedCell ss:Name="Print_Titles" /></ss:Cell>';
	                var fld = this.store.recordType.prototype.fields.get(cm.getDataIndex(i));
	                switch(fld.type) {
	                    case "int":
	                        cellType.push("Number");
	                        cellTypeClass.push("int");
	                        break;
	                    case "float":
	                        cellType.push("Number");
	                        cellTypeClass.push("float");
	                        break;
	                    case "bool":
	                    case "boolean":
	                        cellType.push("String");
	                        cellTypeClass.push("");
	                        break;
	                    case "date":
	                        cellType.push("DateTime");
	                        cellTypeClass.push("date");
	                        break;
	                    default:
	                        cellType.push("String");
	                        cellTypeClass.push("");
	                        break;
	                }
                }
            }
        }
        var visibleColumnCount = cellType.length - visibleColumnCountReduction;

        var result = {
            height: 9000,
            width: Math.floor(totalWidthInPixels * 30) + 50
        };

	// Generate worksheet header details.
        var t = '<ss:Worksheet ss:Name="' + this.title + '">' +
            '<ss:Names>' +
                '<ss:NamedRange ss:Name="Print_Titles" ss:RefersTo="=\'' + this.title + '\'!R1:R2" />' +
            '</ss:Names>' +
            '<ss:Table x:FullRows="1" x:FullColumns="1"' +
                ' ss:ExpandedColumnCount="' + visibleColumnCount +
                '" ss:ExpandedRowCount="' + (this.store.getCount() + 2) + '">' +
                colXml +
                '<ss:Row ss:Height="38">' +
                    '<ss:Cell ss:StyleID="title" ss:MergeAcross="' + (visibleColumnCount - 1) + '">' +
                      '<ss:Data xmlns:html="http://www.w3.org/TR/REC-html40" ss:Type="String">' +
                        '<html:B>Generated by Community Science Institute</html:B></ss:Data><ss:NamedCell ss:Name="Print_Titles" />' +
                    '</ss:Cell>' +
                '</ss:Row>' +
                '<ss:Row ss:AutoFitHeight="1">' +
                headerXml +
                '</ss:Row>';

	// Generate the data rows from the data in the Store
        for (var i = 0, it = this.store.data.items, l = it.length; i < l; i++) {
            t += '<ss:Row>';
            var cellClass = (i & 1) ? 'odd' : 'even';
            r = it[i].data;
            var k = 0;
            for (var j = 0; j < cm.getColumnCount(); j++) {
                if (includeHidden || !cm.isHidden(j)) {
                    var v = r[cm.getDataIndex(j)];
                    if (cellType[k] !== "None") {

	                    t += '<ss:Cell ss:StyleID="' + cellClass + cellTypeClass[k] + '"><ss:Data ss:Type="' + cellType[k] + '">';
	                        if (cellType[k] == 'DateTime') {
	                            t += v.format('Y-m-d');
	                        } else {
	                            t += v;
	                        }
	                    t +='</ss:Data></ss:Cell>';
                    }
                    k++;
                }
            }
            t += '</ss:Row>';
        }

        result.xml = t + '</ss:Table>' +
            '<x:WorksheetOptions>' +
                '<x:PageSetup>' +
                    '<x:Layout x:CenterHorizontal="1" x:Orientation="Landscape" />' +
                    '<x:Footer x:Data="Page &amp;P of &amp;N" x:Margin="0.5" />' +
                    '<x:PageMargins x:Top="0.5" x:Right="0.5" x:Left="0.5" x:Bottom="0.8" />' +
                '</x:PageSetup>' +
                '<x:FitToPage />' +
                '<x:Print>' +
                    '<x:PrintErrors>Blank</x:PrintErrors>' +
                    '<x:FitWidth>1</x:FitWidth>' +
                    '<x:FitHeight>32767</x:FitHeight>' +
                    '<x:ValidPrinterInfo />' +
                    '<x:VerticalResolution>600</x:VerticalResolution>' +
                '</x:Print>' +
                '<x:Selected />' +
                '<x:DoNotDisplayGridlines />' +
                '<x:ProtectObjects>False</x:ProtectObjects>' +
                '<x:ProtectScenarios>False</x:ProtectScenarios>' +
            '</x:WorksheetOptions>' +
        '</ss:Worksheet>';
        return result;
    }
});