Yahoo! UI Library

(function () {

var Paginator = YAHOO.widget.Paginator,
    l         = YAHOO.lang;

/**
 * ui Component to generate the textual report of current pagination status.
 * E.g. "Now viewing page 1 of 13".
 *
 * @namespace YAHOO.widget.Paginator.ui
 * @class CurrentPageReport
 * @for YAHOO.widget.Paginator
 *
 * @constructor
 * @param p {Pagintor} Paginator instance to attach to
 */
Paginator.ui.CurrentPageReport = function (p) {
    this.paginator = p;

    p.createEvent('pageReportClassChange');
    p.createEvent('pageReportTemplateChange');

    p.subscribe('recordOffsetChange', this.update,this,true);
    p.subscribe('rowsPerPageChange', this.update,this,true);
    p.subscribe('totalRecordsChange',this.update,this,true);
    p.subscribe('pageReportTemplateChange', this.update,this,true);
    p.subscribe('destroy',this.destroy,this,true);

    //TODO: make this work
    p.subscribe('pageReportClassChange', this.update,this,true);
};

/**
 * Decorates Paginator instances with new attributes. Called during
 * Paginator instantiation.
 * @method init
 * @param p {Paginator} Paginator instance to decorate
 * @static
 */
Paginator.ui.CurrentPageReport.init = function (p) {

    /**
     * CSS class assigned to the span containing the info.
     * @attribute pageReportClass
     * @default 'yui-pg-current'
     */
    p.setAttributeConfig('pageReportClass', {
        value : 'yui-pg-current',
        validator : l.isString
    });

    /**
     * Used as innerHTML for the span.  Place holders in the form of {name}
     * will be replaced with the so named value from the key:value map
     * generated by the function held in the pageReportValueGenerator attribute.
     * @attribute pageReportTemplate
     * @default '({currentPage} of {totalPages})'
     * @see pageReportValueGenerator attribute
     */
    p.setAttributeConfig('pageReportTemplate', {
        value : '({currentPage} of {totalPages})',
        validator : l.isString
    });

    /**
     * Function to generate the value map used to populate the
     * pageReportTemplate.  The function is passed the Paginator instance as a
     * parameter.  The default function returns a map with the following keys:
     * <ul>
     * <li>currentPage</li>
     * <li>totalPages</li>
     * <li>startIndex</li>
     * <li>endIndex</li>
     * <li>startRecord</li>
     * <li>endRecord</li>
     * <li>totalRecords</li>
     * </ul>
     * @attribute pageReportValueGenarator
     */
    p.setAttributeConfig('pageReportValueGenerator', {
        value : function (paginator) {
            var curPage = paginator.getCurrentPage(),
                records = paginator.getPageRecords();

            return {
                'currentPage' : records ? curPage : 0,
                'totalPages'  : paginator.getTotalPages(),
                'startIndex'  : records ? records[0] : 0,
                'endIndex'    : records ? records[1] : 0,
                'startRecord' : records ? records[0] + 1 : 0,
                'endRecord'   : records ? records[1] + 1 : 0,
                'totalRecords': paginator.get('totalRecords')
            };
        },
        validator : l.isFunction
    });
};

/**
 * Replace place holders in a string with the named values found in an
 * object literal.
 * @static
 * @method sprintf
 * @param template {string} The content string containing place holders
 * @param values {object} The key:value pairs used to replace the place holders
 * @return {string}
 */
Paginator.ui.CurrentPageReport.sprintf = function (template, values) {
    return template.replace(/\{([\w\s\-]+)\}/g, function (x,key) {
            return (key in values) ? values[key] : '';
        });
};

Paginator.ui.CurrentPageReport.prototype = {

    /**
     * Span node containing the formatted info
     * @property span
     * @type HTMLElement
     * @private
     */
    span : null,


    /**
     * Generate the span containing info formatted per the pageReportTemplate
     * attribute.
     * @method render
     * @param id_base {string} used to create unique ids for generated nodes
     * @return {HTMLElement}
     */
    render : function (id_base) {
        this.span = document.createElement('span');
        this.span.id        = id_base + '-page-report';
        this.span.className = this.paginator.get('pageReportClass');
        this.update();
        
        return this.span;
    },
    
    /**
     * Regenerate the content of the span if appropriate. Calls
     * CurrentPageReport.sprintf with the value of the pageReportTemplate
     * attribute and the value map returned from pageReportValueGenerator
     * function.
     * @method update
     * @param e {CustomEvent} The calling change event
     */
    update : function (e) {
        if (e && e.prevValue === e.newValue) {
            return;
        }

        this.span.innerHTML = Paginator.ui.CurrentPageReport.sprintf(
            this.paginator.get('pageReportTemplate'),
            this.paginator.get('pageReportValueGenerator')(this.paginator));
    },

    /**
     * Removes the link/span node and clears event listeners
     * removal.
     * @method destroy
     * @private
     */
    destroy : function () {
        this.span.parentNode.removeChild(this.span);
        this.span = null;
    }

};

})();