// JQuery event-driven pagination plugin
// Written by Mark Perkins, mark@allmarkedup.com
// License: http://unlicense.org/ (i.e. do what you want with it!)

;(function($) {

var defaults = {
perPage : 5, // number of items per page
startPage : 1, // page to begin on - NOT zero indexed
atEnd : 'stop' // loop / stop
};

$.fn.evtpaginate = function( options )
{
return this.each(function(){

var opts = $.extend(true, {}, defaults, options); // set options
var wrap = opts.wrapper = $(this);

wrap.bind( 'show.evtpaginate', function( e, pageNum ){ show( opts, pageNum-1 ); });
wrap.bind( 'next.evtpaginate', function(){ next( opts ); });
wrap.bind( 'prev.evtpaginate', function(){ prev( opts ); });
wrap.bind( 'first.evtpaginate', function(){ show( opts, 0 ); });
wrap.bind( 'last.evtpaginate', function(){ show( opts, opts.totalPages-1 ); });
wrap.bind( 'refresh.evtpaginate', function( e, newopts ){ refresh( opts, newopts ); });

setUp( opts );
});
};

function setUp( opts )
{
opts.perPage = parseInt(opts.perPage);
opts.items = opts.wrapper.children();
opts.totalItems = opts.items.size();
opts.totalPages = Math.ceil( opts.totalItems / opts.perPage );
opts.currentPage = parseInt(opts.startPage) - 1;
opts.first = isFirstPage( opts, opts.currentPage );
opts.last = isLastPage( opts, opts.currentPage );
opts.pages = [];

if ( opts.currentPage > opts.totalPages-1 ) opts.currentPage = opts.totalPages-1;

opts.items.hide();

for ( var i = 0; i < opts.totalPages; i++ )
{
var startItem = i*opts.perPage;
opts.pages[i] = opts.items.slice( startItem, (startItem + opts.perPage) );
}

show( opts, opts.currentPage );

opts.wrapper.trigger( 'initialized.evtpaginate', [opts.currentPage+1, opts.totalPages] );
}

function refresh( opts, newopts )
{
if ( newopts !== undefined ) $.extend(true, opts, newopts); // update options
opts.startPage = parseInt(opts.currentPage)+1;
setUp( opts );
}

function next( opts )
{
switch( opts.atEnd )
{
case 'loop': show( opts, (opts.last ? 0 : opts.currentPage + 1) ); break;
default: show( opts, (opts.last ? opts.totalPages - 1 : opts.currentPage + 1) ); break; // stop when getting to last page
}
}

function prev( opts )
{
switch( opts.atEnd )
{
case 'loop': show( opts, (opts.first ? opts.totalPages - 1 : opts.currentPage - 1) ); break;
default: show( opts, (opts.first ? 0 : opts.currentPage - 1) ); break; // stop when getting to first page
}
}

function show( opts, pageNum )
{
if ( pageNum > opts.totalPages-1 ) pageNum = opts.totalPages-1;

if ( ! opts.pages[opts.currentPage].is(':animated') )
{
opts.wrapper.trigger( 'started.evtpaginate', opts.currentPage+1 );

$.fn.evtpaginate.swapPages( opts, pageNum, function(){

opts.currentPage = pageNum;
opts.first = isFirstPage( opts, opts.currentPage ) ? true : false;
opts.last = isLastPage( opts, opts.currentPage ) ? true : false;

opts.wrapper.trigger( 'finished.evtpaginate', [opts.currentPage+1, opts.first, opts.last] );

});
}
}

// public, can override this if neccessary
$.fn.evtpaginate.swapPages = function( opts, pageNum, onFinish )
{
opts.pages[opts.currentPage].hide();
opts.pages[pageNum].show();
onFinish();
};

// utility functions
function isFirstPage( opts, internalPageNum ) { return ( internalPageNum === 0 ); }
function isLastPage( opts, internalPageNum ) { return ( internalPageNum === opts.totalPages-1 ); }

})(jQuery);