// ==UserScript==
// @name           reddddit
// @version        0.2
// @namespace      http://bender.fesb.hr/~robert/
// @description    Auto append things for reddit page
// @include        http://www.reddit.com/*
// ==/UserScript==

var PAGE_URL = "http://gist.github.com/591568",
	RAW_URL = "http://gist.github.com/raw/591568/"
	SCRIPT_URL = RAW_URL + "reddddit.user.js",
	UPDATE_DATE_URL = RAW_URL + "update_date",

	THING_PARENT = '.sitetable',
	THING = THING_PARENT + ' .thing',
	NEXTPREV = '.nextprev',
	NEXT = NEXTPREV + ' a[rel~="next"]';

//GM_setValue('exclude_promoted', true);
if ( GM_getValue('exclude_promoted') ) {
	THING += ':not(.promoted)';
}

// async auto-update
setTimeout(function(){
	var d = new Date(),
		today = d.getUTCFullYear()+'-'+d.getUTCMonth()+'-'+d.getUTCDate(),
		check_day = GM_getValue('last_version_check_day', '');

	function onload( req ) {
		GM_setValue('last_version_check_day', today);

		var text = req.responseText;
		if ( !/^[\d\s\-]+$/.test(text) ) {
			return;
		}

		var update_day = text.replace(/\s*/g, '');

		if ( check_day < update_day && window.confirm('New version of Reddddit script is available! Do you wont to install it now?') ) {
			window.location.href = SCRIPT_URL;
		}
	}

	if ( !check_day ) {
		// Don't bother on first day.
		GM_setValue('last_version_check_day', today);

	} else if ( check_day < today ) {
		GM_xmlhttpRequest({
			method: 'GET',
			url: UPDATE_DATE_URL,
			onload: onload
		});
	}
}, 100);


function all( a, b ) {
	return all._slice.call( b ? a.querySelectorAll( b ) : document.querySelectorAll( a ), 0 );
}

all._slice = [].slice;

function first( a, b ) {
	return b ? a.querySelector( b ) : document.querySelector( a );
}

function last( a, b ) {
	a = all( a, b );
	return a.length ? a[ a.length - 1 ] : null;
}

function move( a ) {
	var x = null;

	if ( a ) {
		if ( a.nodeType ) {
			a.parentNode && a.parentNode.removeChild( a );
			x = a;

		} else if ( a[0] ) {
			x = ( a[0].ownerDocument || a[0] ).createDocumentFragment();

			for ( var i = 0; a[i]; ++i ) {
				x.appendChild( a[i] );
			}
		}
	}

	move.x = x;
	return move;
}

move.to = function( parent, next ) {
	return this.x && parent.insertBefore( this.x, next || null );
}


move.inPlaceOf = function( node ) {
	return this.x ?
		node && node.parentNode.replaceChild( this.x, node ) :
		node && node.parentNode.removeChild( node ) && null;
}


if ( window === window.top && first(NEXTPREV) ) (function( history ){

var enabled = GM_getValue('enabled', true),
	working,
	delta = 600,
	start_time,
	next_url;


var rbar = first('#header-bottom-right');
if ( rbar ) (function(){

	function toggle( event ) {
		enabled = !enabled;
		GM_setValue( 'enabled', enabled );

		this.textContent = ( enabled ? 'Disable' : 'Enable' ) + ' Auto Append';

		event && event.preventDefault();
	}

	var span = document.createElement('span');
	span.innerHTML = '<a href="#"></a> (<a href="#">*</a>)';

	var a = all( span, 'a' );

	a[0].addEventListener('click', toggle, false);
	enabled = !enabled;
	toggle.call( a[0] );

	a[1].href = PAGE_URL;

	var sep = first( rbar, '.separator' );
	sep && rbar.appendChild( sep.cloneNode(true) );

	rbar.appendChild( span );

})();


function onreadystatechange( req ) {
	if ( req.readyState == 4 ) {
		working = false;

		if ( req.status == 200 ) {
			appendThingsFromHtml( req.responseText );
			delta = Math.round( ( +new Date() - start_time ) * 0.4 ) + 250;
			delta = Math.min( Math.max( 400, delta ), 4000 );

			history && history.replaceState( {}, "", next_url );

		} else {
			last( NEXT + ' i' ).textContent = '(Loading Failed: ' + req.status + ' - ' + req.statusText + ')';
		}
	}
}

function appendThingsFromHtml( html ) {
	var div = document.createElement('div');
	div.innerHTML = html;
	move( all(div, 'script') );

	move( all(div, THING) ).to( last(THING_PARENT) );

	var new_next = first( div, NEXT );
	var old_next = first( NEXT );

	if ( !new_next ) {
		var last_id = last( THING ).className.match(/\bid-(\S+)/i)[1];
		new_next = old_next.cloneNode(true);
		new_next.href = old_next.href.replace( /(\bafter=)[^\&]*/i, last_id );
	}

	move( new_next ).inPlaceOf( old_next );
}

document.addEventListener('scroll', function() {

	if ( working || !enabled ) {
		return;
	}

	if ( document.documentElement.scrollTop + window.innerHeight > document.body.offsetHeight - delta ) {

		var next = first( NEXT );
		if ( !next ) return;

		working = true;
		start_time = +new Date();

		next.innerHTML += ' <i>(Loading...)</i>';

		next_url = next.href.toString()

		GM_xmlhttpRequest({
			method: 'GET',
			url: next_url,
			onreadystatechange: onreadystatechange
		});
	}

}, false);

})( window.history );