/**
 * @copyright Greg Priday - <https://siteorigin.com/>
 * @license GPL 3.0 http://www.gnu.org/licenses/gpl.html
 */

( function( $ ){

	$.fn.siteOriginParallax = function( options ){

		var $$ = $(this);

		if( options === 'refreshParallax' ) {
			return $$.trigger( 'refreshParallax' );
		}

		options = $.extend( {
			// We need to know the background image URL to use
			backgroundUrl: null,
			// And the exact size of that image
			backgroundSize: null,
			// We can work out the aspect ratio from the size
			backgroundAspectRatio: null,
			// How we want to handle sizing of the background image
			backgroundSizing: 'scaled',
			// Should we limit the amount of motion in the background image
			// The number of pixels the background image can move for every pixel of scrolling
			limitMotion: 'auto',
		}, options );

		if( options.backgroundAspectRatio === null ) {
			options.backgroundAspectRatio = options.backgroundSize[0] / options.backgroundSize[1];
		}

		var setupParallax = function( ){
			try {
				var wrapperSize = [
					$$.outerWidth(),
					$$.outerHeight()
				];

				var bounding = $$[0].getBoundingClientRect();
				var windowHeight =  $( window ).outerHeight();

				if( $$.data('siteorigin-parallax-init') === undefined ) {
					// Do the initial setup
					$$.css( {
						'background-image' : 'url(' + options.backgroundUrl + ')'
					} );
				}

				var limitMotion;
				if( options.limitMotion === 'auto' ) {
					if( windowHeight < 720 ) {
						limitMotion = 0.55;
					} else if( windowHeight > 1300 ) {
						limitMotion = 0.45;
					} else {
						limitMotion = (-0.00017 * ( windowHeight - 720 ) ) + 0.55;
					}
				} else {
					limitMotion = parseFloat( options.limitMotion );
				}

				// What percent is this through a screen cycle
				// -1 is when the bottom of the wrapper is at the top of the screen
				// 1 is when the top of the wrapper is at the bottom of the screen
				var position = ( bounding.bottom + ( bounding.top - windowHeight ) ) / ( windowHeight + bounding.height );
				var percent = ( position - 1 ) / - 2;
				var topPosition = 0;
				var limitScale = 1;
				var backgroundSize = options.backgroundSize;

				// Do the setup for every time something changes
				if( options.backgroundSizing === 'scaled' ) {
					// This is the required Y height to create a parallax effect
					var finalY = wrapperSize[1] / ( limitMotion ? limitMotion : 1 );
					var scaleBG = wrapperSize[0] / backgroundSize[0]; // The initial scaling is based on container width

					if( finalY > backgroundSize[1] * scaleBG ) {
						// This image wouldn't be tall enough to give a decent parallax effect, so we'll scale it up
						scaleBG = finalY / backgroundSize[1];
						limitMotion = false;
					}

					$$.css(
						'background-size',
						( backgroundSize[0] * scaleBG ) + 'px ' +
						( backgroundSize[1] * scaleBG ) + 'px'
					);

					// Work out the top position
					if( bounding.top > - wrapperSize[1] && bounding.bottom - windowHeight < wrapperSize[1] ) {
						// This is the scaled background height
						var backgroundHeight = backgroundSize[1] * scaleBG;

						// Check if we need to limit the amount of motion in the background image
						if( limitMotion && backgroundHeight > windowHeight * limitMotion ) {
							// Work out how much to scale percent position based on how much motion we want.
							limitScale = ( windowHeight * limitMotion ) / ( backgroundHeight );
							// Percent is scaled so that the midpoint is still 0.5
							percent = ( percent * limitScale ) + ( ( 1 - limitScale ) / 2 );
						}
						// console.log( percent );

						topPosition = - ( backgroundHeight - wrapperSize[1] ) * percent;
					}

					$$.css( 'background-position', '50% ' + topPosition + 'px' );

				} else if( options.backgroundSizing === 'original' ) {
					// See scaled version or explanation of this code.
					if( limitMotion && backgroundSize[1] > windowHeight * limitMotion ) {
						limitScale = ( windowHeight * limitMotion ) / ( backgroundSize[1] );
						percent = (percent * limitScale) + ( ( 1 - limitScale ) / 2 );
					}

					// In this case, the background height is always the background size
					topPosition = - ( backgroundSize[1] - wrapperSize[1] ) * percent;

					// This is a version with no scaling
					$$.css( 'background-size', 'auto' );
					$$.css( 'background-position', '50% ' + topPosition + 'px' );
				}
			}
			catch( err ) {
				console.log( err.message );
				$$.css( {
					'background-size': options.backgroundSizing === 'scaled' ? 'cover' : 'auto',
					'background-position': '50% 50%'
				} );
			}
		};
		setupParallax();

		// All the events where we'll need to change the parallax
		$( window ).on( 'scroll', setupParallax );
		$( window ).on( 'resize', setupParallax );
		$( window ).on( 'panelsStretchRows', setupParallax );
		$$.on( 'refreshParallax', setupParallax );
		// Ensure that the parallax has run on inital load.
		setTimeout( function () {
			setupParallax();
		}, 100 );
	};

}( jQuery ) );


jQuery( function( $ ){
	$('[data-siteorigin-parallax]' ).each( function(){
		$( this ).siteOriginParallax( $( this ).data('siteorigin-parallax') );
	} );
} );
