'use strict';

module.exports = function() {
	var _this = this;

	if (!this.imagePosition) {
		this.imagePosition = { x: 0, y: 0, width: 0, height: 0 };
	}

	if (this.image.blendingMode) {
		this.context.globalCompositeOperation = this.image.blendingMode;
	}

	if (this.imageNode) {
		setImagePosition();
		return;
	}

	this.imageNode = new Image();
	this.imageNode.onerror = function() {
		throw new Error('Granim: The image source is invalid.');
	};
	this.imageNode.onload = function() {
		_this.imgOriginalWidth = _this.imageNode.width;
		_this.imgOriginalHeight = _this.imageNode.height;
		setImagePosition();
		_this.refreshColorsAndPos();
		if (!_this.isPausedWhenNotInView || _this.isCanvasInWindowView) {
			_this.animation = requestAnimationFrame(_this.animateColors.bind(_this));
		}
		_this.isImgLoaded = true;
	};
	this.imageNode.src = this.image.source;

	function setImagePosition() {
		var i, currentAxis;

		for (i = 0; i < 2; i++) {
			currentAxis = !i ? 'x' : 'y';
			setImageAxisPosition(currentAxis);
		}

		function setImageAxisPosition(axis) {
			var canvasWidthOrHeight = _this[axis + '1'];
			var imgOriginalWidthOrHeight = _this[axis === 'x' ? 'imgOriginalWidth' : 'imgOriginalHeight'];
			var imageAlignIndex = axis === 'x' ? _this.image.position[0] : _this.image.position[1];
			var imageAxisPosition;
			switch(imageAlignIndex) {
				case 'center':
					imageAxisPosition = imgOriginalWidthOrHeight > canvasWidthOrHeight
						? -(imgOriginalWidthOrHeight - canvasWidthOrHeight) / 2
						: (canvasWidthOrHeight - imgOriginalWidthOrHeight) / 2;
					_this.imagePosition[axis] = imageAxisPosition;
					_this.imagePosition[axis === 'x' ? 'width' : 'height'] = imgOriginalWidthOrHeight;
					break;

				case 'top':
					_this.imagePosition['y'] = 0;
					_this.imagePosition['height'] = imgOriginalWidthOrHeight;
					break;

				case 'bottom':
					_this.imagePosition['y'] = canvasWidthOrHeight - imgOriginalWidthOrHeight;
					_this.imagePosition['height'] = imgOriginalWidthOrHeight;
					break;

				case 'right':
					_this.imagePosition['x'] = canvasWidthOrHeight - imgOriginalWidthOrHeight;
					_this.imagePosition['width'] = imgOriginalWidthOrHeight;
					break;

				case 'left':
					_this.imagePosition['x'] = 0;
					_this.imagePosition['width'] = imgOriginalWidthOrHeight;
					break;
			}

			if (_this.image.stretchMode) {
				imageAlignIndex = axis === 'x' ? _this.image.stretchMode[0] : _this.image.stretchMode[1];
				switch(imageAlignIndex) {
					case 'none':
						break;
					case 'stretch':
						_this.imagePosition[axis] = 0;
						_this.imagePosition[axis === 'x' ? 'width' : 'height'] = canvasWidthOrHeight;
						break;

					case 'stretch-if-bigger':
						if (imgOriginalWidthOrHeight < canvasWidthOrHeight) break;
						_this.imagePosition[axis] = 0;
						_this.imagePosition[axis === 'x' ? 'width' : 'height'] = canvasWidthOrHeight;
						break;

					case 'stretch-if-smaller':
						if (imgOriginalWidthOrHeight > canvasWidthOrHeight) break;
						_this.imagePosition[axis] = 0;
						_this.imagePosition[axis === 'x' ? 'width' : 'height'] = canvasWidthOrHeight;
						break;
				}
			}
		}
	}
};