/*!
 * https://github.com/gilmoreorless/css-background-parser
 * Copyright © 2015 Gilmore Davidson under the MIT license: http://gilmoreorless.mit-license.org/
 */
(function (exports) {

    function BackgroundList(backgrounds) {
        if (!(this instanceof BackgroundList)) {
            return new BackgroundList();
        }
        this.backgrounds = backgrounds || [];
    }

    BackgroundList.prototype.toString = function () {
        return this.backgrounds.join(', ');
    };


    function Background(props) {
        if (!(this instanceof Background)) {
            return new Background(props);
        }
        props = props || {};
        var bg = this;

        function defprop(name, defaultValue) {
            bg[name] = (name in props) ? props[name] : defaultValue;
        }

        // http://www.w3.org/TR/css3-background/#backgrounds
        defprop('color', '');
        defprop('image', 'none');
        defprop('attachment', 'scroll');
        defprop('clip', 'border-box');
        defprop('origin', 'padding-box');
        defprop('position', '0% 0%');
        defprop('repeat', 'repeat');
        defprop('size', 'auto');
    }

    Background.prototype.toString = function () {
        var list = [
            this.image,
            this.repeat,
            this.attachment,
            this.position + ' / ' + this.size,
            this.origin,
            this.clip
        ];
        if (this.color) {
            list.unshift(this.color);
        }
        return list.join(' ');
    };

    exports.BackgroundList = BackgroundList;
    exports.Background = Background;


    function parseImages(cssText) {
        var images = [];
        var tokens = /[,\(\)]/;
        var parens = 0;
        var buffer = '';

        if (cssText == null) {
            return images;
        }

        while (cssText.length) {
            var match = tokens.exec(cssText);
            if (!match) {
                break;
            }
            var char = match[0];
            var ignoreChar = false;
            switch (char) {
                case ',':
                    if (!parens) {
                        images.push(buffer.trim());
                        buffer = '';
                        ignoreChar = true;
                    }
                    break;
                case '(':
                    parens++;
                    break;
                case ')':
                    parens--;
                    break;
            }

            var index = match.index + 1;
            buffer += cssText.slice(0, ignoreChar ? index - 1 : index);
            cssText = cssText.slice(index);
        }

        if (buffer.length || cssText.length) {
            images.push((buffer + cssText).trim());
        }

        return images;
    }

    // Helper for .map()
    function trim(str) {
        return str.trim();
    }

    function parseSimpleList(cssText) {
        return (cssText || '').split(',').map(trim);
    }

    exports.parseElementStyle = function (styleObject) {
        var list = new BackgroundList();
        if (styleObject == null) {
            return list;
        }

        var bgImage = parseImages(styleObject.backgroundImage);
        var bgColor = styleObject.backgroundColor;
        var bgAttachment = parseSimpleList(styleObject.backgroundAttachment);
        var bgClip       = parseSimpleList(styleObject.backgroundClip);
        var bgOrigin     = parseSimpleList(styleObject.backgroundOrigin);
        var bgPosition   = parseSimpleList(styleObject.backgroundPosition);
        var bgRepeat     = parseSimpleList(styleObject.backgroundRepeat);
        var bgSize       = parseSimpleList(styleObject.backgroundSize);
        var background;

        for (var i = 0, ii = bgImage.length; i < ii; i++) {
            background = new Background({
                image:      bgImage[i],
                attachment: bgAttachment[i % bgAttachment.length],
                clip:       bgClip[i % bgClip.length],
                origin:     bgOrigin[i % bgOrigin.length],
                position:   bgPosition[i % bgPosition.length],
                repeat:     bgRepeat[i % bgRepeat.length],
                size:       bgSize[i % bgSize.length]
            });
            if (i === ii - 1) {
                background.color = bgColor;
            }
            list.backgrounds.push(background);
        }

        return list;
    };

    // exports.parseCssString = function (cssString) {
    //     return new Background();
    // };

    // exports.parseBackgroundValue = function (cssString) {
    //     return new Background();
    // };

})((function (root) {
    // CommonJS
    if (typeof module !== 'undefined' && module.exports !== undefined) return module.exports;
    // Global `cssBgParser`
    return (root.cssBgParser = {});
})(this));