yahoo/blink-diff

module.exports = function () {

    function versionInfo () {
        return {
            major: 1,
            minor: 0
        };
    }

    function deviceInfo () {
        return {
            userAgent: window.navigator.userAgent,

            app: {
                codeName: window.navigator.appCodeName,
                name: window.navigator.appName,
                version: window.navigator.appVersion,
                buildId: window.navigator.buildID
            },

            languages: window.navigator.languages || [window.navigator.language],

            product: {
                name: window.navigator.product,
                sub: window.navigator.productSub
            },
            vendor: {
                name: window.navigator.vendor,
                sub: window.navigator.vendorSub
            },

            screen: {
                pixelRatio: window.devicePixelRatio || 1,
                colorDepth: window.screen.colorDepth,
                width: Math.min(window.screen.width, window.screen.availWidth),
                height: Math.min(window.screen.height, window.screen.availHeight),
                fullScreen: window.fullScreen
            }
        }
    }

    function documentInfo () {
        var de = document.documentElement,
            body = document.body,
            result = {};

        result.title = document.title;
        result.url = window.location + '';
        result.referrer = document.referrer;

        result.size = {
            width: Math.max(body.scrollWidth, body.offsetWidth, de.clientWidth, de.scrollWidth, de.offsetWidth),
            height: Math.max(body.scrollHeight, body.offsetHeight, de.clientHeight, de.scrollHeight, de.offsetHeight)
        }
    }

    function viewPortInfo () {
        var el = document.createElement('div'),
            de = document.documentElement,
            body = document.body,
            result = {};

        // Get current scroll-position
        result.x = window.pageXOffset || body.scrollLeft || de.scrollLeft;
        result.y = window.pageYOffset || body.scrollTop || de.scrollTop;

        // Get current view-port size
        el.style.position = "fixed";
        el.style.top = 0;
        el.style.left = 0;
        el.style.bottom = 0;
        el.style.right = 0;
        de.insertBefore(el, de.firstChild);
        result.width = el.offsetWidth;
        result.height = el.offsetHeight;
        de.removeChild(el);

        return result;
    }

    function domInfo () {

        var capturedTags = ["A", "SPAN", "OL", "UL", "LI", "HEADER", "FOOTER", "NAV", "ARTICLE", "SECTION", "ASIDE", "DIV", "APPLET", "CANVAS", "VIDEO", "TABLE", "DETAILS", "SUMMARY", "IFRAME", "MENU", "MAIN", "FIGURE", "FIELDSET"];

        function loadDOMNode (inputNode, parentNode) {

            var nodes, length, offset, newNode;

            if (capturedTags.indexOf(inputNode.tagName) !== -1) {

                newNode = {};
                newNode.id = (inputNode.id && inputNode.id.length > 0) ? inputNode.id : null;
                newNode.tagName = inputNode.tagName;
                newNode.classes = (inputNode.className && inputNode.className.length > 0) ? inputNode.className.split(/\s/) : [];

                offset = absoluteOffset(inputNode);
                newNode.rect = {
                    x: offset.x,
                    y: offset.y,
                    width: inputNode.offsetWidth,
                    height: inputNode.offsetHeight
                };

                newNode.nodes = [];

                if ((newNode.rect.width > 0) && (newNode.rect.height > 0)) {
                    parentNode.nodes.push(newNode);
                    parentNode = newNode;
                }
            }

            nodes = inputNode.children;
            length = inputNode.childElementCount;

            if (nodes && length) {
                for (var i = 0; i < length; i++) {
                    loadDOMNode(nodes[i], parentNode);
                }
            }
        }

        function absoluteOffset (element) {

            var x = 0, y = 0;

            do {
                x += element.offsetLeft || 0;
                y += element.offsetTop || 0;
                element = element.offsetParent;
            } while (element);

            return {
                x: x, y: y
            };
        }

        var node = {nodes:[]};

        loadDOMNode(document.body, node);

        return node.nodes[0];
    }

    return JSON.stringify({
        version: versionInfo(),
        device: deviceInfo(),
        document: documentInfo(),
        viewPort: viewPortInfo(),
        screenshot: {
            stitched: false,
            section: {
                x: 0,
                y: 0,
                width: null,
                height: null
            }
        },
        dom: domInfo()
    });
};