/**
 * Serializer module for Rangy.
 * Serializes Ranges and Selections. An example use would be to store a user's selection on a particular page in a
 * cookie or local storage and restore it on the user's next visit to the same page.
 *
 * Part of Rangy, a cross-browser JavaScript range and selection library
 * http://code.google.com/p/rangy/
 *
 * Depends on Rangy core.
 *
 * Copyright 2013, Tim Down
 * Licensed under the MIT license.
 * Version: 1.3alpha.804
 * Build date: 8 December 2013
 */
rangy.createModule("Serializer", ["WrappedSelection"], function(api, module) {
    var UNDEF = "undefined";

    // encodeURIComponent and decodeURIComponent are required for cookie handling
    if (typeof encodeURIComponent == UNDEF || typeof decodeURIComponent == UNDEF) {
        module.fail("Global object is missing encodeURIComponent and/or decodeURIComponent method");
    }

    // Checksum for checking whether range can be serialized
    var crc32 = (function() {
        function utf8encode(str) {
            var utf8CharCodes = [];

            for (var i = 0, len = str.length, c; i < len; ++i) {
                c = str.charCodeAt(i);
                if (c < 128) {
                    utf8CharCodes.push(c);
                } else if (c < 2048) {
                    utf8CharCodes.push((c >> 6) | 192, (c & 63) | 128);
                } else {
                    utf8CharCodes.push((c >> 12) | 224, ((c >> 6) & 63) | 128, (c & 63) | 128);
                }
            }
            return utf8CharCodes;
        }

        var cachedCrcTable = null;

        function buildCRCTable() {
            var table = [];
            for (var i = 0, j, crc; i < 256; ++i) {
                crc = i;
                j = 8;
                while (j--) {
                    if ((crc & 1) == 1) {
                        crc = (crc >>> 1) ^ 0xEDB88320;
                    } else {
                        crc >>>= 1;
                    }
                }
                table[i] = crc >>> 0;
            }
            return table;
        }

        function getCrcTable() {
            if (!cachedCrcTable) {
                cachedCrcTable = buildCRCTable();
            }
            return cachedCrcTable;
        }

        return function(str) {
            var utf8CharCodes = utf8encode(str), crc = -1, crcTable = getCrcTable();
            for (var i = 0, len = utf8CharCodes.length, y; i < len; ++i) {
                y = (crc ^ utf8CharCodes[i]) & 0xFF;
                crc = (crc >>> 8) ^ crcTable[y];
            }
            return (crc ^ -1) >>> 0;
        };
    })();

    var dom = api.dom;

    function escapeTextForHtml(str) {
        return str.replace(/</g, "&lt;").replace(/>/g, "&gt;");
    }

    function nodeToInfoString(node, infoParts) {
        infoParts = infoParts || [];
        var nodeType = node.nodeType, children = node.childNodes, childCount = children.length;
        var nodeInfo = [nodeType, node.nodeName, childCount].join(":");
        var start = "", end = "";
        switch (nodeType) {
            case 3: // Text node
                start = escapeTextForHtml(node.nodeValue);
                break;
            case 8: // Comment
                start = "<!--" + escapeTextForHtml(node.nodeValue) + "-->";
                break;
            default:
                start = "<" + nodeInfo + ">";
                end = "</>";
                break;
        }
        if (start) {
            infoParts.push(start);
        }
        for (var i = 0; i < childCount; ++i) {
            nodeToInfoString(children[i], infoParts);
        }
        if (end) {
            infoParts.push(end);
        }
        return infoParts;
    }

    // Creates a string representation of the specified element's contents that is similar to innerHTML but omits all
    // attributes and comments and includes child node counts. This is done instead of using innerHTML to work around
    // IE <= 8's policy of including element properties in attributes, which ruins things by changing an element's
    // innerHTML whenever the user changes an input within the element.
    function getElementChecksum(el) {
        var info = nodeToInfoString(el).join("");
        return crc32(info).toString(16);
    }

    function serializePosition(node, offset, rootNode) {
        var pathParts = [], n = node;
        rootNode = rootNode || dom.getDocument(node).documentElement;
        while (n && n != rootNode) {
            pathParts.push(dom.getNodeIndex(n, true));
            n = n.parentNode;
        }
        return pathParts.join("/") + ":" + offset;
    }

    function deserializePosition(serialized, rootNode, doc) {
        if (!rootNode) {
            rootNode = (doc || document).documentElement;
        }
        var parts = serialized.split(":");
        var node = rootNode;
        var nodeIndices = parts[0] ? parts[0].split("/") : [], i = nodeIndices.length, nodeIndex;

        while (i--) {
            nodeIndex = parseInt(nodeIndices[i], 10);
            if (nodeIndex < node.childNodes.length) {
                node = node.childNodes[nodeIndex];
            } else {
                throw module.createError("deserializePosition() failed: node " + dom.inspectNode(node) +
                        " has no child with index " + nodeIndex + ", " + i);
            }
        }

        return new dom.DomPosition(node, parseInt(parts[1], 10));
    }

    function serializeRange(range, omitChecksum, rootNode) {
        rootNode = rootNode || api.DomRange.getRangeDocument(range).documentElement;
        if (!dom.isOrIsAncestorOf(rootNode, range.commonAncestorContainer)) {
            throw module.createError("serializeRange(): range " + range.inspect() +
                " is not wholly contained within specified root node " + dom.inspectNode(rootNode));
        }
        var serialized = serializePosition(range.startContainer, range.startOffset, rootNode) + "," +
            serializePosition(range.endContainer, range.endOffset, rootNode);
        if (!omitChecksum) {
            serialized += "{" + getElementChecksum(rootNode) + "}";
        }
        return serialized;
    }

    var deserializeRegex = /^([^,]+),([^,\{]+)(\{([^}]+)\})?$/;
    
    function deserializeRange(serialized, rootNode, doc) {
        if (rootNode) {
            doc = doc || dom.getDocument(rootNode);
        } else {
            doc = doc || document;
            rootNode = doc.documentElement;
        }
        var result = deserializeRegex.exec(serialized);
        var checksum = result[4], rootNodeChecksum = getElementChecksum(rootNode);
        if (checksum && checksum !== getElementChecksum(rootNode)) {
            throw module.createError("deserializeRange(): checksums of serialized range root node (" + checksum +
                    ") and target root node (" + rootNodeChecksum + ") do not match");
        }
        var start = deserializePosition(result[1], rootNode, doc), end = deserializePosition(result[2], rootNode, doc);
        var range = api.createRange(doc);
        range.setStartAndEnd(start.node, start.offset, end.node, end.offset);
        return range;
    }

    function canDeserializeRange(serialized, rootNode, doc) {
        if (!rootNode) {
            rootNode = (doc || document).documentElement;
        }
        var result = deserializeRegex.exec(serialized);
        var checksum = result[3];
        return !checksum || checksum === getElementChecksum(rootNode);
    }

    function serializeSelection(selection, omitChecksum, rootNode) {
        selection = api.getSelection(selection);
        var ranges = selection.getAllRanges(), serializedRanges = [];
        for (var i = 0, len = ranges.length; i < len; ++i) {
            serializedRanges[i] = serializeRange(ranges[i], omitChecksum, rootNode);
        }
        return serializedRanges.join("|");
    }

    function deserializeSelection(serialized, rootNode, win) {
        if (rootNode) {
            win = win || dom.getWindow(rootNode);
        } else {
            win = win || window;
            rootNode = win.document.documentElement;
        }
        var serializedRanges = serialized.split("|");
        var sel = api.getSelection(win);
        var ranges = [];

        for (var i = 0, len = serializedRanges.length; i < len; ++i) {
            ranges[i] = deserializeRange(serializedRanges[i], rootNode, win.document);
        }
        sel.setRanges(ranges);

        return sel;
    }

    function canDeserializeSelection(serialized, rootNode, win) {
        var doc;
        if (rootNode) {
            doc = win ? win.document : dom.getDocument(rootNode);
        } else {
            win = win || window;
            rootNode = win.document.documentElement;
        }
        var serializedRanges = serialized.split("|");

        for (var i = 0, len = serializedRanges.length; i < len; ++i) {
            if (!canDeserializeRange(serializedRanges[i], rootNode, doc)) {
                return false;
            }
        }

        return true;
    }

    var cookieName = "rangySerializedSelection";

    function getSerializedSelectionFromCookie(cookie) {
        var parts = cookie.split(/[;,]/);
        for (var i = 0, len = parts.length, nameVal, val; i < len; ++i) {
            nameVal = parts[i].split("=");
            if (nameVal[0].replace(/^\s+/, "") == cookieName) {
                val = nameVal[1];
                if (val) {
                    return decodeURIComponent(val.replace(/\s+$/, ""));
                }
            }
        }
        return null;
    }

    function restoreSelectionFromCookie(win) {
        win = win || window;
        var serialized = getSerializedSelectionFromCookie(win.document.cookie);
        if (serialized) {
            deserializeSelection(serialized, win.doc);
        }
    }

    function saveSelectionCookie(win, props) {
        win = win || window;
        props = (typeof props == "object") ? props : {};
        var expires = props.expires ? ";expires=" + props.expires.toUTCString() : "";
        var path = props.path ? ";path=" + props.path : "";
        var domain = props.domain ? ";domain=" + props.domain : "";
        var secure = props.secure ? ";secure" : "";
        var serialized = serializeSelection(api.getSelection(win));
        win.document.cookie = encodeURIComponent(cookieName) + "=" + encodeURIComponent(serialized) + expires + path + domain + secure;
    }

    api.serializePosition = serializePosition;
    api.deserializePosition = deserializePosition;

    api.serializeRange = serializeRange;
    api.deserializeRange = deserializeRange;
    api.canDeserializeRange = canDeserializeRange;

    api.serializeSelection = serializeSelection;
    api.deserializeSelection = deserializeSelection;
    api.canDeserializeSelection = canDeserializeSelection;

    api.restoreSelectionFromCookie = restoreSelectionFromCookie;
    api.saveSelectionCookie = saveSelectionCookie;

    api.getElementChecksum = getElementChecksum;
    api.nodeToInfoString = nodeToInfoString;
});
