using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;
using System.Collections;

namespace Framework
{
    /// <summary>
    /// 将xml转换为json
    /// </summary>
    public class XmlToJson
    {
        /// <summary>
        /// 将xml转换为json
        /// </summary>
        /// <param name="xmlFile">xml文件</param>
        /// <returns></returns>
        public static string XmlToJSON(string xmlFile)
        {
            XmlDocument doc = new XmlDocument();
            doc.Load(xmlFile);
            return XmlToJSON(doc);
        }

        /// <summary>
        /// 将xml转换为json
        /// </summary>
        /// <param name="xmlDoc">xml文档</param>
        /// <returns></returns>
        public static string XmlToJSON(XmlDocument xmlDoc)
        {
            StringBuilder sbJSON = new StringBuilder();
            sbJSON.Append("{ ");
            XmlToJSONnode(sbJSON,xmlDoc.DocumentElement,true);
            sbJSON.Append("}");
            return sbJSON.ToString();
        }
        //  XmlToJSONnode:  Output an XmlElement,possibly as part of a higher array
        private static void XmlToJSONnode(StringBuilder sbJSON,XmlElement node,bool showNodeName)
        {
            if (showNodeName)
                sbJSON.Append("\"" + SafeJSON(node.Name) + "\": ");
            sbJSON.Append("{");
            // Build a sorted list of key-value pairs
            //  where   key is case-sensitive nodeName
            //          value is an ArrayList of string or XmlElement
            //  so that we know whether the nodeName is an array or not.
            SortedList childNodeNames = new SortedList();

            //  Add in all node attributes
            if (node.Attributes != null)
                foreach (XmlAttribute attr in node.Attributes)
                    StoreChildNode(childNodeNames,attr.Name,attr.InnerText);

            //  Add in all nodes
            foreach (XmlNode cnode in node.ChildNodes)
            {
                if (cnode is XmlText)
                    StoreChildNode(childNodeNames,"value",cnode.InnerText);
                else if (cnode is XmlElement)
                    StoreChildNode(childNodeNames,cnode.Name,cnode);
            }

            // Now output all stored info
            foreach (string childname in childNodeNames.Keys)
            {
                ArrayList alChild = (ArrayList)childNodeNames[childname];
                if (alChild.Count == 1)
                    OutputNode(childname,alChild[0],sbJSON,true);
                else
                {
                    sbJSON.Append(" \"" + SafeJSON(childname) + "\": [ ");
                    foreach (object Child in alChild)
                        OutputNode(childname,Child,false);
                    sbJSON.Remove(sbJSON.Length - 2,2);
                    sbJSON.Append(" ],");
                }
            }
            sbJSON.Remove(sbJSON.Length - 2,2);
            sbJSON.Append(" }");
        }
        //  StoreChildNode: Store data associated with each nodeName
        //                  so that we know whether the nodeName is an array or not.
        private static void StoreChildNode(SortedList childNodeNames,string nodeName,object nodeValue)
        {
            // Pre-process contraction of XmlElement-s
            if (nodeValue is XmlElement)
            {
                // Convert  <aa></aa> into "aa":null
                //          <aa>xx</aa> into "aa":"xx"
                XmlNode cnode = (XmlNode)nodeValue;
                if (cnode.Attributes.Count == 0)
                {
                    XmlNodeList children = cnode.ChildNodes;
                    if (children.Count == 0)
                        nodeValue = null;
                    else if (children.Count == 1 && (children[0] is XmlText))
                        nodeValue = ((XmlText)(children[0])).InnerText;
                }
            }
            // Add nodeValue to ArrayList associated with each nodeName
            // If nodeName doesn't exist then add it
            object oValuesAL = childNodeNames[nodeName];
            ArrayList ValuesAL;
            if (oValuesAL == null)
            {
                ValuesAL = new ArrayList();
                childNodeNames[nodeName] = ValuesAL;
            }
            else
                ValuesAL = (ArrayList)oValuesAL;
            ValuesAL.Add(nodeValue);
        }
        private static void OutputNode(string childname,object alChild,StringBuilder sbJSON,bool showNodeName)
        {
            if (alChild == null)
            {
                if (showNodeName)
                    sbJSON.Append("\"" + SafeJSON(childname) + "\": ");
                sbJSON.Append("null");
            }
            else if (alChild is string)
            {
                if (showNodeName)
                    sbJSON.Append("\"" + SafeJSON(childname) + "\": ");
                string sChild = (string)alChild;
                sChild = sChild.Trim();
                sbJSON.Append("\"" + SafeJSON(sChild) + "\"");
            }
            else
                XmlToJSONnode(sbJSON,(XmlElement)alChild,showNodeName);
            sbJSON.Append(",");
        }
        // Make a string safe for JSON
        private static string SafeJSON(string sIn)
        {
            StringBuilder sbOut = new StringBuilder(sIn.Length);
            foreach (char ch in sIn)
            {
                if (Char.IsControl(ch) || ch == '\'')
                {
                    int ich = (int)ch;
                    sbOut.Append(@"\u" + ich.ToString("x4"));
                    continue;
                }
                else if (ch == '\"' || ch == '\\' || ch == '/')
                {
                    sbOut.Append('\\');
                }
                sbOut.Append(ch);
            }
            return sbOut.ToString();
        }
    }
}