//------------------------------------------------------------------------------
// <copyright file="XmlCharacterData.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>                                                                
// <owner current="true" primary="true">[....]</owner>
//------------------------------------------------------------------------------
namespace System.Xml {
    using System.Diagnostics;
    using System.Text;
    using System.Xml.XPath;

    // Provides text-manipulation methods that are used by several classes.
    public abstract class XmlCharacterData : XmlLinkedNode {
        string data; 

        //base(doc) will throw exception if doc is null.
        protected internal XmlCharacterData( string data, XmlDocument doc ): base( doc ) {
            this.data = data;
        }

        // Gets or sets the value of the node.
        public override String Value {
            get { return Data;}
            set { Data = value;}
        }

        // Gets or sets the concatenated values of the node and
        // all its children.
        public override string InnerText {
            get { return Value;}
            set { Value = value;}
        }

        // Contains this node's data.
        public virtual string Data {
            get {
                if (data != null) {
                    return data;
                }
                else {
                    return String.Empty;
                }
            }

            set {
                XmlNode parent = ParentNode;
                XmlNodeChangedEventArgs args = GetEventArgs( this, parent, parent, this.data, value, XmlNodeChangedAction.Change );

                if (args != null)
                    BeforeEvent( args );

                data = value;

                if (args != null)
                    AfterEvent( args );
            }
        }

        // Gets the length of the data, in characters.
        public virtual int Length {
            get {
                if (data != null) {
                        return data.Length;
                }
                return 0;
            }
        }

        // Retrieves a substring of the full string from the specified range.
        public virtual String Substring(int offset, int count) {
            int len = data != null ? data.Length : 0; 
            if (len > 0) {
                if (len < (offset + count)) {
                    count = len - offset;
                }
                return data.Substring( offset, count );
            }
            return String.Empty;
        }

        // Appends the specified string to the end of the character
        // data of the node.
        public virtual void AppendData(String strData) {
            XmlNode parent = ParentNode;
            int capacity = data != null ? data.Length : 0; 
            if (strData != null) capacity += strData.Length;
            string newValue = new StringBuilder( capacity ).Append( data ).Append( strData ).ToString();
            XmlNodeChangedEventArgs args = GetEventArgs( this, parent, parent, data, newValue, XmlNodeChangedAction.Change );

            if (args != null)
                BeforeEvent( args );

            this.data = newValue;

            if (args != null)
                AfterEvent( args );
        }

        // Insert the specified string at the specified character offset.
        public virtual void InsertData(int offset, string strData) {
            XmlNode parent = ParentNode;
            int capacity = data != null ? data.Length : 0;
            if (strData != null) capacity += strData.Length;
            string newValue = new StringBuilder( capacity ).Append( data ).Insert(offset, strData).ToString();            
            XmlNodeChangedEventArgs args = GetEventArgs( this, parent, parent, data, newValue, XmlNodeChangedAction.Change );
            if (args != null)
                BeforeEvent( args );

            this.data = newValue;            

            if (args != null)
                AfterEvent( args );
        }

        // Remove a range of characters from the node.
        public virtual void DeleteData(int offset, int count) {
            //Debug.Assert(offset >= 0 && offset <= Length);

            int len = data != null ? data.Length : 0;
            if (len > 0) {
                if (len < (offset + count)) {
                    count = Math.Max ( len - offset, 0);
                }
            }

            string newValue = new StringBuilder( data ).Remove(offset, count).ToString();
            XmlNode parent = ParentNode;
            XmlNodeChangedEventArgs args = GetEventArgs( this, parent, parent, data, newValue, XmlNodeChangedAction.Change );

            if (args != null)
                BeforeEvent( args );

            this.data = newValue;            

            if (args != null)
                AfterEvent( args );
        }

        // Replace the specified number of characters starting at the specified offset with the
        // specified string.
        public virtual void ReplaceData(int offset, int count, String strData) {
            //Debug.Assert(offset >= 0 && offset <= Length);

            int len = data != null ? data.Length : 0;
            if (len > 0) {
                if (len < (offset + count)) {
                    count = Math.Max ( len - offset, 0);
                }
            }

            StringBuilder temp = new StringBuilder( data ).Remove( offset, count );
            string newValue = temp.Insert( offset, strData ).ToString();
            
            XmlNode parent = ParentNode;
            XmlNodeChangedEventArgs args = GetEventArgs( this, parent, parent, data, newValue, XmlNodeChangedAction.Change );

            if (args != null)
                BeforeEvent( args );
            
            this.data = newValue;            

            if (args != null)
                AfterEvent( args );
        }

        internal bool CheckOnData( string data ) {
            return XmlCharType.Instance.IsOnlyWhitespace( data );
        }

        internal bool DecideXPNodeTypeForTextNodes(XmlNode node, ref XPathNodeType xnt) {
            //returns true - if all siblings of the node are processed else returns false.
            //The reference XPathNodeType argument being passed in is the watermark that
            //changes according to the siblings nodetype and will contain the correct
            //nodetype when it returns.

            Debug.Assert(XmlDocument.IsTextNode(node.NodeType) || (node.ParentNode != null && node.ParentNode.NodeType == XmlNodeType.EntityReference));
            while (node != null) {
                switch (node.NodeType) {
                case XmlNodeType.Whitespace :
                    break;
                case XmlNodeType.SignificantWhitespace :
                    xnt = XPathNodeType.SignificantWhitespace;
                    break;
                case XmlNodeType.Text :
                case XmlNodeType.CDATA:
                    xnt = XPathNodeType.Text;
                    return false;
                case XmlNodeType.EntityReference :
                    if (!DecideXPNodeTypeForTextNodes(node.FirstChild, ref xnt)) {
                        return false;
                    }
                    break;
                default :
                    return false;
                }
                node = node.NextSibling;
            }
            return true;
        }
    }
}