//------------------------------------------------------------------------------
// <copyright file="XmlRawWriter.cs" company="Microsoft">
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------

using System;
using System.IO;
using System.Diagnostics;
#if !SILVERLIGHT
using System.Xml.XPath;
#endif
using System.Xml.Schema;
using System.Collections;

namespace System.Xml {

    /// <summary>
    /// Implementations of XmlRawWriter are intended to be wrapped by the XmlWellFormedWriter.  The
    /// well-formed writer performs many checks in behalf of the raw writer, and keeps state that the
    /// raw writer otherwise would have to keep.  Therefore, the well-formed writer will call the
    /// XmlRawWriter using the following rules, in order to make raw writers easier to implement:
    ///
    ///  1. The well-formed writer keeps a stack of element names, and always calls
    ///     WriteEndElement(string, string, string) instead of WriteEndElement().
    ///  2. The well-formed writer tracks namespaces, and will pass himself in via the
    ///     WellformedWriter property. It is used in the XmlRawWriter's implementation of IXmlNamespaceResolver.
    ///     Thus, LookupPrefix does not have to be implemented.
    ///  3. The well-formed writer tracks write states, so the raw writer doesn't need to.
    ///  4. The well-formed writer will always call StartElementContent.
    ///  5. The well-formed writer will always call WriteNamespaceDeclaration for namespace nodes,
    ///     rather than calling WriteStartAttribute(). If the writer is supporting namespace declarations in chunks
    ///     (SupportsNamespaceDeclarationInChunks is true), the XmlWellFormedWriter will call WriteStartNamespaceDeclaration,
    ///      then any method that can be used to write out a value of an attribute (WriteString, WriteChars, WriteRaw, WriteCharEntity...) 
    ///      and then WriteEndNamespaceDeclaration - instead of just a single WriteNamespaceDeclaration call. This feature will be 
    ///      supported by raw writers serializing to text that wish to preserve the attribute value escaping etc.
    ///  6. The well-formed writer guarantees a well-formed document, including correct call sequences,
    ///     correct namespaces, and correct document rule enforcement.
    ///  7. All element and attribute names will be fully resolved and validated.  Null will never be
    ///     passed for any of the name parts.
    ///  8. The well-formed writer keeps track of xml:space and xml:lang.
    ///  9. The well-formed writer verifies NmToken, Name, and QName values and calls WriteString().
    /// </summary>
    internal abstract partial class XmlRawWriter : XmlWriter {

//
// Fields
//
        // base64 converter
        protected XmlRawWriterBase64Encoder base64Encoder;

        // namespace resolver
        protected IXmlNamespaceResolver resolver;

//
// XmlWriter implementation
//

        // Raw writers do not have to track whether this is a well-formed document.
        public override void WriteStartDocument() {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        public override void WriteStartDocument(bool standalone) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        public override void WriteEndDocument() {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

#if !SILVERLIGHT // This code is not being hit in Silverlight
        public override void WriteDocType(string name, string pubid, string sysid, string subset) {

        }
#endif

        // Raw writers do not have to keep a stack of element names.
        public override void WriteEndElement() {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        // Raw writers do not have to keep a stack of element names.
        public override void WriteFullEndElement() {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        // By default, convert base64 value to string and call WriteString.
        public override void WriteBase64( byte[] buffer, int index, int count ) {
            if ( base64Encoder == null ) {
                base64Encoder = new XmlRawWriterBase64Encoder( this );
            }
            // Encode will call WriteRaw to write out the encoded characters
            base64Encoder.Encode( buffer, index, count );
        }

        // Raw writers do not have to keep track of namespaces.
        public override string LookupPrefix( string ns ) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        // Raw writers do not have to keep track of write states.
        public override WriteState WriteState {
            get {
                throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
            }
        }

        // Raw writers do not have to keep track of xml:space.
        public override XmlSpace XmlSpace { 
            get { throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) ); }
        }

        // Raw writers do not have to keep track of xml:lang.
        public override string XmlLang { 
            get { throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) ); }
        }

        // Raw writers do not have to verify NmToken values.
        public override void WriteNmToken( string name ) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        // Raw writers do not have to verify Name values.
        public override void WriteName( string name ) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        // Raw writers do not have to verify QName values.
        public override void WriteQualifiedName( string localName, string ns ) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

#if !SILVERLIGHT // This code is not being hit in Silverlight
        // Forward call to WriteString(string).
        public override void WriteCData( string text ) {
            WriteString( text );
        }

        // Forward call to WriteString(string).
        public override void WriteCharEntity( char ch ) {
            WriteString( new string( new char[] {ch} ) );
        }

        // Forward call to WriteString(string).
        public override void WriteSurrogateCharEntity( char lowChar, char highChar ) {
            WriteString( new string( new char[] {lowChar, highChar} ) );
        }

        // Forward call to WriteString(string).
        public override void WriteWhitespace( string ws ) {
            WriteString( ws );
        }

        // Forward call to WriteString(string).
        public override void WriteChars( char[] buffer, int index, int count ) {
            WriteString( new string( buffer, index, count ) );
        }

        // Forward call to WriteString(string).
        public override void WriteRaw(char[] buffer, int index, int count) {
            WriteString( new string( buffer, index, count ) );
        }

        // Forward call to WriteString(string).
        public override void WriteRaw(string data) {
            WriteString( data );
        }
#endif

        // Override in order to handle Xml simple typed values and to pass resolver for QName values
        public override void WriteValue(object value) {
            if ( value == null ) {
                throw new ArgumentNullException( "value" );
            }
#if SILVERLIGHT // 
            WriteString(XmlUntypedStringConverter.Instance.ToString( value, resolver ) );
#else
            WriteString(XmlUntypedConverter.Untyped.ToString( value, resolver ) );
#endif
        }

        // Override in order to handle Xml simple typed values and to pass resolver for QName values
        public override void WriteValue( string value ) {
            WriteString( value );
        }

        public override void WriteValue(DateTimeOffset value) {
            // For compatibility with custom writers, XmlWriter writes DateTimeOffset as DateTime. 
            // Our internal writers should use the DateTimeOffset-String conversion from XmlConvert.
            WriteString(XmlConvert.ToString(value));
        }

        // Copying to XmlRawWriter is not currently supported.
        public override void WriteAttributes( XmlReader reader, bool defattr ) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

        public override void WriteNode( XmlReader reader, bool defattr ) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }

#if !SILVERLIGHT  // Removing dependency on XPathNavigator
        public override void WriteNode( System.Xml.XPath.XPathNavigator navigator, bool defattr ) {
            throw new InvalidOperationException( Res.GetString( Res.Xml_InvalidOperation ) );
        }
#endif

//
// XmlRawWriter methods and properties
//

        // Get and set the namespace resolver that's used by this RawWriter to resolve prefixes.
        internal virtual IXmlNamespaceResolver NamespaceResolver  {
            get {
                return resolver;
            }
            set {
                resolver = value;
            }
        }

        // Write the xml declaration.  This must be the first call.
#if !SILVERLIGHT // This code is not being hit in Silverlight
        internal virtual void WriteXmlDeclaration( XmlStandalone standalone ) {

        }
        internal virtual void WriteXmlDeclaration( string xmldecl ) {

        }
#else

        internal abstract void WriteXmlDeclaration(XmlStandalone standalone);

        internal abstract void WriteXmlDeclaration(string xmldecl);

#endif

        // Called after an element's attributes have been enumerated, but before any children have been
        // enumerated.  This method must always be called, even for empty elements.

        internal abstract void StartElementContent();

        // Called before a root element is written (before the WriteStartElement call)
        //   the conformanceLevel specifies the current conformance level the writer is operating with.
        internal virtual void OnRootElement(ConformanceLevel conformanceLevel) { }

        // WriteEndElement() and WriteFullEndElement() overloads, in which caller gives the full name of the
        // element, so that raw writers do not need to keep a stack of element names.  This method should
        // always be called instead of WriteEndElement() or WriteFullEndElement() without parameters.

        internal abstract void WriteEndElement( string prefix, string localName, string ns );

#if !SILVERLIGHT // This code is not being hit in Silverlight
        internal virtual void WriteFullEndElement( string prefix, string localName, string ns ) {
            WriteEndElement( prefix, localName, ns );
        }
#else

        internal abstract void WriteFullEndElement(string prefix, string localName, string ns);

#endif

        internal virtual void WriteQualifiedName( string prefix, string localName, string ns ) {
            if ( prefix.Length != 0 ) {
                WriteString( prefix );
                WriteString( ":" );
            }
            WriteString( localName );
        }

        // This method must be called instead of WriteStartAttribute() for namespaces.

        internal abstract void WriteNamespaceDeclaration( string prefix, string ns );

        // When true, the XmlWellFormedWriter will call:
        //      1) WriteStartNamespaceDeclaration
        //      2) any method that can be used to write out a value of an attribute: WriteString, WriteChars, WriteRaw, WriteCharEntity... 
        //      3) WriteEndNamespaceDeclaration
        // instead of just a single WriteNamespaceDeclaration call. 
        //
        // This feature will be supported by raw writers serializing to text that wish to preserve the attribute value escaping and entities.
        internal virtual bool SupportsNamespaceDeclarationInChunks {
            get {
                return false;
            }
        }

        internal virtual void WriteStartNamespaceDeclaration(string prefix) {
            throw new NotSupportedException();
        }

        internal virtual void WriteEndNamespaceDeclaration() {
            throw new NotSupportedException();
        }

        // This is called when the remainder of a base64 value should be output.
        internal virtual void WriteEndBase64() {
            // The Flush will call WriteRaw to write out the rest of the encoded characters
            base64Encoder.Flush();
        }

        internal virtual void Close( WriteState currentState ) {
            Close();
        }

    }
}