package net.sf.saxon.dotnet;

import cli.System.Xml.Schema.XmlSchemaException;
import cli.System.Xml.*;
import net.sf.saxon.event.PipelineConfiguration;
import net.sf.saxon.event.SaxonLocator;
import net.sf.saxon.event.SourceLocationProvider;
import net.sf.saxon.expr.ExpressionLocation;
import net.sf.saxon.om.*;
import net.sf.saxon.pull.PullProvider;
import net.sf.saxon.tinytree.CompressedWhitespace;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.value.AtomicValue;

import javax.xml.transform.SourceLocator;
import java.util.List;


/**
 * This class implements the Saxon PullProvider interface as a wrapper around a .NET XmlReader.
 */

public class DotNetPullProvider implements PullProvider, SaxonLocator, SourceLocationProvider {

    private PipelineConfiguration pipe;
    private XmlReader parser;
    private NamePool pool;
    private String baseURI;
    private boolean isEmptyElement = false;
    private int current = START_OF_INPUT;

    /**
     * Create a PullProvider that wraps a .NET XML parser
     * @param parser the .NET XML parser. In practice, the code relies on this being an XMLValidatingReader
     */

    public DotNetPullProvider(XmlReader parser) {
        this.parser = parser;
    }

    /**
     * Set the base URI to be used. This is used only if the XmlReader cannot supply
     * a base URI.
     * @param base the base URI
     */

    public void setBaseURI(String base) {
        baseURI = base;
    }

    /**
     * Close the event reader. This indicates that no further events are required.
     * It is not necessary to close an event reader after {@link #END_OF_INPUT} has
     * been reported, but it is recommended to close it if reading terminates
     * prematurely. Once an event reader has been closed, the effect of further
     * calls on next() is undefined.
     */

    public void close() {
        parser.Close();
    }

    /**
     * Get the event most recently returned by next(), or by other calls that change
     * the position, for example getStringValue() and skipToMatchingEnd(). This
     * method does not change the position of the PullProvider.
     *
     * @return the current event
     */

    public int current() {
        return current;
    }

    /**
     * Get an atomic value. This call may be used only when the last event reported was
     * ATOMIC_VALUE. This indicates that the PullProvider is reading a sequence that contains
     * a free-standing atomic value; it is never used when reading the content of a node.
     */

    public AtomicValue getAtomicValue() {
        return null;
    }

    /**
     * Get the attributes associated with the current element. This method must
     * be called only after a START_ELEMENT event has been notified. The contents
     * of the returned AttributeCollection are guaranteed to remain unchanged
     * until the next START_ELEMENT event, but may be modified thereafter. The object
     * should not be modified by the client.
     * <p/>
     * <p>Attributes may be read before or after reading the namespaces of an element,
     * but must not be read after the first child node has been read, or after calling
     * one of the methods skipToEnd(), getStringValue(), or getTypedValue().</p>
     *
     * @return an AttributeCollection representing the attributes of the element
     *         that has just been notified.
     */

    public AttributeCollection getAttributes() throws XPathException {
        if (parser.get_HasAttributes()) {
            AttributeCollectionImpl atts = new AttributeCollectionImpl(pipe.getConfiguration());
            for (int i=0; i<parser.get_AttributeCount(); i++) {
                parser.MoveToAttribute(i);
                final String prefix = parser.get_Prefix();
                final String namespaceURI = parser.get_NamespaceURI();
                final String localName = parser.get_LocalName();
                if ("xmlns".equals(prefix) || ("".equals(prefix) && "xmlns".equals(localName))) {
                    // skip the namespace declaration
                } else {
                    int nc = pool.allocate(prefix, namespaceURI, localName);
                    // .NET does not report the attribute type (even if it's an ID...)
                    atts.addAttribute(nc, StandardNames.XS_UNTYPED_ATOMIC, parser.get_Value(), 0, 0);
                }
            }
            return atts;
        } else {
            return AttributeCollectionImpl.EMPTY_ATTRIBUTE_COLLECTION;
        }
    }

    /**
     * Get the fingerprint of the name of the element. This is similar to the nameCode, except that
     * it does not contain any information about the prefix: so two elements with the same fingerprint
     * have the same name, excluding prefix. This method
     * can be used after the {@link #START_ELEMENT}, {@link #END_ELEMENT}, {@link #PROCESSING_INSTRUCTION},
     * {@link #ATTRIBUTE}, or {@link #NAMESPACE} events.
     * If called at other times, the result is undefined and may result in an IllegalStateException.
     * If called when the current node is an unnamed namespace node (a node representing the default namespace)
     * the returned value is -1.
     *
     * @return the fingerprint. The fingerprint can be used to obtain the local name
     *         and namespace URI from the name pool.
     */

    public int getFingerprint() {
        return getNameCode() & NamePool.FP_MASK;
    }

    /**
     * Get the nameCode identifying the name of the current node. This method
     * can be used after the {@link #START_ELEMENT}, {@link #PROCESSING_INSTRUCTION},
     * {@link #ATTRIBUTE}, or {@link #NAMESPACE} events. With some PullProvider implementations,
     * it can also be used after {@link #END_ELEMENT}, but this is not guaranteed: a client who
     * requires the information at that point (for example, to do serialization) should insert an
     * {@link net.sf.saxon.pull.ElementNameTracker} into the pipeline.
     * If called at other times, the result is undefined and may result in an IllegalStateException.
     * If called when the current node is an unnamed namespace node (a node representing the default namespace)
     * the returned value is -1.
     *
     * @return the nameCode. The nameCode can be used to obtain the prefix, local name,
     *         and namespace URI from the name pool.
     */

    public int getNameCode() {
        return pool.allocate(parser.get_Prefix(), parser.get_NamespaceURI(), parser.get_LocalName());
    }

    /**
     * Get the namespace declarations associated with the current element. This method must
     * be called only after a START_ELEMENT event has been notified. In the case of a top-level
     * START_ELEMENT event (that is, an element that either has no parent node, or whose parent
     * is not included in the sequence being read), the NamespaceDeclarations object returned
     * will contain a namespace declaration for each namespace that is in-scope for this element
     * node. In the case of a non-top-level element, the NamespaceDeclarations will contain
     * a set of namespace declarations and undeclarations, representing the differences between
     * this element and its parent.
     * <p/>
     * <p>It is permissible for this method to return namespace declarations that are redundant.</p>
     * <p/>
     * <p>The NamespaceDeclarations object is guaranteed to remain unchanged until the next START_ELEMENT
     * event, but may then be overwritten. The object should not be modified by the client.</p>
     * <p/>
     * <p>Namespaces may be read before or after reading the attributes of an element,
     * but must not be read after the first child node has been read, or after calling
     * one of the methods skipToEnd(), getStringValue(), or getTypedValue().</p>*
     */

    public NamespaceDeclarations getNamespaceDeclarations() throws XPathException {
        if (parser.get_HasAttributes()) {
            int limit = parser.get_AttributeCount();
            int[] nscodes = new int[limit];
            int used = 0;
            for (int i=0; i<limit; i++) {
                parser.MoveToAttribute(i);
                final String prefix = parser.get_Prefix();
                final String localName = parser.get_LocalName();
                if ("xmlns".equals(prefix))  {
                    int nscode = pool.allocateNamespaceCode(localName, parser.get_Value());
                    nscodes[used++] = nscode;
                } else if ("".equals(prefix) && "xmlns".equals(localName)) {
                    int nscode = pool.allocateNamespaceCode("", parser.get_Value());
                    nscodes[used++] = nscode;
                } else {
                    // ignore real attributes
                }
            }
            if (used < limit) {
                nscodes[used] = -1;
            }
            return new NamespaceDeclarationsImpl(pool, nscodes);
        } else {
            return EmptyNamespaceDeclarationList.getInstance();
        }

    }

    /**
     * Get configuration information.
     */

    public PipelineConfiguration getPipelineConfiguration() {
        return pipe;
    }

    /**
     * Get the location of the current event.
     * For an event stream representing a real document, the location information
     * should identify the location in the lexical XML source. For a constructed document, it should
     * identify the location in the query or stylesheet that caused the node to be created.
     * A value of null can be returned if no location information is available.
     */

    public SourceLocator getSourceLocator() {
        if (parser instanceof XmlTextReader || parser instanceof XmlValidatingReader) {
            return this;
        } else {
            return null;
        }
    }

    /**
     * Get the string value of the current element, text node, processing-instruction,
     * or top-level attribute or namespace node, or atomic value.
     * <p/>
     * <p>In other situations the result is undefined and may result in an IllegalStateException.</p>
     * <p/>
     * <p>If the most recent event was a {@link #START_ELEMENT}, this method causes the content
     * of the element to be read. The current event on completion of this method will be the
     * corresponding {@link #END_ELEMENT}. The next call of next() will return the event following
     * the END_ELEMENT event.</p>
     *
     * @return the String Value of the node in question, defined according to the rules in the
     *         XPath data model.
     */

    public CharSequence getStringValue() throws XPathException {
        if (current == TEXT) {
            return CompressedWhitespace.compress(parser.get_Value());
        } else {
            return parser.get_Value();
        }
    }

    /**
     * Get the type annotation of the current attribute or element node, or atomic value.
     * The result of this method is undefined unless the most recent event was START_ELEMENT,
     * ATTRIBUTE, or ATOMIC_VALUE.  In the case of an attribute node, the additional bit NodeInfo.IS_DTD_TYPE
     * may be set to indicate a DTD-derived ID or IDREF/S type.
     *
     * @return the type annotation. This code is the fingerprint of a type name, which may be
     *         resolved to a {@link net.sf.saxon.type.SchemaType} by access to the Configuration.
     */

    public int getTypeAnnotation() {
        return StandardNames.XS_UNTYPED;
    }

    /**
     * Get the next event
     *
     * @return an integer code indicating the type of event. The code
     *         {@link #END_OF_INPUT} is returned at the end of the sequence.
     */

    public int next() throws XPathException {
        //System.err.println("next(), current = " + current + " empty: " + isEmptyElement);
        if (current == START_OF_INPUT) {
            current = START_DOCUMENT;
            return current;
        } else if (current == END_DOCUMENT || current == END_OF_INPUT) {
            current = END_OF_INPUT;
            return current;
        } else if (current == START_ELEMENT && isEmptyElement) {
            current = END_ELEMENT;
            return current;
        }

        do {
            try {
                parser.Read();
                //noinspection ConstantIfStatement
                if (false) throw new XmlException("dummy"); // keeps the compiler happy
                //noinspection ConstantIfStatement
                if (false) throw new XmlSchemaException("dummy", new XmlException("dummy")); // keeps the compiler happy
            } catch (XmlException e) {
                XPathException de = new XPathException("Error reported by XML parser: " + e.getMessage(), e);
                ExpressionLocation loc = new ExpressionLocation();
                loc.setSystemId(getSystemId());
                loc.setLineNumber(e.get_LineNumber());
                loc.setColumnNumber(e.get_LinePosition());
                de.setLocator(loc);
                throw de;
            } catch (XmlSchemaException e) {
                XPathException de = new XPathException("Validation error reported by XML parser: " + e.getMessage(), e);
                ExpressionLocation loc = new ExpressionLocation();
                loc.setSystemId(getSystemId());
                loc.setLineNumber(e.get_LineNumber());
                //System.err.println("** parser reported line " + e.get_LineNumber());
                loc.setColumnNumber(e.get_LinePosition());
                de.setLocator(loc);
                throw de;
            } catch (Exception e) {
                // The Microsoft spec says that the only exception thrown is XmlException. But
                // we've seen others, for example System.IO.FileNotFoundException when the DTD can't
                // be located
                XPathException de = new XPathException("Error reported by XML parser: " + e.getMessage(), e);
                ExpressionLocation loc = new ExpressionLocation();
                loc.setSystemId(getSystemId());
                de.setLocator(loc);
                throw de;
            }
            int intype = parser.get_NodeType().Value;
            isEmptyElement = parser.get_IsEmptyElement();
            //System.err.println("Next event: " + intype + " at depth " + parser.get_Depth() + " empty: " + isEmptyElement + "," + parser.get_IsEmptyElement());
            if (parser.get_EOF()) {
                current = END_DOCUMENT;
                return current;
            }
            if (intype == XmlNodeType.EntityReference) {
                //parser.ResolveEntity();
                current = -1;
            } else {
                current = mapInputKindToOutputKind(intype);
                if (current == TEXT && parser.get_Depth() == 0) {
                    current = -1;
                }
            }
        } while (current == -1);

        return current;
    }

    /**
     * Map the numbers used to identify events in the .NET XMLReader interface to the numbers used
     * by the Saxon PullProvider interface
     * @param in the XMLReader event number
     * @return the Saxon PullProvider event number
     */

    private int mapInputKindToOutputKind(int in) {
        // Note: we are losing unparsedEntities - see test expr02. Apparently unparsed entities are not
        // available via an XMLValidatingReader. We would have to build a DOM to get them, and that's too high
        // a price to pay.
        switch (in) {
            case XmlNodeType.Attribute:
                return PullProvider.ATTRIBUTE;
            case XmlNodeType.CDATA:
                return PullProvider.TEXT;
            case XmlNodeType.Comment:
                return PullProvider.COMMENT;
            case XmlNodeType.Document:
                return PullProvider.START_DOCUMENT;
            case XmlNodeType.DocumentFragment:
                return PullProvider.START_DOCUMENT;
            case XmlNodeType.Element:
                return PullProvider.START_ELEMENT;
            case XmlNodeType.EndElement:
                return PullProvider.END_ELEMENT;
            case XmlNodeType.ProcessingInstruction:
                return PullProvider.PROCESSING_INSTRUCTION;
            case XmlNodeType.SignificantWhitespace:
                //System.err.println("Significant whitespace");
                return PullProvider.TEXT;
            case XmlNodeType.Text:
                return PullProvider.TEXT;
            case XmlNodeType.Whitespace:
                //System.err.println("Plain whitespace");
                return PullProvider.TEXT;
                //return -1;
            default:
                return -1;
        }
    }

    /**
     * Set configuration information. This must only be called before any events
     * have been read.
     */

    public void setPipelineConfiguration(PipelineConfiguration pipe) {
        this.pipe = pipe;
        pool = pipe.getConfiguration().getNamePool();
    }

    /**
     * Skip the current subtree. This method may be called only immediately after
     * a START_DOCUMENT or START_ELEMENT event. This call returns the matching
     * END_DOCUMENT or END_ELEMENT event; the next call on next() will return
     * the event following the END_DOCUMENT or END_ELEMENT.
     *
     * @throws IllegalStateException if the method is called at any time other than
     *                               immediately after a START_DOCUMENT or START_ELEMENT event.
     */

    public int skipToMatchingEnd() throws XPathException {
        if (current == START_ELEMENT) {
            current = END_ELEMENT;
            parser.Skip();
        } else if (current == START_DOCUMENT) {
            current = END_DOCUMENT;
        } else {
            throw new IllegalStateException(current + "");
        }
        return current;
    }

    /**
     * Return the character position where the current document event ends.
     * <p/>
     * <p><strong>Warning:</strong> The return value from the method
     * is intended only as an approximation for the sake of error
     * reporting; it is not intended to provide sufficient information
     * to edit the character content of the original XML document.</p>
     * <p/>
     * <p>The return value is an approximation of the column number
     * in the document entity or external parsed entity where the
     * markup that triggered the event appears.</p>
     *
     * @return The column number, or -1 if none is available.
     * @see #getLineNumber
     */
    public int getColumnNumber() {
        if (parser instanceof XmlTextReader) {
            return ((XmlTextReader)parser).get_LinePosition();
        } else if (parser instanceof XmlValidatingReader) {
            return ((XmlValidatingReader)parser).get_LinePosition();
        } else {
            return -1;
        }
    }

    /**
     * Return the line number where the current document event ends.
     * <p/>
     * <p><strong>Warning:</strong> The return value from the method
     * is intended only as an approximation for the sake of error
     * reporting; it is not intended to provide sufficient information
     * to edit the character content of the original XML document.</p>
     * <p/>
     * <p>The return value is an approximation of the line number
     * in the document entity or external parsed entity where the
     * markup that triggered the event appears.</p>
     *
     * @return The line number, or -1 if none is available.
     * @see #getColumnNumber
     */
    public int getLineNumber() {
        if (parser instanceof XmlTextReader) {
            //System.err.println("DotNetPullProvider lineNumber = " + ((XmlTextReader)parser).get_LineNumber());
            return ((XmlTextReader)parser).get_LineNumber();
        } else if (parser instanceof XmlValidatingReader) {
            return ((XmlValidatingReader)parser).get_LineNumber();
        } else {
            return -1;
        }
    }

    /**
     * Return the public identifier for the current document event.
     * <p/>
     * <p>The return value is the public identifier of the document
     * entity or of the external parsed entity in which the markup that
     * triggered the event appears.</p>
     *
     * @return A string containing the public identifier, or
     *         null if none is available.
     * @see #getSystemId
     */
    public String getPublicId() {
        return null;
    }

    /**
     * Return the system identifier for the current document event.
     * <p/>
     * <p>The return value is the system identifier of the document
     * entity or of the external parsed entity in which the markup that
     * triggered the event appears.</p>
     * <p/>
     * <p>If the system identifier is a URL, the parser must resolve it
     * fully before passing it to the application.</p>
     *
     * @return A string containing the system identifier, or null
     *         if none is available.
     * @see #getPublicId
     */
    public String getSystemId() {
        String base = parser.get_BaseURI();
        if (base == null || base.length() == 0) {
            return baseURI;
        } else {
            return base;
        }
    }

    public int getLineNumber(long locationId) {
        return getLineNumber();
    }

    public int getColumnNumber(long locationId) {
        return getColumnNumber();
    }

    public String getSystemId(long locationId) {
        return getSystemId();
    }

    /**
     * Get a list of unparsed entities.
     *
     * @return a list of unparsed entities, or null if the information is not available, or
     *         an empty list if there are no unparsed entities.
     */

    public List getUnparsedEntities() {
        return null; 
    }

}

//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (the "License");
// you may not use this file except in compliance with the License. You may obtain a copy of the
// License at http://www.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//
