/*   Copyright 2004 The Apache Software Foundation
 *
 *   Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.xmlbeans.impl.marshal;

import org.apache.xmlbeans.Marshaller;
import org.apache.xmlbeans.XmlException;
import org.apache.xmlbeans.XmlObject;
import org.apache.xmlbeans.XmlOptions;
import org.apache.xmlbeans.impl.binding.bts.BindingLoader;
import org.apache.xmlbeans.impl.binding.bts.BindingType;
import org.apache.xmlbeans.impl.binding.bts.BindingTypeName;
import org.apache.xmlbeans.impl.binding.bts.JavaTypeName;
import org.apache.xmlbeans.impl.binding.bts.SimpleDocumentBinding;
import org.apache.xmlbeans.impl.binding.bts.XmlTypeName;

import javax.xml.namespace.NamespaceContext;
import javax.xml.namespace.QName;
import javax.xml.stream.XMLOutputFactory;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;
import javax.xml.stream.XMLStreamWriter;
import java.io.IOException;
import java.io.OutputStream;

final class MarshallerImpl
    implements Marshaller
{
    //per binding context constants
    private final BindingLoader loader;
    private final RuntimeBindingTypeTable typeTable;

    private static final XMLOutputFactory XML_OUTPUT_FACTORY =
        XMLOutputFactory.newInstance();

    private static final String XML_VERSION = "1.0";

    public MarshallerImpl(BindingLoader loader,
                          RuntimeBindingTypeTable typeTable)
    {
        this.loader = loader;
        this.typeTable = typeTable;
    }

    public XMLStreamReader marshal(Object obj,
                                   NamespaceContext nscontext)
        throws XmlException
    {
        final JavaTypeName jname = determineJavaType(obj);
        final XmlTypeName elem = lookupRootElementName(jname);
        final BindingType btype = loadBindingTypeForGlobalElem(elem, jname, obj);
        return createMarshalResult(btype, elem.getQName(), nscontext, obj);
    }

    private XmlTypeName lookupRootElementName(final JavaTypeName jname)
        throws XmlException
    {
        final BindingTypeName root_elem_btype = loader.lookupElementFor(jname);
        if (root_elem_btype == null) {
            final String msg = "failed to find root " +
                "element corresponding to " + jname;
            throw new XmlException(msg);
        }

        final XmlTypeName elem = root_elem_btype.getXmlName();
        assert elem.getComponentType() == XmlTypeName.ELEMENT;
        return elem;
    }


    private PullMarshalResult createMarshalResult(final BindingType btype,
                                                  QName elem_qn,
                                                  NamespaceContext nscontext,
                                                  Object obj)
        throws XmlException
    {
        assert btype != null;

        final RuntimeBindingType runtime_type =
            typeTable.createRuntimeType(btype, loader);

        runtime_type.checkInstance(obj);

        RuntimeGlobalProperty prop =
            new RuntimeGlobalProperty(elem_qn, runtime_type);

        return new LiteralMarshalResult(loader, typeTable,
                                        nscontext, prop, obj, null);
    }


    public XMLStreamReader marshal(Object obj,
                                   XmlOptions options)
        throws XmlException
    {
        //TODO: actually use the options!
        NamespaceContext nscontext = getNamespaceContextFromOptions(options);
        return marshal(obj, nscontext);
    }

    private static JavaTypeName determineJavaType(Object obj)
    {
        return determineJavaType(obj.getClass());
    }

    private static JavaTypeName determineJavaType(Class clazz)
    {
        return JavaTypeName.forClassName(clazz.getName());
    }

    public void marshal(XMLStreamWriter writer, Object obj)
        throws XmlException
    {
        marshal(writer, obj, null);
    }

    public void marshal(XMLStreamWriter writer, Object obj, XmlOptions options)
        throws XmlException
    {
        //TODO: javadoc that pretty is not supported here.

        final JavaTypeName jname = determineJavaType(obj);
        final XmlTypeName elem = lookupRootElementName(jname);
        BindingType btype = loadBindingTypeForGlobalElem(elem, jname, obj);

        String encoding = getEncoding(options);
        try {
            if (encoding != null) {
                writer.writeStartDocument(encoding, XML_VERSION);
            }
            marshalBindingType(writer, btype, obj, elem.getQName());
            writer.writeEndDocument();
        }
        catch (XMLStreamException e) {
            throw new XmlException(e);
        }
    }

    private BindingType loadBindingTypeForGlobalElem(final XmlTypeName elem,
                                                     final JavaTypeName jname,
                                                     Object obj)
        throws XmlException
    {
        final XmlTypeName elem_type =
            determineDocumentType(elem).getTypeOfElement();
        final BindingType btype = loadBindingType(elem_type, jname, loader);
        if (btype == null) {
            final String msg = "failed to find a suitable binding type for" +
                " use in marshalling object \"" + obj + "\". " +
                " using schema type: " + elem_type;
            throw new XmlException(msg);
        }
        return btype;
    }

    private static String getEncoding(XmlOptions options)
    {
        return (String)XmlOptions.safeGet(options,
                                          XmlOptions.CHARACTER_ENCODING);
    }

    public void marshal(OutputStream out, Object obj)
        throws XmlException
    {
        marshal(out, obj, (XmlOptions)null);
    }

    public void marshal(OutputStream out, Object obj, XmlOptions options)
        throws XmlException
    {
        if (options != null && options.hasOption(XmlOptions.SAVE_PRETTY_PRINT)) {
            marshalPretty(out, obj, options);
        } else {
            final String encoding = getEncoding(options);
            final XMLStreamWriter writer;
            try {
                writer = createXmlStreamWriter(out, encoding);
                marshal(writer, obj);
                writer.close();
            }
            catch (XMLStreamException e) {
                throw new XmlException(e);
            }
        }
    }


    private void marshalPretty(OutputStream out,
                               Object obj,
                               XmlOptions options)
        throws XmlException
    {
        NamespaceContext nscontext = getNamespaceContextFromOptions(options);
        XMLStreamReader rdr = marshal(obj, nscontext);
        XmlObject xobj = XmlObject.Factory.parse(rdr);
        try {
            xobj.save(out, options);
        }
        catch (IOException e) {
            throw new XmlException(e);
        }
    }

    private static XMLStreamWriter createXmlStreamWriter(OutputStream out,
                                                         final String encoding)
        throws XMLStreamException
    {
        final XMLStreamWriter writer;
        if (encoding != null) {
            writer = XML_OUTPUT_FACTORY.createXMLStreamWriter(out, encoding);
        } else {
            writer = XML_OUTPUT_FACTORY.createXMLStreamWriter(out);
        }
        return writer;
    }

    public void marshal(OutputStream out, Object obj, String encoding)
        throws XmlException
    {
        if (encoding == null) {
            throw new IllegalArgumentException("null encoding");
        }

        XmlOptions opts = new XmlOptions();
        opts.setCharacterEncoding(encoding);

        marshal(out, obj, opts);
    }


    public XMLStreamReader marshalType(Object obj,
                                       QName elementName,
                                       QName schemaType,
                                       String javaType,
                                       NamespaceContext namespaceContext)
        throws XmlException
    {
        BindingType type = lookupBindingType(schemaType, javaType,
                                             elementName, obj, loader);

        return createMarshalResult(type, elementName, namespaceContext, obj);
    }

    static BindingType lookupBindingType(QName schemaType,
                                         String javaType,
                                         QName elementName,
                                         Object obj,
                                         BindingLoader loader)
        throws XmlException
    {
        return lookupBindingType(XmlTypeName.forTypeNamed(schemaType),
                                 javaType,
                                 elementName, obj, loader);
    }

    private static BindingType lookupBindingType(XmlTypeName schema_type,
                                                 String javaType,
                                                 QName elementName,
                                                 Object obj,
                                                 BindingLoader loader)
        throws XmlException
    {
        final BindingType type =
            loadBindingType(schema_type,
                            JavaTypeName.forClassName(javaType),
                            loader);

        if (type == null) {
            final String msg = "failed to find a suitable binding type for" +
                " use in marshalling \"" + elementName + "\". " +
                " using java type: " + javaType +
                " schema type: " + schema_type +
                " instance type: " + obj.getClass().getName();
            throw new XmlException(msg);
        }
        return type;
    }

    public void marshalType(XMLStreamWriter writer,
                            Object obj,
                            QName elementName,
                            QName schemaType,
                            String javaType)
        throws XmlException
    {
        final BindingType btype = lookupBindingType(schemaType, javaType,
                                                    elementName, obj, loader);
        assert btype != null;

        marshalBindingType(writer, btype, obj, elementName);
    }

    private void marshalBindingType(XMLStreamWriter writer,
                                    final BindingType btype,
                                    final Object obj,
                                    QName elementName)
        throws XmlException
    {
        final RuntimeBindingType runtime_type =
            typeTable.createRuntimeType(btype, loader);

        runtime_type.checkInstance(obj);

        final RuntimeGlobalProperty prop =
            new RuntimeGlobalProperty(elementName, runtime_type);

        final PushMarshalResult pmr =
            new LiteralPushMarshalResult(loader, typeTable, writer, null);

        final RuntimeBindingType actual_rtt =
            prop.getActualRuntimeType(obj, pmr);
        pmr.marshalType(obj, prop, actual_rtt);
    }

    public void marshalElement(XMLStreamWriter writer,
                               Object obj,
                               QName elementName,
                               String javaType,
                               XmlOptions options)
        throws XmlException
    {
        if (writer == null)
            throw new IllegalArgumentException("null writer");

        final XmlTypeName elem_name =
            XmlTypeName.forGlobalName(XmlTypeName.ELEMENT, elementName);

        final BindingType btype =
            loadBindingTypeForGlobalElem(elem_name,
                                         determineJavaType(obj), obj);

        marshalBindingType(writer, btype, obj, elementName);
    }

    public void marshalType(XMLStreamWriter writer,
                            Object obj,
                            QName elementName,
                            QName schemaType,
                            String javaType,
                            XmlOptions options)
        throws XmlException
    {
        marshalType(writer, obj, elementName, schemaType, javaType);
    }

    public XMLStreamReader marshalType(Object obj,
                                       QName elementName,
                                       QName schemaType,
                                       String javaType,
                                       XmlOptions options)
        throws XmlException
    {
        NamespaceContext nscontext = getNamespaceContextFromOptions(options);

        return marshalType(obj, elementName, schemaType, javaType,
                           nscontext);
    }

    public XMLStreamReader marshalElement(Object obj,
                                          QName elementName,
                                          String javaType,
                                          XmlOptions options)
        throws XmlException
    {
        if (elementName == null)
            throw new IllegalArgumentException("null elementName");

        //TODO: we could allow javaType to be null in which case we could
        //use our usual lookup methods (as in plain marshal)
        if (javaType == null)
            throw new IllegalArgumentException("null javaType");


        final SimpleDocumentBinding doc_binding =
            determineDocumentType(elementName);

        final XmlTypeName elem_type = doc_binding.getTypeOfElement();

        final BindingType type =
            lookupBindingType(elem_type, javaType, elementName, obj, loader);

        NamespaceContext nscontext = getNamespaceContextFromOptions(options);
        return createMarshalResult(type, elementName,
                                   nscontext, obj);
    }

    static NamespaceContext getNamespaceContextFromOptions(XmlOptions options)
    {
        //TODO: do this properly
        return EmptyNamespaceContext.getInstance();
    }

    private SimpleDocumentBinding determineDocumentType(QName global_element)
        throws XmlException
    {
        final XmlTypeName type_name =
            XmlTypeName.forGlobalName(XmlTypeName.ELEMENT, global_element);
        return determineDocumentType(type_name);
    }

    private SimpleDocumentBinding determineDocumentType(XmlTypeName global_element)
        throws XmlException
    {
        BindingType doc_binding_type = getPojoBindingType(global_element);
        assert doc_binding_type != null;
        return (SimpleDocumentBinding)doc_binding_type;
    }


    private BindingType getPojoBindingType(final XmlTypeName type_name)
        throws XmlException
    {
        final BindingTypeName btName = loader.lookupPojoFor(type_name);
        if (btName == null) {
            final String msg = "failed to load java type corresponding " +
                "to " + type_name;
            throw new XmlException(msg);
        }

        BindingType bt = loader.getBindingType(btName);

        if (bt == null) {
            final String msg = "failed to load BindingType for " + btName;
            throw new XmlException(msg);
        }

        assert bt != null;
        return bt;
    }


    //TODO: refine this algorithm to deal better
    //with primitives/interfaces/other oddities
    //we are basically just walking up the super types
    //till we hit a class that we can deal with.

    //returns null if we fail
    static BindingType lookupBindingType(Class instance_type,
                                         JavaTypeName java_type,
                                         XmlTypeName xml_type,
                                         BindingLoader loader)
        throws XmlException
    {
        //look first for exact match
        {
            JavaTypeName jname = determineJavaType(instance_type);
            BindingType bt = loadBindingType(xml_type, jname, loader);
            if (bt != null) return bt;  //success!
        }


        BindingType binding_type = null;
        Class curr_class = instance_type;
        Class super_type = null;

        while (true) {
            JavaTypeName jname = determineJavaType(curr_class);

            BindingTypeName btype_name = loader.lookupTypeFor(jname);
            if (btype_name != null) {
                binding_type = loader.getBindingType(btype_name);
                if (binding_type == null) {
                    String e = "binding configuration inconsistency: found " +
                        btype_name + " defined for " + jname + " but failed " +
                        "to load the type";
                    throw new XmlException(e);
                } else {
                    return binding_type; //success!
                }
            }

            super_type = curr_class.getSuperclass();

            //note that we check that this super-super type check is to avoid
            //getting a match on java.lang.Object, which doesn't do us any good
            if (super_type == null || (super_type.getSuperclass() == null)) {
                break;
            }

            curr_class = super_type;
        }

        //reaching here means that we've failed using the actual instance,
        //so let's try the expected type
        assert (binding_type == null);
        return loadBindingType(xml_type, java_type, loader);
    }


    private static BindingType loadBindingType(XmlTypeName xname,
                                               JavaTypeName jname,
                                               BindingLoader loader)
    {
        BindingTypeName btname = BindingTypeName.forPair(jname, xname);
        return loader.getBindingType(btname);
    }

}