/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.maven.impl;

import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.CharArrayReader;
import java.io.CharArrayWriter;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.net.URL;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.function.Function;

import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.di.Named;
import org.apache.maven.api.di.Singleton;
import org.apache.maven.api.model.InputLocation;
import org.apache.maven.api.model.InputSource;
import org.apache.maven.api.model.Model;
import org.apache.maven.api.services.xml.ModelXmlFactory;
import org.apache.maven.api.services.xml.XmlReaderException;
import org.apache.maven.api.services.xml.XmlReaderRequest;
import org.apache.maven.api.services.xml.XmlWriterException;
import org.apache.maven.api.services.xml.XmlWriterRequest;
import org.apache.maven.api.xml.XmlService;
import org.apache.maven.model.v4.MavenStaxReader;
import org.apache.maven.model.v4.MavenStaxWriter;

import static java.util.Objects.requireNonNull;
import static org.apache.maven.impl.StaxLocation.getLocation;
import static org.apache.maven.impl.StaxLocation.getMessage;

@Named
@Singleton
public class DefaultModelXmlFactory implements ModelXmlFactory {
    @Override
    @Nonnull
    public Model read(@Nonnull XmlReaderRequest request) throws XmlReaderException {
        requireNonNull(request, "request");
        Model model = doRead(request);
        if (isModelVersionGreaterThan400(model)
                && !model.getNamespaceUri().startsWith("http://maven.apache.org/POM/")) {
            throw new XmlReaderException(
                    "Invalid namespace '" + model.getNamespaceUri() + "' for model version " + model.getModelVersion(),
                    null,
                    null);
        }
        return model;
    }

    private boolean isModelVersionGreaterThan400(Model model) {
        String version = model.getModelVersion();
        if (version == null) {
            return false;
        }
        try {
            String[] parts = version.split("\\.");
            int major = Integer.parseInt(parts[0]);
            int minor = parts.length > 1 ? Integer.parseInt(parts[1]) : 0;
            return major > 4 || (major == 4 && minor > 0);
        } catch (NumberFormatException | IndexOutOfBoundsException e) {
            return false;
        }
    }

    @Nonnull
    private Model doRead(XmlReaderRequest request) throws XmlReaderException {
        Path path = request.getPath();
        URL url = request.getURL();
        Reader reader = request.getReader();
        InputStream inputStream = request.getInputStream();
        if (path == null && url == null && reader == null && inputStream == null) {
            throw new IllegalArgumentException("path, url, reader or inputStream must be non null");
        }
        try {
            String modelId = request.getModelId();

            if (modelId == null) {
                if (inputStream != null) {
                    ByteArrayOutputStream baos = new ByteArrayOutputStream();
                    inputStream.transferTo(baos);
                    byte[] buf = baos.toByteArray();
                    modelId = extractModelId(new ByteArrayInputStream(buf));
                    inputStream = new ByteArrayInputStream(buf);
                } else if (reader != null) {
                    CharArrayWriter caw = new CharArrayWriter();
                    reader.transferTo(caw);
                    char[] buf = caw.toCharArray();
                    modelId = extractModelId(new CharArrayReader(buf));
                    reader = new CharArrayReader(buf);
                } else if (path != null) {
                    try (InputStream is = Files.newInputStream(path)) {
                        modelId = extractModelId(is);
                    }
                }
            }

            InputSource source = null;
            if (modelId != null || request.getLocation() != null) {
                source = new InputSource(modelId, path != null ? path.toUri().toString() : null);
            }
            MavenStaxReader xml = request.getTransformer() != null
                    ? new MavenStaxReader(request.getTransformer()::transform)
                    : new MavenStaxReader();
            xml.setAddDefaultEntities(request.isAddDefaultEntities());
            if (inputStream != null) {
                return xml.read(inputStream, request.isStrict(), source);
            } else if (reader != null) {
                return xml.read(reader, request.isStrict(), source);
            } else if (path != null) {
                try (InputStream is = Files.newInputStream(path)) {
                    return xml.read(is, request.isStrict(), source);
                }
            } else {
                try (InputStream is = url.openStream()) {
                    return xml.read(is, request.isStrict(), source);
                }
            }
        } catch (Exception e) {
            throw new XmlReaderException("Unable to read model: " + getMessage(e), getLocation(e), e);
        }
    }

    private static String extractModelId(InputStream inputStream) {
        try {
            XMLStreamReader xmlReader = XmlService.newXMLInputFactory().createXMLStreamReader(inputStream);
            try {
                return extractModelId(xmlReader);
            } finally {
                xmlReader.close();
            }
        } catch (Exception e) {
            return null;
        }
    }

    private static String extractModelId(Reader reader) {
        try {
            XMLStreamReader xmlReader = XmlService.newXMLInputFactory().createXMLStreamReader(reader);
            try {
                return extractModelId(xmlReader);
            } finally {
                xmlReader.close();
            }
        } catch (Exception e) {
            return null;
        }
    }

    private static String extractModelId(XMLStreamReader reader) throws XMLStreamException {
        String groupId = null;
        String artifactId = null;
        String version = null;
        String parentGroupId = null;
        String parentVersion = null;

        int depth = 0;
        boolean inProject = false;
        boolean inParent = false;
        String currentElement = null;

        while (reader.hasNext()) {
            int event = reader.next();

            if (event == XMLStreamConstants.START_ELEMENT) {
                depth++;
                String localName = reader.getLocalName();

                if (depth == 1 && "project".equals(localName)) {
                    inProject = true;
                } else if (inProject && depth == 2 && "parent".equals(localName)) {
                    inParent = true;
                } else if (inProject
                        && (depth == 2 || (depth == 3 && inParent))
                        && ("groupId".equals(localName)
                                || "artifactId".equals(localName)
                                || "version".equals(localName))) {
                    currentElement = localName;
                }
            } else if (event == XMLStreamConstants.END_ELEMENT) {
                String localName = reader.getLocalName();

                if ("parent".equals(localName)) {
                    inParent = false;
                } else if ("project".equals(localName)) {
                    break;
                }
                currentElement = null;
                depth--;
            } else if (event == XMLStreamConstants.CHARACTERS && currentElement != null) {
                String text = reader.getText().trim();
                if (!text.isEmpty()) {
                    if (inParent) {
                        switch (currentElement) {
                            case "groupId":
                                parentGroupId = text;
                                break;
                            case "version":
                                parentVersion = text;
                                break;
                            default:
                                break;
                        }
                    } else {
                        switch (currentElement) {
                            case "groupId":
                                groupId = text;
                                break;
                            case "artifactId":
                                artifactId = text;
                                break;
                            case "version":
                                version = text;
                                break;
                            default:
                                break;
                        }
                    }
                }
            }

            if (groupId != null && artifactId != null && version != null) {
                break;
            }
        }

        if (groupId == null) {
            groupId = parentGroupId;
        }
        if (version == null) {
            version = parentVersion;
        }

        if (groupId != null && artifactId != null && version != null) {
            return groupId + ":" + artifactId + ":" + version;
        }

        return null;
    }

    @Override
    public void write(XmlWriterRequest<Model> request) throws XmlWriterException {
        requireNonNull(request, "request");
        Model content = requireNonNull(request.getContent(), "content");
        Path path = request.getPath();
        OutputStream outputStream = request.getOutputStream();
        Writer writer = request.getWriter();

        if (writer == null && outputStream == null && path == null) {
            throw new IllegalArgumentException("writer, outputStream or path must be non null");
        }

        try {
            MavenStaxWriter xmlWriter = new MavenStaxWriter();
            xmlWriter.setAddLocationInformation(false);

            Function<Object, String> formatter = request.getInputLocationFormatter();
            if (formatter != null) {
                xmlWriter.setAddLocationInformation(true);
                Function<InputLocation, String> adapter = formatter::apply;
                xmlWriter.setStringFormatter(adapter);
            }

            if (writer != null) {
                xmlWriter.write(writer, content);
            } else if (outputStream != null) {
                xmlWriter.write(outputStream, content);
            } else {
                try (OutputStream os = Files.newOutputStream(path)) {
                    xmlWriter.write(os, content);
                }
            }
        } catch (Exception e) {
            throw new XmlWriterException("Unable to write model: " + getMessage(e), getLocation(e), e);
        }
    }

    /**
     * Simply parse the given xml string.
     *
     * @param xml the input XML string
     * @return the parsed object
     * @throws XmlReaderException if an error occurs during the parsing
     * @see #toXmlString(Object)
     */
    public static Model fromXml(@Nonnull String xml) throws XmlReaderException {
        return new DefaultModelXmlFactory().fromXmlString(xml);
    }

    /**
     * Simply converts the given content to an XML string.
     *
     * @param content the object to convert
     * @return the XML string representation
     * @throws XmlWriterException if an error occurs during the transformation
     * @see #fromXmlString(String)
     */
    public static String toXml(@Nonnull Model content) throws XmlWriterException {
        return new DefaultModelXmlFactory().toXmlString(content);
    }
}
