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package com.crabshue.commons.xml;

import java.io.File;
import java.io.IOException;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.xml.sax.EntityResolver;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import com.crabshue.commons.exceptions.ApplicationException;
import com.crabshue.commons.exceptions.SystemException;
import com.crabshue.commons.xml.error.XmlErrorHandler;
import com.crabshue.commons.xml.exceptions.XmlErrorType;
import com.crabshue.commons.xml.inputsource.InputSourceBuilder;
import lombok.NonNull;
import net.sf.saxon.lib.StandardEntityResolver;

/**
 * {@link Document} builder from various XML document sources.
 * 
 * Default options for {@link DocumentBuilderFactory} are:
 * 
 * 
 * namespaceAware: true
 * validating: false
 * 
 * 
 * Default {@link ErrorHandler} for {@link DocumentBuilder}: {@link XmlErrorHandler}.
 * 
 *
 */
public class XmlDocumentBuilder {

    private InputSource inputSource;

    private boolean namespaceAware = true;

    private boolean validationEnabled = false;

    private ErrorHandler errorHandler = new XmlErrorHandler();

    private EntityResolver entityResolver = new StandardEntityResolver();

    /**
     * Start a {@link XmlDocumentBuilder} based on a {@link InputSource}.
     *
     * @param inputSource the XML input source.
     * @return a new instance of {@link XmlDocumentBuilder}
     */
    public static XmlDocumentBuilder of(@NonNull final InputSource inputSource) {

        final XmlDocumentBuilder ret = new XmlDocumentBuilder();
        ret.inputSource = inputSource;
        return ret;
    }


    /**
     * Start a {@link XmlDocumentBuilder} based on an {@link File XML file}.
     *
     * @param xmlFile the XML file.
     * @return a new instance of {@link XmlDocumentBuilder}
     */
    public static XmlDocumentBuilder of(@NonNull final File xmlFile) {

        return XmlDocumentBuilder.of(InputSourceBuilder.newInputSource(xmlFile));
    }

    /**
     * Start a {@link XmlDocumentBuilder} based on an {@link String XML as a string}.
     *
     * @param xmlAsString the XML file.
     * @return a new instance of {@link XmlDocumentBuilder}
     */
    public static XmlDocumentBuilder of(@NonNull final String xmlAsString) {

        return XmlDocumentBuilder.of(InputSourceBuilder.newInputSource(xmlAsString));
    }

    /**
     * Set option {@code namespaceAware} of {@link DocumentBuilderFactory}.
     *
     * @param namespaceAware toggle namespace awareness.
     * @return the current {@link XmlDocumentBuilder} instance
     */
    public XmlDocumentBuilder withNamespaceAwareness(@NonNull final boolean namespaceAware) {

        this.namespaceAware = namespaceAware;
        return this;
    }

    /**
     * Set option {@code validating} of {@link DocumentBuilderFactory}.
     *
     * @param validationEnabled toggle validation.
     * @return the current {@link XmlDocumentBuilder} instance
     */
    public XmlDocumentBuilder withValidationEnabled(@NonNull final boolean validationEnabled) {

        this.validationEnabled = validationEnabled;
        return this;
    }

    /**
     * Set {@link ErrorHandler}.
     *
     * @param errorHandler the error handler.
     * @return the current {@link XmlDocumentBuilder} instance
     */
    public XmlDocumentBuilder withErrorHandler(@NonNull final ErrorHandler errorHandler) {

        this.errorHandler = errorHandler;
        return this;
    }

    public XmlDocumentBuilder withEntityResolver(@NonNull final EntityResolver entityResolver) {

        this.entityResolver = entityResolver;
        return this;
    }

    /**
     * Build the {@link Document XML document}.
     *
     * @return the built XML document.
     */
    public Document build() {
        final DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
        dbf.setNamespaceAware(this.namespaceAware);
        dbf.setValidating(this.validationEnabled);

        final DocumentBuilder documentBuilder;
        try {
            documentBuilder = dbf.newDocumentBuilder();
        } catch (ParserConfigurationException e) {
            throw new SystemException(XmlErrorType.DOCUMENT_BUILDER_INITIALIZATION_ISSUE, e);
        }

        documentBuilder.setErrorHandler(this.errorHandler);

        documentBuilder.setEntityResolver(this.entityResolver);

        final Document ret;
        try {
            ret = documentBuilder.parse(this.inputSource);
        } catch (SAXException e) {
            throw new ApplicationException(XmlErrorType.ERROR_PARSING_XML, e);
        } catch (IOException e) {
            throw new SystemException(XmlErrorType.ERROR_PARSING_XML, e);
        }

        return ret;
    }

    private XmlDocumentBuilder() {
    }
}