/*
    * Metis: Java Data Framework
    * Copyright 2012-2026. Tony Washer
    *
    * 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 io.github.tonywasher.joceanus.metis.viewer;
  
  import io.github.tonywasher.joceanus.metis.data.MetisDataDelta;
  import io.github.tonywasher.joceanus.metis.data.MetisDataDifference;
  import io.github.tonywasher.joceanus.metis.exc.MetisIOException;
  import io.github.tonywasher.joceanus.oceanus.base.OceanusException;
  import io.github.tonywasher.joceanus.oceanus.format.OceanusDataFormatter;
  import io.github.tonywasher.joceanus.oceanus.logger.OceanusLogManager;
  import io.github.tonywasher.joceanus.oceanus.logger.OceanusLogger;
  import org.w3c.dom.Document;
  import org.w3c.dom.Element;
  
  import javax.xml.XMLConstants;
  import javax.xml.parsers.DocumentBuilder;
  import javax.xml.parsers.DocumentBuilderFactory;
  import javax.xml.transform.Transformer;
  import javax.xml.transform.TransformerException;
  import javax.xml.transform.TransformerFactory;
  import javax.xml.transform.dom.DOMSource;
  import javax.xml.transform.stream.StreamResult;
  import java.io.StringWriter;
  
  /**
   * Data Viewer Builder.
   */
  public class MetisViewerBuilder {
      /**
       * Logger.
       */
      private static final OceanusLogger LOGGER = OceanusLogManager.getLogger(MetisViewerBuilder.class);
  
      /**
       * Wrap for hex string.
       */
      private static final int WRAP_HEXSTRING = 60;
  
      /**
       * The HTML element.
       */
      private static final String ELEMENT_HTML = "html";
  
      /**
       * The body element.
       */
      private static final String ELEMENT_BODY = "body";
  
      /**
       * The title element.
       */
      private static final String ELEMENT_TITLE = "h2";
  
      /**
       * The link element.
       */
      private static final String ELEMENT_LINK = "a";
  
      /**
       * The table element.
       */
      private static final String ELEMENT_TABLE = "table";
  
      /**
       * The tableHead element.
       */
      private static final String ELEMENT_THEAD = "thead";
  
      /**
       * The tableBody element.
       */
      private static final String ELEMENT_TBODY = "tbody";
  
      /**
       * The tableRow element.
       */
      private static final String ELEMENT_TROW = "tr";
  
      /**
       * The tableHdr element.
       */
      private static final String ELEMENT_THDR = "th";
  
      /**
       * The tableCell element.
      */
     private static final String ELEMENT_TCELL = "td";
 
     /**
      * The class attribute.
      */
     private static final String ATTR_CLASS = "class";
 
     /**
      * The hRef attribute.
      */
     private static final String ATTR_HREF = "href";
 
     /**
      * Name of table class.
      */
     private static final String CLASS_VIEWER = "-metis-viewer";
 
     /**
      * Name of odd table row class.
      */
     private static final String CLASS_ODDROW = "-metis-oddrow";
 
     /**
      * Name of even table row class.
      */
     private static final String CLASS_EVENROW = "-metis-evenrow";
 
     /**
      * Name of changed cell class.
      */
     private static final String CLASS_CHANGED = "-metis-changed";
 
     /**
      * Name of security changed cell class.
      */
     private static final String CLASS_SECCHANGED = "-metis-security";
 
     /**
      * Blank link indication.
      */
     private static final String BLANK_LINK = "<Blank>";
 
     /**
      * The data formatter.
      */
     private final OceanusDataFormatter theFormatter;
 
     /**
      * Transformer.
      */
     private final Transformer theXformer;
 
     /**
      * The document.
      */
     private final Document theDocument;
 
     /**
      * The document body.
      */
     private final Element theBody;
 
     /**
      * The page.
      */
     private MetisViewerPage thePage;
 
     /**
      * The table Header row.
      */
     private Element theTblHdr;
 
     /**
      * The table body.
      */
     private Element theTblBody;
 
     /**
      * The current table row.
      */
     private Element theTblRow;
 
     /**
      * The number of rows.
      */
     private int theNumRows;
 
     /**
      * Constructor.
      *
      * @param pFormatter the data formatter
      * @throws OceanusException on error
      */
     protected MetisViewerBuilder(final OceanusDataFormatter pFormatter) throws OceanusException {
         /* Protect against exceptions */
         try {
             /* Store parameters */
             theFormatter = pFormatter;
 
             /* Create the document builder */
             final DocumentBuilderFactory myDocFactory = DocumentBuilderFactory.newInstance();
             myDocFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
             myDocFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
             myDocFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_SCHEMA, "");
 
             /* Create the document builder */
             final DocumentBuilder myBuilder = myDocFactory.newDocumentBuilder();
 
             /* Create the transformer */
             final TransformerFactory myXformFactory = TransformerFactory.newInstance();
             myXformFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, true);
             myXformFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_DTD, "");
             myXformFactory.setAttribute(XMLConstants.ACCESS_EXTERNAL_STYLESHEET, "");
             theXformer = myXformFactory.newTransformer();
 
             /* Create the document */
             theDocument = myBuilder.newDocument();
 
             /* Create the standard structure */
             final Element myHtml = theDocument.createElement(ELEMENT_HTML);
             theDocument.appendChild(myHtml);
             theBody = theDocument.createElement(ELEMENT_BODY);
             myHtml.appendChild(theBody);
 
         } catch (Exception e) {
             throw new MetisIOException("Failed to create", e);
         }
     }
 
     /**
      * Format document.
      */
     protected void formatDocument() {
         /* protect against exceptions */
         try {
             /* Format the XML and write to stream */
             final StringWriter myWriter = new StringWriter();
             theXformer.transform(new DOMSource(theDocument), new StreamResult(myWriter));
 
             /* Convert result to string */
             thePage.setHtml(myWriter.toString());
 
         } catch (TransformerException e) {
             LOGGER.error("Failed to format document", e);
         }
     }
 
     /**
      * Clear an element.
      *
      * @param pElement the element to clear
      */
     private static void clearElement(final Element pElement) {
         /* Clear the existing elements */
         while (pElement.hasChildNodes()) {
             pElement.removeChild(pElement.getFirstChild());
         }
     }
 
     /**
      * Reset the document.
      *
      * @param pPage the associated page
      */
     protected void resetDocument(final MetisViewerPage pPage) {
         /* Reset the page */
         thePage = pPage;
         thePage.resetPage();
 
         /* Reset the document */
         clearElement(theBody);
     }
 
     /**
      * Make title.
      *
      * @param pTitle the title
      */
     protected void newTitle(final String pTitle) {
         /* Create the title */
         final Element myTitle = theDocument.createElement(ELEMENT_TITLE);
         theBody.appendChild(myTitle);
         myTitle.setTextContent(pTitle);
     }
 
     /**
      * Make new table.
      */
     protected void newTable() {
         /* Create the table */
         final Element myTable = theDocument.createElement(ELEMENT_TABLE);
         myTable.setAttribute(ATTR_CLASS, CLASS_VIEWER);
         theBody.appendChild(myTable);
         final Element myHead = theDocument.createElement(ELEMENT_THEAD);
         myTable.appendChild(myHead);
         theTblHdr = theDocument.createElement(ELEMENT_TROW);
         myHead.appendChild(theTblHdr);
         theTblBody = theDocument.createElement(ELEMENT_TBODY);
         myTable.appendChild(theTblBody);
 
         /* Set counters */
         theTblRow = null;
         theNumRows = 0;
     }
 
     /**
      * Make new title cell.
      *
      * @param pTitle the title
      */
     protected void newTitleCell(final String pTitle) {
         /* Create the title cell */
         final Element myCell = theDocument.createElement(ELEMENT_THDR);
         theTblHdr.appendChild(myCell);
         myCell.setTextContent(pTitle);
     }
 
     /**
      * Make new table row.
      */
     protected void newTableRow() {
         /* Create the table row */
         theTblRow = theDocument.createElement(ELEMENT_TROW);
         theTblBody.appendChild(theTblRow);
 
         /* Set correct class */
         theTblRow.setAttribute(ATTR_CLASS, (theNumRows % 2 == 0)
                 ? CLASS_EVENROW
                 : CLASS_ODDROW);
         theNumRows++;
     }
 
     /**
      * Make new data cell.
      *
      * @param pData the data
      */
     protected void newDataCell(final Object pData) {
         newDataCell(pData, false);
     }
 
     /**
      * Make new data cell.
      *
      * @param pData    the data
      * @param pChanged is this a changed field true/false
      */
     protected void newDataCell(final Object pData,
                                final boolean pChanged) {
         /* Create the data cell */
         final Element myCell = theDocument.createElement(ELEMENT_TCELL);
         theTblRow.appendChild(myCell);
 
         /* Determine the text */
         String myText = formatValue(pData);
 
         /* If the Object is a data delta */
         if (pData instanceof MetisDataDelta myDelta) {
             /* Access the difference */
             final MetisDataDifference myDiff = myDelta.getDifference();
 
             /* If there is a difference */
             if (!myDiff.isIdentical()) {
                 myCell.setAttribute(ATTR_CLASS, myDiff.isValueChanged()
                         ? CLASS_CHANGED
                         : CLASS_SECCHANGED);
             }
         } else if (pChanged) {
             myCell.setAttribute(ATTR_CLASS, CLASS_CHANGED);
         }
 
         /* If the object is link-able */
         if (MetisViewerPage.isLinkable(pData)) {
             /* Create the link */
             final Element myLink = theDocument.createElement(ELEMENT_LINK);
             myCell.appendChild(myLink);
             myLink.setAttribute(ATTR_HREF, thePage.newLink(pData));
             myText = myText.isEmpty() ? BLANK_LINK : myText;
             myLink.setTextContent(myText);
 
             /* else just record the formatted text */
         } else {
             myCell.setTextContent(myText);
         }
     }
 
     /**
      * Format a value.
      *
      * @param pValue the value to format
      * @return the formatted value
      */
     private String formatValue(final Object pValue) {
         /* Format the value */
         String myFormat = theFormatter.formatObject(pValue);
 
         /* Perform special formatting for a long byte[] */
         if (needsWrapping(pValue)
                 && (myFormat.length() > WRAP_HEXSTRING)) {
             final StringBuilder myBuffer = new StringBuilder(myFormat.length() << 1);
 
             /* Format the buffer */
             myBuffer.append(myFormat);
 
             /* Insert new lines */
             int iCount = myFormat.length()
                     / WRAP_HEXSTRING;
             while (iCount > 0) {
                 myBuffer.insert(WRAP_HEXSTRING
                         * iCount--, '\n');
             }
 
             /* Obtain new format */
             myFormat = myBuffer.toString();
         }
 
         /* Return the formatted value */
         return myFormat;
     }
 
     /**
      * does the object format need wrapping?
      *
      * @param pObject the object
      * @return true/false
      */
     private static boolean needsWrapping(final Object pObject) {
         /* Determine whether we need wrapping */
         Object myObject = pObject;
         if (myObject instanceof MetisDataDelta) {
             myObject = ((MetisDataDelta) pObject).getObject();
         }
         return myObject instanceof byte[];
     }
 }