org.eclipse.osbp.xtext.datamart.common/src/org/eclipse/osbp/xtext/datamart/common/olap/CellSetToD3JsonConverter.java

/**
 *                                                                            
 *  Copyright (c) 2011, 2019 - Loetz GmbH&Co.KG (69115 Heidelberg, Germany) 
 *                                                                            
 *  All rights reserved. This program and the accompanying materials           
 *  are made available under the terms of the Eclipse Public License 2.0        
 *  which accompanies this distribution, and is available at                  
 *  https://www.eclipse.org/legal/epl-2.0/                                 
 *                                 
 *  SPDX-License-Identifier: EPL-2.0                                 
 *                                                                            
 *  Contributors:                                                      
 * 	   Christophe Loetz (Loetz GmbH&Co.KG) - initial implementation
 * 
 */
 package org.eclipse.osbp.xtext.datamart.common.olap;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import elemental.json.JsonFactory;
import elemental.json.impl.JreJsonArray;
import elemental.json.impl.JreJsonFactory;
import elemental.json.impl.JreJsonObject;

public class CellSetToD3JsonConverter {
	
	private static final String KEY_CHILDREN="children";
	private static final String KEY_NAME="name";
	private static final String KEY_TOOLTIPNAME="tooltipName";
	private static JsonFactory factory = new JreJsonFactory();

	public CellSetToD3JsonConverter() {
	}
	
	public static String getD3JsonString(DerivedCellSet cxCellSet, boolean noMeasures) {
	    // generate a new result component
	    if (cxCellSet == null) {
	    	return "";
	    }
		ArrayList<Integer> coordinateSystem = new ArrayList<>();
    	// create a multidimensional coordinate system against the cellSet
    	for	(int axis = 0; axis < cxCellSet.getAxes().size(); axis++) {
    		coordinateSystem.add(0);
    	}
	    List<Integer> coordinate = new ArrayList<>(coordinateSystem);
	    // add styles to page for the axis's custom styles
	    List<String> dataColumns = getDataColumnNameList(cxCellSet);
		
	    Node root = new Node();
	    // for every data row
	    for	(DerivedPosition rows : cxCellSet.getAxes().get(1).getPositions()) {
	    	// row Data
	    	coordinate.set(1, rows.getOrdinal());
	    	// fill in the row members for the row axis
	    	for (DerivedMember member : rows.getMembers()) {
	    		String qualifiedName = member.getUniqueName().replace("[", "").replace("]", "");
	    		if(!noMeasures) {
		    		JreJsonObject childrenListMap = new JreJsonObject(factory);
		    		// create a concatenated name of all members for the data column
		    		childrenListMap.put(KEY_TOOLTIPNAME, qualifiedName.replace(".", "-"));
		    		childrenListMap.put(KEY_NAME, member.getCaption());
			    	for	(DerivedPosition columns : cxCellSet.getAxes().get(0).getPositions()) {
			    		coordinate.set(0, columns.getOrdinal());
			    		childrenListMap.put(dataColumns.get(columns.getOrdinal()), ((Double)cxCellSet.getCell(coordinate).getValue()).toString());
			    	}
		    		addToHierachy(root, qualifiedName.split("\\."), childrenListMap);
	    		}
	    		addToHierachy(root, qualifiedName.split("\\."), null);
	    	}
	    }
	    
	    JreJsonArray json = convertToJSON(root);
	    String result = json.toJson().toString();
	    return result.substring(1, result.length()-1);
	}

	public static List<String> getDataColumnNameList(DerivedCellSet cxCellSet) {
		// create a table column for all data column
	    List<String> dataColumns = new LinkedList<>();
	    for	(DerivedPosition columns : cxCellSet.getAxes().get(0).getPositions()) {
	    	String title = null;
	    	for (DerivedMember member : columns.getMembers()) {
	    		if	(title == null) {
	    			title = member.getCaption();
	    		}
	    		else {
	    			title += " "+member.getCaption();
	    		}
	    	}
	    	dataColumns.add(title);
	    }
		return dataColumns;
	}

    private static void addToHierachy(Node root, Object[] row, JreJsonObject valueMap) {
        Node current = root;

        // Go through each column in the row
        for(Object col : row) {
        	// this is the last row element, so add the values
        	current = current.getOrCreateChild((String) col);
        	if(valueMap != null && col.equals(row[row.length-1])) {
        		current.setValueMap(valueMap);
        	}
        }
    }

    private static JreJsonArray convertToJSON(Node root) {
        // Use recursion to build the result JSON
    	JreJsonArray array = new JreJsonArray(factory);

        // Starting at this root, go through all of the child entries
        for(Map.Entry<String, Node> child : root.getChildren().entrySet()) {
            Node childNode = child.getValue();

            // New object for this entry...
            JreJsonObject object = new JreJsonObject(factory);
            // Set the name
            object.put(KEY_NAME, child.getKey());

            // Set the value if it is present on this node
            if(childNode.getValueMap() != null) {
            	JreJsonArray values = new JreJsonArray(factory);
            	values.set(0, childNode.getValueMap());
                object.put(KEY_CHILDREN, values);
            }

            // Generate the child hierarchy if it has children
            if(!childNode.getChildren().isEmpty()) {
            	JreJsonArray childHierachy = convertToJSON(childNode);
                object.put(KEY_CHILDREN, childHierachy);
            }

            array.set(array.length(), object);
        }

        return array;
    }

    // Class used to build the hierarchy
    static class Node {
        // The map of children, LABEL -> NODE
        private Map<String, Node> children = new HashMap<>();
		private JreJsonObject valueMap;

        public Node getOrCreateChild(String key) {
            Node node = children.get(key);

            if(node == null) {
                node = new Node();
                children.put(key, node);
            }

            return node;
        }

        public Map<String, Node> getChildren() {
            return children;
        }

        public JreJsonObject getValueMap() {
            return valueMap;
        }

        public void setValueMap(JreJsonObject valueMap) {
            this.valueMap = valueMap;
        }
    }	
}