/*
 * Copyright 2007 - 2023 Ralf Wisser.
 *
 * 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 net.sf.jailer.ui;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Locale;

import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.DOMException;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.xml.sax.SAXException;

import net.sf.jailer.datamodel.AggregationSchema;
import net.sf.jailer.datamodel.Association;
import net.sf.jailer.datamodel.Cardinality;
import net.sf.jailer.datamodel.Table;
import net.sf.jailer.xml.XmlUtil;

/**
 * Builds XML sketches.
 * 
 * @author Ralf Wisser
 */
public class XmlSketchBuilder {

	/**
	 * Builds XML sketches for given table.
	 * 
	 * @param table the table
	 * @return xml sketch for table 
	 */
	public static String buildSketch(Table table, int depth) throws Exception {
		if (table == null) {
			return "";
		}
		Document sketch = table.getXmlTemplateAsDocument(null);
		if (sketch.getChildNodes().getLength() > 0 && sketch.getChildNodes().item(0) instanceof Element) {
			insertAssociationSketch(sketch.getChildNodes().item(0), table, sketch, depth);
		}
		return XmlUtil.buildOmitDeclaration(sketch);
	}
	
	private static void insertAssociationSketch(Node node, Table table, Document doc, int depth) throws DOMException, ParserConfigurationException, SAXException, IOException {
		NodeList children = node.getChildNodes();
		int i = 0;
		while (i < children.getLength()) {
			if (children.item(i) instanceof Element) {
				Node e = children.item(i);
				if (XmlUtil.NS_URI.equals(e.getNamespaceURI()) && XmlUtil.ASSOCIATION_TAG.equals(e.getLocalName()) && e.getTextContent() != null) {
					Association association = null;
					for (Association a: table.associations) {
						if (a.getAggregationSchema() != AggregationSchema.NONE) {
							if (a.getName().equals(e.getTextContent().trim())) {
								association = a;
								break;
							}
						}
					}
					  if (association != null && depth < 3) {
						  Node[] ae = insertAssociationSketch(association, doc, depth + 1);
						if (ae != null) {
							for (Node n: ae) {
								node.insertBefore(doc.importNode(n, true), e);
								++i;
							}
						}
					  }
					  node.removeChild(e);
				} else {
					++i;
				}
			} else {
				++i;
			}
		}
	}

	private static Node[] insertAssociationSketch(Association association, Document doc, int depth) throws ParserConfigurationException, SAXException, IOException {
		if (association.getAggregationSchema() == AggregationSchema.EXPLICIT_LIST) {
			Element e1 = doc.createElement(association.getAggregationTagName());
			Element e2 = doc.createElement(association.destination.getUnqualifiedName().toLowerCase(Locale.ENGLISH));
			e1.appendChild(e2);
			if (association.getCardinality() != Cardinality.MANY_TO_ONE && association.getCardinality() != Cardinality.ONE_TO_ONE) {
				e1.appendChild(doc.createComment("..."));
			}
			return new Node[] { e1 };
		}
		else if (association.getAggregationSchema() == AggregationSchema.IMPLICIT_LIST) {
			Element e1 = doc.createElement(association.getAggregationTagName());
			if (association.getCardinality() != Cardinality.MANY_TO_ONE && association.getCardinality() != Cardinality.ONE_TO_ONE) {
				Node c = doc.createComment("...");
				return new Node[] { e1, c };
			}
			return new Node[] { e1 };
		} else if (association.getAggregationSchema() == AggregationSchema.FLAT) {
			Document sketch = association.destination.getXmlTemplateAsDocument(null);
			List<Node> nodes = new ArrayList<Node>();
			if (sketch.getChildNodes().getLength() > 0 && sketch.getChildNodes().item(0) instanceof Element) {
				insertAssociationSketch(sketch.getChildNodes().item(0), association.destination, sketch, depth + 1);
			}
			NodeList children = sketch.getChildNodes().item(0).getChildNodes();
			for (int i = 0; i < children.getLength(); ++i) {
				nodes.add(children.item(i));
			}
			if (association.getCardinality() != Cardinality.MANY_TO_ONE && association.getCardinality() != Cardinality.ONE_TO_ONE) {
				nodes.add(sketch.createComment("..."));
			}
			return nodes.toArray(new Node[nodes.size()]);
		}
		return null;
	}

	/**
	 * Builds XML sketches for given table.
	 * 
	 * @param table the table
	 * @return xml sketch for table 
	 */
	public static String buildSketch2(Table table, int depth) {
		StringBuilder sb = new StringBuilder();
		
		if (table != null && depth < 2) {
			List<Association> sortedSourceAssociations = new ArrayList<Association>(table.associations);
			Collections.sort(sortedSourceAssociations, new Comparator<Association>() {
				@Override
				public int compare(Association o1, Association o2) {
					return o1.destination.getName().compareTo(o2.destination.getName());
				}
			});

			if (depth == 0) {
				sb.append("<" + table.getUnqualifiedName().toLowerCase(Locale.ENGLISH) + ">\n");
				sb.append("    -- elements of " + table.getUnqualifiedName() + " --\n");
			}
			String indent = "    ";
			for (Association a: sortedSourceAssociations) {
				if (a.getAggregationSchema() == AggregationSchema.EXPLICIT_LIST) {
					sb.append(indent + "<" + a.getAggregationTagName() + ">\n");
					sb.append(indent + "    <" + a.destination.getUnqualifiedName().toLowerCase(Locale.ENGLISH) + "/>\n");
					if (a.getCardinality() != Cardinality.MANY_TO_ONE && a.getCardinality() != Cardinality.ONE_TO_ONE) {
						sb.append(indent + "    <" + a.destination.getUnqualifiedName().toLowerCase(Locale.ENGLISH) + "/>\n");
						sb.append(indent + "      ...\n");
					}
					sb.append(indent + "</" + a.getAggregationTagName() + ">\n");
				} else if (a.getAggregationSchema() == AggregationSchema.IMPLICIT_LIST) {
					sb.append(indent + "<" + a.getAggregationTagName() + "/>\n");
					if (a.getCardinality() != Cardinality.MANY_TO_ONE && a.getCardinality() != Cardinality.ONE_TO_ONE) {
						sb.append(indent + "<" + a.getAggregationTagName() + "/>\n");
						sb.append(indent + "  ...\n");
					}
				} else if (a.getAggregationSchema() == AggregationSchema.FLAT) {
					sb.append(indent + "-- elements of " + a.destination.getUnqualifiedName() + "(flattened " + a.getName() + ") --\n");
					sb.append(buildSketch2(a.destination, depth + 1));
					if (a.getCardinality() != Cardinality.MANY_TO_ONE && a.getCardinality() != Cardinality.ONE_TO_ONE) {
						sb.append(indent + "-- elements of " + a.destination.getUnqualifiedName() + "(flattened " + a.getName() + ") --\n");
						sb.append(indent + "     ...\n");
					}
				}
			}
			if (depth == 0) {
				sb.append("</" + table.getUnqualifiedName().toLowerCase(Locale.ENGLISH) + ">\n");
			}
		}
		
		return sb.toString();
	}

}
