/*
 * Copyright 2006-2023 Prowide
 *
 * 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 com.prowidesoftware.swift.model;

import com.prowidesoftware.swift.utils.SafeXmlUtils;
import java.io.IOException;
import java.io.PrintStream;
import java.io.StringReader;
import java.util.*;
import java.util.logging.Level;
import org.apache.commons.lang3.StringUtils;
import org.apache.commons.lang3.Validate;
import org.xml.sax.XMLReader;

/**
 * <p>This class represents a node element within a tree of MX message.
 * It is basically a generic <b>XML node</b> structure used to provide basic parsing functionality.
 *
 * @since 7.6
 */
public class MxNode {
    public static final transient String PATH_SEPARATOR = "/";
    private static final transient java.util.logging.Logger log =
            java.util.logging.Logger.getLogger(MxNode.class.getName());
    private final List<MxNode> children;
    private MxNode parent;
    private String value;
    private String localName;
    private Map<String, String> attributes = null;

    public MxNode() {
        this.parent = null;
        this.children = new ArrayList<>();
        this.value = null;
    }

    public MxNode(final MxNode parent, final String localName) {
        this();
        this.localName = localName;
        if (parent != null) {
            this.parent = parent;
            parent.addChild(this);
        }
    }

    /**
     * Parses the complete message content into an {@link MxNode} tree structure.
     *
     * @since 9.1.2
     */
    public static MxNode parse(final String xml) {
        Objects.requireNonNull(xml, "the XML to parser cannot be null");
        Validate.notBlank(xml, "the XML to parser cannot be blank");
        try {
            XMLReader xmlReader = SafeXmlUtils.reader(true, null);
            final MxNodeContentHandler contentHandler = new MxNodeContentHandler();
            xmlReader.setContentHandler(contentHandler);
            xmlReader.parse(new org.xml.sax.InputSource(new StringReader(xml)));
            return contentHandler.getRootNode();
        } catch (final Exception e) {
            log.log(Level.SEVERE, "Error parsing XML", e);
        }
        return null;
    }

    private static MxNode _getRoot(final MxNode mxNode) {
        if (mxNode == null) {
            return null;
        }
        return mxNode.parent == null ? mxNode : _getRoot(mxNode.parent);
    }

    private void addChild(final MxNode child) {
        this.children.add(child);
    }

    public String singlePathValue(final String path) {
        final MxNode first = findFirst(path);
        if (first != null) {
            return first.getValue();
        }
        return null;
    }

    /**
     * Given a basic path, find the first instance of a node matching the
     * path parameter.<br>
     * <p>
     * If the path starts with '/' it will search from the root element,
     * else it will search from this node.
     *
     * @param path absolute or relative path to find
     * @return found node or null
     * @since 7.7
     */
    public MxNode findFirst(final String path) {
        final List<MxNode> found = find(path);
        if (!found.isEmpty()) {
            return found.get(0);
        } else {
            return null;
        }
    }

    /**
     * Given a basic path, find all nodes matching the path parameter.<br>
     * <p>
     * If the path starts with '/' it will search from the root element,
     * else it will search from this node.
     *
     * @param path absolute or relative path to find
     * @return found node or null
     * @since 7.7
     */
    public List<MxNode> find(final String path) {
        final String[] segments = StringUtils.split(path, PATH_SEPARATOR);
        final MxNode start = path != null && path.startsWith(PATH_SEPARATOR) ? getRoot() : this;
        return _find2(0, segments, start);
    }

    private List<MxNode> _find2(int index, final String[] segments, final MxNode node) {
        if (index >= segments.length) {
            return new ArrayList<>();
        }
        final List<MxNode> result = new ArrayList<>();
        final String segment = segments[index];
        int nextIndex = index + 1;

        // TODO en vez de remover el predicado, habria que soportarlo, devolviendo la/s instancia/s pedidas
        if (StringUtils.equals(".", segment)
                || StringUtils.equalsIgnoreCase(node.localName, removePredicate(segment))) {
            if (nextIndex == segments.length) {
                result.add(node);
                return result;
            } else if (node.children != null) {
                for (final MxNode n : node.children) {
                    result.addAll(_find2(nextIndex, segments, n));
                }
                return result;
            }
        }
        return result;
    }

    private String removePredicate(final String segment) {
        int index = segment.indexOf('[');
        if (index > 0) {
            return segment.substring(0, index);
        } else {
            return segment;
        }
    }

    public MxNode getRoot() {
        return _getRoot(this);
    }

    public String getValue() {
        return value;
    }

    public void setValue(final String value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return "MxNode{" + "localName='" + localName + '\'' + '}';
    }

    /**
     * Prints this node tree structure in standard output
     */
    public void print() {
        final PrintStream w = System.out;
        try {
            _print(0, getRoot(), w);
        } catch (final IOException e) {
            log.log(Level.WARNING, "exception printing node structure", e);
        }
    }

    private void _print(int level, final MxNode node, final PrintStream w) throws IOException {
        for (int i = 0; i < level; i++) {
            w.write("   ".getBytes());
        }
        w.write((node.localName + "\n").getBytes());
        int nextLevel = level + 1;
        for (final MxNode child : node.children) {
            _print(nextLevel, child, w);
        }
    }

    public MxNode getParent() {
        return parent;
    }

    /**
     * Traverse the tree from this node looking for the first node matching the given name.
     *
     * @param name a node name to find
     * @return the found node or null if not found
     * @since 7.7
     */
    public MxNode findFirstByName(final String name) {
        return _findFirstByName(this, name);
    }

    /**
     * Recursive implementation of the find by name
     */
    private MxNode _findFirstByName(final MxNode node, final String name) {
        if (node == null) {
            return null;
        }
        if (StringUtils.equalsIgnoreCase(node.localName, name)) {
            return node;
        } else if (node.children != null) {
            for (final MxNode child : node.children) {
                final MxNode found = _findFirstByName(child, name);
                if (found != null) {
                    return found;
                }
            }
        }
        return null;
    }

    /**
     * @return returns this node children nodes
     * @since 7.8
     */
    public List<MxNode> getChildren() {
        return children;
    }

    /**
     * @since 7.8
     */
    public Map<String, String> getAttributes() {
        return attributes;
    }

    /**
     * @since 7.8
     */
    public void setAttributes(Map<String, String> attributes) {
        this.attributes = attributes;
    }

    /**
     * Adds the given attribute to the node.
     * If an attribute already exist with the same local name, its value is updated.
     *
     * @since 7.8
     */
    public void addAttribute(final String name, final String value) {
        if (this.attributes == null) {
            this.attributes = new HashMap<>();
        }
        this.attributes.remove(name);
        this.attributes.put(name, value);
    }

    /**
     * @return found attribute value or null if not found or node does not contain attributes
     * @since 7.8
     */
    public String getAttribute(final String name) {
        if (this.attributes != null) {
            return this.attributes.get(name);
        }
        return null;
    }

    /**
     * Builds this node's path up to the root element
     *
     * @return the absolute path of the node in the form /foo/foo/foo
     * @since 7.8
     */
    public String path() {
        if (this.parent == null) {
            return PATH_SEPARATOR + this.localName;
        } else {
            return this.parent.path() + PATH_SEPARATOR + this.localName;
        }
    }
}
