/****************************************************************
 * Licensed to the Apache Software Foundation (ASF) under one   *
 * or more contributor license agreements.  See the NOTICE file *
 * distributed with this work for additional information        *
 * regarding copyright ownership.  The ASF licenses this file   *
 * to you 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 org.apache.james.mime4j.field.address;

import java.util.ArrayList;
import java.util.Iterator;

import org.apache.james.mime4j.decoder.DecoderUtil;
import org.apache.james.mime4j.field.address.parser.ASTaddr_spec;
import org.apache.james.mime4j.field.address.parser.ASTaddress;
import org.apache.james.mime4j.field.address.parser.ASTaddress_list;
import org.apache.james.mime4j.field.address.parser.ASTangle_addr;
import org.apache.james.mime4j.field.address.parser.ASTdomain;
import org.apache.james.mime4j.field.address.parser.ASTgroup_body;
import org.apache.james.mime4j.field.address.parser.ASTlocal_part;
import org.apache.james.mime4j.field.address.parser.ASTmailbox;
import org.apache.james.mime4j.field.address.parser.ASTname_addr;
import org.apache.james.mime4j.field.address.parser.ASTphrase;
import org.apache.james.mime4j.field.address.parser.ASTroute;
import org.apache.james.mime4j.field.address.parser.Node;
import org.apache.james.mime4j.field.address.parser.SimpleNode;
import org.apache.james.mime4j.field.address.parser.Token;

/**
 * Transforms the JJTree-generated abstract syntax tree
 * into a graph of org.apache.james.mime4j.field.address objects.
 *
 *
 */
class Builder {

	private static Builder singleton = new Builder();

	public static Builder getInstance() {
		return singleton;
	}


	public AddressList buildAddressList(ASTaddress_list node) {
		ArrayList<Address> list = new ArrayList<Address>();
		for (int i = 0; i < node.jjtGetNumChildren(); i++) {
			ASTaddress childNode = (ASTaddress) node.jjtGetChild(i);
			Address address = buildAddress(childNode);
			list.add(address);
		}
		return new AddressList(list, true);
	}

	private Address buildAddress(ASTaddress node) {
		ChildNodeIterator it = new ChildNodeIterator(node);
		Node n = it.nextNode();
		if (n instanceof ASTaddr_spec) {
			return buildAddrSpec((ASTaddr_spec)n);
		}
		else if (n instanceof ASTangle_addr) {
			return buildAngleAddr((ASTangle_addr)n);
		}
		else if (n instanceof ASTphrase) {
			String name = buildString((ASTphrase)n, false);
			Node n2 = it.nextNode();
			if (n2 instanceof ASTgroup_body) {
				return new Group(name, buildGroupBody((ASTgroup_body)n2));
			}
			else if (n2 instanceof ASTangle_addr) {
                name = DecoderUtil.decodeEncodedWords(name);
				return new NamedMailbox(name, buildAngleAddr((ASTangle_addr)n2));
			}
			else {
				throw new IllegalStateException();
			}
		}
		else {
			throw new IllegalStateException();
		}
	}


	private MailboxList buildGroupBody(ASTgroup_body node) {
		ArrayList<Address> results = new ArrayList<Address>();
		ChildNodeIterator it = new ChildNodeIterator(node);
		while (it.hasNext()) {
			Node n = it.nextNode();
			if (n instanceof ASTmailbox)
				results.add(buildMailbox((ASTmailbox)n));
			else
				throw new IllegalStateException();
		}
		return new MailboxList(results, true);
	}

	private Mailbox buildMailbox(ASTmailbox node) {
		ChildNodeIterator it = new ChildNodeIterator(node);
		Node n = it.nextNode();
		if (n instanceof ASTaddr_spec) {
			return buildAddrSpec((ASTaddr_spec)n);
		}
		else if (n instanceof ASTangle_addr) {
			return buildAngleAddr((ASTangle_addr)n);
		}
		else if (n instanceof ASTname_addr) {
			return buildNameAddr((ASTname_addr)n);
		}
		else {
			throw new IllegalStateException();
		}
	}

	private NamedMailbox buildNameAddr(ASTname_addr node) {
		ChildNodeIterator it = new ChildNodeIterator(node);
		Node n = it.nextNode();
		String name;
		if (n instanceof ASTphrase) {
			name = buildString((ASTphrase)n, false);
		}
		else {
			throw new IllegalStateException();
		}

		n = it.nextNode();
		if (n instanceof ASTangle_addr) {
            name = DecoderUtil.decodeEncodedWords(name);
			return new NamedMailbox(name, buildAngleAddr((ASTangle_addr) n));
		}
		else {
			throw new IllegalStateException();
		}
	}

	private Mailbox buildAngleAddr(ASTangle_addr node) {
		ChildNodeIterator it = new ChildNodeIterator(node);
		DomainList route = null;
		Node n = it.nextNode();
		if (n instanceof ASTroute) {
			route = buildRoute((ASTroute)n);
			n = it.nextNode();
		}
		else if (n instanceof ASTaddr_spec)
			; // do nothing
		else
			throw new IllegalStateException();

		if (n instanceof ASTaddr_spec)
			return buildAddrSpec(route, (ASTaddr_spec)n);
		else
			throw new IllegalStateException();
	}

	private DomainList buildRoute(ASTroute node) {
		ArrayList<String> results = new ArrayList<String>(node.jjtGetNumChildren());
		ChildNodeIterator it = new ChildNodeIterator(node);
		while (it.hasNext()) {
			Node n = it.nextNode();
			if (n instanceof ASTdomain)
				results.add(buildString((ASTdomain)n, true));
			else
				throw new IllegalStateException();
		}
		return new DomainList(results, true);
	}

	private Mailbox buildAddrSpec(ASTaddr_spec node) {
		return buildAddrSpec(null, node);
	}
	private Mailbox buildAddrSpec(DomainList route, ASTaddr_spec node) {
		ChildNodeIterator it = new ChildNodeIterator(node);
		String localPart = buildString((ASTlocal_part)it.nextNode(), true);
		String domain = buildString((ASTdomain)it.nextNode(), true);
		return new Mailbox(route, localPart, domain);
	}


	private String buildString(SimpleNode node, boolean stripSpaces) {
		Token head = node.firstToken;
		Token tail = node.lastToken;
		StringBuffer out = new StringBuffer();

		while (head != tail) {
			out.append(head.image);
			head = head.next;
			if (!stripSpaces)
				addSpecials(out, head.specialToken);
		}
		out.append(tail.image);

		return out.toString();
	}

	private void addSpecials(StringBuffer out, Token specialToken) {
		if (specialToken != null) {
			addSpecials(out, specialToken.specialToken);
			out.append(specialToken.image);
		}
	}

	private static class ChildNodeIterator implements Iterator<Node> {

		private SimpleNode simpleNode;
		private int index;
		private int len;

		public ChildNodeIterator(SimpleNode simpleNode) {
			this.simpleNode = simpleNode;
			this.len = simpleNode.jjtGetNumChildren();
			this.index = 0;
		}

		public void remove() {
			throw new UnsupportedOperationException();
		}

		public boolean hasNext() {
			return index < len;
		}

		public Node next() {
			return nextNode();
		}

		public Node nextNode() {
			return simpleNode.jjtGetChild(index++);
		}

	}
}