/**
 * 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.commons.cli;

import java.io.File;
import java.io.FileInputStream;
import java.net.URL;
import java.util.Date;

/**
 * <p>
 * Allows Options to be created from a single String. The pattern contains various single character flags and via an
 * optional punctuation character, their expected type.
 * </p>
 * <table border="1">
 * <caption>Overview of PatternOptionBuilder patterns</caption>
 * <tr>
 * <td>a</td>
 * <td>-a flag</td>
 * </tr>
 * <tr>
 * <td>b@</td>
 * <td>-b [classname]</td>
 * </tr>
 * <tr>
 * <td>c&gt;</td>
 * <td>-c [filename]</td>
 * </tr>
 * <tr>
 * <td>d+</td>
 * <td>-d [classname] (creates object via empty constructor)</td>
 * </tr>
 * <tr>
 * <td>e%</td>
 * <td>-e [number] (creates Double/Long instance depending on existing of a '.')</td>
 * </tr>
 * <tr>
 * <td>f/</td>
 * <td>-f [url]</td>
 * </tr>
 * <tr>
 * <td>g:</td>
 * <td>-g [string]</td>
 * </tr>
 * </table>
 * <p>
 * For example, the following allows command line flags of '-v -p string-value -f /dir/file'. The exclamation mark
 * precede a mandatory option.
 * </p>
 *
 * <pre>
 * Options options = PatternOptionBuilder.parsePattern("vp:!f/");
 * </pre>
 * <p>
 * TODO: These need to break out to OptionType and also to be pluggable.
 * </p>
 *
 * @version $Id: PatternOptionBuilder.java 1677406 2015-05-03 14:27:31Z britter $
 */
public class PatternOptionBuilder {
	/** String class */
	public static final Class<String> STRING_VALUE = String.class;
	
	/** Object class */
	public static final Class<Object> OBJECT_VALUE = Object.class;
	
	/** Number class */
	public static final Class<Number> NUMBER_VALUE = Number.class;
	
	/** Date class */
	public static final Class<Date> DATE_VALUE = Date.class;
	
	/** Class class */
	public static final Class<?> CLASS_VALUE = Class.class;
	
	/// can we do this one??
	// is meant to check that the file exists, else it errors.
	// ie) it's for reading not writing.
	
	/** FileInputStream class */
	public static final Class<FileInputStream> EXISTING_FILE_VALUE = FileInputStream.class;
	
	/** File class */
	public static final Class<File> FILE_VALUE = File.class;
	
	/** File array class */
	public static final Class<File[]> FILES_VALUE = File[].class;
	
	/** URL class */
	public static final Class<URL> URL_VALUE = URL.class;
	
	/** Boolean class */
	public static final Class<Boolean> BOOLEAN_VALUE = Boolean.class;
	
	public static final Class<?> INTEGER_VALUE = Integer.class;
	
	/**
	 * Retrieve the class that <code>ch</code> represents.
	 *
	 * @param ch
	 *            the specified character
	 * @return The class that <code>ch</code> represents
	 */
	public static Object getValueClass(final char ch) {
		switch (ch) {
		case '@':
			return PatternOptionBuilder.OBJECT_VALUE;
		case ':':
			return PatternOptionBuilder.STRING_VALUE;
		case '%':
			return PatternOptionBuilder.NUMBER_VALUE;
		case '+':
			return PatternOptionBuilder.CLASS_VALUE;
		case '#':
			return PatternOptionBuilder.DATE_VALUE;
		case '<':
			return PatternOptionBuilder.EXISTING_FILE_VALUE;
		case '>':
			return PatternOptionBuilder.FILE_VALUE;
		case '*':
			return PatternOptionBuilder.FILES_VALUE;
		case '/':
			return PatternOptionBuilder.URL_VALUE;
		}
		
		return null;
	}
	
	/**
	 * Returns whether <code>ch</code> is a value code, i.e. whether it represents a class in a pattern.
	 *
	 * @param ch
	 *            the specified character
	 * @return true if <code>ch</code> is a value code, otherwise false.
	 */
	public static boolean isValueCode(final char ch) {
		return ch == '@' || ch == ':' || ch == '%' || ch == '+' || ch == '#' || ch == '<' || ch == '>' || ch == '*'
				|| ch == '/' || ch == '!';
	}
	
	/**
	 * Returns the {@link Options} instance represented by <code>pattern</code>.
	 *
	 * @param pattern
	 *            the pattern string
	 * @return The {@link Options} instance
	 */
	public static Options parsePattern(final String pattern) {
		char opt = ' ';
		boolean required = false;
		Class<?> type = null;
		
		final Options options = new Options();
		
		for (int i = 0; i < pattern.length(); i++) {
			final char ch = pattern.charAt(i);
			
			// a value code comes after an option and specifies
			// details about it
			if (!isValueCode(ch)) {
				if (opt != ' ') {
					final Option option = Option.builder(String.valueOf(opt)).hasArg(type != null).required(required)
							.type(type).build();
					
					// we have a previous one to deal with
					options.addOption(option);
					required = false;
					type = null;
					opt = ' ';
				}
				
				opt = ch;
			} else if (ch == '!') {
				required = true;
			} else {
				type = (Class<?>) getValueClass(ch);
			}
		}
		
		if (opt != ' ') {
			final Option option =
					Option.builder(String.valueOf(opt)).hasArg(type != null).required(required).type(type).build();
			
			// we have a final one to deal with
			options.addOption(option);
		}
		
		return options;
	}
}