/**

  * Alt2XML

  * Copyright © 2014 František Kučera (frantovo.cz)

  *

  * This program is free software: you can redistribute it and/or modify

  * it under the terms of the GNU General Public License as published by

  * the Free Software Foundation, either version 3 of the License, or

  * (at your option) any later version.

  *

  * This program is distributed in the hope that it will be useful,

  * but WITHOUT ANY WARRANTY; without even the implied warranty of

  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

  * GNU General Public License for more details.

  *

  * You should have received a copy of the GNU General Public License

  * along with this program. If not, see <http://www.gnu.org/licenses/>.

  */

 package cz.frantovo.alt2xml.cli;

 import java.io.File;

 /**

  * Converts command line arguments from String array to object.

  * Checks basic constraints (if only supported options are used and if they have correct number of

  * parameters)

  *

  * @author Ing. František Kučera (frantovo.cz)

  */

 public class CLIParser {

 	public CLIOptions parseOptions(String[] args) throws CLIParserException {

 		CLIOptions options = new CLIOptions();

 		for (int i = 0; i < args.length; i++) {

 			String arg = args[i];

 			boolean matches = false;

 			for (Token t : Token.values()) {

 				if (t.matches(arg)) {

 					int parsedArgs = t.parse(args, i, options);

 					i = i + parsedArgs;

 					matches = true;

 				}

 			}

 			if (!matches) {

 				throw new CLIParserException("Unknown option: " + arg);

 			}

 		}

 		// Default output:

 		options.setOutputStream(System.out);

 		return options;

 	}

 	private static String fetchNext(String[] args, int index) throws CLIParserException {

 		if (index < args.length) {

 			return args[index];

 		} else {

 			throw new CLIParserException("Expecting value for option: " + args[index - 1]);

 		}

 	}

 	private static enum Token {

 		INPUT_FILE("--input-file") {

 					@Override

 					public int parse(String[] args, int index, CLIOptions options) throws CLIParserException {

 						int originalIndex = index;

 						options.setInputFile(new File(fetchNext(args, ++index)));

 						return index - originalIndex;

 					}

 				},

 		INPUT_STDIN("--input-stdin") {

 					@Override

 					public int parse(String[] args, int index, CLIOptions options) throws CLIParserException {

 						options.setInputStream(System.in);

 						return 0;

 					}

 				},

 		SYSTEM_ID("--system-id") {

 					@Override

 					public int parse(String[] args, int index, CLIOptions options) throws CLIParserException {

 						int originalIndex = index;

 						options.setSystemId(fetchNext(args, ++index));

 						return index - originalIndex;

 					}

 				},

 		READER_PROPERTY("--reader-property") {

 					@Override

 					public int parse(String[] args, int index, CLIOptions options) throws CLIParserException {

 						int originalIndex = index;

 						String name = fetchNext(args, ++index);

 						String value = fetchNext(args, ++index);

 						options.addReaderProperty(name, value);

 						return index - originalIndex;

 					}

 				},

 		ACTION("--action") {

 					@Override

 					public int parse(String[] args, int index, CLIOptions options) throws CLIParserException {

 						int originalIndex = index;

 						options.setAction(fetchNext(args, ++index));

 						return index - originalIndex;

 					}

 				},

 		ACTION_PROPERTY("--action-property") {

 					@Override

 					public int parse(String[] args, int index, CLIOptions options) throws CLIParserException {

 						int originalIndex = index;

 						String name = fetchNext(args, ++index);

 						String value = fetchNext(args, ++index);

 						options.addActionProperty(name, value);

 						return index - originalIndex;

 					}

 				},

 		ACTION_DATA("--") {

 					@Override

 					public int parse(String[] args, int index, CLIOptions options) throws CLIParserException {

 						int originalIndex = index;

 						for (index++; index < args.length; index++) {

 							options.addActionData(args[index]);

 						}

 						return index - originalIndex;

 					}

 				};

 		private final String option;

 		private Token(String option) {

 			this.option = option;

 		}

 		/**

 		 * @param option e.g. „--input-file“

 		 * @return whether option is this token

 		 */

 		public boolean matches(String option) {

 			return this.option.equals(option);

 		}

 		/**

 		 * Parse String arguments and fill values into the options object.

 		 *

 		 * @param args CLI arguments

 		 * @param index index of the option matched by this token, like „--input-file“

 		 * @param options object to be filled

 		 * @return number of parsed arguments – if option has no arguments (just boolean flag),

 		 * return 0, otherwise return positive integer: number of eaten arguments.

 		 * @throws CLIParserException

 		 */

 		public abstract int parse(String[] args, int index, CLIOptions options) throws CLIParserException;

 	}

 }