/**

 * 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;

import java.io.InputStream;

/**

 * 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, InputStream in) throws CLIParserException {

		CLIOptions options = new CLIOptions();

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

			String arg = args[i];

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

				if (t.matches(arg)) {

					t.parse(args, i, options);

				}

			}

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

		}

		// Default output: STDOUT

		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;

					}

				},

		INPUT_URL("--input-url") {

					@Override

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

						int originalIndex = index;

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

						return index - originalIndex;

					}

				},

		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;

	}

}