/**

 * copy-image-resizer

 * 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.copyImageResizer.cli;

import java.io.File;

import java.util.Arrays;

import java.util.Collection;

/**

 *

 * @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);

			}

		}

		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_DIR("--input-dir") { // bash-completion: option

					@Override

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

						int originalIndex = index;

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

						options.setInput(new File(name));

						return index - originalIndex;

					}

				},

		OUTPUT_DIR("--output-dir") { // bash-completion: option

					@Override

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

						int originalIndex = index;

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

						options.setOutput(new File(name));

						return index - originalIndex;

					}

				},

		SIZE("--size") { // bash-completion: option

					@Override

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

						int originalIndex = index;

						int width = parseInt(fetchNext(args, ++index));

						int height = parseInt(fetchNext(args, ++index));

						String directory = width + "x" + height;

						options.addSize(new CLIOptions.SizeSpecification(width, height, directory));

						return index - originalIndex;

					}

				},

		SIZE_NAMED("--size-named") { // bash-completion: option

					@Override

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

						int originalIndex = index;

						int width = parseInt(fetchNext(args, ++index));

						int height = parseInt(fetchNext(args, ++index));

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

						options.addSize(new CLIOptions.SizeSpecification(width, height, directory));

						return index - originalIndex;

					}

				};

		private final Collection<String> options;

		private Token(String... options) {

			this.options = Arrays.asList(options);

		}

		/**

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

		 * @return whether option is this token

		 */

		public boolean matches(String option) {

			return options.contains(option);

		}

		private static int parseInt(String number) throws CLIParserException {

			try {

				return Integer.parseInt(number);

			} catch (Exception e) {

				throw new CLIParserException("Unable to parse integer: " + number, e);

			}

		}

		/**

		 * 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;

	}

}