/*******************************************************************************
 * Copyright (c) 2001-2005 Sasa Markovic and Ciaran Treanor.
 * Copyright (c) 2011 The OpenNMS Group, Inc.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *******************************************************************************/
package org.jrobin.core.timespec;

class TimeScanner {
	private String dateString;

	private int pos, pos_save;
	private TimeToken token, token_save;

	static final TimeToken[] WORDS = {
			new TimeToken("midnight", TimeToken.MIDNIGHT),	/* 00:00:00 of today or tomorrow */
			new TimeToken("noon", TimeToken.NOON),		/* 12:00:00 of today or tomorrow */
			new TimeToken("teatime", TimeToken.TEATIME),	/* 16:00:00 of today or tomorrow */
			new TimeToken("am", TimeToken.AM),		/* morning times for 0-12 clock */
			new TimeToken("pm", TimeToken.PM),		/* evening times for 0-12 clock */
			new TimeToken("tomorrow", TimeToken.TOMORROW),
			new TimeToken("yesterday", TimeToken.YESTERDAY),
			new TimeToken("today", TimeToken.TODAY),
			new TimeToken("now", TimeToken.NOW),
			new TimeToken("n", TimeToken.NOW),
			new TimeToken("start", TimeToken.START),
			new TimeToken("s", TimeToken.START),
			new TimeToken("end", TimeToken.END),
			new TimeToken("e", TimeToken.END),
			new TimeToken("jan", TimeToken.JAN),
			new TimeToken("feb", TimeToken.FEB),
			new TimeToken("mar", TimeToken.MAR),
			new TimeToken("apr", TimeToken.APR),
			new TimeToken("may", TimeToken.MAY),
			new TimeToken("jun", TimeToken.JUN),
			new TimeToken("jul", TimeToken.JUL),
			new TimeToken("aug", TimeToken.AUG),
			new TimeToken("sep", TimeToken.SEP),
			new TimeToken("oct", TimeToken.OCT),
			new TimeToken("nov", TimeToken.NOV),
			new TimeToken("dec", TimeToken.DEC),
			new TimeToken("january", TimeToken.JAN),
			new TimeToken("february", TimeToken.FEB),
			new TimeToken("march", TimeToken.MAR),
			new TimeToken("april", TimeToken.APR),
			new TimeToken("may", TimeToken.MAY),
			new TimeToken("june", TimeToken.JUN),
			new TimeToken("july", TimeToken.JUL),
			new TimeToken("august", TimeToken.AUG),
			new TimeToken("september", TimeToken.SEP),
			new TimeToken("october", TimeToken.OCT),
			new TimeToken("november", TimeToken.NOV),
			new TimeToken("december", TimeToken.DEC),
			new TimeToken("sunday", TimeToken.SUN),
			new TimeToken("sun", TimeToken.SUN),
			new TimeToken("monday", TimeToken.MON),
			new TimeToken("mon", TimeToken.MON),
			new TimeToken("tuesday", TimeToken.TUE),
			new TimeToken("tue", TimeToken.TUE),
			new TimeToken("wednesday", TimeToken.WED),
			new TimeToken("wed", TimeToken.WED),
			new TimeToken("thursday", TimeToken.THU),
			new TimeToken("thu", TimeToken.THU),
			new TimeToken("friday", TimeToken.FRI),
			new TimeToken("fri", TimeToken.FRI),
			new TimeToken("saturday", TimeToken.SAT),
			new TimeToken("sat", TimeToken.SAT),
			new TimeToken(null, 0)			/*** SENTINEL ***/
	};

	static TimeToken[] MULTIPLIERS = {
			new TimeToken("second", TimeToken.SECONDS),	/* seconds multiplier */
			new TimeToken("seconds", TimeToken.SECONDS),	/* (pluralized) */
			new TimeToken("sec", TimeToken.SECONDS),		/* (generic) */
			new TimeToken("s", TimeToken.SECONDS),		/* (short generic) */
			new TimeToken("minute", TimeToken.MINUTES),	/* minutes multiplier */
			new TimeToken("minutes", TimeToken.MINUTES),	/* (pluralized) */
			new TimeToken("min", TimeToken.MINUTES),		/* (generic) */
			new TimeToken("m", TimeToken.MONTHS_MINUTES),	/* (short generic) */
			new TimeToken("hour", TimeToken.HOURS),		/* hours ... */
			new TimeToken("hours", TimeToken.HOURS),		/* (pluralized) */
			new TimeToken("hr", TimeToken.HOURS),		/* (generic) */
			new TimeToken("h", TimeToken.HOURS),		/* (short generic) */
			new TimeToken("day", TimeToken.DAYS),		/* days ... */
			new TimeToken("days", TimeToken.DAYS),		/* (pluralized) */
			new TimeToken("d", TimeToken.DAYS),		/* (short generic) */
			new TimeToken("week", TimeToken.WEEKS),		/* week ... */
			new TimeToken("weeks", TimeToken.WEEKS),		/* (pluralized) */
			new TimeToken("wk", TimeToken.WEEKS),		/* (generic) */
			new TimeToken("w", TimeToken.WEEKS),		/* (short generic) */
			new TimeToken("month", TimeToken.MONTHS),	/* week ... */
			new TimeToken("months", TimeToken.MONTHS),	/* (pluralized) */
			new TimeToken("mon", TimeToken.MONTHS),		/* (generic) */
			new TimeToken("year", TimeToken.YEARS),		/* year ... */
			new TimeToken("years", TimeToken.YEARS),		/* (pluralized) */
			new TimeToken("yr", TimeToken.YEARS),		/* (generic) */
			new TimeToken("y", TimeToken.YEARS),		/* (short generic) */
			new TimeToken(null, 0)			/*** SENTINEL ***/
	};

	TimeToken[] specials = WORDS;

	public TimeScanner(String dateString) {
		this.dateString = dateString;
	}

	void setContext(boolean parsingWords) {
		specials = parsingWords ? WORDS : MULTIPLIERS;
	}

	TimeToken nextToken() {
		StringBuffer buffer = new StringBuffer("");
		while (pos < dateString.length()) {
			char c = dateString.charAt(pos++);
			if (Character.isWhitespace(c) || c == '_' || c == ',') {
				continue;
			}
			buffer.append(c);
			if (Character.isDigit(c)) {
				// pick as many digits as possible
				while (pos < dateString.length()) {
					char next = dateString.charAt(pos);
					if (Character.isDigit(next)) {
						buffer.append(next);
						pos++;
					}
					else {
						break;
					}
				}
				String value = buffer.toString();
				return token = new TimeToken(value, TimeToken.NUMBER);
			}
			if (Character.isLetter(c)) {
				// pick as many letters as possible
				while (pos < dateString.length()) {
					char next = dateString.charAt(pos);
					if (Character.isLetter(next)) {
						buffer.append(next);
						pos++;
					}
					else {
						break;
					}
				}
				String value = buffer.toString();
				return token = new TimeToken(value, parseToken(value));
			}
			switch (c) {
				case ':':
					return token = new TimeToken(":", TimeToken.COLON);
				case '.':
					return token = new TimeToken(".", TimeToken.DOT);
				case '+':
					return token = new TimeToken("+", TimeToken.PLUS);
				case '-':
					return token = new TimeToken("-", TimeToken.MINUS);
				case '/':
					return token = new TimeToken("/", TimeToken.SLASH);
				default:
					pos--;
					return token = new TimeToken(null, TimeToken.EOF);
			}
		}
		return token = new TimeToken(null, TimeToken.EOF);
	}

	TimeToken resolveMonthsMinutes(int newId) {
		assert token.id == TimeToken.MONTHS_MINUTES;
		assert newId == TimeToken.MONTHS || newId == TimeToken.MINUTES;
		return token = new TimeToken(token.value, newId);
	}

	void saveState() {
		token_save = token;
		pos_save = pos;
	}

	TimeToken restoreState() {
		pos = pos_save;
		return token = token_save;
	}

	private int parseToken(String arg) {
		for (int i = 0; specials[i].value != null; i++) {
			if (specials[i].value.equalsIgnoreCase(arg)) {
				return specials[i].id;
			}
		}
		return TimeToken.ID;
	}
}