/*
 * 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.kylin.common.util;

import java.time.Instant;
import java.time.LocalDate;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.util.Calendar;
import java.util.Locale;
import java.util.TimeZone;
import java.util.concurrent.TimeUnit;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.google.common.collect.ImmutableMap;

/**
 */
public class TimeUtil {

    private static long ONE_MINUTE_TS = 60 * 1000L;
    private static long ONE_HOUR_TS = 60 * ONE_MINUTE_TS;
    private static final ImmutableMap<String, TimeUnit> timeSuffixes = ImmutableMap.<String, TimeUnit> builder()
            .put("us", TimeUnit.MICROSECONDS).put("ms", TimeUnit.MILLISECONDS).put("s", TimeUnit.SECONDS)
            .put("m", TimeUnit.MINUTES).put("min", TimeUnit.MINUTES).put("h", TimeUnit.HOURS).put("d", TimeUnit.DAYS)
            .build();

    public static long getMinuteStart(long ts) {
        return ts / ONE_MINUTE_TS * ONE_MINUTE_TS;
    }

    public static long getHourStart(long ts) {
        return ts / ONE_HOUR_TS * ONE_HOUR_TS;
    }

    public static int getHour(long ts) {
        return (int) ((ts - getDayStart(ts)) / ONE_HOUR_TS);
    }

    public static long getDayStart(long ts) {
        ZoneId zoneId = TimeZone.getDefault().toZoneId();
        LocalDate localDate = Instant.ofEpochMilli(ts).atZone(zoneId).toLocalDate();
        return localDate.atStartOfDay().atZone(zoneId).toInstant().toEpochMilli();
    }

    public static long getWeekStart(long ts) {
        Calendar calendar = Calendar.getInstance(TimeZone.getDefault(), Locale.getDefault());
        calendar.setTimeInMillis(getDayStart(ts));
        calendar.add(Calendar.DAY_OF_WEEK, calendar.getFirstDayOfWeek() - calendar.get(Calendar.DAY_OF_WEEK));
        return calendar.getTimeInMillis();
    }

    public static long getMonthStart(long ts) {
        Calendar calendar = Calendar.getInstance(TimeZone.getDefault(), Locale.getDefault());
        calendar.setTimeInMillis(ts);
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        calendar.clear();
        calendar.set(year, month, 1);
        return calendar.getTimeInMillis();
    }

    public static long getQuarterStart(long ts) {
        Calendar calendar = Calendar.getInstance(TimeZone.getDefault(), Locale.getDefault());
        calendar.setTimeInMillis(ts);
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        calendar.clear();
        calendar.set(year, month / 3 * 3, 1);
        return calendar.getTimeInMillis();
    }

    public static long getYearStart(long ts) {
        Calendar calendar = Calendar.getInstance(TimeZone.getDefault(), Locale.getDefault());
        calendar.setTimeInMillis(ts);
        int year = calendar.get(Calendar.YEAR);
        calendar.clear();
        calendar.set(year, 0, 1);
        return calendar.getTimeInMillis();
    }

    public static long timeStringAs(String str, TimeUnit unit) {
        String lower = str.toLowerCase(Locale.ROOT).trim();

        try {
            Matcher m = Pattern.compile("(-?[0-9]+)([a-z]+)?").matcher(lower);
            if (!m.matches()) {
                throw new NumberFormatException("Failed to parse time string: " + str);
            }

            long val = Long.parseLong(m.group(1));
            String suffix = m.group(2);

            // Check for invalid suffixes
            if (suffix != null && !timeSuffixes.containsKey(suffix)) {
                throw new NumberFormatException("Invalid suffix: \"" + suffix + "\"");
            }

            // If suffix is valid use that, otherwise none was provided and use the default passed
            return unit.convert(val, suffix != null ? timeSuffixes.get(suffix) : unit);
        } catch (NumberFormatException e) {
            String timeError = "Time must be specified as seconds (s), "
                    + "milliseconds (ms), microseconds (us), minutes (m or min), hour (h), or day (d). "
                    + "E.g. 50s, 100ms, or 250us.";

            throw new NumberFormatException(timeError + "\n" + e.getMessage());
        }
    }

    public static long minusDays(long ts, int days) {
        ZoneId zoneId = TimeZone.getDefault().toZoneId();
        ZonedDateTime zonedDateTime = Instant.ofEpochMilli(ts).atZone(zoneId);
        return zonedDateTime.minusDays(days).toInstant().toEpochMilli();
    }

}
