// 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.doris.monitor.unit;

import org.apache.doris.monitor.utils.Strings;

import java.util.Collections;
import java.util.EnumMap;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.TimeUnit;

public class TimeValue implements Comparable<TimeValue> {

    /**
     * How many nano-seconds in one milli-second
     */
    public static final long NSEC_PER_MSEC = TimeUnit.NANOSECONDS.convert(1, TimeUnit.MILLISECONDS);

    private static Map<TimeUnit, Byte> TIME_UNIT_BYTE_MAP;
    private static Map<Byte, TimeUnit> BYTE_TIME_UNIT_MAP;

    static {
        final Map<TimeUnit, Byte> timeUnitByteMap = new EnumMap<>(TimeUnit.class);
        timeUnitByteMap.put(TimeUnit.NANOSECONDS, (byte) 0);
        timeUnitByteMap.put(TimeUnit.MICROSECONDS, (byte) 1);
        timeUnitByteMap.put(TimeUnit.MILLISECONDS, (byte) 2);
        timeUnitByteMap.put(TimeUnit.SECONDS, (byte) 3);
        timeUnitByteMap.put(TimeUnit.MINUTES, (byte) 4);
        timeUnitByteMap.put(TimeUnit.HOURS, (byte) 5);
        timeUnitByteMap.put(TimeUnit.DAYS, (byte) 6);

        final Set<Byte> bytes = new HashSet<>();
        for (TimeUnit value : TimeUnit.values()) {
            assert timeUnitByteMap.containsKey(value) : value;
            assert bytes.add(timeUnitByteMap.get(value));
        }

        final Map<Byte, TimeUnit> byteTimeUnitMap = new HashMap<>();
        for (Map.Entry<TimeUnit, Byte> entry : timeUnitByteMap.entrySet()) {
            byteTimeUnitMap.put(entry.getValue(), entry.getKey());
        }

        TIME_UNIT_BYTE_MAP = Collections.unmodifiableMap(timeUnitByteMap);
        BYTE_TIME_UNIT_MAP = Collections.unmodifiableMap(byteTimeUnitMap);
    }

    public static final TimeValue MINUS_ONE = timeValueMillis(-1);
    public static final TimeValue ZERO = timeValueMillis(0);

    public static TimeValue timeValueNanos(long nanos) {
        return new TimeValue(nanos, TimeUnit.NANOSECONDS);
    }

    public static TimeValue timeValueMillis(long millis) {
        return new TimeValue(millis, TimeUnit.MILLISECONDS);
    }

    public static TimeValue timeValueSeconds(long seconds) {
        return new TimeValue(seconds, TimeUnit.SECONDS);
    }

    public static TimeValue timeValueMinutes(long minutes) {
        return new TimeValue(minutes, TimeUnit.MINUTES);
    }

    public static TimeValue timeValueHours(long hours) {
        return new TimeValue(hours, TimeUnit.HOURS);
    }

    private final long duration;

    // visible for testing
    long duration() {
        return duration;
    }

    private final TimeUnit timeUnit;

    // visible for testing
    TimeUnit timeUnit() {
        return timeUnit;
    }

    public TimeValue(long millis) {
        this(millis, TimeUnit.MILLISECONDS);
    }

    public TimeValue(long duration, TimeUnit timeUnit) {
        this.duration = duration;
        this.timeUnit = timeUnit;
    }


    public long nanos() {
        return timeUnit.toNanos(duration);
    }

    public long getNanos() {
        return nanos();
    }

    public long micros() {
        return timeUnit.toMicros(duration);
    }

    public long getMicros() {
        return micros();
    }

    public long millis() {
        return timeUnit.toMillis(duration);
    }

    public long getMillis() {
        return millis();
    }

    public long seconds() {
        return timeUnit.toSeconds(duration);
    }

    public long getSeconds() {
        return seconds();
    }

    public long minutes() {
        return timeUnit.toMinutes(duration);
    }

    public long getMinutes() {
        return minutes();
    }

    public long hours() {
        return timeUnit.toHours(duration);
    }

    public long getHours() {
        return hours();
    }

    public long days() {
        return timeUnit.toDays(duration);
    }

    public long getDays() {
        return days();
    }

    public double microsFrac() {
        return ((double) nanos()) / C1;
    }

    public double getMicrosFrac() {
        return microsFrac();
    }

    public double millisFrac() {
        return ((double) nanos()) / C2;
    }

    public double getMillisFrac() {
        return millisFrac();
    }

    public double secondsFrac() {
        return ((double) nanos()) / C3;
    }

    public double getSecondsFrac() {
        return secondsFrac();
    }

    public double minutesFrac() {
        return ((double) nanos()) / C4;
    }

    public double getMinutesFrac() {
        return minutesFrac();
    }

    public double hoursFrac() {
        return ((double) nanos()) / C5;
    }

    public double getHoursFrac() {
        return hoursFrac();
    }

    public double daysFrac() {
        return ((double) nanos()) / C6;
    }

    public double getDaysFrac() {
        return daysFrac();
    }

    /**
     * Returns a {@link String} representation of the current {@link TimeValue}.
     * <p>
     * Note that this method might produce fractional time values (ex 1.6m) which cannot be
     * parsed by method like {@link TimeValue#parse(String, String, String)}.
     */
    @Override
    public String toString() {
        if (duration < 0) {
            return Long.toString(duration);
        }
        long nanos = nanos();
        if (nanos == 0) {
            return "0s";
        }
        double value = nanos;
        String suffix = "nanos";
        if (nanos >= C6) {
            value = daysFrac();
            suffix = "d";
        } else if (nanos >= C5) {
            value = hoursFrac();
            suffix = "h";
        } else if (nanos >= C4) {
            value = minutesFrac();
            suffix = "m";
        } else if (nanos >= C3) {
            value = secondsFrac();
            suffix = "s";
        } else if (nanos >= C2) {
            value = millisFrac();
            suffix = "ms";
        } else if (nanos >= C1) {
            value = microsFrac();
            suffix = "micros";
        }
        return Strings.format1Decimals(value, suffix);
    }

    public String getStringRep() {
        if (duration < 0) {
            return Long.toString(duration);
        }
        switch (timeUnit) {
            case NANOSECONDS:
                return duration + "nanos";
            case MICROSECONDS:
                return duration + "micros";
            case MILLISECONDS:
                return duration + "ms";
            case SECONDS:
                return duration + "s";
            case MINUTES:
                return duration + "m";
            case HOURS:
                return duration + "h";
            case DAYS:
                return duration + "d";
            default:
                throw new IllegalArgumentException("unknown time unit: " + timeUnit.name());
        }
    }

    public static TimeValue parseTimeValue(String sValue, String settingName) throws Exception {
        Objects.requireNonNull(settingName);
        Objects.requireNonNull(sValue);
        return parseTimeValue(sValue, null, settingName);
    }

    public static TimeValue parseTimeValue(String sValue, TimeValue defaultValue, String settingName)
            throws Exception {
        settingName = Objects.requireNonNull(settingName);
        if (sValue == null) {
            return defaultValue;
        }
        final String normalized = sValue.toLowerCase(Locale.ROOT).trim();
        if (normalized.endsWith("nanos")) {
            return new TimeValue(parse(sValue, normalized, "nanos"), TimeUnit.NANOSECONDS);
        } else if (normalized.endsWith("micros")) {
            return new TimeValue(parse(sValue, normalized, "micros"), TimeUnit.MICROSECONDS);
        } else if (normalized.endsWith("ms")) {
            return new TimeValue(parse(sValue, normalized, "ms"), TimeUnit.MILLISECONDS);
        } else if (normalized.endsWith("s")) {
            return new TimeValue(parse(sValue, normalized, "s"), TimeUnit.SECONDS);
        } else if (sValue.endsWith("m")) {
            // parsing minutes should be case-sensitive as 'M' means "months", not "minutes"; this is the only special case.
            return new TimeValue(parse(sValue, normalized, "m"), TimeUnit.MINUTES);
        } else if (normalized.endsWith("h")) {
            return new TimeValue(parse(sValue, normalized, "h"), TimeUnit.HOURS);
        } else if (normalized.endsWith("d")) {
            return new TimeValue(parse(sValue, normalized, "d"), TimeUnit.DAYS);
        } else if (normalized.matches("-0*1")) {
            return TimeValue.MINUS_ONE;
        } else if (normalized.matches("0+")) {
            return TimeValue.ZERO;
        } else {
            // Missing units:
            throw new Exception(
                    "failed to parse setting [{}] with value [{}] as a time value: unit is missing or unrecognized");
        }
    }

    private static long parse(final String initialInput, final String normalized, final String suffix) {
        final String s = normalized.substring(0, normalized.length() - suffix.length()).trim();
        try {
            return Long.parseLong(s);
        } catch (final NumberFormatException e) {
            try {
                @SuppressWarnings("unused") final double ignored = Double.parseDouble(s);
                throw new NumberFormatException("failed to parse, fractional time values are not supported");
            } catch (final NumberFormatException ignored) {
                throw new NumberFormatException("failed to parse");
            }
        }
    }

    private static final long C0 = 1L;
    private static final long C1 = C0 * 1000L;
    private static final long C2 = C1 * 1000L;
    private static final long C3 = C2 * 1000L;
    private static final long C4 = C3 * 60L;
    private static final long C5 = C4 * 60L;
    private static final long C6 = C5 * 24L;

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;

        return this.compareTo(((TimeValue) o)) == 0;
    }

    @Override
    public int hashCode() {
        return Double.hashCode(((double) duration) * timeUnit.toNanos(1));
    }

    public static long nsecToMSec(long ns) {
        return ns / NSEC_PER_MSEC;
    }

    @Override
    public int compareTo(TimeValue timeValue) {
        double thisValue = ((double) duration) * timeUnit.toNanos(1);
        double otherValue = ((double) timeValue.duration) * timeValue.timeUnit.toNanos(1);
        return Double.compare(thisValue, otherValue);
    }
}
