/*_############################################################################
  _## 
  _##  SNMP4J-Agent 3 - DateAndTime.java  
  _## 
  _##  Copyright (C) 2005-2025  Frank Fock (SNMP4J.org)
  _##  
  _##  Licensed 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.snmp4j.agent.mo.snmp;

import org.snmp4j.agent.mo.MOMutableColumn;
import org.snmp4j.agent.MOAccess;
import org.snmp4j.smi.Variable;
import org.snmp4j.smi.SMIConstants;
import org.snmp4j.smi.OctetString;

import java.util.GregorianCalendar;
import java.util.Calendar;
import java.util.TimeZone;

import org.snmp4j.mp.SnmpConstants;
import org.snmp4j.agent.mo.MOScalar;
import org.snmp4j.agent.request.SubRequest;
import org.snmp4j.smi.OID;
// JavaDoc DateAndTimeTC
import org.snmp4j.agent.mo.snmp.tc.DateAndTimeTC;

/**
 * The {@code DateAndTime} implements the DateAndTime textual convention (TC) from the SNMPv2-TC MIB specification for
 * columnar objects.
 * <p>
 * {@code DateAndTime} subclasses {@code MOMutableColumn} and can thus directly be used with tables. To use this TC
 * implementation as {@code MOScalar} create the corresponding instance using {@link #createMOScalar} or even better use
 * the {@link DateAndTimeTC} textual convention in conjunction with a {@code MOFactory}.
 *
 * @param <T> the {@link OctetString} type of the values of this column.
 * @author Frank Fock
 * @version 1.0
 */
public class DateAndTime<T extends OctetString> extends MOMutableColumn<T> {

    public DateAndTime(int columnID, MOAccess access, T defaultValue, boolean mutableInService) {
        super(columnID, SMIConstants.SYNTAX_OCTET_STRING,
                access, defaultValue, mutableInService);
    }

    public DateAndTime(int columnID, MOAccess access, T defaultValue) {
        super(columnID, SMIConstants.SYNTAX_OCTET_STRING,
                access, defaultValue);
    }

    /**
     * Tests a variable for DateAndTime conformance.
     *
     * @param dateAndTime
     *         a Variable.
     *
     * @return {@link SnmpConstants#SNMP_ERROR_SUCCESS} if {@code dateAndTime} is valid or an appropriate SNMP error
     * code if not.
     */
    public static int validateDateAndTime(Variable dateAndTime) {
        if (dateAndTime instanceof OctetString) {
            OctetString os = (OctetString) dateAndTime;
            if ((os.length() != 8) && (os.length() != 11)) {
                return SnmpConstants.SNMP_ERROR_WRONG_LENGTH;
            }
            int month = (os.get(2) & 0xFF);
            int date = (os.get(3) & 0xFF);
            int hour = (os.get(4) & 0xFF);
            int minute = (os.get(5) & 0xFF);
            int second = (os.get(6) & 0xFF);
            int deci = (os.get(7) & 0xFF);
            if ((month < 1) || (month > 12) ||
                    (date < 1) || (date > 31) || (hour > 23) || (second > 59) ||
                    (minute > 59) || (deci > 9)) {
                return SnmpConstants.SNMP_ERROR_WRONG_VALUE;
            }
            if (os.length() == 11) {
                if ((os.get(8) != '+') && (os.get(8) != '-')) {
                    return SnmpConstants.SNMP_ERROR_WRONG_VALUE;
                }
            }
            return SnmpConstants.SNMP_ERROR_SUCCESS;
        }
        return SnmpConstants.SNMP_ERROR_WRONG_TYPE;
    }

    /**
     * Creates a DateAndTime {@link OctetString} value from a {@link GregorianCalendar}.
     *
     * @param dateAndTime
     *         a {@code GregorianCalendar} instance.
     *
     * @return the corresponding DateAndTime {@code OctetString}.
     */
    public static OctetString makeDateAndTime(GregorianCalendar dateAndTime) {
        return makeDateAndTime(dateAndTime, new OctetString());
    }


    /**
     * Creates a DateAndTime {@code OctetString} value from a {@code GregorianCalendar}.
     *
     * @param dateAndTime
     *         a {@code GregorianCalendar} instance.
     * @param os
     *         the OctetString instance where to store the value.
     * @param <T>
     *         the {@link OctetString} type to return and modify.
     *
     * @return the os instance with the set calendar value.
     * @since 2.0.5
     */
    public static <T extends OctetString> T makeDateAndTime(GregorianCalendar dateAndTime, T os) {
        os.append((byte) (dateAndTime.get(Calendar.YEAR) / 256));
        os.append((byte) (dateAndTime.get(Calendar.YEAR) % 256));
        os.append((byte) (dateAndTime.get(Calendar.MONTH) + 1));
        os.append((byte) (dateAndTime.get(Calendar.DAY_OF_MONTH)));
        os.append((byte) (dateAndTime.get(Calendar.HOUR_OF_DAY)));
        os.append((byte) (dateAndTime.get(Calendar.MINUTE)));
        os.append((byte) (dateAndTime.get(Calendar.SECOND)));
        os.append((byte) (dateAndTime.get(Calendar.MILLISECOND) / 100));
        if (dateAndTime.getTimeZone() != null) {
            TimeZone tz = dateAndTime.getTimeZone();
            os.append((tz.getRawOffset() >= 0) ? "+" : "-");
            os.append((byte) (Math.abs(tz.getOffset(dateAndTime.getTimeInMillis()) / 3600000)));
            os.append((byte) (Math.abs(tz.getOffset(dateAndTime.getTimeInMillis()) % 3600000) / 60000));
        }
        return os;
    }

    /**
     * Creates a {@code GregorianCalendar} from a properly formatted DateAndTime {@code OctetString}.
     *
     * @param dateAndTimeValue
     *         an OctetString conforming to the DateAndTime TC.
     *
     * @return the corresponding {@code GregorianCalendar} instance.
     */
    public static GregorianCalendar makeCalendar(OctetString dateAndTimeValue) {
        int year = (dateAndTimeValue.get(0) & 0xFF) * 256 +
                (dateAndTimeValue.get(1) & 0xFF);
        int month = (dateAndTimeValue.get(2) & 0xFF);
        int date = (dateAndTimeValue.get(3) & 0xFF);
        int hour = (dateAndTimeValue.get(4) & 0xFF);
        int minute = (dateAndTimeValue.get(5) & 0xFF);
        int second = (dateAndTimeValue.get(6) & 0xFF);
        int deci = (dateAndTimeValue.get(7) & 0xFF);
        if (dateAndTimeValue.length() == 11) {
            String timezone = String.format("GMT%c%02d:%02d", dateAndTimeValue.get(8),
                    dateAndTimeValue.get(9), dateAndTimeValue.get(10));
            GregorianCalendar tgc =
                    new GregorianCalendar(TimeZone.getTimeZone(timezone));
            tgc.set(year, month - 1, date, hour, minute, second);
            tgc.set(Calendar.MILLISECOND, deci * 100);
            return tgc;
        } else {
            GregorianCalendar gc =
                    new GregorianCalendar(year, month - 1, date, hour, minute, second);
            gc.set(Calendar.MILLISECOND, deci * 100);
            return gc;
        }
    }

    public synchronized int validate(T newValue, T oldValue, OID instanceOID) {
        int result = validateDateAndTime(newValue);
        if (result == SnmpConstants.SNMP_ERROR_SUCCESS) {
            result = super.validate(newValue, oldValue, instanceOID);
        }
        return result;
    }

    /**
     * Create a {@code MOScalar} DateAndTime instance.
     *
     * @param oid
     *         the OID of the scalar (including the .0 suffix).
     * @param access
     *         the {@code MOAccess} instance defining the maximum access rights.
     * @param value
     *         the initial value.
     * @param localtime
     *         if {@code true} the returned DateAndTime instance will always return the local time (does only makes
     *         sense for a read-only instance). Otherwise the value last set will be returned on GET like requests.
     *
     * @return the {@code MOScalar} instance.
     */
    public static MOScalar<OctetString> createMOScalar(final OID oid,
                                                       final MOAccess access,
                                                       final OctetString value,
                                                       final boolean localtime) {
        return new MOScalar<>(oid, access, value) {
            public int isValueOK(SubRequest<?> sreq) {
                return validateDateAndTime(sreq.getVariableBinding().getVariable());
            }

            public OctetString getValue() {
                OctetString value = super.getValue();
                if (localtime) {
                    value = makeDateAndTime(new GregorianCalendar());
                }
                return value;
            }
        };
    }
}
