/*_############################################################################
  _## 
  _##  SNMP4J-Agent 3 - MOTableIndex.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;

import org.snmp4j.smi.*;

import java.util.Arrays;

/**
 * The {@code MOTableIndex} class represents a index definition of a
 * conceptual table. An index always has to implement also the
 * {@link MOTableIndexValidator} interface for validation of index values
 * for newly created rows.
 *
 * @author Frank Fock
 * @version 1.0
 */
public class MOTableIndex implements MOTableIndexValidator {

    public static final int MAX_INDEX_OID_LENGTH = 127;

    private MOTableSubIndex[] subindexes;
    private boolean impliedLength = false;
    private MOTableIndexValidator validator;


    /**
     * Creates a index definition from an array of sub-index definitions.
     *
     * @param subIndexes
     *         an array of sub-index definitions with at least one element.
     */
    public MOTableIndex(MOTableSubIndex[] subIndexes) {
        if ((subIndexes == null) || (subIndexes.length < 1)) {
            throw new IllegalArgumentException(
                    "Index definition must have at least one sub-index");
        }
        this.subindexes = subIndexes;
    }

    /**
     * Creates a index definition from an array of sub-index definitions where
     * the last sub-index may have an implied length.
     *
     * @param subIndexes
     *         an array of sub-index definitions with at least one element.
     * @param impliedLength
     *         if {@code true} the last sub-index has an implied length if at has
     *         a variable length at all.
     */
    public MOTableIndex(MOTableSubIndex[] subIndexes, boolean impliedLength) {
        this(subIndexes);
        this.impliedLength = impliedLength;
    }

    /**
     * Creates a index definition from an array of sub-index definitions where
     * the last sub-index may have an implied length.
     *
     * @param subIndexes
     *         an array of sub-index definitions with at least one element.
     * @param impliedLength
     *         if {@code true} the last sub-index has an implied length if at has
     *         a variable length at all.
     * @param validator
     *         an index validator that is called whenever a new index value needs to
     *         validated.
     */
    public MOTableIndex(MOTableSubIndex[] subIndexes, boolean impliedLength,
                        MOTableIndexValidator validator) {
        this(subIndexes, impliedLength);
        this.validator = validator;
    }

    /**
     * Gets the sub-index definition at the specified index.
     *
     * @param index
     *         a valid sub-index index (zero-based).
     *
     * @return the {@code MOTableSubIndex}.
     */
    public MOTableSubIndex getIndex(int index) {
        return this.subindexes[index];
    }

    public boolean isImpliedLength() {
        return impliedLength;
    }

    /**
     * Gets the index validator (if present).
     *
     * @return the {@code MOTableIndexValidator} associated with this index or
     * {@code null}.
     */
    public MOTableIndexValidator getValidator() {
        return validator;
    }

    /**
     * Sets the index validator associated with this index definition.
     *
     * @param validator
     *         a {@code MOTableIndexValidator} instance.
     */
    public void setValidator(MOTableIndexValidator validator) {
        this.validator = validator;
    }

    /**
     * Gets the number of sub-index definitions in this index definition.
     *
     * @return the sub-index count.
     */
    public int size() {
        return subindexes.length;
    }

    private static boolean checkIndexBytes(OID index, long start, long end) {
        if ((start < 0) || (start > MOTableIndex.MAX_INDEX_OID_LENGTH) ||
                (end < 0) || (end > MOTableIndex.MAX_INDEX_OID_LENGTH)) {
            return false;
        }
        for (int i = (int) start; ((i < index.size()) && (i < end)); i++) {
            if (index.getUnsigned(i) > 255) {
                return false;
            }
        }
        return true;
    }

    private static boolean isStringSyntax(int smiSyntax) {
        switch (smiSyntax) {
            case SMIConstants.SYNTAX_OCTET_STRING:
            case SMIConstants.SYNTAX_IPADDRESS:
            case SMIConstants.SYNTAX_OPAQUE: {
                return true;
            }
        }
        return false;
    }

    /**
     * Checks whether an index OID is a valid index for this index definition
     * or not.
     *
     * @param index
     *         an OID (possibly zero length).
     *
     * @return {@code true} if the index is valid or {@code false} otherwise.
     */
    public boolean isValidIndex(OID index) {
        if ((index != null) && (index.size() > MOTableIndex.MAX_INDEX_OID_LENGTH)) {
            return false;
        }
        int l = 0;
        int i;
        for (i = 0; (index != null) && ((i < size()) && (l < index.size())); i++) {
            MOTableSubIndex subIndex = getIndex(i);
            if ((i + 1 == size()) && (isImpliedLength())) {
                int type = subIndex.getSmiSyntax();
                switch (type) {
                    case SMIConstants.SYNTAX_OCTET_STRING:
                    case SMIConstants.SYNTAX_IPADDRESS:
                        if (!checkIndexBytes(index, l, index.size())) {
                            return false;
                        }
                        break;
                }
                return true;
            } else if ((subIndex.getMinLength() != subIndex.getMaxLength())) {
                if (index.size() < index.get(l) + 1) {
                    return false;
                }
                if ((index.get(l) < subIndex.getMinLength()) ||
                        (index.get(l) > subIndex.getMaxLength())) {
                    return false;
                }
                if (isStringSyntax(subIndex.getSmiSyntax())) {
                    if (!checkIndexBytes(index, l + 1, l + index.getUnsigned(l) + 1)) {
                        return false;
                    }
                }
                l += index.getUnsigned(l) + 1;
            } else {
                if (isStringSyntax(subIndex.getSmiSyntax())) {
                    if (!checkIndexBytes(index, l, l + subIndex.getMaxLength())) {
                        return false;
                    }
                }
                // min == max
                l += subIndex.getMaxLength();
            }
        }
        return (((index.size() == l) && (i >= size())) &&
                ((validator == null) || (validator.isValidIndex(index))));
    }

    private static Variable getIndexVariable(MOTableSubIndex subIndexDef,
                                             OID subIndex,
                                             boolean impliedLength) {
        switch (subIndexDef.getSmiSyntax()) {
            case SMIConstants.SYNTAX_OCTET_STRING: {
                if ((impliedLength) ||
                        (subIndexDef.getMinLength() == subIndexDef.getMaxLength())) {
                    OctetString s = new OctetString(subIndex.toByteArray());
                    return s;
                }
                OID suffix = new OID(subIndex.getValue(), 1, subIndex.size() - 1);
                return new OctetString(suffix.toByteArray());
            }
            case SMIConstants.SYNTAX_OBJECT_IDENTIFIER: {
                if ((impliedLength) ||
                        (subIndexDef.getMinLength() == subIndexDef.getMaxLength())) {
                    return subIndex;
                }
                return new OID(subIndex.getValue(), 1, subIndex.size() - 1);
            }
            case SMIConstants.SYNTAX_UNSIGNED_INTEGER32: {
                return new Gauge32(subIndex.get(subIndex.size() - 1));
            }
            case SMIConstants.SYNTAX_TIMETICKS: {
                return new TimeTicks(subIndex.get(subIndex.size() - 1));
            }
            case SMIConstants.SYNTAX_INTEGER: {
                return new Integer32(subIndex.get(subIndex.size() - 1));
            }
            case SMIConstants.SYNTAX_IPADDRESS: {
                return new IpAddress(subIndex.toString());
            }
/*
      case SMIConstants.SYN_NETADDRESS: {
        String id = subIndex.toString();
        return new IpAddress(id.substring(id.indexOf(".") + 1));
      }
*/
        }
        return null;
    }

    /**
     * Split a table index into an array of object IDs each representing the
     * value of its corresponding index object. For example if a table's index
     * would be defined as INDEX { ifIndex, ipAddress } and the index given
     * would be "1.127.0.0.1" the resulting array would be { "1", "127.0.0.1" }
     *
     * @param index
     *         an OID denoting a table's index value.
     *
     * @return an array of OID instances with the same size as returned by
     * {@link #size}. If the given index is not a valid object ID
     * {@code null} is returned.
     */
    public OID[] getIndexOIDs(OID index) {
        OID[] r = new OID[size()];
        int[] ind = index.getValue();
        int pos = 0;
        for (int i = 0; i < subindexes.length; i++) {
            if ((i + 1 == size()) && (isImpliedLength())) {
                r[i] = new OID(ind, pos, index.size() - pos);
                break;
            } else if ((subindexes[i].getMinLength() != subindexes[i].getMaxLength())) {
                r[i] = new OID(ind, pos, index.get(pos) + 1);
            } else {
                r[i] = new OID(index.getValue(), pos, subindexes[i].getMaxLength());
            }
            pos += r[i].size();
        }
        return r;
    }

    /**
     * Gets the index values contained in an index OID.
     *
     * @param index
     *         the index OID.
     *
     * @return an array of values representing the index.
     * @see #getIndexOID
     */
    public Variable[] getIndexValues(OID index) {
        OID[] oids = getIndexOIDs(index);
        Variable[] values = new Variable[oids.length];
        for (int i = 0; i < oids.length; i++) {
            boolean implied = ((isImpliedLength()) && (i + 1 == size()));
            values[i] = getIndexVariable(subindexes[i], oids[i], implied);
        }
        return values;
    }

    /**
     * Gets the index OID from an array of index values.
     *
     * @param indexValues
     *         an array of Variable instances that has to match the number and type
     *         of sub-indexes in this index.
     *
     * @return the corresponding index OID.
     * @see #getIndexValues
     */
    public OID getIndexOID(Variable[] indexValues) {
        if (indexValues.length != size()) {
            throw new IllegalArgumentException("Index value length != size()");
        }
        OID index = new OID();
        for (int i = 0; i < indexValues.length; i++) {
            MOTableSubIndex subIndex = this.subindexes[i];
            if (indexValues[i].getSyntax() == subIndex.getSmiSyntax()) {
                index.append(indexValues[i].toSubIndex((i + 1 == indexValues.length) &&
                        impliedLength || subIndex.getMinLength() == subIndex.getMaxLength()));
            } else {
                throw new IllegalArgumentException("Syntax of index value #" + i +
                        " = " +
                        indexValues[i].getSyntaxString() +
                        " does not match index definition " +
                        AbstractVariable.getSyntaxString(
                                this.subindexes[i].getSmiSyntax()));
            }
        }
        return index;
    }

    @Override
    public String toString() {
        return "MOTableIndex{" +
                "subindexes=" + Arrays.toString(subindexes) +
                ", impliedLength=" + impliedLength +
                ", validator=" + validator +
                '}';
    }
}
