/*
* Copyright @ 2013 CurisTEC, S.A.S. All Rights Reserved.
*/
package net.curisit.securis.db.common;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import org.hibernate.HibernateException;
import org.hibernate.engine.spi.SharedSessionContractImplementor;
import org.hibernate.usertype.UserType;

/**
* PersistentEnumUserType
* <p>
* Base Hibernate {@link UserType} for enums implementing {@link CodedEnum}.
* Stores the enum's <b>short code</b> (VARCHAR) and reconstructs the enum
* from that code on load.
*
* Notes:
* - SQL type is {@code VARCHAR}.
* - Immutable by default ({@link #isMutable()} returns false).
* - {@link #equals(Object, Object)} compares by reference (adequate for enums).
*
* @param <T> enum type implementing {@link CodedEnum}
*
* @author JRA
* Last reviewed by JRA on Oct 7, 2025.
*/
public abstract class PersistentEnumUserType<T extends CodedEnum> implements UserType {

    /** 
     * assemble<p>
     * Return cached value as-is (immutable semantics). 
     * 
     * @param cached
     * @param owner
     * @return assembleObject
     * @throws HibernateException
     */
    @Override
    public Object assemble(Serializable cached, Object owner) throws HibernateException {
        return cached;
    }

    /** 
     * deepCopy<p>
     * Enums are immutable; return value as-is. 
     * 
     * @param value
     * @return deepCopy
     */
    @Override
    public Object deepCopy(Object value) throws HibernateException {
        return value;
    }

    /** 
     * disassemble<p>
     * Return value for 2nd-level cache.
     * 
     * @param value
     * @return disassembleObject
     * @throw HibernateException
     */
    @Override
    public Serializable disassemble(Object value) throws HibernateException {
        return (Serializable) value;
    }

    /** 
     * equals<p>
     * Reference equality is fine for enums.
     * 
     * @param x
     * @param y
     * @param isEqual
     * @throws HibernateException
     */
    @Override
    public boolean equals(Object x, Object y) throws HibernateException {
        return x == y;
    }

    /** 
     * hashCode<p>
     * Delegate to value hashCode; 0 for null. 
     * 
     * @param object
     * @return hashCode
     * @throws HibernateException
     */
    @Override
    public int hashCode(Object x) throws HibernateException {
        return x == null ? 0 : x.hashCode();
    }

    /** 
     * isMutable<p>
     * Enums are immutable. 
     * 
     * @return isMutable
     */
    @Override
    public boolean isMutable() {
        return false;
    }

    /** 
     * replace<p>
     * Immutable; return original. 
     * 
     * @param original
     * @param target
     * @param owner
     * @return object
     * @throws HibernateException
     */
    @Override
    public Object replace(Object original, Object target, Object owner) throws HibernateException {
        return original;
    }

    /** 
     * returnedClass<p>
     * Concrete types must provide the enum class. 
     */
    @Override
    public abstract Class<T> returnedClass();

    /** 
     * sqlTypes<p>
     * Persist as single VARCHAR column
     * 
     * @return sqlTypes
     */
    @Override
    public int[] sqlTypes() {
        return new int[] { Types.VARCHAR };
    }

    /**
    * nullSafeGet<p>
    * Read code from result set and map to the corresponding enum constant.
    *
    * @param resultSet
    * @param names
    * @param session
    * @param owner
    * @return enum instance or null if DB value is null or code not matched
    */
    @Override
    public Object nullSafeGet(ResultSet rs, String[] names, SharedSessionContractImplementor session, Object owner)
            throws HibernateException, SQLException {
        String code = rs.getString(names[0]);
        if (code == null) return null;
        for (CodedEnum en : returnedClass().getEnumConstants()) {
            if (en.getCode().equals(code)) {
                return en;
            }
        }
        return null;
    }

    /**
    * nullSafeSet<p>
    * Write enum code as VARCHAR or set NULL if value is null.
    * 
    * @param statement
    * @param value
    * @param index
    * @param session
    */
    @Override
    public void nullSafeSet(PreparedStatement st, Object value, int index, SharedSessionContractImplementor session)
            throws HibernateException, SQLException {
        if (value == null) {
            st.setNull(index, java.sql.Types.VARCHAR);
        } else {
            st.setString(index, ((CodedEnum) value).getCode());
        }
    }
}