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SADU module to map values received from a database to java objects using the queries module.
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/*
 *     SPDX-License-Identifier: LGPL-3.0-or-later
 *
 *     Copyright (C) RainbowDashLabs and Contributor
 */

package de.chojo.sadu.mapper.reader;

import de.chojo.sadu.core.exceptions.ThrowingBiFunction;
import de.chojo.sadu.mapper.wrapper.Row;
import org.jetbrains.annotations.NotNull;

import java.sql.SQLException;
import java.util.function.Function;
import java.util.function.Supplier;

/**
 * Definition of a ValueReader to read columns from a {@link Row} and parse it to a java type.
 *
 * @param  The java type that is returned by the adapter
 * @param  The intermediate SQL type that is retrieved from the row
 * @see StandardReader
 */
public interface ValueReader {
    static  ValueReader create(Function parser,
                                           ThrowingBiFunction nameReader,
                                           ThrowingBiFunction indexReader) {
        return new ValueReader<>() {
            @Override
            public Function<@NotNull V, T> reader() {
                return parser;
            }

            @Override
            public ThrowingBiFunction namedReader() {
                return nameReader;
            }

            @Override
            public ThrowingBiFunction indexedReader() {
                return indexReader;
            }
        };
    }

    static  ValueReader create(Function parser,
                                           ThrowingBiFunction nameReader,
                                           ThrowingBiFunction indexReader,
                                           Supplier defaultValue) {
        return new ValueReader<>() {
            @Override
            public Function<@NotNull V, T> reader() {
                return parser;
            }

            @Override
            public ThrowingBiFunction namedReader() {
                return nameReader;
            }

            @Override
            public ThrowingBiFunction indexedReader() {
                return indexReader;
            }

            @Override
            public T defaultValue() {
                return defaultValue.get();
            }
        };
    }

    /**
     * A reader that takes the sql type and converts it into a java type.
     * The passed sql type instance is never null.
     *
     * @return a converted java instance of the sql object
     */
    Function<@NotNull V, T> reader();

    /**
     * Function that provides access to a reader that returns the column value via column name
     *
     * @return function
     */
    ThrowingBiFunction namedReader();

    /**
     * Function that provides access to a reader that returns the column value via column index
     *
     * @return function
     */
    ThrowingBiFunction indexedReader();

    /**
     * A default value that should be returned when the SQL value is null
     *
     * @return a default value or null
     */
    default T defaultValue() {
        return null;
    }
}