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 * Copyright (c) 1999, 2023, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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 */

package javax.security.auth.callback;

import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;

/**
 * <p> Underlying security services instantiate and pass a
 * {@code ChoiceCallback} to the {@code handle}
 * method of a {@code CallbackHandler} to display a list of choices
 * and to retrieve the selected choice(s).
 *
 * @see javax.security.auth.callback.CallbackHandler
 */
public class ChoiceCallback implements Callback, java.io.Serializable {

    private static final long serialVersionUID = -3975664071579892167L;

    /**
     * @serial
     * @since 1.4
     */
    private String prompt;
    /**
     * @serial the list of choices
     * @since 1.4
     */
    private String[] choices;
    /**
     * @serial the choice to be used as the default choice
     * @since 1.4
     */
    private int defaultChoice;
    /**
     * @serial whether multiple selections are allowed from the list of
     * choices
     * @since 1.4
     */
    private boolean multipleSelectionsAllowed;
    /**
     * @serial the selected choices, represented as indexes into the
     *          {@code choices} list.
     * @since 1.4
     */
    private int[] selections;

    /**
     * Construct a {@code ChoiceCallback} with a prompt,
     * a list of choices, a default choice, and a boolean specifying
     * whether or not multiple selections from the list of choices are allowed.
     *
     * <p>
     *
     * @param prompt the prompt used to describe the list of choices. <p>
     *
     * @param choices the list of choices. <p>
     *
     * @param defaultChoice the choice to be used as the default choice
     *                  when the list of choices are displayed.  This value
     *                  is represented as an index into the
     *                  {@code choices} array. <p>
     *
     * @param multipleSelectionsAllowed boolean specifying whether or
     *                  not multiple selections can be made from the
     *                  list of choices.
     *
     * @exception IllegalArgumentException if {@code prompt} is null,
     *                  if {@code prompt} has a length of 0,
     *                  if {@code choices} is null,
     *                  if {@code choices} has a length of 0,
     *                  if any element from {@code choices} is null,
     *                  if any element from {@code choices}
     *                  has a length of 0 or if {@code defaultChoice}
     *                  does not fall within the array boundaries of
     *                  {@code choices}.
     */
    public ChoiceCallback(String prompt, String[] choices,
                int defaultChoice, boolean multipleSelectionsAllowed) {

        if (prompt == null || prompt.isEmpty() ||
            choices == null || choices.length == 0 ||
            defaultChoice < 0 || defaultChoice >= choices.length)
            throw new IllegalArgumentException();

        this.prompt = prompt;
        this.defaultChoice = defaultChoice;
        this.multipleSelectionsAllowed = multipleSelectionsAllowed;

        this.choices = choices.clone();
        for (int i = 0; i < choices.length; i++) {
            if (choices[i] == null || choices[i].isEmpty())
                throw new IllegalArgumentException();
        }

    }

    /**
     * Get the prompt.
     *
     * <p>
     *
     * @return the prompt.
     */
    public String getPrompt() {
        return prompt;
    }

    /**
     * Get the list of choices.
     *
     * <p>
     *
     * @return the list of choices.
     */
    public String[] getChoices() {
        return choices;
    }

    /**
     * Get the defaultChoice.
     *
     * <p>
     *
     * @return the defaultChoice, represented as an index into
     *          the {@code choices} list.
     */
    public int getDefaultChoice() {
        return defaultChoice;
    }

    /**
     * Get the boolean determining whether multiple selections from
     * the {@code choices} list are allowed.
     *
     * <p>
     *
     * @return whether multiple selections are allowed.
     */
    public boolean allowMultipleSelections() {
        return multipleSelectionsAllowed;
    }

    /**
     * Set the selected choice.
     *
     * <p>
     *
     * @param selection the selection represented as an index into the
     *          {@code choices} list.
     *
     * @see #getSelectedIndexes
     */
    public void setSelectedIndex(int selection) {
        this.selections = new int[1];
        this.selections[0] = selection;
    }

    /**
     * Set the selected choices.
     *
     * <p>
     *
     * @param selections the selections represented as indexes into the
     *          {@code choices} list.
     *
     * @exception UnsupportedOperationException if multiple selections are
     *          not allowed, as determined by
     *          {@code allowMultipleSelections}.
     *
     * @see #getSelectedIndexes
     */
    public void setSelectedIndexes(int[] selections) {
        if (!multipleSelectionsAllowed)
            throw new UnsupportedOperationException();
        this.selections = selections;
    }

    /**
     * Get the selected choices.
     *
     * <p>
     *
     * @return the selected choices, represented as indexes into the
     *          {@code choices} list.
     *
     * @see #setSelectedIndexes
     */
    public int[] getSelectedIndexes() {
        return selections;
    }

    /**
     * Restores the state of this object from the stream.
     *
     * @param  stream the {@code ObjectInputStream} from which data is read
     * @throws IOException if an I/O error occurs
     * @throws ClassNotFoundException if a serialized class cannot be loaded
     */
    private void readObject(ObjectInputStream stream)
            throws IOException, ClassNotFoundException {
        stream.defaultReadObject();

        if ((prompt == null) || prompt.isEmpty() ||
                (choices == null) || (choices.length == 0) ||
                (defaultChoice < 0) || (defaultChoice >= choices.length)) {
            throw new InvalidObjectException(
                    "Missing/invalid prompt/choices");
        }
        choices = choices.clone();
        for (int i = 0; i < choices.length; i++) {
            if ((choices[i] == null) || choices[i].isEmpty())
                throw new InvalidObjectException("Null/empty choices");
        }

        if (selections != null) {
            selections = selections.clone();
            if (!multipleSelectionsAllowed && (selections.length != 1)) {
                throw new InvalidObjectException(
                        "Multiple selections not allowed");
            }
        }
    }
}
