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package Torello.HTML;

import java.util.HashMap;

/**
 * An enumeration of the standard Search Engine index-directives.
 * 
 * <BR /><BR /><EMBED CLASS="external-html" DATA-FILE-ID=ROBOTS>
 *
 * @see Features.Meta#insertRobots(Vector, boolean, boolean)
 * @see Features.Meta#getAllRobots(Vector)
 * @see Features.Meta#robotsMetaTag
 */
public enum Robots
{
    /**
     * Tells a search engine to index a page. Note that you don’t need to add this meta tag; it’s
     * the default.
     */
    Index("Index"),

    /** Tells a search engine not to index a page.*/
    NoIndex("NoIndex"),

    /**
     * Even if the page isn’t indexed, the crawler should follow all the links on a page and pass
     * equity to the linked pages.
     */
    Follow("Follow"),

    /** Tells a crawler not to follow any links on a page or pass along any link equity. */
    NoFollow("NoFollow"),

    /** Tells a crawler not to index any images on a page. */
    NoImageIndex("NoImageIndex"),

    /**
     * Equivalent to using both the {@code 'noindex'} and {@code 'nofollow'} tags
     * simultaneously.
     */
    None("None"),

    /** Search engines should not show a cached link to this page on a SERP. */
    NoArchive("NoArchive"),

    /** Same as {@code 'noarchive'}, but only used by Internet Explorer and Firefox. */
    NoCache("NoCache"),

    /**
     * Tells a search engine not to show a snippet of this page (i.e. meta {@code 'description'})
     * of this page on a SERP.
     */
    NoSnippet("NoSnippet"),

    /** Prevents all search-engine stuff. */
    All("All"),

    /**
     * [OBSOLETE]: Prevents search engines from using a page’s DMOZ description as the SERP snippet
     * for this page. However, DMOZ was retired in early 2017, making this tag obsolete.
     */
    NoYDir("NoYDir"),

    /**
     * [OBSOLETE]: Prevents search engines from using a page’s DMOZ description as the SERP snippet
     * for this page. However, DMOZ was retired in early 2017, making this tag obsolete.
     */
    NoODP("NoODP");

    public final String name;

    // The constructor
    private Robots(String name) { this.name = name; }

    // a robots lookup table.... Populate the lookup table on loading time
    private static final HashMap<String, Robots> lookup = new HashMap<>();

    // static initializer for the above hashmap
    static { for (Robots r : Robots.values()) lookup.put(r.name.toLowerCase(), r); }

    /**
     * This will retrieve the robot that maps to this parameter-{@code String}.  The {@code String}
     * should be a valid HMTL Meta-Tag {@code 'robots'} attribute-<B STYLE="color:red;">value</B>.
     * The valid values are the ones listed by this enumeration.  If an attempt is made to retrieve
     * a copy of an invalid {@code 'robots'} attribute-<B STYLE="color:red;">value</B>, then a 
     * {@code MalformedHTMLException} will be thrown.
     *
     * @param robotParam This parameter should be a {@code String} retrieved from a vectorized-html
     * page that is was found inside the {@code content='...'}
     * attribute-<B STYLE="color:red;">value</B> of a {@code 'robots'} meta-tag.
     *
     * @return An instance of this enumerated type.  The instance will map to the
     * passed-{@code String} parameter.
     *
     * @throws MalformedHTMLException If the passed parameter was not a valid robotParam.
     *
     * @see Features.Meta#insertRobots(Vector, boolean, boolean)
     * @see Features.Meta#getAllRobots(Vector)
     */
    public static Robots getRobot(String robotParam) throws MalformedHTMLException
    {
        Robots r = lookup.get(robotParam.toLowerCase());

        if (r != null) return r;

        else

            throw new MalformedHTMLException(
                "The robot parameter you are asking about does not exist: [" + robotParam + "]. " +
                "Please review the list of valid parameters to meta-tag robots."
            );
    }

    /**
     * This will retrieve the robot that maps to this parameter string.  The string should be a
     * valid HMTL Meta-Tag robots attribute value.  The valid values are the ones listed by this
     * enumeration.
     *
     * <BR /><BR /><B>NOTE:</B> This method will not throw an "Invalid HTML Exception" if an
     * invalid robots-parameter is passed.  Instead {@code 'null'} will simply be returned.
     *
     * @param robotParam This parameter should be a string retrieved from a vectorized-html page
     * that was in the {@code content='...'} attribute-field of a robots meta-tag.
     * 
     * @return An instance of this enumerated type.  The instance will be retrieved using
     * {@code 'robotParam'}.
     *
     *  @see Features.Meta#insertRobots(Vector, boolean, boolean)
     * @see Features.Meta#getAllRobots(Vector)
     */
    public static Robots getRobotNOMHE(String robotParam)
    { return lookup.get(robotParam.toLowerCase()); }
}