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package Torello.CSS;

import Torello.Java.Additional.ByRef;

import java.util.Vector;
import java.util.function.Consumer;

/** Any sequence of Whitespace */
@Torello.JavaDoc.JDHeaderBackgroundImg(EmbedTagFileID="CSS_TOK")
public class Whitespace extends CSSToken
    implements CharSequence, java.io.Serializable, Comparable<CharSequence>
{
    /** <EMBED CLASS='external-html' DATA-FILE-ID=SVUID> */
    protected static final long serialVersionUID = 1;


    // ********************************************************************************************
    // ********************************************************************************************
    // Private Constructor, API "is" and "if" Methods
    // ********************************************************************************************
    // ********************************************************************************************


    private Whitespace(final int[] css, final int sPos, final int ePos)
    { super(css, sPos, ePos); }

    @Override 
    public final boolean isWhitespace() { return true; }

    @Override
    public final Whitespace ifWhitespace() { return this; }


    // ********************************************************************************************
    // ********************************************************************************************
    // Tokenizer's "is" Method(s)
    // ********************************************************************************************
    // ********************************************************************************************


    // Currently this is Nearly Identical to what the CSSWG.org website says.  I am just not
    // going to analyze \n\r today.  I truly have no way of testing this type of crap.
    //
    // Note that the JDK-21 JavaDoc has a rather lengthy list of what will make Java's
    // java.lang.Character(int) is WhiteSpace return TRUE.
    // 
    // I will possibly change this to Character.isWhitespace(int codePoint) later...
    // For Now - the Plan is to follow the "W3" ==> 
    //      https://drafts.csswg.org/css-syntax/#whitespace

    private static final char[] WHITE_SPACE_ARR =
        { '\t', ' ', '\n', '\r', '\f', '\u000B' };

    static boolean is(final int c)
    {
        for (char ws : WHITE_SPACE_ARR) if (c == ws) return true;
        return false;
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // User's Constructor: a static "build" method
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * <EMBED CLASS=defs DATA-TOK=Whitespace DATA-P=ws>
     * <EMBED CLASS='external-html' DATA-FILE-ID=BUILD_DESC>
     * @param ws <EMBED CLASS='external-html' DATA-FILE-ID=BUILD_PARAM>
     * @return <EMBED CLASS='external-html' DATA-FILE-ID=BUILD_RET>
     * @throws TokenizeException <EMBED CLASS='external-html' DATA-FILE-ID=BUILD_TOK_EX>
     */
    @SuppressWarnings("unchecked")
    public static Whitespace build(final String ws)
    { return (Whitespace) CSSToken.build(ws, INPUT_CHECKER, Whitespace::consume); }

    private static final CSSToken.InputChecker INPUT_CHECKER = (int[] css) ->
    {
        if (css.length == 0) throw new TokenizeException 
            ("Input-String cannot have length 0.");

        if (! is(css[0])) throw new TokenizeException
            ("Input String does not start with a white-space character");
    };


    // ********************************************************************************************
    // ********************************************************************************************
    // CONSUME
    // ********************************************************************************************
    // ********************************************************************************************


    /**
     * This is a tokenizer method which <B>"consumes"</B> as much white-space as possible for the
     * purpose of building a Whitespace Token.
     * 
     * <EMBED CLASS=defs DATA-TOK=Whitespace-Token DATA-URL=whitespace-token-diagram
     *      DATA-OP=Consume>
     * <EMBED CLASS=external-html DATA-FILE-ID=COPIED_CSS_WG_RR>
     * <EMBED CLASS=external-html DATA-FILE-ID=WS_STAR_SVG>
     * <EMBED CLASS=external-html DATA-FILE-ID=WHITESPACE_SVG>
     * <EMBED CLASS=external-html DATA-FILE-ID=WHITESPACE_TOK_SVG>
     */
    protected static void consume(                          // When invoked from 'CSSTokenizer'
            final int[]                 css,                // C, int[] css
            final ByRef<Integer>        POS,                // P, array-pos loop-variable
            final Consumer<CSSToken>    returnParsedToken   // T, Vector<CSSToken>.add
        )
    {
        // NOTE: The algorithm will have already checked that css[0] is whitespace, or else it
        //       would have not invoked this method in the first place.  This is what the CSS
        //       Working Group Web-Site Pseudo-Code says, and this package "Sticks to the Plan"

        int pos=(POS.f+1); // input-pos + 1 !!  Doesn't check the first character

        TOP:
        for (; pos < css.length; pos++)
        {
            int c = css[pos];
            for (char ws : WHITE_SPACE_ARR) if (c == ws) continue TOP;
            break TOP;
        }

        returnParsedToken.accept(new Whitespace(css, POS.f, pos));
        POS.f = pos;
    }
}