/*
 * This file is part of the Illarion project.
 *
 * Copyright © 2014 - Illarion e.V.
 *
 * Illarion is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Illarion is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
package illarion.easynpc.gui.syntax;

import org.antlr.v4.runtime.ANTLRInputStream;
import org.antlr.v4.runtime.Lexer;
import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.UnbufferedTokenStream;
import org.fife.ui.rsyntaxtextarea.AbstractTokenMaker;
import org.fife.ui.rsyntaxtextarea.Token;

import javax.annotation.Nonnull;
import javax.swing.text.Segment;
import java.beans.ConstructorProperties;
import java.io.CharArrayReader;
import java.io.IOException;
import java.io.Reader;

/**
 * This token maker is dedicated to handle the lexer tokens generated by ANTLRv4.
 *
 * @author Martin Karing <nitram@illarion.org>
 */
public abstract class AbstractAntlrTokenMaker<T extends Lexer> extends AbstractTokenMaker {
    /**
     * The lexer that provides the data.
     */
    @Nonnull
    private final T lexer;

    @ConstructorProperties("lexer")
    protected AbstractAntlrTokenMaker(@Nonnull T lexer) {
        this.lexer = lexer;
    }

    @Override
    public Token getTokenList(@Nonnull Segment text, int initialTokenType, int startOffset) {
        try (Reader textReader = new CharArrayReader(text.array, text.offset, text.count)) {
            lexer.setInputStream(new ANTLRInputStream(textReader));
            TokenStream tokenStream = new UnbufferedTokenStream(lexer);

            resetTokenList();

            while (true) {
                org.antlr.v4.runtime.Token currentToken = tokenStream.LT(1);

                if (currentToken.getType() == org.antlr.v4.runtime.Token.EOF) {
                    break;
                }
                tokenStream.consume();

                // convert the ANTLR token to a RSyntaxTextArea token and add it to the linked list
                int tokenStart = currentToken.getCharPositionInLine() + text.offset;
                int tokenEnd = (tokenStart + currentToken.getText().length()) - 1;
                int tokenOffset = startOffset + currentToken.getCharPositionInLine();

                addToken(text.array, tokenStart, tokenEnd, convertTokenType(currentToken.getType()), tokenOffset);
            } // end while

            // add a null token to indicate end of line; note that the test grammar has no multiline token types
            addNullToken();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return firstToken;
    }

    protected abstract int convertTokenType(int antlrType);
}