/*
 * Copyright 2013-2026, Seqera Labs
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package nextflow.script.parser;

import org.antlr.v4.runtime.BailErrorStrategy;
import org.antlr.v4.runtime.CharStream;
import org.antlr.v4.runtime.FailedPredicateException;
import org.antlr.v4.runtime.InputMismatchException;
import org.antlr.v4.runtime.NoViableAltException;
import org.antlr.v4.runtime.Parser;
import org.antlr.v4.runtime.ParserRuleContext;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.atn.PredictionMode;
import org.antlr.v4.runtime.misc.Interval;
import org.antlr.v4.runtime.misc.ParseCancellationException;

/**
 * Provide friendly error messages when parsing errors occurred.
 */
public class DescriptiveErrorStrategy extends BailErrorStrategy {
    private CharStream charStream;

    public DescriptiveErrorStrategy(CharStream charStream) {
        this.charStream = charStream;
    }

    @Override
    public void recover(Parser recognizer, RecognitionException e) {
        for (ParserRuleContext context = recognizer.getContext(); context != null; context = context.getParent()) {
            context.exception = e;
        }

        if (PredictionMode.LL.equals(recognizer.getInterpreter().getPredictionMode())) {
            if (e instanceof NoViableAltException) {
                this.reportNoViableAlternative(recognizer, (NoViableAltException) e);
            } else if (e instanceof InputMismatchException) {
                this.reportInputMismatch(recognizer, (InputMismatchException) e);
            } else if (e instanceof FailedPredicateException) {
                this.reportFailedPredicate(recognizer, (FailedPredicateException) e);
            }
        }

        throw new ParseCancellationException(e);
    }

    @Override
    public Token recoverInline(Parser recognizer)
            throws RecognitionException {

        this.recover(recognizer, new InputMismatchException(recognizer)); // stop parsing
        return null;
    }

    @Override
    public void reportError(Parser recognizer, RecognitionException e) {
    }

    protected String createNoViableAlternativeErrorMessage(Parser recognizer, NoViableAltException e) {
        TokenStream tokens = recognizer.getInputStream();
        String input;
        if (tokens != null) {
            if (e.getStartToken().getType() == Token.EOF) {
                input = "<EOF>";
            } else {
                input = e.getOffendingToken().getText();
            }
        } else {
            input = "<unknown input>";
        }

        return "Unexpected input: " + escapeWSAndQuote(input);
    }

    @Override
    protected void reportNoViableAlternative(Parser recognizer,
                                             NoViableAltException e) {

        notifyErrorListeners(recognizer, this.createNoViableAlternativeErrorMessage(recognizer, e), e);
    }

    protected String createInputMismatchErrorMessage(Parser recognizer,
                                                     InputMismatchException e) {
        return "Unexpected input: " + getTokenErrorDisplay(e.getOffendingToken());
    }

    @Override
    protected void reportInputMismatch(Parser recognizer,
                                       InputMismatchException e) {

        notifyErrorListeners(recognizer, this.createInputMismatchErrorMessage(recognizer, e), e);
    }

    protected String createFailedPredicateErrorMessage(Parser recognizer,
                                                       FailedPredicateException e) {
        return e.getMessage();
    }

    @Override
    protected void reportFailedPredicate(Parser recognizer,
                                         FailedPredicateException e) {
        notifyErrorListeners(recognizer, this.createFailedPredicateErrorMessage(recognizer, e), e);
    }

    protected void notifyErrorListeners(Parser recognizer, String message, RecognitionException e) {
        recognizer.notifyErrorListeners(e.getOffendingToken(), message, e);
    }
}
