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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
 * one is included with the Software each a "Larger Work" to which the Software
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
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package com.oracle.graal.python.parser;

import static com.oracle.graal.python.nodes.BuiltinNames.EXEC;
import static com.oracle.graal.python.nodes.BuiltinNames.PRINT;

import org.antlr.v4.runtime.DefaultErrorStrategy;
import org.antlr.v4.runtime.InputMismatchException;
import org.antlr.v4.runtime.NoViableAltException;
import org.antlr.v4.runtime.Parser;
import org.antlr.v4.runtime.RecognitionException;
import org.antlr.v4.runtime.Token;
import org.antlr.v4.runtime.TokenStream;
import org.antlr.v4.runtime.misc.Interval;

import com.oracle.graal.python.parser.antlr.DescriptiveBailErrorListener;
import com.oracle.graal.python.runtime.PythonParser.ErrorType;
import com.oracle.truffle.api.source.Source;
import com.oracle.truffle.api.source.SourceSection;

public class PythonErrorStrategy extends DefaultErrorStrategy {
    private static final String LINE_PADDING = "  ";

    @Override
    public void recover(Parser recognizer, RecognitionException e) {
        super.recover(recognizer, e);
    }

    public static SourceSection getPosition(Source source, Exception e) {
        RecognitionException r;
        if (e instanceof RecognitionException) {
            r = (RecognitionException) e;
        } else {
            Throwable cause = e.getCause();
            if (cause instanceof RecognitionException) {
                r = (RecognitionException) cause;
            } else {
                return source.createUnavailableSection();
            }
        }
        Token token = r.getOffendingToken();
        return source.createSection(token.getStartIndex(), Math.max(0, token.getStopIndex() - token.getStartIndex()));
    }

    public static ErrorType getErrorType(Exception e, SourceSection section) {
        if (e instanceof DescriptiveBailErrorListener.EmptyRecognitionException) {
            DescriptiveBailErrorListener.EmptyRecognitionException except = ((DescriptiveBailErrorListener.EmptyRecognitionException) e);
            ErrorType type = except.getErrorType();
            if (section.isAvailable() && type == ErrorType.Generic) {
                String prev = except.getPreviousToken();
                if (prev != null) {
                    if (prev.equals(PRINT)) {
                        return ErrorType.Print;
                    }
                    if (prev.equals(EXEC)) {
                        return ErrorType.Exec;
                    }
                }
            }
            return type;
        }
        return ErrorType.Generic;
    }

    private static String getTokeLineText(Parser recognizer, Token token) {
        TokenStream tokenStream = recognizer.getTokenStream();
        int index = token.getTokenIndex();
        // search for line start
        int tokenIndex = index;
        int start = 0;
        while (tokenIndex >= 0) {
            Token t = tokenStream.get(tokenIndex);
            if (t.getText().equals("\n")) {
                break;
            }
            start = t.getStartIndex();
            tokenIndex--;
        }

        // search for line stop
        tokenIndex = index;
        int stop = -1;
        while (tokenIndex < tokenStream.size()) {
            Token t = tokenStream.get(tokenIndex);
            stop = t.getStopIndex();
            if (t.getText().equals("\n")) {
                break;
            }
            tokenIndex++;
        }
        return token.getInputStream().getText(Interval.of(start, stop));
    }

    private static void handlePythonSyntaxError(Parser recognizer, RecognitionException e) {
        Token offendingToken = e.getOffendingToken();
        String lineText = getTokeLineText(recognizer, offendingToken);
        String errorMarker = new String(new char[offendingToken.getCharPositionInLine()]).replace('\0', ' ') + "^";
        String pythonSyntaxErrorMessage = "\n" + LINE_PADDING + lineText + "\n" + LINE_PADDING + errorMarker;
        recognizer.notifyErrorListeners(offendingToken, pythonSyntaxErrorMessage, e);
    }

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

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

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

}
