Intuitive DSL for Java

/*
 * This file is part of the Intuitive DSL project.
 * Copyright (c) 2026 DBA Labs - Switzerland. All rights reserved.
 *
 * This program is dual-licensed under a commercial license and the AGPLv3.
 * For commercial licensing, contact us at [email protected] or visit https://www.dbalabs.ch.
 *
 * AGPLv3 licensing:
 * This program 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, version 3 (19 November 2007).
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <https://www.gnu.org/licenses/agpl-3.0.html>.
 */

package ch.dbalabs.intuitivedsl.parser;

import ch.dbalabs.intuitivedsl.exception.DslSyntaxException;
import ch.dbalabs.intuitivedsl.grammar.GrammarCompiler;
import ch.dbalabs.intuitivedsl.grammar.GroupNode;
import org.junit.jupiter.api.Test;

import java.util.List;

import static org.assertj.core.api.Assertions.assertThat;
import static org.assertj.core.api.Assertions.assertThatCode;
import static org.assertj.core.api.Assertions.assertThatThrownBy;

class ParserRobustnessFuzzLikeTest {

    private final Lexer lexer = new Lexer();
    private final AstNavigator navigator = new AstNavigator();
    private final GrammarCompiler compiler = new GrammarCompiler();

    @Test
    void shouldParseManyValidVariantsOfNestedGrammarWithoutThrowing() {
        GroupNode ast = compiler.compile("ROUTE { HTTP { GET | POST } | MQ { PUBLISH | SUBSCRIBE } } target [ WITH payload ] ;");

        List<String> validInputs = List.of(
                "ROUTE HTTP GET users ;",
                "ROUTE HTTP POST jobs WITH 'priority=high' ;",
                "ROUTE MQ PUBLISH invoices ;",
                "ROUTE MQ SUBSCRIBE billing WITH 'region=eu' ;"
        );

        assertThatCode(() -> {
            for (String input : validInputs) {
                ParseResult result = navigator.parse(input, lexer.tokenize(input), ast, name -> List.of());
                assertThat(result.getKeywords()).isNotEmpty();
            }
        }).doesNotThrowAnyException();
    }

    @Test
    void shouldRejectManyNearMissVariantsAtThePreciseFailurePoint() {
        GroupNode ast = compiler.compile("ROUTE { HTTP { GET | POST } | MQ { PUBLISH | SUBSCRIBE } } target [ WITH payload ] ;");

        List<String> invalidInputs = List.of(
                "ROUTE FTP GET users ;",
                "ROUTE HTTP PUT users ;",
                "ROUTE MQ EMIT jobs ;",
                "ROUTE HTTP GET users WITH ;",
                "ROUTE MQ SUBSCRIBE ;"
        );

        for (String input : invalidInputs) {
            assertThatThrownBy(() -> navigator.parse(input, lexer.tokenize(input), ast, name -> List.of()))
                    .isInstanceOf(DslSyntaxException.class)
                    .extracting(ex -> ((DslSyntaxException) ex).getRichMessage())
                    .asString()
                    .contains("Syntax Error at col")
                    .contains("Input: " + input);
        }
    }

    @Test
    void shouldRemainStableAcrossManyRepeatableVariants() {
        GroupNode ast = compiler.compile("GRANT role_name TO user_name ... [ IN scope_name ] ... ;");

        List<String> validInputs = List.of(
                "GRANT admin TO alice ;",
                "GRANT admin TO alice bob charlie ;",
                "GRANT reader TO alice IN eu ;",
                "GRANT reader TO alice bob IN eu IN finance IN archive ;"
        );

        assertThatCode(() -> {
            for (String input : validInputs) {
                navigator.parse(input, lexer.tokenize(input), ast, name -> List.of());
            }
        }).doesNotThrowAnyException();
    }

    @Test
    void shouldNotLoopOrCorruptStateWhenOptionalRepeatableGroupIsAbsent() {
        GroupNode ast = compiler.compile("GENERATE REPORT [ WITH metric_name ] ... ;");
        String input = "GENERATE REPORT ;";

        ParseResult result = navigator.parse(input, lexer.tokenize(input), ast, name -> List.of());

        assertThat(result.getParameters()).isEmpty();
        // Adjacent keywords are intentionally merged into a single keyword node/value.
        assertThat(result.getKeywords()).contains("GENERATE REPORT");
    }
}