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The first Static Analysis and REMEDIATION tool
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/*
 * Copyright 2024 the original author or authors.
 * 
 * Licensed under the Moderne Source Available License (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 

 * https://docs.moderne.io/licensing/moderne-source-available-license
 * 
 * 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 org.openrewrite.staticanalysis;

import org.jspecify.annotations.Nullable;
import org.openrewrite.*;
import org.openrewrite.java.JavaIsoVisitor;
import org.openrewrite.java.search.UsesMethod;
import org.openrewrite.java.style.Checkstyle;
import org.openrewrite.java.style.EqualsAvoidsNullStyle;
import org.openrewrite.java.tree.J;
import org.openrewrite.java.tree.JavaSourceFile;

import java.time.Duration;
import java.util.Collections;
import java.util.Set;

import static java.util.Objects.requireNonNull;

public class EqualsAvoidsNull extends Recipe {

    @Override
    public String getDisplayName() {
        return "Equals avoids null";
    }

    @Override
    public String getDescription() {
        return "Checks that any combination of String literals is on the left side of an `equals()` comparison. Also checks for String literals assigned to some field (such as `someString.equals(anotherString = \"text\"))`.";
    }

    @Override
    public Set getTags() {
        return Collections.singleton("RSPEC-S1132");
    }

    @Override
    public Duration getEstimatedEffortPerOccurrence() {
        return Duration.ofMinutes(10);
    }

    @Override
    public TreeVisitor getVisitor() {
        JavaIsoVisitor replacementVisitor = new JavaIsoVisitor() {
            @Override
            public J visit(@Nullable Tree tree, ExecutionContext ctx) {
                if (tree instanceof JavaSourceFile) {
                    JavaSourceFile cu = (JavaSourceFile) requireNonNull(tree);
                    EqualsAvoidsNullStyle style = cu.getStyle(EqualsAvoidsNullStyle.class);
                    if (style == null) {
                        style = Checkstyle.equalsAvoidsNull();
                    }
                    return new EqualsAvoidsNullVisitor<>(style).visitNonNull(cu, ctx);
                }
                //noinspection DataFlowIssue
                return (J) tree;
            }
        };
        return Preconditions.check(
                Preconditions.or(
                        new UsesMethod<>("java.lang.String equals*(..)"),
                        new UsesMethod<>("java.lang.String co*(..)")
                ),
                replacementVisitor
        );
    }
}