/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.kernel.impl.api;

import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.neo4j.internal.kernel.api.security.LoginContext.AUTH_DISABLED;
import static org.neo4j.kernel.api.KernelTransaction.Type.IMPLICIT;

import java.util.concurrent.locks.LockSupport;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.neo4j.exceptions.KernelException;
import org.neo4j.internal.kernel.api.exceptions.TransactionFailureException;
import org.neo4j.internal.kernel.api.exceptions.schema.IndexNotFoundKernelException;
import org.neo4j.internal.schema.ConstraintDescriptor;
import org.neo4j.internal.schema.IndexDescriptor;
import org.neo4j.internal.schema.IndexPrototype;
import org.neo4j.internal.schema.LabelSchemaDescriptor;
import org.neo4j.internal.schema.SchemaDescriptors;
import org.neo4j.kernel.api.Kernel;
import org.neo4j.kernel.api.KernelTransaction;
import org.neo4j.kernel.impl.api.index.SchemaIndexTestHelper;
import org.neo4j.kernel.internal.GraphDatabaseAPI;
import org.neo4j.test.extension.ImpermanentDbmsExtension;
import org.neo4j.test.extension.Inject;

@ImpermanentDbmsExtension
class KernelSchemaStateFlushingTest {
    @Inject
    private GraphDatabaseAPI db;

    @Inject
    private Kernel kernel;

    private int labelId;
    private int propId;

    @BeforeEach
    void setup() throws KernelException {
        try (KernelTransaction transaction = beginTransaction()) {
            // Make sure that a label token with id 1, and a property key token, also with id 1, both exists.
            transaction.tokenWrite().labelGetOrCreateForName("Label0");
            labelId = transaction.tokenWrite().labelGetOrCreateForName("Label1");
            transaction.tokenWrite().propertyKeyGetOrCreateForName("prop0");
            propId = transaction.tokenWrite().propertyKeyGetOrCreateForName("prop1");
            transaction.commit();
        }
    }

    @Test
    void shouldKeepSchemaStateIfSchemaIsNotModified() throws TransactionFailureException {
        // given
        String before = commitToSchemaState("test", "before");

        // then
        assertEquals("before", before);

        // given
        String after = commitToSchemaState("test", "after");

        // then
        assertEquals("before", after);
    }

    @Test
    void shouldInvalidateSchemaStateOnCreateIndex() throws Exception {
        // given
        commitToSchemaState("test", "before");

        awaitIndexOnline(createIndex(), "test");

        // when
        String after = commitToSchemaState("test", "after");

        // then
        assertEquals("after", after);
    }

    @Test
    void shouldInvalidateSchemaStateOnDropIndex() throws Exception {
        IndexDescriptor ref = createIndex();

        awaitIndexOnline(ref, "test");

        commitToSchemaState("test", "before");

        dropIndex(ref);

        // when
        String after = commitToSchemaState("test", "after");

        // then
        assertEquals("after", after);
    }

    @Test
    void shouldInvalidateSchemaStateOnCreateConstraint() throws Exception {
        // given
        commitToSchemaState("test", "before");

        createConstraint();

        // when
        String after = commitToSchemaState("test", "after");

        // then
        assertEquals("after", after);
    }

    @Test
    void shouldInvalidateSchemaStateOnDropConstraint() throws Exception {
        // given
        ConstraintDescriptor descriptor = createConstraint();

        commitToSchemaState("test", "before");

        dropConstraint(descriptor);

        // when
        String after = commitToSchemaState("test", "after");

        // then
        assertEquals("after", after);
    }

    private ConstraintDescriptor createConstraint() throws KernelException {
        try (KernelTransaction transaction = beginTransaction()) {
            ConstraintDescriptor descriptor = transaction
                    .schemaWrite()
                    .uniquePropertyConstraintCreate(
                            IndexPrototype.uniqueForSchema(SchemaDescriptors.forLabel(labelId, propId)));
            transaction.commit();
            return descriptor;
        }
    }

    private void dropConstraint(ConstraintDescriptor descriptor) throws KernelException {
        try (KernelTransaction transaction = beginTransaction()) {
            transaction.schemaWrite().constraintDrop(descriptor);
            transaction.commit();
        }
    }

    private IndexDescriptor createIndex() throws KernelException {
        try (KernelTransaction transaction = beginTransaction()) {
            LabelSchemaDescriptor schema = SchemaDescriptors.forLabel(labelId, propId);
            IndexDescriptor reference = transaction.schemaWrite().indexCreate(IndexPrototype.forSchema(schema));
            transaction.commit();
            return reference;
        }
    }

    private void dropIndex(IndexDescriptor reference) throws KernelException {
        try (KernelTransaction transaction = beginTransaction()) {
            transaction.schemaWrite().indexDrop(reference);
            transaction.commit();
        }
    }

    private void awaitIndexOnline(IndexDescriptor descriptor, String keyForProbing)
            throws IndexNotFoundKernelException, TransactionFailureException {
        try (KernelTransaction transaction = beginTransaction()) {
            SchemaIndexTestHelper.awaitIndexOnline(transaction.schemaRead(), descriptor);
            transaction.commit();
        }
        awaitSchemaStateCleared(keyForProbing);
    }

    private void awaitSchemaStateCleared(String keyForProbing) throws TransactionFailureException {
        try (KernelTransaction transaction = beginTransaction()) {
            while (transaction.schemaRead().schemaStateGetOrCreate(keyForProbing, ignored -> null) != null) {
                LockSupport.parkNanos(MILLISECONDS.toNanos(10));
            }
            transaction.commit();
        }
    }

    private String commitToSchemaState(String key, String value) throws TransactionFailureException {
        try (KernelTransaction transaction = beginTransaction()) {
            String result = getOrCreateFromState(transaction, key, value);
            transaction.commit();
            return result;
        }
    }

    private static String getOrCreateFromState(KernelTransaction tx, String key, final String value) {
        return tx.schemaRead().schemaStateGetOrCreate(key, from -> value);
    }

    private KernelTransaction beginTransaction() throws TransactionFailureException {
        return kernel.beginTransaction(IMPLICIT, AUTH_DISABLED);
    }
}
