/*
 * Copyright (c) 2020 PANTHEON.tech, s.r.o. and others.  All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
 * and is available at http://www.eclipse.org/legal/epl-v10.html
 */
package org.opendaylight.yangtools.yang.data.impl.schema.tree;

import static com.google.common.base.Verify.verifyNotNull;
import static java.util.Objects.requireNonNull;

import com.google.common.base.MoreObjects.ToStringHelper;
import java.util.Optional;
import org.eclipse.jdt.annotation.NonNull;
import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier.PathArgument;
import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
import org.opendaylight.yangtools.yang.data.api.schema.tree.DataValidationFailedException;
import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.TreeNode;
import org.opendaylight.yangtools.yang.data.api.schema.tree.spi.Version;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * A forwarding {@link ModificationApplyOperation}. Useful for strategies which do not deal with data layout, but rather
 * perform additional validation.
 */
abstract class AbstractValidation extends ModificationApplyOperation {
    private static final Logger LOG = LoggerFactory.getLogger(AbstractValidation.class);

    private final @NonNull ModificationApplyOperation delegate;

    AbstractValidation(final ModificationApplyOperation delegate) {
        this.delegate = requireNonNull(delegate);
    }

    @Override
    public final Optional<ModificationApplyOperation> getChild(final PathArgument child) {
        return delegate.getChild(child);
    }

    @Override
    final ChildTrackingPolicy getChildPolicy() {
        return delegate.getChildPolicy();
    }

    @Override
    final void mergeIntoModifiedNode(final ModifiedNode node, final NormalizedNode<?, ?> value, final Version version) {
        delegate.mergeIntoModifiedNode(node, value, version);
    }

    @Override
    final void quickVerifyStructure(final NormalizedNode<?, ?> modification) {
        delegate.quickVerifyStructure(modification);
    }

    @Override
    final void recursivelyVerifyStructure(final NormalizedNode<?, ?> value) {
        delegate.recursivelyVerifyStructure(value);
    }

    @Override
    final Optional<? extends TreeNode> apply(final ModifiedNode modification,
            final Optional<? extends TreeNode> storeMeta, final Version version) {
        Optional<? extends TreeNode> ret = modification.getValidatedNode(this, storeMeta);
        if (ret == null) {
            // This might also mean the delegate is maintaining validation
            if (delegate instanceof AbstractValidation) {
                ret = modification.getValidatedNode(delegate, storeMeta);
                if (ret != null) {
                    return ret;
                }
            }

            // Deal with the result moving on us
            ret = delegate.apply(modification, storeMeta, version);
            ret.ifPresent(meta -> enforceOnData(meta.getData()));
        }
        return ret;
    }

    @Override
    final void checkApplicable(final ModificationPath path, final NodeModification modification,
            final Optional<? extends TreeNode> current, final Version version) throws DataValidationFailedException {
        delegate.checkApplicable(path, modification, current, version);
        if (!(modification instanceof ModifiedNode)) {
            // FIXME: 7.0.0: turn this into a verify?
            LOG.debug("Could not validate {}, does not implement expected class {}", modification, ModifiedNode.class);
            return;
        }

        final ModifiedNode modified = (ModifiedNode) modification;
        if (delegate instanceof AbstractValidation) {
            checkApplicable(path, verifyNotNull(modified.getValidatedNode(delegate, current)));
            return;
        }

        // We need to actually perform the operation to deal with merge in a sane manner. We know the modification
        // is immutable, so the result of validation will probably not change. Note we should not be checking number
        final Optional<? extends TreeNode> applied = delegate.apply(modified, current, version);
        checkApplicable(path, applied);

        // Everything passed. We now have a snapshot of the result node, it would be too bad if we just threw it out.
        // We know what the result of an apply operation is going to be *if* the following are kept unchanged:
        // - the 'current' node
        // - the effective model context (therefore, the fact this object is associated with the modification)
        //
        // So let's stash the result. We will pick it up during apply operation.
        modified.setValidatedNode(this, current, applied);
    }

    private void checkApplicable(final ModificationPath path, final Optional<? extends TreeNode> applied)
            throws DataValidationFailedException {
        if (applied.isPresent()) {
            // We only enforce min/max on present data and rely on MandatoryLeafEnforcer to take care of the empty case
            enforceOnData(path, applied.orElseThrow().getData());
        }
    }

    @Override
    void fullVerifyStructure(final NormalizedNode<?, ?> modification) {
        delegate.fullVerifyStructure(modification);
        enforceOnData(modification);
    }

    final @NonNull ModificationApplyOperation delegate() {
        return delegate;
    }

    abstract void enforceOnData(ModificationPath path, NormalizedNode<?, ?> value)
        throws DataValidationFailedException;

    abstract void enforceOnData(@NonNull NormalizedNode<?, ?> data);

    @Override
    ToStringHelper addToStringAttributes(final ToStringHelper helper) {
        return helper.add("delegate", delegate);
    }
}