/*
 * Copyright (c) 2017 Pantheon Technologies, 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.parser.rfc7950.stmt.uses;

import com.google.common.base.Verify;
import com.google.common.collect.ImmutableSet;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Optional;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.common.QNameModule;
import org.opendaylight.yangtools.yang.common.YangVersion;
import org.opendaylight.yangtools.yang.model.api.YangStmtMapping;
import org.opendaylight.yangtools.yang.model.api.meta.StatementDefinition;
import org.opendaylight.yangtools.yang.model.api.stmt.RefineStatement;
import org.opendaylight.yangtools.yang.model.api.stmt.SchemaNodeIdentifier;
import org.opendaylight.yangtools.yang.model.api.stmt.UsesEffectiveStatement;
import org.opendaylight.yangtools.yang.model.api.stmt.UsesStatement;
import org.opendaylight.yangtools.yang.parser.rfc7950.namespace.ChildSchemaNodeNamespace;
import org.opendaylight.yangtools.yang.parser.rfc7950.reactor.YangValidationBundles;
import org.opendaylight.yangtools.yang.parser.spi.GroupingNamespace;
import org.opendaylight.yangtools.yang.parser.spi.meta.AbstractQNameStatementSupport;
import org.opendaylight.yangtools.yang.parser.spi.meta.CopyType;
import org.opendaylight.yangtools.yang.parser.spi.meta.InferenceException;
import org.opendaylight.yangtools.yang.parser.spi.meta.ModelActionBuilder;
import org.opendaylight.yangtools.yang.parser.spi.meta.ModelActionBuilder.InferenceAction;
import org.opendaylight.yangtools.yang.parser.spi.meta.ModelActionBuilder.InferenceContext;
import org.opendaylight.yangtools.yang.parser.spi.meta.ModelActionBuilder.Prerequisite;
import org.opendaylight.yangtools.yang.parser.spi.meta.ModelProcessingPhase;
import org.opendaylight.yangtools.yang.parser.spi.meta.StmtContext;
import org.opendaylight.yangtools.yang.parser.spi.meta.StmtContext.Mutable;
import org.opendaylight.yangtools.yang.parser.spi.meta.StmtContextUtils;
import org.opendaylight.yangtools.yang.parser.spi.meta.SubstatementValidator;
import org.opendaylight.yangtools.yang.parser.spi.source.ModuleCtxToModuleQName;
import org.opendaylight.yangtools.yang.parser.spi.source.SourceException;
import org.opendaylight.yangtools.yang.parser.spi.validation.ValidationBundlesNamespace;
import org.opendaylight.yangtools.yang.parser.spi.validation.ValidationBundlesNamespace.ValidationBundleType;
import org.opendaylight.yangtools.yang.parser.stmt.reactor.StatementContextBase;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public final class UsesStatementSupport
        extends AbstractQNameStatementSupport<UsesStatement, UsesEffectiveStatement> {
    private static final Logger LOG = LoggerFactory.getLogger(UsesStatementSupport.class);
    private static final SubstatementValidator SUBSTATEMENT_VALIDATOR = SubstatementValidator.builder(YangStmtMapping
        .USES)
        .addAny(YangStmtMapping.AUGMENT)
        .addOptional(YangStmtMapping.DESCRIPTION)
        .addAny(YangStmtMapping.IF_FEATURE)
        .addAny(YangStmtMapping.REFINE)
        .addOptional(YangStmtMapping.REFERENCE)
        .addOptional(YangStmtMapping.STATUS)
        .addOptional(YangStmtMapping.WHEN)
        .build();
    private static final UsesStatementSupport INSTANCE = new UsesStatementSupport();

    private UsesStatementSupport() {
        super(YangStmtMapping.USES);
    }

    public static UsesStatementSupport getInstance() {
        return INSTANCE;
    }

    @Override
    public QName parseArgumentValue(final StmtContext<?, ?, ?> ctx, final String value) {
        return StmtContextUtils.parseNodeIdentifier(ctx, value);
    }

    @Override
    public void onFullDefinitionDeclared(final Mutable<QName, UsesStatement, UsesEffectiveStatement> usesNode) {
        if (!usesNode.isSupportedByFeatures()) {
            return;
        }
        super.onFullDefinitionDeclared(usesNode);

        final ModelActionBuilder usesAction = usesNode.newInferenceAction(ModelProcessingPhase.EFFECTIVE_MODEL);
        final QName groupingName = usesNode.getStatementArgument();

        final Prerequisite<StmtContext<?, ?, ?>> sourceGroupingPre = usesAction.requiresCtx(usesNode,
                GroupingNamespace.class, groupingName, ModelProcessingPhase.EFFECTIVE_MODEL);
        final Prerequisite<? extends StmtContext.Mutable<?, ?, ?>> targetNodePre = usesAction.mutatesEffectiveCtx(
                usesNode.getParentContext());

        usesAction.apply(new InferenceAction() {

            @Override
            public void apply(final InferenceContext ctx) {
                final StatementContextBase<?, ?, ?> targetNodeStmtCtx =
                        (StatementContextBase<?, ?, ?>) targetNodePre.resolve(ctx);
                final StatementContextBase<?, ?, ?> sourceGrpStmtCtx =
                        (StatementContextBase<?, ?, ?>) sourceGroupingPre.resolve(ctx);

                copyFromSourceToTarget(sourceGrpStmtCtx, targetNodeStmtCtx, usesNode);
                resolveUsesNode(usesNode, targetNodeStmtCtx);
                StmtContextUtils.validateIfFeatureAndWhenOnListKeys(usesNode);
            }

            @Override
            public void prerequisiteFailed(final Collection<? extends Prerequisite<?>> failed) {
                InferenceException.throwIf(failed.contains(sourceGroupingPre),
                        usesNode.getStatementSourceReference(), "Grouping '%s' was not resolved.", groupingName);
                throw new InferenceException("Unknown error occurred.", usesNode.getStatementSourceReference());
            }
        });
    }

    @Override
    public UsesStatement createDeclared(final StmtContext<QName, UsesStatement, ?> ctx) {
        return new UsesStatementImpl(ctx);
    }

    @Override
    public UsesEffectiveStatement createEffective(final StmtContext<QName, UsesStatement, UsesEffectiveStatement> ctx) {
        return new UsesEffectiveStatementImpl(ctx);
    }

    @Override
    protected SubstatementValidator getSubstatementValidator() {
        return SUBSTATEMENT_VALIDATOR;
    }

    /**
     * Copy statements from a grouping to a target node.
     *
     * @param sourceGrpStmtCtx
     *            source grouping statement context
     * @param targetCtx
     *            target context
     * @param usesNode
     *            uses node
     * @throws SourceException
     *             instance of SourceException
     */
    private static void copyFromSourceToTarget(final Mutable<?, ?, ?> sourceGrpStmtCtx,
            final StatementContextBase<?, ?, ?> targetCtx,
            final Mutable<QName, UsesStatement, UsesEffectiveStatement> usesNode) {
        final Collection<? extends Mutable<?, ?, ?>> declared = sourceGrpStmtCtx.mutableDeclaredSubstatements();
        final Collection<? extends Mutable<?, ?, ?>> effective = sourceGrpStmtCtx.mutableEffectiveSubstatements();
        final Collection<Mutable<?, ?, ?>> buffer = new ArrayList<>(declared.size() + effective.size());
        final QNameModule newQNameModule = getNewQNameModule(targetCtx, sourceGrpStmtCtx);

        for (final Mutable<?, ?, ?> original : declared) {
            if (original.isSupportedByFeatures()) {
                copyStatement(original, targetCtx, newQNameModule, buffer);
            }
        }

        for (final Mutable<?, ?, ?> original : effective) {
            copyStatement(original, targetCtx, newQNameModule, buffer);
        }

        targetCtx.addEffectiveSubstatements(buffer);
        usesNode.addAsEffectOfStatement(buffer);
    }

    // FIXME: YANGTOOLS-652: this map looks very much like InferredStatementContext.REUSED_DEF_SET
    // FIXME: YANGTOOLS-694: we should take advantage of CopyPolicy
    private static final ImmutableSet<? extends StatementDefinition> TOP_REUSED_DEF_SET = ImmutableSet.of(
        YangStmtMapping.TYPE, YangStmtMapping.TYPEDEF);
    private static final ImmutableSet<? extends StatementDefinition> DOCUMENTATION_STATEMENTS = ImmutableSet.of(
        YangStmtMapping.DESCRIPTION, YangStmtMapping.REFERENCE, YangStmtMapping.STATUS);

    private static void copyStatement(final Mutable<?, ?, ?> original,
            final StatementContextBase<?, ?, ?> targetCtx, final QNameModule targetModule,
            final Collection<Mutable<?, ?, ?>> buffer) {

        // FIXME: YANGTOOLS-694: This method needs to be adjusted to account for RFC7950,
        //                       https://tools.ietf.org/html/rfc7950#section-7.13, which states that:
        //
        //        The effect of a "uses" reference to a grouping is that the nodes
        //        defined by the grouping are copied into the current schema tree and
        //        are then updated according to the "refine" and "augment" statements.
        //
        //                       This means that the statement that is about to be copied (and can be subjected to
        //                       buildEffective() I think) is actually a SchemaTreeEffectiveStatement -- i.e. if it
        //                       is not a SchemaTreeEffectiveStatement, it just cannot be added to target's tree and
        //                       hence it should not be copied.

        final StatementDefinition def = original.getPublicDefinition();
        if (DOCUMENTATION_STATEMENTS.contains(def)) {
            // We do not want to propagate description/reference/status statements, as they are the source grouping's
            // documentation, not target statement's
            return;
        }
        if (TOP_REUSED_DEF_SET.contains(def)) {
            // a grouping's type/typedef statements are fully defined at the grouping, we want the same effective
            // statement
            buffer.add(original);
            return;
        }
        if (YangStmtMapping.USES.equals(def)) {
            // Do not propagate uses, as their effects have been accounted for in effective statements
            // FIXME: YANGTOOLS-652: this check is different from InferredStatementContext. Why is that? We should
            //                       express a common condition in our own implementation of applyCopyPolicy()
            // FIXME: YANGTOOLS-694: note that if the above is true, why are we propagating grouping statements?
            return;
        }
        original.copyAsChildOf(targetCtx, CopyType.ADDED_BY_USES, targetModule).ifPresent(buffer::add);
    }

    private static QNameModule getNewQNameModule(final StmtContext<?, ?, ?> targetCtx,
            final StmtContext<?, ?, ?> stmtContext) {
        if (targetCtx.getParentContext() == null) {
            return targetCtx.getFromNamespace(ModuleCtxToModuleQName.class, targetCtx);
        }
        if (targetCtx.getPublicDefinition() == YangStmtMapping.AUGMENT) {
            return StmtContextUtils.getRootModuleQName(targetCtx);
        }

        final Object targetStmtArgument = targetCtx.getStatementArgument();
        final Object sourceStmtArgument = stmtContext.getStatementArgument();
        if (targetStmtArgument instanceof QName && sourceStmtArgument instanceof QName) {
            return ((QName) targetStmtArgument).getModule();
        }

        return null;
    }

    private static void resolveUsesNode(final Mutable<QName, UsesStatement, UsesEffectiveStatement> usesNode,
            final StmtContext<?, ?, ?> targetNodeStmtCtx) {
        for (final Mutable<?, ?, ?> subStmtCtx : usesNode.mutableDeclaredSubstatements()) {
            if (StmtContextUtils.producesDeclared(subStmtCtx, RefineStatement.class)
                    && areFeaturesSupported(subStmtCtx)) {
                performRefine(subStmtCtx, targetNodeStmtCtx);
            }
        }
    }

    private static boolean areFeaturesSupported(final StmtContext<?, ?, ?> subStmtCtx) {
        /*
         * In case of Yang 1.1, checks whether features are supported.
         */
        return !YangVersion.VERSION_1_1.equals(subStmtCtx.getRootVersion()) || subStmtCtx.isSupportedByFeatures();
    }

    private static void performRefine(final Mutable<?, ?, ?> subStmtCtx, final StmtContext<?, ?, ?> usesParentCtx) {
        final Object refineArgument = subStmtCtx.getStatementArgument();
        InferenceException.throwIf(!(refineArgument instanceof SchemaNodeIdentifier),
            subStmtCtx.getStatementSourceReference(),
            "Invalid refine argument %s. It must be instance of SchemaNodeIdentifier.", refineArgument);

        final Optional<StmtContext<?, ?, ?>> optRefineTargetCtx = ChildSchemaNodeNamespace.findNode(
            usesParentCtx, (SchemaNodeIdentifier) refineArgument);
        InferenceException.throwIf(!optRefineTargetCtx.isPresent(), subStmtCtx.getStatementSourceReference(),
            "Refine target node %s not found.", refineArgument);

        final StmtContext<?, ?, ?> refineTargetNodeCtx = optRefineTargetCtx.get();
        if (StmtContextUtils.isUnknownStatement(refineTargetNodeCtx)) {
            LOG.trace("Refine node '{}' in uses '{}' has target node unknown statement '{}'. "
                + "Refine has been skipped. At line: {}", subStmtCtx.getStatementArgument(),
                subStmtCtx.coerceParentContext().getStatementArgument(),
                refineTargetNodeCtx.getStatementArgument(), subStmtCtx.getStatementSourceReference());
            subStmtCtx.addAsEffectOfStatement(refineTargetNodeCtx);
            return;
        }

        Verify.verify(refineTargetNodeCtx instanceof StatementContextBase);
        addOrReplaceNodes(subStmtCtx, (StatementContextBase<?, ?, ?>) refineTargetNodeCtx);
        subStmtCtx.addAsEffectOfStatement(refineTargetNodeCtx);
    }

    private static void addOrReplaceNodes(final Mutable<?, ?, ?> subStmtCtx,
            final StatementContextBase<?, ?, ?> refineTargetNodeCtx) {
        for (final Mutable<?, ?, ?> refineSubstatementCtx : subStmtCtx.mutableDeclaredSubstatements()) {
            if (isSupportedRefineSubstatement(refineSubstatementCtx)) {
                addOrReplaceNode(refineSubstatementCtx, refineTargetNodeCtx);
            }
        }
    }

    private static void addOrReplaceNode(final Mutable<?, ?, ?> refineSubstatementCtx,
            final StatementContextBase<?, ?, ?> refineTargetNodeCtx) {

        final StatementDefinition refineSubstatementDef = refineSubstatementCtx.getPublicDefinition();

        SourceException.throwIf(!isSupportedRefineTarget(refineSubstatementCtx, refineTargetNodeCtx),
                refineSubstatementCtx.getStatementSourceReference(),
                "Error in module '%s' in the refine of uses '%s': can not perform refine of '%s' for the target '%s'.",
                refineSubstatementCtx.getRoot().getStatementArgument(),
                refineSubstatementCtx.coerceParentContext().getStatementArgument(),
                refineSubstatementCtx.getPublicDefinition(), refineTargetNodeCtx.getPublicDefinition());

        if (isAllowedToAddByRefine(refineSubstatementDef)) {
            refineTargetNodeCtx.addEffectiveSubstatement(refineSubstatementCtx);
        } else {
            refineTargetNodeCtx.removeStatementFromEffectiveSubstatements(refineSubstatementDef);
            refineTargetNodeCtx.addEffectiveSubstatement(refineSubstatementCtx);
        }
    }

    private static boolean isAllowedToAddByRefine(final StatementDefinition publicDefinition) {
        return YangStmtMapping.MUST.equals(publicDefinition);
    }

    private static boolean isSupportedRefineSubstatement(final StmtContext<?, ?, ?> refineSubstatementCtx) {
        final Collection<?> supportedRefineSubstatements = refineSubstatementCtx.getFromNamespace(
                ValidationBundlesNamespace.class, ValidationBundleType.SUPPORTED_REFINE_SUBSTATEMENTS);

        return supportedRefineSubstatements == null || supportedRefineSubstatements.isEmpty()
                || supportedRefineSubstatements.contains(refineSubstatementCtx.getPublicDefinition())
                || StmtContextUtils.isUnknownStatement(refineSubstatementCtx);
    }

    private static boolean isSupportedRefineTarget(final StmtContext<?, ?, ?> refineSubstatementCtx,
            final StmtContext<?, ?, ?> refineTargetNodeCtx) {
        final Collection<?> supportedRefineTargets = YangValidationBundles.SUPPORTED_REFINE_TARGETS.get(
            refineSubstatementCtx.getPublicDefinition());

        return supportedRefineTargets == null || supportedRefineTargets.isEmpty()
                || supportedRefineTargets.contains(refineTargetNodeCtx.getPublicDefinition());
    }
}