/*
 * 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.deviate;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMap.Builder;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.SetMultimap;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import org.opendaylight.yangtools.yang.common.QNameModule;
import org.opendaylight.yangtools.yang.common.YangVersion;
import org.opendaylight.yangtools.yang.model.api.DeviateKind;
import org.opendaylight.yangtools.yang.model.api.YangStmtMapping;
import org.opendaylight.yangtools.yang.model.api.meta.EffectiveStatement;
import org.opendaylight.yangtools.yang.model.api.meta.StatementDefinition;
import org.opendaylight.yangtools.yang.model.api.stmt.DeviateStatement;
import org.opendaylight.yangtools.yang.model.api.stmt.SchemaNodeIdentifier;
import org.opendaylight.yangtools.yang.parser.rfc7950.namespace.SchemaNodeIdentifierBuildNamespace;
import org.opendaylight.yangtools.yang.parser.rfc7950.reactor.YangValidationBundles;
import org.opendaylight.yangtools.yang.parser.spi.meta.AbstractStatementSupport;
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.ModulesDeviatedByModules;
import org.opendaylight.yangtools.yang.parser.spi.source.ModulesDeviatedByModules.SupportedModules;
import org.opendaylight.yangtools.yang.parser.spi.source.SourceException;
import org.opendaylight.yangtools.yang.parser.stmt.reactor.StatementContextBase;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

abstract class AbstractDeviateStatementSupport extends AbstractStatementSupport<DeviateKind, DeviateStatement,
        EffectiveStatement<DeviateKind, DeviateStatement>> {
    private static final Logger LOG = LoggerFactory.getLogger(DeviateStatementImpl.class);

    private static final SubstatementValidator DEVIATE_NOT_SUPPORTED_SUBSTATEMENT_VALIDATOR =
            SubstatementValidator.builder(YangStmtMapping.DEVIATE).build();

    private static final SubstatementValidator DEVIATE_ADD_SUBSTATEMENT_VALIDATOR =
            SubstatementValidator.builder(YangStmtMapping.DEVIATE)
                .addOptional(YangStmtMapping.CONFIG)
                .addOptional(YangStmtMapping.DEFAULT)
                .addOptional(YangStmtMapping.MANDATORY)
                .addOptional(YangStmtMapping.MAX_ELEMENTS)
                .addOptional(YangStmtMapping.MIN_ELEMENTS)
                .addAny(YangStmtMapping.MUST)
                .addAny(YangStmtMapping.UNIQUE)
                .addOptional(YangStmtMapping.UNITS)
                .build();

    private static final SubstatementValidator DEVIATE_REPLACE_SUBSTATEMENT_VALIDATOR =
            SubstatementValidator.builder(YangStmtMapping.DEVIATE)
                .addOptional(YangStmtMapping.CONFIG)
                .addOptional(YangStmtMapping.DEFAULT)
                .addOptional(YangStmtMapping.MANDATORY)
                .addOptional(YangStmtMapping.MAX_ELEMENTS)
                .addOptional(YangStmtMapping.MIN_ELEMENTS)
                .addOptional(YangStmtMapping.TYPE)
                .addOptional(YangStmtMapping.UNITS)
                .build();

    private static final SubstatementValidator DEVIATE_DELETE_SUBSTATEMENT_VALIDATOR =
            SubstatementValidator.builder(YangStmtMapping.DEVIATE)
                .addOptional(YangStmtMapping.DEFAULT)
                .addAny(YangStmtMapping.MUST)
                .addAny(YangStmtMapping.UNIQUE)
                .addOptional(YangStmtMapping.UNITS)
                .build();

    private static final Map<String, DeviateKind> KEYWORD_TO_DEVIATE_MAP;

    static {
        final Builder<String, DeviateKind> keywordToDeviateMapBuilder = ImmutableMap.builder();
        for (final DeviateKind deviate : DeviateKind.values()) {
            keywordToDeviateMapBuilder.put(deviate.getKeyword(), deviate);
        }
        KEYWORD_TO_DEVIATE_MAP = keywordToDeviateMapBuilder.build();
    }

    private static final Set<YangStmtMapping> SINGLETON_STATEMENTS = ImmutableSet.of(
            YangStmtMapping.UNITS, YangStmtMapping.CONFIG, YangStmtMapping.MANDATORY,
            YangStmtMapping.MIN_ELEMENTS, YangStmtMapping.MAX_ELEMENTS);

    private static final Set<YangStmtMapping> IMPLICIT_STATEMENTS = ImmutableSet.of(YangStmtMapping.CONFIG,
            YangStmtMapping.MANDATORY, YangStmtMapping.MAX_ELEMENTS, YangStmtMapping.MIN_ELEMENTS);

    AbstractDeviateStatementSupport() {
        super(YangStmtMapping.DEVIATE);
    }

    @Override
    public final DeviateKind parseArgumentValue(final StmtContext<?, ?, ?> ctx, final String value) {
        return SourceException.throwIfNull(KEYWORD_TO_DEVIATE_MAP.get(value),
            ctx.getStatementSourceReference(), "String '%s' is not valid deviate argument", value);
    }

    @Override
    public final DeviateStatement createDeclared(final StmtContext<DeviateKind, DeviateStatement, ?> ctx) {
        return new DeviateStatementImpl(ctx);
    }

    @Override
    public final EffectiveStatement<DeviateKind, DeviateStatement> createEffective(
            final StmtContext<DeviateKind, DeviateStatement, EffectiveStatement<DeviateKind,
                    DeviateStatement>> ctx) {
        return new DeviateEffectiveStatementImpl(ctx);
    }

    @Override
    public final void onFullDefinitionDeclared(final Mutable<DeviateKind, DeviateStatement,
            EffectiveStatement<DeviateKind, DeviateStatement>> deviateStmtCtx) {
        final DeviateKind deviateKind = deviateStmtCtx.getStatementArgument();
        getSubstatementValidatorForDeviate(deviateKind).validate(deviateStmtCtx);

        final SchemaNodeIdentifier deviationTarget =
                (SchemaNodeIdentifier) deviateStmtCtx.getParentContext().getStatementArgument();

        if (!isDeviationSupported(deviateStmtCtx, deviationTarget)) {
            return;
        }

        final ModelActionBuilder deviateAction = deviateStmtCtx.newInferenceAction(
                ModelProcessingPhase.EFFECTIVE_MODEL);

        final Prerequisite<StmtContext<DeviateKind, DeviateStatement, EffectiveStatement<DeviateKind,
                DeviateStatement>>> sourceCtxPrerequisite =
                deviateAction.requiresCtx(deviateStmtCtx, ModelProcessingPhase.EFFECTIVE_MODEL);

        final Prerequisite<Mutable<?, ?, EffectiveStatement<?, ?>>> targetCtxPrerequisite =
                deviateAction.mutatesEffectiveCtx(deviateStmtCtx.getRoot(),
                    SchemaNodeIdentifierBuildNamespace.class,  deviationTarget);

        deviateAction.apply(new InferenceAction() {
            @Override
            public void apply(final InferenceContext ctx) throws InferenceException {
                // FIXME once BUG-7760 gets fixed, there will be no need for these dirty casts
                final StatementContextBase<?, ?, ?> sourceNodeStmtCtx =
                        (StatementContextBase<?, ?, ?>) sourceCtxPrerequisite.resolve(ctx);
                final StatementContextBase<?, ?, ?> targetNodeStmtCtx =
                        (StatementContextBase<?, ?, ?>) targetCtxPrerequisite.resolve(ctx);

                switch (deviateKind) {
                    case NOT_SUPPORTED:
                        targetNodeStmtCtx.setIsSupportedToBuildEffective(false);
                        break;
                    case ADD:
                        performDeviateAdd(sourceNodeStmtCtx, targetNodeStmtCtx);
                        break;
                    case REPLACE:
                        performDeviateReplace(sourceNodeStmtCtx, targetNodeStmtCtx);
                        break;
                    case DELETE:
                        performDeviateDelete(sourceNodeStmtCtx, targetNodeStmtCtx);
                        break;
                    default:
                        throw new IllegalStateException("Unsupported deviate " + deviateKind);
                }
            }

            @Override
            public void prerequisiteFailed(final Collection<? extends Prerequisite<?>> failed) {
                throw new InferenceException(deviateStmtCtx.getParentContext().getStatementSourceReference(),
                    "Deviation target '%s' not found.", deviationTarget);
            }
        });
    }

    @Override
    protected final SubstatementValidator getSubstatementValidator() {
        return null;
    }

    protected SubstatementValidator getSubstatementValidatorForDeviate(final DeviateKind deviateKind) {
        switch (deviateKind) {
            case NOT_SUPPORTED:
                return DEVIATE_NOT_SUPPORTED_SUBSTATEMENT_VALIDATOR;
            case ADD:
                return DEVIATE_ADD_SUBSTATEMENT_VALIDATOR;
            case REPLACE:
                return DEVIATE_REPLACE_SUBSTATEMENT_VALIDATOR;
            case DELETE:
                return DEVIATE_DELETE_SUBSTATEMENT_VALIDATOR;
            default:
                throw new IllegalStateException(String.format(
                        "Substatement validator for deviate %s has not been defined.", deviateKind));
        }
    }

    private static boolean isDeviationSupported(final Mutable<DeviateKind, DeviateStatement,
            EffectiveStatement<DeviateKind, DeviateStatement>> deviateStmtCtx,
            final SchemaNodeIdentifier deviationTarget) {
        final SetMultimap<QNameModule, QNameModule> modulesDeviatedByModules = deviateStmtCtx.getFromNamespace(
                ModulesDeviatedByModules.class, SupportedModules.SUPPORTED_MODULES);
        if (modulesDeviatedByModules == null) {
            return true;
        }

        final QNameModule currentModule = deviateStmtCtx.getFromNamespace(ModuleCtxToModuleQName.class,
                deviateStmtCtx.getRoot());
        final QNameModule targetModule = deviationTarget.getLastComponent().getModule();

        final Set<QNameModule> deviationModulesSupportedByTargetModule = modulesDeviatedByModules.get(targetModule);
        if (deviationModulesSupportedByTargetModule != null) {
            return deviationModulesSupportedByTargetModule.contains(currentModule);
        }

        return false;
    }

    private static void performDeviateAdd(final StatementContextBase<?, ?, ?> deviateStmtCtx,
            final StatementContextBase<?, ?, ?> targetCtx) {
        for (Mutable<?, ?, ?> originalStmtCtx : deviateStmtCtx.mutableDeclaredSubstatements()) {
            validateDeviationTarget(originalStmtCtx, targetCtx);
            addStatement(originalStmtCtx, targetCtx);
        }
    }

    private static void addStatement(final Mutable<?, ?, ?> stmtCtxToBeAdded,
            final StatementContextBase<?, ?, ?> targetCtx) {
        if (!StmtContextUtils.isUnknownStatement(stmtCtxToBeAdded)) {
            final StatementDefinition stmtToBeAdded = stmtCtxToBeAdded.getPublicDefinition();
            if (SINGLETON_STATEMENTS.contains(stmtToBeAdded) || YangStmtMapping.DEFAULT.equals(stmtToBeAdded)
                    && YangStmtMapping.LEAF.equals(targetCtx.getPublicDefinition())) {
                for (final StmtContext<?, ?, ?> targetCtxSubstatement : targetCtx.allSubstatements()) {
                    InferenceException.throwIf(stmtToBeAdded.equals(targetCtxSubstatement.getPublicDefinition()),
                        stmtCtxToBeAdded.getStatementSourceReference(),
                        "Deviation cannot add substatement %s to target node %s because it is already defined "
                        + "in target and can appear only once.",
                        stmtToBeAdded.getStatementName(), targetCtx.getStatementArgument());
                }
            }
        }

        copyStatement(stmtCtxToBeAdded, targetCtx);
    }

    private static void performDeviateReplace(final StatementContextBase<?, ?, ?> deviateStmtCtx,
            final StatementContextBase<?, ?, ?> targetCtx) {
        for (Mutable<?, ?, ?> originalStmtCtx : deviateStmtCtx.mutableDeclaredSubstatements()) {
            validateDeviationTarget(originalStmtCtx, targetCtx);
            replaceStatement(originalStmtCtx, targetCtx);
        }
    }

    private static void replaceStatement(final Mutable<?, ?, ?> stmtCtxToBeReplaced,
            final StatementContextBase<?, ?, ?> targetCtx) {
        final StatementDefinition stmtToBeReplaced = stmtCtxToBeReplaced.getPublicDefinition();

        if (YangStmtMapping.DEFAULT.equals(stmtToBeReplaced)
                && YangStmtMapping.LEAF_LIST.equals(targetCtx.getPublicDefinition())) {
            LOG.error("Deviation cannot replace substatement {} in target leaf-list {} because a leaf-list can "
                    + "have multiple default statements. At line: {}", stmtToBeReplaced.getStatementName(),
                    targetCtx.getStatementArgument(), stmtCtxToBeReplaced.getStatementSourceReference());
            return;
        }

        for (final StmtContext<?, ?, ?> targetCtxSubstatement : targetCtx.effectiveSubstatements()) {
            if (stmtToBeReplaced.equals(targetCtxSubstatement.getPublicDefinition())) {
                targetCtx.removeStatementFromEffectiveSubstatements(stmtToBeReplaced);
                copyStatement(stmtCtxToBeReplaced, targetCtx);
                return;
            }
        }

        for (final Mutable<?, ?, ?> targetCtxSubstatement : targetCtx.mutableDeclaredSubstatements()) {
            if (stmtToBeReplaced.equals(targetCtxSubstatement.getPublicDefinition())) {
                targetCtxSubstatement.setIsSupportedToBuildEffective(false);
                copyStatement(stmtCtxToBeReplaced, targetCtx);
                return;
            }
        }

        // This is a special case when deviate replace of a config/mandatory/max/min-elements substatement targets
        // a node which does not contain an explicitly declared config/mandatory/max/min-elements.
        // However, according to RFC6020/RFC7950, these properties are always implicitly present.
        if (IMPLICIT_STATEMENTS.contains(stmtToBeReplaced)) {
            addStatement(stmtCtxToBeReplaced, targetCtx);
            return;
        }

        throw new InferenceException(stmtCtxToBeReplaced.getStatementSourceReference(), "Deviation cannot replace "
                + "substatement %s in target node %s because it does not exist in target node.",
                stmtToBeReplaced.getStatementName(), targetCtx.getStatementArgument());
    }

    private static void performDeviateDelete(final StatementContextBase<?, ?, ?> deviateStmtCtx,
            final StatementContextBase<?, ?, ?> targetCtx) {
        for (Mutable<?, ?, ?> originalStmtCtx : deviateStmtCtx.mutableDeclaredSubstatements()) {
            validateDeviationTarget(originalStmtCtx, targetCtx);
            deleteStatement(originalStmtCtx, targetCtx);
        }
    }

    private static void deleteStatement(final StmtContext<?, ?, ?> stmtCtxToBeDeleted,
            final StatementContextBase<?, ?, ?> targetCtx) {
        final StatementDefinition stmtToBeDeleted = stmtCtxToBeDeleted.getPublicDefinition();
        final String stmtArgument = stmtCtxToBeDeleted.rawStatementArgument();

        for (final Mutable<?, ?, ?> targetCtxSubstatement : targetCtx.mutableEffectiveSubstatements()) {
            if (statementsAreEqual(stmtToBeDeleted, stmtArgument, targetCtxSubstatement.getPublicDefinition(),
                    targetCtxSubstatement.rawStatementArgument())) {
                targetCtx.removeStatementFromEffectiveSubstatements(stmtToBeDeleted, stmtArgument);
                return;
            }
        }

        for (final Mutable<?, ?, ?> targetCtxSubstatement : targetCtx.mutableDeclaredSubstatements()) {
            if (statementsAreEqual(stmtToBeDeleted, stmtArgument, targetCtxSubstatement.getPublicDefinition(),
                    targetCtxSubstatement.rawStatementArgument())) {
                targetCtxSubstatement.setIsSupportedToBuildEffective(false);
                return;
            }
        }

        LOG.error("Deviation cannot delete substatement {} with argument '{}' in target node {} because it does "
                + "not exist in the target node. At line: {}", stmtToBeDeleted.getStatementName(), stmtArgument,
                targetCtx.getStatementArgument(), stmtCtxToBeDeleted.getStatementSourceReference());
    }

    private static void copyStatement(final Mutable<?, ?, ?> stmtCtxToBeCopied,
            final StatementContextBase<?, ?, ?> targetCtx) {
        // we need to make a copy of the statement context only if it is an unknown statement, otherwise
        // we can reuse the original statement context
        if (!StmtContextUtils.isUnknownStatement(stmtCtxToBeCopied)) {
            targetCtx.addEffectiveSubstatement(stmtCtxToBeCopied);
        } else {
            targetCtx.addEffectiveSubstatement(targetCtx.childCopyOf(stmtCtxToBeCopied, CopyType.ORIGINAL));
        }
    }

    private static boolean statementsAreEqual(final StatementDefinition firstStmtDef, final String firstStmtArg,
            final StatementDefinition secondStmtDef, final String secondStmtArg) {
        return firstStmtDef.equals(secondStmtDef) && Objects.equals(firstStmtArg, secondStmtArg);
    }

    private static void validateDeviationTarget(final StmtContext<?, ?, ?> deviateSubStmtCtx,
            final StmtContext<?, ?, ?> targetCtx) {
        InferenceException.throwIf(!isSupportedDeviationTarget(deviateSubStmtCtx, targetCtx,
                targetCtx.getRootVersion()), deviateSubStmtCtx.getStatementSourceReference(),
                "%s is not a valid deviation target for substatement %s.",
                targetCtx.getStatementArgument(), deviateSubStmtCtx.getPublicDefinition().getStatementName());
    }

    private static boolean isSupportedDeviationTarget(final StmtContext<?, ?, ?> deviateSubstatementCtx,
            final StmtContext<?, ?, ?> deviateTargetCtx, final YangVersion yangVersion) {
        Set<StatementDefinition> supportedDeviationTargets =
                YangValidationBundles.SUPPORTED_DEVIATION_TARGETS.get(deviateTargetCtx.getRootVersion(),
                        deviateSubstatementCtx.getPublicDefinition());

        if (supportedDeviationTargets == null) {
            supportedDeviationTargets = YangValidationBundles.SUPPORTED_DEVIATION_TARGETS.get(YangVersion.VERSION_1,
                    deviateSubstatementCtx.getPublicDefinition());
        }

        // if supportedDeviationTargets is null, it means that the deviate substatement is an unknown statement
        return supportedDeviationTargets == null || supportedDeviationTargets.contains(
                deviateTargetCtx.getPublicDefinition());
    }
}