/*
 * Copyright (c) 2015 Cisco Systems, Inc. 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.stmt.reactor;

import com.google.common.base.Preconditions;
import com.google.common.base.Verify;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableTable;
import com.google.common.collect.Multimap;
import com.google.common.collect.Table;
import java.net.URI;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Optional;
import java.util.Set;
import javax.annotation.Nullable;
import org.opendaylight.yangtools.concepts.Mutable;
import org.opendaylight.yangtools.yang.common.QName;
import org.opendaylight.yangtools.yang.common.QNameModule;
import org.opendaylight.yangtools.yang.common.YangConstants;
import org.opendaylight.yangtools.yang.common.YangVersion;
import org.opendaylight.yangtools.yang.model.api.ModuleIdentifier;
import org.opendaylight.yangtools.yang.model.api.YangStmtMapping;
import org.opendaylight.yangtools.yang.model.api.meta.DeclaredStatement;
import org.opendaylight.yangtools.yang.model.api.meta.EffectiveStatement;
import org.opendaylight.yangtools.yang.model.api.meta.IdentifierNamespace;
import org.opendaylight.yangtools.yang.model.api.meta.StatementSource;
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.ModelProcessingPhase;
import org.opendaylight.yangtools.yang.parser.spi.meta.MutableStatement;
import org.opendaylight.yangtools.yang.parser.spi.meta.NamespaceBehaviour;
import org.opendaylight.yangtools.yang.parser.spi.meta.NamespaceBehaviour.NamespaceStorageNode;
import org.opendaylight.yangtools.yang.parser.spi.meta.NamespaceBehaviour.StorageNodeType;
import org.opendaylight.yangtools.yang.parser.spi.meta.StatementDefinitionNamespace;
import org.opendaylight.yangtools.yang.parser.spi.meta.StatementSupport;
import org.opendaylight.yangtools.yang.parser.spi.meta.StatementSupportBundle;
import org.opendaylight.yangtools.yang.parser.spi.source.BelongsToModuleContext;
import org.opendaylight.yangtools.yang.parser.spi.source.BelongsToPrefixToModuleIdentifier;
import org.opendaylight.yangtools.yang.parser.spi.source.ImpPrefixToModuleIdentifier;
import org.opendaylight.yangtools.yang.parser.spi.source.ImpPrefixToNamespace;
import org.opendaylight.yangtools.yang.parser.spi.source.ImportedModuleContext;
import org.opendaylight.yangtools.yang.parser.spi.source.ModuleIdentifierToModuleQName;
import org.opendaylight.yangtools.yang.parser.spi.source.PrefixToModule;
import org.opendaylight.yangtools.yang.parser.spi.source.PrefixToModuleMap;
import org.opendaylight.yangtools.yang.parser.spi.source.QNameToStatementDefinition;
import org.opendaylight.yangtools.yang.parser.spi.source.QNameToStatementDefinitionMap;
import org.opendaylight.yangtools.yang.parser.spi.source.SourceException;
import org.opendaylight.yangtools.yang.parser.spi.source.StatementSourceReference;
import org.opendaylight.yangtools.yang.parser.spi.source.StatementStreamSource;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.BitsSpecificationImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.Decimal64SpecificationImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.EnumSpecificationImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.IdentityRefSpecificationImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.InstanceIdentifierSpecificationImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.LeafrefSpecificationImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.ModelDefinedStatementDefinition;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.TypeUtils;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.UnionSpecificationImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.UnknownStatementImpl;
import org.opendaylight.yangtools.yang.parser.stmt.rfc6020.Utils;
import org.opendaylight.yangtools.yang.parser.stmt.rfc7950.IdentityrefSpecificationRfc7950Support;
import org.opendaylight.yangtools.yang.parser.stmt.rfc7950.LeafrefSpecificationRfc7950Support;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class SourceSpecificContext implements NamespaceStorageNode, NamespaceBehaviour.Registry, Mutable {

    public enum PhaseCompletionProgress {
        NO_PROGRESS,
        PROGRESS,
        FINISHED
    }

    private static final Logger LOG = LoggerFactory.getLogger(SourceSpecificContext.class);
    private static final Table<YangVersion, String, StatementSupport<?, ?, ?>> BUILTIN_TYPE_SUPPORTS =
            ImmutableTable.<YangVersion, String, StatementSupport<?, ?, ?>>builder()
            .put(YangVersion.VERSION_1, TypeUtils.DECIMAL64, new Decimal64SpecificationImpl.Definition())
            .put(YangVersion.VERSION_1, TypeUtils.UNION, new UnionSpecificationImpl.Definition())
            .put(YangVersion.VERSION_1, TypeUtils.ENUMERATION, new EnumSpecificationImpl.Definition())
            .put(YangVersion.VERSION_1, TypeUtils.LEAF_REF, new LeafrefSpecificationImpl.Definition())
            .put(YangVersion.VERSION_1_1, TypeUtils.LEAF_REF, new LeafrefSpecificationRfc7950Support())
            .put(YangVersion.VERSION_1, TypeUtils.BITS, new BitsSpecificationImpl.Definition())
            .put(YangVersion.VERSION_1, TypeUtils.IDENTITY_REF, new IdentityRefSpecificationImpl.Definition())
            .put(YangVersion.VERSION_1_1, TypeUtils.IDENTITY_REF, new IdentityrefSpecificationRfc7950Support())
            .put(YangVersion.VERSION_1, TypeUtils.INSTANCE_IDENTIFIER, new InstanceIdentifierSpecificationImpl.Definition())
                    .build();

    private static final QName TYPE = YangStmtMapping.TYPE.getStatementName();

    private final Multimap<ModelProcessingPhase, ModifierImpl> modifiers = HashMultimap.create();
    private final QNameToStatementDefinitionMap qNameToStmtDefMap = new QNameToStatementDefinitionMap();
    private final PrefixToModuleMap prefixToModuleMap = new PrefixToModuleMap();
    private final BuildGlobalContext currentContext;
    private final StatementStreamSource source;

    /*
     * "imported" namespaces in this source -- this points to RootStatementContexts of
     * - modules imported via 'import' statement
     * - parent module, declared via 'belongs-to' statement
     */
    private Collection<RootStatementContext<?, ?, ?>> importedNamespaces = ImmutableList.of();
    private ModelProcessingPhase finishedPhase = ModelProcessingPhase.INIT;
    private ModelProcessingPhase inProgressPhase;
    private RootStatementContext<?, ?, ?> root;

    SourceSpecificContext(final BuildGlobalContext currentContext, final StatementStreamSource source) {
        this.currentContext = Preconditions.checkNotNull(currentContext);
        this.source = Preconditions.checkNotNull(source);
    }

    boolean isEnabledSemanticVersioning(){
        return currentContext.isEnabledSemanticVersioning();
    }

    ModelProcessingPhase getInProgressPhase() {
        return inProgressPhase;
    }

    StatementContextBase<?, ?, ?> createDeclaredChild(final StatementContextBase<?, ?, ?> current, final int childId,
            QName name, final String argument, final StatementSourceReference ref) {
        if (current != null) {
            // Fast path: we are entering a statement which was emitted in previous phase
            StatementContextBase<?, ?, ?> existing = current.lookupSubstatement(childId);
            while (existing != null && StatementSource.CONTEXT == existing.getStatementSource()) {
                existing = existing.lookupSubstatement(childId);
            }
            if (existing != null) {
                return existing;
            }
        }

        // FIXME: BUG-7038: Refactor/clean up this special case
        if (TYPE.equals(name)) {
            SourceException.throwIfNull(argument, ref, "Type statement requires an argument");
            if (TypeUtils.isYangTypeBodyStmtString(argument)) {
                name = QName.create(YangConstants.RFC6020_YIN_MODULE, argument);
            } else {
                name = QName.create(YangConstants.RFC6020_YIN_MODULE, TYPE.getLocalName());
            }
        }

        StatementDefinitionContext<?, ?, ?> def = currentContext.getStatementDefinition(getRootVersion(), name);
        if (def == null) {
            final StatementSupport<?, ?, ?> extension = qNameToStmtDefMap.get(name);
            if (extension != null) {
                def = new StatementDefinitionContext<>(extension);
            } else {
                // type-body-stmts
                def = resolveTypeBodyStmts(name.getLocalName(), getRootVersion());
            }
        } else if (current != null && current.definition().getRepresentingClass().equals(UnknownStatementImpl.class)) {
            /*
             * This code wraps statements encountered inside an extension so they do not get confused with regular
             * statements.
             *
             * FIXME: BUG-7037: re-evaluate whether this is really needed, as this is a very expensive way of making
             *        this work. We really should be peeking into the extension definition to find these nodes,
             *        as otherwise we are not reusing definitions nor support for these nodes.
             */
            final QName qName = Utils.qNameFromArgument(current, name.getLocalName());
            def = new StatementDefinitionContext<>(new UnknownStatementImpl.Definition(
                new ModelDefinedStatementDefinition(qName, argument != null)));
        }

        InferenceException.throwIfNull(def, ref, "Statement %s does not have type mapping defined.", name);
        if (def.hasArgument()) {
            SourceException.throwIfNull(argument, ref, "Statement %s requires an argument", name);
        } else {
            SourceException.throwIf(argument != null, ref, "Statement %s does not take argument", name);
        }

        if (current != null) {
            return current.createSubstatement(childId, def, ref, argument);
        }

        /*
         * If root is null or root version is other than default,
         * we need to create new root.
         */
        if (root == null) {
            root = new RootStatementContext<>(this, def, ref, argument);
        } else if (!RootStatementContext.DEFAULT_VERSION.equals(root.getRootVersion())
                && inProgressPhase == ModelProcessingPhase.SOURCE_LINKAGE) {
            root = new RootStatementContext<>(this, def, ref, argument, root.getRootVersion(), root.getRootIdentifier());
        } else {
            final QName rootStatement = root.definition().getStatementName();
            final String rootArgument = root.rawStatementArgument();

            Preconditions.checkState(Objects.equals(def.getStatementName(), rootStatement)
                && Objects.equals(argument, rootArgument),
                "Root statement was already defined as '%s %s'.", rootStatement, rootArgument);
        }
        return root;
    }

    RootStatementContext<?, ?, ?> getRoot() {
        return root;
    }

    /**
     * Return version of root statement context.
     *
     * @return version of root statement context
     */
    YangVersion getRootVersion() {
        return root != null ? root.getRootVersion() : RootStatementContext.DEFAULT_VERSION;
    }

    DeclaredStatement<?> buildDeclared() {
        return root.buildDeclared();
    }

    EffectiveStatement<?, ?> buildEffective() {
        return root.buildEffective();
    }

    void startPhase(final ModelProcessingPhase phase) {
        @Nullable final ModelProcessingPhase previousPhase = phase.getPreviousPhase();
        Verify.verify(Objects.equals(previousPhase, finishedPhase),
            "Phase sequencing violation: previous phase should be %s, source %s has %s", previousPhase, source,
            finishedPhase);

        final Collection<ModifierImpl> previousModifiers = modifiers.get(previousPhase);
        Preconditions.checkState(previousModifiers.isEmpty(),
            "Previous phase %s has unresolved modifiers %s in source %s",
            previousPhase, previousModifiers, source);

        inProgressPhase = phase;
        LOG.debug("Source {} started phase {}", source, phase);
    }

    private void updateImportedNamespaces(final Class<?> type, final Object value) {
        if (BelongsToModuleContext.class.isAssignableFrom(type) || ImportedModuleContext.class.isAssignableFrom(type)) {
            if (importedNamespaces.isEmpty()) {
                importedNamespaces = new ArrayList<>(1);
            }

            Verify.verify(value instanceof RootStatementContext);
            importedNamespaces.add((RootStatementContext<?, ?, ?>) value);
        }
    }

    @Override
    public <K, V, N extends IdentifierNamespace<K, V>> V putToLocalStorage(final Class<N> type, final K key,
           final V value) {
        // RootStatementContext takes care of IncludedModuleContext and the rest...
        final V ret = getRoot().putToLocalStorage(type, key, value);
        // FIXME: what about duplicates?
        updateImportedNamespaces(type, value);
        return ret;
    }

    @Override
    public <K, V, N extends IdentifierNamespace<K, V>> V putToLocalStorageIfAbsent(final Class<N> type, final K key,
           final V value) {
        // RootStatementContext takes care of IncludedModuleContext and the rest...
        final V ret = getRoot().putToLocalStorageIfAbsent(type, key, value);
        if (ret == null) {
            updateImportedNamespaces(type, value);
        }
        return ret;
    }

    @Override
    public StorageNodeType getStorageNodeType() {
        return StorageNodeType.SOURCE_LOCAL_SPECIAL;
    }

    @Override
    public <K, V, N extends IdentifierNamespace<K, V>> V getFromLocalStorage(final Class<N> type, final K key) {
        final V potentialLocal = getRoot().getFromLocalStorage(type, key);
        if (potentialLocal != null) {
            return potentialLocal;
        }

        for (final NamespaceStorageNode importedSource : importedNamespaces) {
            final V potential = importedSource.getFromLocalStorage(type, key);
            if (potential != null) {
                return potential;
            }
        }
        return null;
    }

    @Nullable
    @Override
    public <K, V, N extends IdentifierNamespace<K, V>> Map<K, V> getAllFromLocalStorage(final Class<N> type) {
        final Map<K, V> potentialLocal = getRoot().getAllFromLocalStorage(type);
        if (potentialLocal != null) {
            return potentialLocal;
        }

        for (final NamespaceStorageNode importedSource : importedNamespaces) {
            final Map<K, V> potential = importedSource.getAllFromLocalStorage(type);

            if (potential != null) {
                return potential;
            }
        }
        return null;
    }

    @Override
    public <K, V, N extends IdentifierNamespace<K, V>> NamespaceBehaviour<K, V, N> getNamespaceBehaviour(
            final Class<N> type) {
        return currentContext.getNamespaceBehaviour(type);
    }

    @Override
    public NamespaceStorageNode getParentNamespaceStorage() {
        return currentContext;
    }

    PhaseCompletionProgress tryToCompletePhase(final ModelProcessingPhase phase) throws SourceException {
        final Collection<ModifierImpl> currentPhaseModifiers = modifiers.get(phase);

        boolean hasProgressed = tryToProgress(currentPhaseModifiers);

        Preconditions.checkNotNull(this.root, "Malformed source. Valid root element is missing.");
        final boolean phaseCompleted = root.tryToCompletePhase(phase);

        hasProgressed |= tryToProgress(currentPhaseModifiers);

        if (phaseCompleted && currentPhaseModifiers.isEmpty()) {
            finishedPhase = phase;
            LOG.debug("Source {} finished phase {}", source, phase);
            return PhaseCompletionProgress.FINISHED;

        }

        return hasProgressed ? PhaseCompletionProgress.PROGRESS : PhaseCompletionProgress.NO_PROGRESS;
    }

    private static boolean tryToProgress(final Collection<ModifierImpl> currentPhaseModifiers) {
        boolean hasProgressed = false;

        final Iterator<ModifierImpl> modifier = currentPhaseModifiers.iterator();
        while (modifier.hasNext()) {
            if (modifier.next().tryApply()) {
                modifier.remove();
                hasProgressed = true;
            }
        }

        return hasProgressed;
    }

    ModelActionBuilder newInferenceAction(final ModelProcessingPhase phase) {
        final ModifierImpl action = new ModifierImpl(phase);
        modifiers.put(phase, action);
        return action;
    }

    @Override
    public String toString() {
        return "SourceSpecificContext [source=" + source + ", current=" + inProgressPhase + ", finished="
                + finishedPhase + "]";
    }

    Optional<SourceException> failModifiers(final ModelProcessingPhase identifier) {
        final List<SourceException> exceptions = new ArrayList<>();
        for (final ModifierImpl mod : modifiers.get(identifier)) {
            try {
                mod.failModifier();
            } catch (final SourceException e) {
                exceptions.add(e);
            }
        }

        if (exceptions.isEmpty()) {
            return Optional.empty();
        }

        final String message = String.format("Yang model processing phase %s failed", identifier);
        final InferenceException e = new InferenceException(message, root.getStatementSourceReference(),
            exceptions.get(0));
        exceptions.listIterator(1).forEachRemaining(e::addSuppressed);

        return Optional.of(e);
    }

    void loadStatements() throws SourceException {
        LOG.trace("Source {} loading statements for phase {}", source, inProgressPhase);

        switch (inProgressPhase) {
            case SOURCE_PRE_LINKAGE:
                source.writePreLinkage(new StatementContextWriter(this, inProgressPhase), stmtDef());
                break;
            case SOURCE_LINKAGE:
                source.writeLinkage(new StatementContextWriter(this, inProgressPhase), stmtDef(), preLinkagePrefixes(), getRootVersion());
                break;
            case STATEMENT_DEFINITION:
                source.writeLinkageAndStatementDefinitions(new StatementContextWriter(this, inProgressPhase), stmtDef(), prefixes(), getRootVersion());
                break;
            case FULL_DECLARATION:
                source.writeFull(new StatementContextWriter(this, inProgressPhase), stmtDef(), prefixes(), getRootVersion());
                break;
            default:
                break;
        }
    }

    private static StatementDefinitionContext<?, ?, ?> resolveTypeBodyStmts(final String typeArgument,
            final YangVersion version) {
        StatementSupport<?, ?, ?> support = BUILTIN_TYPE_SUPPORTS.get(version, typeArgument);

        if (support == null) {
            support = BUILTIN_TYPE_SUPPORTS.get(YangVersion.VERSION_1, typeArgument);
        }

        return support == null ? null : new StatementDefinitionContext<>(support);
    }

    private PrefixToModule preLinkagePrefixes() {
        final PrefixToModuleMap preLinkagePrefixes = new PrefixToModuleMap(true);
        final Map<String, URI> prefixToNamespaceMap = getAllFromLocalStorage(ImpPrefixToNamespace.class);
        if (prefixToNamespaceMap == null) {
            //:FIXME if it is a submodule without any import, the map is null. Handle also submodules and includes...
            return null;
        }

        prefixToNamespaceMap.forEach((key, value) -> preLinkagePrefixes.put(key, QNameModule.create(value, null)));
        return preLinkagePrefixes;
    }

    private PrefixToModule prefixes() {
        final Map<String, ModuleIdentifier> allPrefixes = getRoot().getAllFromNamespace(ImpPrefixToModuleIdentifier
                .class);
        final Map<String, ModuleIdentifier> belongsToPrefixes = getRoot().getAllFromNamespace
                (BelongsToPrefixToModuleIdentifier.class);
        if (belongsToPrefixes != null) {
            allPrefixes.putAll(belongsToPrefixes);
        }

        allPrefixes.forEach((key, value) ->
            prefixToModuleMap.put(key, getRoot().getFromNamespace(ModuleIdentifierToModuleQName.class, value)));

        return prefixToModuleMap;
    }

    private QNameToStatementDefinition stmtDef() {
        // regular YANG statements and extension supports added
        final StatementSupportBundle supportsForPhase = currentContext.getSupportsForPhase(inProgressPhase);
        qNameToStmtDefMap.putAll(supportsForPhase.getCommonDefinitions());
        qNameToStmtDefMap.putAll(supportsForPhase.getDefinitionsSpecificForVersion(getRootVersion()));

        // No further actions needed
        if (inProgressPhase != ModelProcessingPhase.FULL_DECLARATION) {
            return qNameToStmtDefMap;
        }

        // We need to any and all extension statements which have been declared in the context
        final Map<QName, StatementSupport<?, ?, ?>> extensions = currentContext.getAllFromNamespace(
                StatementDefinitionNamespace.class);
        if (extensions != null) {
            extensions.forEach((qname, support) -> {
                final StatementSupport<?, ?, ?> existing = qNameToStmtDefMap.putIfAbsent(qname, support);
                if (existing != null) {
                    LOG.debug("Source {} already defines statement {} as {}", source, qname, existing);
                } else {
                    LOG.debug("Source {} defined statement {} as {}", source, qname, support);
                }
            });
        }

        return qNameToStmtDefMap;
    }

    public Set<YangVersion> getSupportedVersions() {
        return currentContext.getSupportedVersions();
    }

    void addMutableStmtToSeal(final MutableStatement mutableStatement) {
        currentContext.addMutableStmtToSeal(mutableStatement);
    }

    Collection<ModuleIdentifier> getRequiredModules() {
        return root.getRequiredModules();
    }

    ModuleIdentifier getRootIdentifier() {
        return root.getRootIdentifier();
    }
}