/*
 * Copyright (c) 2018 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.model.export;

import static com.google.common.base.Preconditions.checkArgument;
import static java.util.Objects.requireNonNull;

import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableListMultimap.Builder;
import com.google.common.collect.Iterators;
import com.google.common.collect.ListMultimap;
import com.google.common.collect.Maps;
import java.util.AbstractMap.SimpleImmutableEntry;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Optional;
import javax.xml.XMLConstants;
import javax.xml.namespace.NamespaceContext;
import org.eclipse.jdt.annotation.NonNull;
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.model.api.stmt.ModuleEffectiveStatement;
import org.opendaylight.yangtools.yang.model.api.stmt.ModuleEffectiveStatement.PrefixToEffectiveModuleNamespace;
import org.opendaylight.yangtools.yang.model.api.stmt.ModuleEffectiveStatement.QNameModuleToPrefixNamespace;

final class ModuleNamespaceContext implements NamespaceContext {
    private static final Entry<String, String> YIN_PREFIX_AND_NAMESPACE =
            new SimpleImmutableEntry<>(XMLConstants.DEFAULT_NS_PREFIX, YangConstants.RFC6020_YIN_NAMESPACE_STRING);

    private final ListMultimap<@NonNull String, @NonNull String> namespaceToPrefix;
    private final Map<String, @NonNull ModuleEffectiveStatement> prefixToModule;
    private final Map<QNameModule, @NonNull String> moduleToPrefix;

    ModuleNamespaceContext(final ModuleEffectiveStatement module) {
        this.prefixToModule = requireNonNull(module.getAll(PrefixToEffectiveModuleNamespace.class));
        this.moduleToPrefix = requireNonNull(module.getAll(QNameModuleToPrefixNamespace.class));

        final Builder<String, String> namespaces = ImmutableListMultimap.builder();
        for (Entry<QNameModule, @NonNull String> e : moduleToPrefix.entrySet()) {
            namespaces.put(e.getKey().getNamespace().toString(), e.getValue());
        }
        namespaceToPrefix = namespaces.build();
    }

    @Override
    public String getNamespaceURI(final String prefix) {
        checkArgument(prefix != null);

        switch (prefix) {
            case XMLConstants.DEFAULT_NS_PREFIX:
                return YangConstants.RFC6020_YIN_NAMESPACE_STRING;
            case XMLConstants.XML_NS_PREFIX:
                return XMLConstants.XML_NS_URI;
            case XMLConstants.XMLNS_ATTRIBUTE:
                return XMLConstants.XMLNS_ATTRIBUTE_NS_URI;
            default:
                final ModuleEffectiveStatement module = prefixToModule.get(prefix);
                return module != null ? module.localQNameModule().getNamespace().toString()
                        : XMLConstants.NULL_NS_URI;
        }
    }

    @Override
    public String getPrefix(final String namespaceURI) {
        checkArgument(namespaceURI != null);

        switch (namespaceURI) {
            case YangConstants.RFC6020_YIN_NAMESPACE_STRING:
                return XMLConstants.DEFAULT_NS_PREFIX;
            case XMLConstants.XML_NS_URI:
                return XMLConstants.XML_NS_PREFIX;
            case XMLConstants.XMLNS_ATTRIBUTE_NS_URI:
                return XMLConstants.XMLNS_ATTRIBUTE;
            default:
                final List<@NonNull String> prefixes = namespaceToPrefix.get(namespaceURI);
                return prefixes.isEmpty() ? null : prefixes.get(0);
        }
    }

    @Override
    public Iterator<String> getPrefixes(final String namespaceURI) {
        checkArgument(namespaceURI != null);

        switch (namespaceURI) {
            case YangConstants.RFC6020_YIN_NAMESPACE_STRING:
                return Iterators.singletonIterator(XMLConstants.DEFAULT_NS_PREFIX);
            case XMLConstants.XML_NS_URI:
                return Iterators.singletonIterator(XMLConstants.XML_NS_PREFIX);
            case XMLConstants.XMLNS_ATTRIBUTE_NS_URI:
                return Iterators.singletonIterator(XMLConstants.XMLNS_ATTRIBUTE);
            default:
                return namespaceToPrefix.get(namespaceURI).iterator();
        }
    }

    Entry<String, String> prefixAndNamespaceFor(final QNameModule module) {
        if (YangConstants.RFC6020_YIN_MODULE.equals(module)) {
            return YIN_PREFIX_AND_NAMESPACE;
        }

        final String prefix = moduleToPrefix.get(module);
        checkArgument(prefix != null, "Module %s does not map to a prefix", module);
        return new SimpleImmutableEntry<>(prefix, module.getNamespace().toString());
    }

    Entry<String, String> prefixAndNamespaceForStatement(final QName stmtName) {
        final Optional<String> prefix = ExportUtils.statementPrefix(moduleToPrefix, stmtName);
        if (!prefix.isPresent()) {
            return YIN_PREFIX_AND_NAMESPACE;
        }

        return new SimpleImmutableEntry<>(prefix.get(), stmtName.getNamespace().toString());
    }

    Map<String, String> prefixesAndNamespaces() {
        return Maps.transformValues(prefixToModule, module -> module.localQNameModule().getNamespace().toString());
    }
}