/*
 * The contents of this file are subject to the terms of the Common Development and
 * Distribution License (the License). You may not use this file except in compliance with the
 * License.
 *
 * You can obtain a copy of the License at legal/CDDLv1.0.txt. See the License for the
 * specific language governing permission and limitations under the License.
 *
 * When distributing Covered Software, include this CDDL Header Notice in each file and include
 * the License file at legal/CDDLv1.0.txt. If applicable, add the following below the CDDL
 * Header, with the fields enclosed by brackets [] replaced by your own identifying
 * information: "Portions Copyright [year] [name of copyright owner]".
 *
 * Copyright 2012-2013 ForgeRock AS.
 */
package org.forgerock.opendj.rest2ldap;

import static org.forgerock.opendj.rest2ldap.Utils.attributeToJson;
import static org.forgerock.opendj.rest2ldap.Utils.getAttributeName;
import static org.forgerock.opendj.rest2ldap.Utils.toFilter;
import static org.forgerock.opendj.rest2ldap.Utils.toLowerCase;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.forgerock.json.fluent.JsonPointer;
import org.forgerock.json.fluent.JsonValue;
import org.forgerock.json.resource.BadRequestException;
import org.forgerock.json.resource.ResultHandler;
import org.forgerock.opendj.ldap.Attribute;
import org.forgerock.opendj.ldap.AttributeDescription;
import org.forgerock.opendj.ldap.Attributes;
import org.forgerock.opendj.ldap.Entry;
import org.forgerock.opendj.ldap.Filter;

/**
 * An attribute mapper that directly maps a configurable selection of attributes
 * to and from LDAP without any transformation.
 */
final class DefaultAttributeMapper extends AttributeMapper {
    // All user attributes by default.
    private final Map<String, String> excludedAttributes = new LinkedHashMap<String, String>();
    private final Map<String, String> includedAttributes = new LinkedHashMap<String, String>();

    /**
     * Creates a new default attribute mapper which will map all user attributes
     * to JSON by default.
     */
    DefaultAttributeMapper() {
        // No implementation required.
    }

    /**
     * Excludes one or more LDAP attributes from this mapping.
     *
     * @param attributes
     *            The attributes to be excluded.
     * @return This attribute mapper.
     */
    DefaultAttributeMapper excludeAttribute(final String... attributes) {
        for (final String attribute : attributes) {
            excludedAttributes.put(toLowerCase(attribute), attribute);
        }
        return this;
    }

    @Override
    void getLDAPAttributes(final Context c, final JsonPointer jsonAttribute,
            final Set<String> ldapAttributes) {
        switch (jsonAttribute.size()) {
        case 0:
            // Requested everything.
            if (!includedAttributes.isEmpty()) {
                ldapAttributes.addAll(includedAttributes.values());
            } else {
                // All user attributes.
                ldapAttributes.add("*");
            }
            break;
        default:
            final String name = jsonAttribute.get(0);
            if (isIncludedAttribute(name)) {
                ldapAttributes.add(name);
            }
            break;
        }
    }

    @Override
    void getLDAPFilter(final Context c, final FilterType type, final JsonPointer jsonAttribute,
            final String operator, final Object valueAssertion, final ResultHandler<Filter> h) {
        if (jsonAttribute.size() == 1 && isIncludedAttribute(jsonAttribute.get(0))) {
            h.handleResult(toFilter(c, type, jsonAttribute.get(0), valueAssertion));
        } else {
            // This attribute mapper cannot handle the provided filter component.
            h.handleResult(null);
        }
    }

    /**
     * Includes one or more LDAP attributes in this mapping.
     *
     * @param attributes
     *            The attributes to be included.
     * @return This attribute mapper.
     */
    DefaultAttributeMapper includeAttribute(final String... attributes) {
        for (final String attribute : attributes) {
            includedAttributes.put(toLowerCase(attribute), attribute);
        }
        return this;
    }

    @Override
    void toJSON(final Context c, final Entry e, final ResultHandler<Map<String, Object>> h) {
        // FIXME: this will leave out attributes which were not included in the LDAP entry. We should
        // ensure that JSON attributes are present, even if they are null or an empty array.
        final Map<String, Object> result = new LinkedHashMap<String, Object>(e.getAttributeCount());
        for (final Attribute a : e.getAllAttributes()) {
            final String name = getAttributeName(a);
            if (isIncludedAttribute(name)) {
                result.put(name, attributeToJson(a));
            }
        }
        h.handleResult(result);
    }

    @Override
    void toLDAP(final Context c, final JsonValue v, final ResultHandler<List<Attribute>> h) {
        if (v.isMap()) {
            List<Attribute> result = new ArrayList<Attribute>(v.size());
            for (Map.Entry<String, Object> field : v.asMap().entrySet()) {
                final AttributeDescription ad;
                try {
                    ad = AttributeDescription.valueOf(field.getKey(), c.getConfig().schema());
                } catch (Exception e) {
                    // FIXME: improve error message.
                    h.handleError(new BadRequestException("The field " + field.getKey()
                            + " is invalid"));
                    return;
                }
                Object value = field.getValue();
                if (isJSONPrimitive(value)) {
                    result.add(Attributes.singletonAttribute(ad, value));
                } else if (value instanceof Collection<?>) {
                    Attribute a =
                            c.getConfig().decodeOptions().getAttributeFactory().newAttribute(ad);
                    for (Object o : (Collection<?>) value) {
                        if (isJSONPrimitive(o)) {
                            a.add(o);
                        } else {
                            // FIXME: improve error message.
                            h.handleError(new BadRequestException("The field " + field.getKey()
                                    + " is invalid"));
                            return;
                        }
                    }
                    result.add(a);
                } else {
                    // FIXME: improve error message.
                    h.handleError(new BadRequestException("The field " + field.getKey()
                            + " is invalid"));
                    return;
                }
            }
            h.handleResult(result);
        } else {
            h.handleResult(Collections.<Attribute> emptyList());
        }
    }

    private boolean isJSONPrimitive(Object value) {
        return value instanceof String || value instanceof Boolean || value instanceof Number;
    }

    private boolean isIncludedAttribute(final String name) {
        final String lowerName = toLowerCase(name);

        // Ignore the requested attribute if it has been excluded.
        if (excludedAttributes.containsKey(lowerName)) {
            return false;
        }

        // Include all attributes by default.
        if (includedAttributes.isEmpty() || includedAttributes.containsKey(lowerName)) {
            return true;
        }

        return false;
    }
}