/*
 * Copyright (C) 2024 johan@nosd.in
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the Server Side Public License, version 1,
 * as published by MongoDB, Inc.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * Server Side Public License for more details.
 *
 * You should have received a copy of the Server Side Public License
 * along with this program. If not, see
 * <http://www.mongodb.com/licensing/server-side-public-license>.
 */
package in.nosd.redis.functions;

import com.google.common.base.Strings;

import in.nosd.redis.functions.GenericLookupResult;
import in.nosd.redis.functions.LookupTableFunction;

import org.graylog.plugins.pipelineprocessor.EvaluationContext;
import org.graylog.plugins.pipelineprocessor.ast.functions.FunctionArgs;
import org.graylog.plugins.pipelineprocessor.ast.functions.FunctionDescriptor;
import org.graylog.plugins.pipelineprocessor.ast.functions.ParameterDescriptor;
import org.graylog2.lookup.LookupTableService;
import org.graylog2.plugin.lookup.LookupResult;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.inject.Inject;

public class RedisLookupPluginFunction extends LookupTableFunction<GenericLookupResult> {

    private static final Logger LOG = LoggerFactory.getLogger(RedisLookupPluginFunction.class);

    public static final String NAME = "redis_lookup";
    private static final String VALUE = "value";
    private static final String LOOKUP_TABLE_NAME = "redis-lookup";

    private final ParameterDescriptor<String, String> keyParam = ParameterDescriptor.string(VALUE).description("The key to look up.").build();

    private final LookupTableService.Function lookupFunction;

    @Inject
    public RedisLookupPluginFunction(final LookupTableService lookupTableService) {
        this.lookupFunction = lookupTableService.newBuilder().lookupTable(LOOKUP_TABLE_NAME).build();
    }

    @Override
    public GenericLookupResult evaluate(FunctionArgs args, EvaluationContext context) {
        String key = keyParam.required(args, context);
        if (key == null) {
            LOG.error("NULL parameter passed to Redis lookup.");
            return null;
        }

        LOG.debug("Running Redis lookup for key [{}].", key);

        final LookupResult lookupResult = this.lookupFunction.lookup(key.trim());
        if (lookupResult != null && !lookupResult.isEmpty()) {

            // If not a String, then fall through to false at the end of the method.
            final Object value = lookupResult.singleValue();
            if (value instanceof String) {
                return !Strings.isNullOrEmpty((String) value) ? GenericLookupResult.TRUE : GenericLookupResult.FALSE;
            }
        }

        return GenericLookupResult.FALSE;
    }

    @Override
    public FunctionDescriptor<GenericLookupResult> descriptor() {
        return FunctionDescriptor.<GenericLookupResult>builder()
                .name(NAME)
                .description("Match a key into Redis instance and return value")
                .params(keyParam)
                .returnType(GenericLookupResult.class)
                .build();
    }

}