package org.onlab.onos.store.service;

import java.util.List;

import com.google.common.base.MoreObjects;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;

/**
 * Collection of read requests to be submitted as one batch.
 */
public final class BatchReadRequest {

    private final List<ReadRequest> readRequests;

    /**
     * Creates a new BatchReadRequest object from the specified list of read requests.
     * @param readRequests read requests.
     * @return BatchReadRequest object.
     */
    public static BatchReadRequest create(List<ReadRequest> readRequests) {
        return new BatchReadRequest(readRequests);
    }

    private BatchReadRequest(List<ReadRequest> readRequests) {
        this.readRequests = ImmutableList.copyOf(readRequests);
    }

    /**
     * Returns the number of requests in this batch.
     * @return size of request batch.
     */
    public int batchSize() {
        return readRequests.size();
    }

    /**
     * Returns the requests in this batch as a list.
     * @return list of read requests
     */
    public List<ReadRequest> getAsList() {
        return readRequests;
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(getClass())
                .add("readRequests", readRequests)
                .toString();
    }

    /**
     * Builder for BatchReadRequest.
     */
    public static class Builder {

        private final List<ReadRequest> readRequests = Lists.newLinkedList();

        /**
         * Append a get request.
         * @param tableName table name
         * @param key key to fetch.
         * @return this Builder
         */
        public Builder get(String tableName, String key) {
            readRequests.add(new ReadRequest(tableName, key));
            return this;
        }

        /**
         * Builds a BatchReadRequest.
         * @return BatchReadRequest
         */
        public BatchReadRequest build() {
            return new BatchReadRequest(readRequests);
        }
    }
}