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package api;

import java.util.Collection;
import java.util.Objects;
import java.util.function.Predicate;
import java.util.stream.Stream;

/**
 * Connects to a database
 * @param  The type of the schema the database has to fulfill.
 *           For an SQL database S should be an instance of SQLSchema.
 * @param  Type of the data that is to be stored in the database.
 * @param  Type of the predicates for read and update operations.
 * @param  Type of the predicates for insert operations.
 */
public interface DatabaseConnection {
    class Value{
        private final String value;

        public Value(String value) {
            assert value != null;
            this.value = value;
        }

        public String get(){
            return value;
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            Value value1 = (Value) o;
            return value.equals(value1.value);
        }

        @Override
        public int hashCode() {
            return Objects.hash(value);
        }

        @Override
        public String toString() {
            return "Value{" +
                    "value='" + value + '\'' +
                    '}';
        }
    }

    /**
     * Builds up the database according to the given schema.
     * Data will be deleted, if it conflicts with the schema.
     * @param schemas The schema the database shall meet
     */
    void init(Collection schemas);

    /**
     * Inserts a row into the table.
     * @param data The data to be inserted
     * @param predicates Predicates that have to match before inserting the given data.
     *                   Each time one of the predicates match, the data will be inserted into
     *                   the database. If you want the data to be inserted just once, make sure
     *                   only one predicate matches once. If no predicates are given, no data will
     *                   be inserted.
     */
    void insert(D data, Collection> predicates);

    /**
     * Reads data from the database.
     * If one or more predicates are given only data that matches
     * the predicates will be returned.
     * @param predicates Predicates the data should be matched against.
     *                   If no predicates are given, all data of the database will be returned.
     * @return Stream of data that has been found
     */
    Stream read(Collection> predicates);
}