
package {{package}};

import javax.json.JsonArray;
import javax.json.JsonObject;
import javax.json.JsonReader;
import javax.json.JsonValue;
import java.util.concurrent.ExecutionException;

import io.helidon.common.reactive.Single;
import io.helidon.dbclient.DbClient;
import io.helidon.dbclient.DbExecute;

import static javax.json.Json.createReader;

/**
 * Initialize JDBC database schema and populate it with sample data.
 *
 * Pokémon, and Pokémon character names are trademarks of Nintendo.
 */
public class InitializeDb {

    /**
     * Pokemon types source file.
     * */
    private static final String TYPES = "/Types.json";

    /**
     * Pokemons source file.
     * */
    private static final String POKEMONS = "/Pokemons.json";

    private InitializeDb() {
        throw new UnsupportedOperationException("Instances of InitializeDb utility class are not allowed");
    }

    /**
     * Initialize JDBC database schema and populate it with sample data.
     *
     * @param dbClient database client
     */
    static void init(DbClient dbClient) {
        try {
            initSchema(dbClient);
            initData(dbClient);
        } catch (ExecutionException | InterruptedException e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Initializes database schema.
     *
     * @param dbClient database client
     */
    private static void initSchema(DbClient dbClient) {
        try {
            dbClient.execute(exec -> exec
                    .namedDml("create-types")
                    .flatMapSingle(result -> exec.namedDml("create-pokemons")))
                    .await();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    /**
     * Initialize database content.
     *
     * @param dbClient database client
     * @throws ExecutionException when database query failed
     * @throws InterruptedException if the current thread was interrupted
     */
    private static void initData(DbClient dbClient) throws InterruptedException, ExecutionException {
        dbClient.execute(exec -> initTypes(exec).flatMapSingle(count -> initPokemons(exec)))
                .toCompletableFuture()
                .get();
    }

    /**
     * Initialize Pokemon types.
     *
     * @param exec database client executor
     * @return executed statements future
     */
    private static Single<Long> initTypes(DbExecute exec) {
        Single<Long> stage = Single.just(0L);
        try (JsonReader reader = createReader(InitializeDb.class.getResourceAsStream(TYPES))) {
            JsonArray types = reader.readArray();
            for (JsonValue typeValue : types) {
                JsonObject type = typeValue.asJsonObject();
                stage = stage.flatMapSingle(it -> exec.namedInsert(
                            "insert-type", type.getInt("id"), type.getString("name")));
            }
        }
        return stage;
    }

    /**
     * Initialize Pokemons.
     *
     * @param exec database client executor
     * @return executed statements future
     */
    private static Single<Long> initPokemons(DbExecute exec) {
        Single<Long> stage = Single.just(0L);
        try (JsonReader reader = createReader(InitializeDb.class.getResourceAsStream(POKEMONS))) {
            JsonArray pokemons = reader.readArray();
            for (JsonValue pokemonValue : pokemons) {
                JsonObject pokemon = pokemonValue.asJsonObject();
                stage = stage.flatMapSingle(result -> exec.namedInsert("insert-pokemon",
                        pokemon.getInt("id"), pokemon.getString("name"), pokemon.getInt("idType")));
            }
        }
        return stage;
    }
}
