/*
 * Copyright (C) 2017 Julien Viet
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 */

package io.vertx.sqlclient.impl;

import io.vertx.core.AsyncResult;
import io.vertx.core.Future;
import io.vertx.core.Handler;
import io.vertx.core.Vertx;
import io.vertx.sqlclient.Cursor;
import io.vertx.sqlclient.Row;
import io.vertx.sqlclient.RowSet;
import io.vertx.sqlclient.impl.command.ExtendedQueryCommand;

import java.util.UUID;

/**
 * @author <a href="mailto:julien@julienviet.com">Julien Viet</a>
 */
public class CursorImpl implements Cursor {

  private final PreparedStatementImpl ps;
  private final TupleInternal params;

  private String id;
  private boolean closed;
  private SqlResultHandler<RowSet<Row>, RowSetImpl<Row>, RowSet<Row>> result;

  CursorImpl(PreparedStatementImpl ps, TupleInternal params) {
    this.ps = ps;
    this.params = params;
  }

  @Override
  public synchronized boolean hasMore() {
    if (result == null) {
      throw new IllegalStateException("No current cursor read");
    }
    return result.isSuspended();
  }

  @Override
  public synchronized void read(int count, Handler<AsyncResult<RowSet<Row>>> handler) {
    if (ps.context == Vertx.currentContext()) {
      SqlResultBuilder<RowSet<Row>, RowSetImpl<Row>, RowSet<Row>> builder = new SqlResultBuilder<>(RowSetImpl.FACTORY, RowSetImpl.COLLECTOR);
      SqlResultHandler<RowSet<Row>, RowSetImpl<Row>, RowSet<Row>> resultHandler = builder.createHandler(handler);
      ExtendedQueryCommand<RowSet<Row>> cmd;
      if (id == null) {
        id = UUID.randomUUID().toString();
        cmd = builder.createExtendedQuery(ps.ps, params, count, id, false, resultHandler);
      } else if (result.isSuspended()) {
        cmd = builder.createExtendedQuery(ps.ps, params, count, id, true, resultHandler);
      } else {
        throw new IllegalStateException();
      }
      result = resultHandler;
      ps.conn.schedule(cmd, resultHandler);
    } else {
      ps.context.runOnContext(v -> read(count, handler));
    }
  }

  @Override
  public synchronized void close(Handler<AsyncResult<Void>> completionHandler) {
    if (!closed) {
      closed = true;
      if (id == null) {
        completionHandler.handle(Future.succeededFuture());
      } else {
        String id = this.id;
        this.id = null;
        result = null;
        ps.closeCursor(id, completionHandler);
      }
    }
  }
}
