/**
 * Copyright 2009 Google Inc.
 *
 * 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 org.waveprotocol.wave.model.operation.testing;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import org.waveprotocol.wave.model.operation.testing.StringDomain.Data;
import org.waveprotocol.wave.model.operation.testing.StringDomain.StringOp;
import org.waveprotocol.wave.model.operation.testing.StringDomain.StringOp.Component;
import org.waveprotocol.wave.model.operation.testing.StringDomain.StringOp.Delete;
import org.waveprotocol.wave.model.operation.testing.StringDomain.StringOp.Insert;
import org.waveprotocol.wave.model.operation.testing.StringDomain.StringOp.Skip;

public class StringOpGenerator implements RandomOpGenerator<Data, StringOp> {

  final int maxComponents = 20;

  @Override
  public StringOp randomOperation(Data state, Random random) {

    int numComponents = random.nextInt(maxComponents);

    List<Component> components = new ArrayList<Component>();

    String str = state.toString();
    int remainingLength = str.length();
    while (numComponents > 0 && remainingLength >= 0) {
      if (remainingLength == 0) {
        components.add(new Insert((char) (random.nextInt(26) + 'A')));
      } else {
        switch (random.nextInt(3)) {
        case 0:
          components.add(new Insert((char) (random.nextInt(26) + 'A')));
          break;
        case 1:
          components.add(new Delete(str.charAt(str.length() - remainingLength)));
          remainingLength--;
          break;
        default:
          components.add(Skip.INSTANCE);
          remainingLength--;
          break;
        }
      }
      numComponents--;
    }

    StringOp op = new StringOp(components);

    return op;
  }

}