/*
 * Copyright (c) 2015 Google Inc.
 *
 * All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse
 * Public License v1.0 which accompanies this distribution, and is available at
 *
 * http://www.eclipse.org/legal/epl-v10.html
 */
package com.google.eclipse.protobuf.model.util;

import com.google.common.collect.Range;
import com.google.eclipse.protobuf.protobuf.IndexRange;
import com.google.eclipse.protobuf.services.ProtobufGrammarAccess;
import com.google.inject.Inject;
import com.google.inject.Singleton;

/**
 * Utility methods related to <code>{@link IndexRange}</code>.
 *
 * @author jogl@google.com (John Glassmyer)
 */
@Singleton public class IndexRanges {
  /**
   * Thrown to indicate that a range's end number is less than its start number.
   */
  public static class BackwardsRangeException extends Exception {
    private static final long serialVersionUID = 1L;
  }

  private ProtobufGrammarAccess protobufGrammarAccess;

  @Inject
  IndexRanges(ProtobufGrammarAccess protobufGrammarAccess) {
    this.protobufGrammarAccess = protobufGrammarAccess;
  }

  /**
   * @throws BackwardsRangeException if the end number is less than the start number
   */
  public Range<Long> toLongRange(IndexRange indexRange) throws BackwardsRangeException {
    long from = indexRange.getFrom();

    Range<Long> range;
    String toString = indexRange.getTo();
    if (toString == null) {
      range = Range.singleton(from);
    } else if (toString.equals(getMaxKeyword())) {
      range = Range.atLeast(from);
    } else {
      Long to = Long.valueOf(toString);

      if (to < from) {
        throw new BackwardsRangeException();
      }

      range = Range.closed(from, to);
    }

    return range;
  }

  public String getMaxKeyword() {
    return protobufGrammarAccess.getIndexRangeMaxAccess().getMaxKeyword_1().getValue();
  }
}