// Copyright 2018 The Bazel Authors. All rights reserved.
//
// 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 com.google.devtools.build.lib.remote;

import build.bazel.semver.SemVer;

/** Represents a version of the Remote Execution API. */
public class ApiVersion implements Comparable<ApiVersion> {
  public final int major;
  public final int minor;
  public final int patch;
  public final String prerelease;

  // The current lowest/highest versions (inclusive) of the Remote Execution API that Bazel
  // supports. These fields will need to be updated together with all version changes.
  public static final ApiVersion low =
      new ApiVersion(SemVer.newBuilder().setMajor(2).setMinor(0).build());
  public static final ApiVersion high =
      new ApiVersion(SemVer.newBuilder().setMajor(2).setMinor(0).build());

  public ApiVersion(int major, int minor, int patch, String prerelease) {
    this.major = major;
    this.minor = minor;
    this.patch = patch;
    this.prerelease = prerelease;
  }

  public ApiVersion(SemVer semver) {
    this(semver.getMajor(), semver.getMinor(), semver.getPatch(), semver.getPrerelease());
  }

  @Override
  public String toString() {
    if (!prerelease.isEmpty()) {
      return prerelease;
    }
    StringBuilder builder = new StringBuilder();
    builder.append(major);
    builder.append(".");
    builder.append(minor);
    if (patch != 0) {
      builder.append(".");
      builder.append(patch);
    }
    return builder.toString();
  }

  public SemVer toSemVer() {
    return SemVer.newBuilder()
        .setMajor(major)
        .setMinor(minor)
        .setPatch(patch)
        .setPrerelease(prerelease)
        .build();
  }

  /**
   * Compares the current API version to another API version.
   *
   * @param other the API version to compare to.
   * @return 0 if the API versions are equal, a number less than 0 if the current version is earlier
   *     than other, and a number greater than 0 if the current version is later than other. It is
   *     assumed that all prerelease versions are earlier than all released versions.
   */
  @Override
  public int compareTo(ApiVersion other) {
    if (!prerelease.isEmpty()) {
      if (other.prerelease.isEmpty()) {
        return -1;
      }
      return prerelease.compareTo(other.prerelease);
    }
    if (!other.prerelease.isEmpty()) {
      return 1;
    }
    if (major != other.major) {
      return Integer.compare(major, other.major);
    }
    if (minor != other.minor) {
      return Integer.compare(minor, other.minor);
    }
    return Integer.compare(patch, other.patch);
  }
}