/*
 * Copyright 2017 The Android Open Source Project
 *
 * 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.android.tv.twopanelsettings.slices.compat;

import android.net.Uri;
import androidx.annotation.NonNull;

/**
 * Class describing the structure of the data contained within a slice.
 *
 * <p>A data version contains a string which describes the type of structure and a revision which
 * denotes this specific implementation. Revisions are expected to be backwards compatible and
 * monotonically increasing. Meaning if a SliceSpec has the same type and an equal or lesser
 * revision, it is expected to be compatible.
 *
 * <p>Apps rendering slices will provide a list of supported versions to the OS which will also be
 * given to the app. Apps should only return a {@link Slice} with a {@link SliceSpec} that one of
 * the supported {@link SliceSpec}s provided {@link #canRender}.
 *
 * @see Slice
 * @see SliceProvider#onBindSlice(Uri)
 */
public final class SliceSpec {

  String mType;

  int mRevision = 1;

  public SliceSpec(@NonNull String type, int revision) {
    mType = type;
    mRevision = revision;
  }

  /** Gets the type of the version. */
  @NonNull
  public String getType() {
    return mType;
  }

  /** Gets the revision of the version. */
  public int getRevision() {
    return mRevision;
  }

  /**
   * Indicates that this spec can be used to render the specified spec.
   *
   * <p>Rendering support is not bi-directional (e.g. Spec v3 can render Spec v2, but Spec v2 cannot
   * render Spec v3).
   *
   * @param candidate candidate format of data.
   * @return true if versions are compatible.
   * @see com.android.tv.twopanelsettings.slices.compat.widget.SliceView
   */
  public boolean canRender(@NonNull SliceSpec candidate) {
    if (!mType.equals(candidate.mType)) {
      return false;
    }
    return mRevision >= candidate.mRevision;
  }

  @Override
  public boolean equals(Object obj) {
    if (!(obj instanceof SliceSpec)) {
      return false;
    }
    SliceSpec other = (SliceSpec) obj;
    return mType.equals(other.mType) && mRevision == other.mRevision;
  }

  @Override
  public int hashCode() {
    return mType.hashCode() + mRevision;
  }

  @Override
  public String toString() {
    return String.format("SliceSpec{%s,%d}", mType, mRevision);
  }
}