/*
 * Copyright 2019 Flipkart Internet Pvt. Ltd.
 *
 * 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.flipkart.android.proteus;

import android.os.Parcel;
import android.os.Parcelable;
import java.util.HashMap;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * SimpleIdGenerator
 *
 * <p>
 *
 * <p>An built in implementation of {@link IdGenerator} interface
 *
 * @author aditya.sharat
 */
public class SimpleIdGenerator implements IdGenerator {
  public static final Parcelable.Creator<SimpleIdGenerator> CREATOR =
      new Creator<SimpleIdGenerator>() {
        @Override
        public SimpleIdGenerator createFromParcel(Parcel source) {
          return new SimpleIdGenerator(source);
        }

        @Override
        public SimpleIdGenerator[] newArray(int size) {
          return new SimpleIdGenerator[size];
        }
      };
  private final HashMap<String, Integer> idMap = new HashMap<>();
  private final AtomicInteger sNextGeneratedId;

  public SimpleIdGenerator() {
    sNextGeneratedId = new AtomicInteger(1);
  }

  public SimpleIdGenerator(Parcel source) {
    sNextGeneratedId = new AtomicInteger(source.readInt());
    source.readMap(idMap, null);
  }

  /**
   * Flatten this object in to a Parcel.
   *
   * @param dest The Parcel in which the object should be written.
   * @param flags Additional flags about how the object should be written. May be 0 or {@link
   *     #PARCELABLE_WRITE_RETURN_VALUE}.
   */
  @Override
  public void writeToParcel(Parcel dest, int flags) {
    dest.writeInt(sNextGeneratedId.get());
    dest.writeMap(idMap);
  }

  /**
   * Generates and returns a unique id, for the given key. If key exists, returns old value. Ensure
   * that all
   *
   * @param idKey
   * @return a unique ID integer for use with {@link android.view.View#setId(int)}.
   */
  @Override
  public synchronized int getUnique(String idKey) {
    Integer existingId = idMap.get(idKey);
    if (existingId == null) {
      int newId = generateViewId();
      idMap.put(idKey, newId);
      existingId = newId;
    }
    return existingId;
  }

  /**
   * Taken from Android View Source code API 17+
   *
   * <p>Generate a value suitable for use. This value will not collide with ID values generated at
   * inflate time by aapt for R.id.
   *
   * @return a generated ID value
   */
  private int generateViewId() {
    for (; ; ) {
      final int result = sNextGeneratedId.get();

      // aapt-generated IDs have the high byte nonzero; clamp to the range under that.
      int newValue = result + 1;
      if (newValue > 0x00FFFFFF) {
        newValue = 1; // Roll over to 1, not 0.
      }
      if (sNextGeneratedId.compareAndSet(result, newValue)) {
        return result;
      }
    }
  }

  /**
   * Describe the kinds of special objects contained in this Parcelable's marshalled representation.
   *
   * @return a bitmask indicating the set of special object types marshalled by the Parcelable.
   */
  @Override
  public int describeContents() {
    return 0;
  }
}
