/*
 * Copyright (C) 2016 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 androidx.test.espresso.remote;

import static androidx.test.internal.util.Checks.checkNotNull;
import static androidx.test.internal.util.Checks.checkState;

import androidx.annotation.NonNull;
import androidx.test.espresso.remote.annotation.RemoteMsgField;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.TreeMap;

/**
 * Provides additional meta data about a {@link Field} declared in a class.
 *
 * <p>The data provided here is used at runtime to reflectively access fields that require proto
 * serialization.
 */
public final class FieldDescriptor {
  public final Class<?> fieldType;
  public final String fieldName;
  public final int order;

  private FieldDescriptor(@NonNull Class<?> fieldType, @NonNull String fieldName, int order) {
    this.fieldType = checkNotNull(fieldType, "fieldType cannot be null!");
    this.fieldName = checkNotNull(fieldName, "fieldName cannot be null!");
    checkState(order >= 0, "Field order must be greater then or equal to 0!");
    this.order = order;
  }

  /**
   * Creates a {@link FieldDescriptor} instance.
   *
   * @param fieldType the type of the field
   * @param fieldName the name of the field as declared in the class
   * @param order the declared order of the field, order values need to start with 0
   */
  public static FieldDescriptor of(
      @NonNull Class<?> fieldType, @NonNull String fieldName, int order) {
    return new FieldDescriptor(fieldType, fieldName, order);
  }

  /**
   * Creates a {@link FieldDescriptor} instance from a {@link Field} and {@link Annotation}.
   *
   * @param field a {@link Field} object
   * @param remoteMsgFieldAnnotation an {@link Annotation} attached to {@code field}
   */
  static FieldDescriptor of(
      @NonNull Field field, @NonNull RemoteMsgField remoteMsgFieldAnnotation) {
    checkNotNull(field, "field cannot be null");
    checkNotNull(remoteMsgFieldAnnotation, "remoteMsgFieldAnnotation cannot be null");
    return of(field.getType(), field.getName(), remoteMsgFieldAnnotation.order());
  }

  static List<FieldDescriptor> getFieldDescriptorsFromAnnotation(
      Class<?> clazz, Class<RemoteMsgField> annotation) {
    TreeMap<Integer, FieldDescriptor> targetFields = new TreeMap<>();
    Field[] declaredFields = clazz.getDeclaredFields();
    for (Field field : declaredFields) {
      if (field.isAnnotationPresent(annotation)) {
        RemoteMsgField remoteMsgFieldAnnotation = field.getAnnotation(annotation);
        int order = remoteMsgFieldAnnotation.order();
        if (targetFields.containsKey(order)) {
          throw new IllegalStateException(
              String.format(
                  Locale.ROOT, "Duplicate field order %s for field %s", order, field.getName()));
        }
        targetFields.put(order, of(field, remoteMsgFieldAnnotation));
      }
    }
    return new ArrayList<>(targetFields.values());
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }

    FieldDescriptor that = (FieldDescriptor) o;

    if (order != that.order) {
      return false;
    }
    if (fieldType != null ? !fieldType.equals(that.fieldType) : that.fieldType != null) {
      return false;
    }
    return fieldName != null ? fieldName.equals(that.fieldName) : that.fieldName == null;
  }

  @Override
  public int hashCode() {
    int result = fieldType != null ? fieldType.hashCode() : 0;
    result = 31 * result + (fieldName != null ? fieldName.hashCode() : 0);
    result = 31 * result + order;
    return result;
  }
}