/*
 * Copyright 2019 Amazon.com, Inc. or its affiliates. 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.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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.amplifyframework.datastore.appsync;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.util.ObjectsCompat;

import com.amplifyframework.core.model.Model;
import com.amplifyframework.core.model.annotations.ModelConfig;
import com.amplifyframework.core.model.annotations.ModelField;
import com.amplifyframework.core.model.temporal.Temporal;

import java.util.Objects;

/**
 * A system model to house versioning/sync metadata associated with a model instance.
 * This is _also_ used as a model of a portion of an AppSync response, that includes
 * metadata about a particular model. The metadata fields are unique to the AppSync protocol,
 * and these fields exist in GraphQL responses from AppSync.
 */
@ModelConfig
@SuppressWarnings({"MemberName", "ParameterName"})
public final class ModelMetadata implements Model {
    private final @ModelField(targetType = "ID", isRequired = true) String id;
    private final @ModelField(targetType = "Boolean") Boolean _deleted;
    private final @ModelField(targetType = "Int") Integer _version;
    private final @ModelField(targetType = "AWSTimestamp") Temporal.Timestamp _lastChangedAt;

    /**
     * Constructor for this metadata model.
     * @param id The identifier of the object this is holding the metadata for (also this object's own identifier)
     * @param deleted Whether this object was deleted since the last sync time specified
     * @param version What version this object was last seen at
     * @param lastChangedAt When was this object last changed
     */
    public ModelMetadata(
            @NonNull String id,
            @Nullable Boolean deleted,
            @Nullable Integer version,
            @Nullable Temporal.Timestamp lastChangedAt) {
        this.id = Objects.requireNonNull(id);
        this._deleted = deleted;
        this._version = version;
        this._lastChangedAt = lastChangedAt;
    }

    /**
     * Gets identifier.
     * @return identifier
     */
    @NonNull
    public String resolveIdentifier() {
        return id;
    }

    /**
     * Gets the deleted status.
     * @return True if deleted, False otherwise
     */
    @Nullable
    public Boolean isDeleted() {
        return _deleted;
    }

    /**
     * Gets the version.
     * @return version
     */
    @Nullable
    public Integer getVersion() {
        return _version;
    }

    /**
     * Gets the type of the model.
     * @return Type of the Model.
     */
    @Nullable
    public String getTypename() {
        return id.split("\\|")[0];
    }

    /**
     * Gets last changed at time.
     * @return last changed at time
     */
    @Nullable
    public Temporal.Timestamp getLastChangedAt() {
        return _lastChangedAt;
    }

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

        ModelMetadata metadata = (ModelMetadata) thatObject;

        if (!ObjectsCompat.equals(id, metadata.id)) {
            return false;
        }
        if (!ObjectsCompat.equals(_deleted, metadata._deleted)) {
            return false;
        }
        if (!ObjectsCompat.equals(_version, metadata._version)) {
            return false;
        }
        return ObjectsCompat.equals(_lastChangedAt, metadata._lastChangedAt);
    }

    @Override
    public int hashCode() {
        int result = id.hashCode();
        result = 31 * result + (_deleted != null ? _deleted.hashCode() : 0);
        result = 31 * result + (_version != null ? _version.hashCode() : 0);
        result = 31 * result + (_lastChangedAt != null ? _lastChangedAt.hashCode() : 0);
        return result;
    }

    @Override
    public String toString() {
        return "ModelMetadata{" +
            "id='" + id + '\'' +
            ", _deleted=" + _deleted +
            ", _version=" + _version +
            ", _lastChangedAt=" + _lastChangedAt +
            '}';
    }
}