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Library code for Realm Kotlin. This artifact is not supposed to be consumed directly, but through 'io.realm.kotlin:gradle-plugin:1.11.1' instead.

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/*
 * Copyright 2022 Realm Inc.
 *
 * 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 io.realm.kotlin.internal

import io.realm.kotlin.internal.query.ObjectBoundQuery
import io.realm.kotlin.internal.util.terminateWhen
import io.realm.kotlin.notifications.DeletedObject
import io.realm.kotlin.notifications.ResultsChange
import io.realm.kotlin.query.RealmQuery
import io.realm.kotlin.query.RealmResults
import io.realm.kotlin.types.BaseRealmObject
import kotlinx.coroutines.flow.Flow

/**
 * Class that binds a RealmResults to an Object lifecycle. Flows resulting from this class would be
 * completed once the object gets deleted.
 *
 * It makes it possible to simulate the behavior of RealmLists on subqueries and backlinks.
 */
internal class ObjectBoundRealmResults(
    val targetObject: RealmObjectReference<*>,
    val realmResults: RealmResults,
) : RealmResults by realmResults, InternalDeleteable {

    override val size: Int by realmResults::size

    override fun get(index: Int): E = realmResults[index]

    override fun query(query: String, vararg args: Any?): RealmQuery = ObjectBoundQuery(
        targetObject,
        realmResults.query(query, *args)
    )

    /**
     * Because backlinks don't have native notifications when the target object gets deleted we
     * cannot properly close the communication channel.
     *
     * The logic within this flow tries to address this issue by combining a notification flow from the
     * target object, which emits deletion events, with the linking object notifications flow.
     *
     * First we filter the target object flow to discard any UpdateObject event. We only require of
     * the InitialObject event to allow the combine to emit values, and the DeletedObject to cancel the
     * flow.
     *
     * Then we combine it with the backlinks flow, and apply a transformation t
     * hat only emit
     * values, if the object has not been deleted, if not it closes cancels the flow.
     */

    override fun asFlow(keyPaths: List?): Flow> {
        return realmResults.asFlow(keyPaths).bind(targetObject)
    }

    override fun delete() {
        if (realmResults is InternalDeleteable) {
            realmResults.delete()
        } else {
            // Should never happen, so fail with some debug information
            throw IllegalStateException("This class cannot be deleted: $this. It was holding a $realmResults")
        }
    }
}

/**
 * Binds a flow to an object lifecycle. It allows flows on queries to complete once the object gets
 * deleted. It is used on sub-queries and backlinks.
 */
internal fun  Flow.bind(
    reference: RealmObjectReference
): Flow =
    this.terminateWhen(reference.asFlow(null)) { it is DeletedObject }