/*
 * Copyright 2023, 2024 New Vector Ltd.
 *
 * SPDX-License-Identifier: AGPL-3.0-only
 * Please see LICENSE in the repository root for full details.
 */

package io.element.android.libraries.androidutils.diff

import androidx.recyclerview.widget.DiffUtil

/**
 *  Default implementation of [DiffUtil.Callback] that uses [areItemsTheSame] to compare items.
 */
internal class DefaultDiffCallback<T>(
    private val oldList: List<T>,
    private val newList: List<T>,
    private val areItemsTheSame: (oldItem: T?, newItem: T?) -> Boolean,
) : DiffUtil.Callback() {
    override fun getOldListSize(): Int {
        return oldList.size
    }

    override fun getNewListSize(): Int {
        return newList.size
    }

    override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
        val oldItem = oldList.getOrNull(oldItemPosition)
        val newItem = newList.getOrNull(newItemPosition)
        return areItemsTheSame(oldItem, newItem)
    }

    override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int): Boolean {
        val oldItem = oldList.getOrNull(oldItemPosition)
        val newItem = newList.getOrNull(newItemPosition)
        return oldItem == newItem
    }
}
