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/*
 * Copyright 2022 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.compose.foundation.lazy.grid

import androidx.collection.IntList
import androidx.compose.foundation.ExperimentalFoundationApi
import androidx.compose.foundation.internal.requirePrecondition
import androidx.compose.foundation.lazy.layout.LazyLayoutKeyIndexMap
import androidx.compose.foundation.lazy.layout.LazyLayoutMeasureScope
import androidx.compose.foundation.lazy.layout.LazyLayoutMeasuredItemProvider
import androidx.compose.ui.layout.Placeable
import androidx.compose.ui.unit.Constraints

/** Abstracts away the subcomposition from the measuring logic. */
@OptIn(ExperimentalFoundationApi::class)
internal abstract class LazyGridMeasuredItemProvider(
    private val itemProvider: LazyGridItemProvider,
    private val measureScope: LazyLayoutMeasureScope,
    private val defaultMainAxisSpacing: Int
) : LazyLayoutMeasuredItemProvider {
    override fun getAndMeasure(
        index: Int,
        lane: Int,
        span: Int,
        constraints: Constraints
    ): LazyGridMeasuredItem =
        getAndMeasure(
            index = index,
            constraints = constraints,
            lane = lane,
            span = span,
            mainAxisSpacing = defaultMainAxisSpacing
        )

    /**
     * Used to subcompose individual items of lazy grids. Composed placeables will be measured with
     * the provided [constraints] and wrapped into [LazyGridMeasuredItem].
     */
    fun getAndMeasure(
        index: Int,
        constraints: Constraints,
        lane: Int,
        span: Int,
        mainAxisSpacing: Int
    ): LazyGridMeasuredItem {
        val key = itemProvider.getKey(index)
        val contentType = itemProvider.getContentType(index)
        val placeables = measureScope.measure(index, constraints)
        val crossAxisSize =
            if (constraints.hasFixedWidth) {
                constraints.minWidth
            } else {
                requirePrecondition(constraints.hasFixedHeight) { "does not have fixed height" }
                constraints.minHeight
            }
        return createItem(
            index,
            key,
            contentType,
            crossAxisSize,
            mainAxisSpacing,
            placeables,
            constraints,
            lane,
            span
        )
    }

    /**
     * Contains the mapping between the key and the index. It could contain not all the items of the
     * list as an optimization.
     */
    val keyIndexMap: LazyLayoutKeyIndexMap
        get() = itemProvider.keyIndexMap

    val headerIndices: IntList
        get() = itemProvider.headerIndexes

    abstract fun createItem(
        index: Int,
        key: Any,
        contentType: Any?,
        crossAxisSize: Int,
        mainAxisSpacing: Int,
        placeables: List,
        constraints: Constraints,
        lane: Int,
        span: Int
    ): LazyGridMeasuredItem
}