/*
 * Copyright (C) 2024 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 com.android.systemui.kosmos

import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.filters.SmallTest
import com.android.systemui.SysuiTestCase
import com.google.common.truth.Truth.assertThat
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.SharingStarted
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.flow.stateIn
import kotlinx.coroutines.test.runTest
import org.junit.Test
import org.junit.runner.RunWith

@SmallTest
@RunWith(AndroidJUnit4::class)
class GeneralKosmosTest : SysuiTestCase() {
    @Test
    fun stateCurrentValueMutableStateFlow() = runTest {
        val source = MutableStateFlow(1)
        val mapped =
            source
                .map { it * 2 }
                .stateIn(
                    scope = backgroundScope,
                    started = SharingStarted.WhileSubscribed(),
                    initialValue = source.value * 2,
                )
        assertThat(currentValue(mapped)).isEqualTo(2)

        source.value = 3
        assertThat(currentValue(mapped)).isEqualTo(6)
    }

    @Test
    fun stateCurrentValueOnEmittedFlow() = runTest {
        val source = flow {
            emit(1)
            emit(2)
        }
        val mapped =
            source
                .map { it * 2 }
                .stateIn(
                    scope = backgroundScope,
                    started = SharingStarted.WhileSubscribed(),
                    initialValue = 2,
                )
        assertThat(currentValue(mapped)).isEqualTo(4)
    }

    @Test
    fun currentValueIsNull() = runTest {
        val source = MutableStateFlow<Int?>(null)
        assertThat(currentValue(source)).isEqualTo(null)
    }
}