Add a composable chronometer for status bar chips

/*

 * 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.statusbar.chips.ui.compose

import android.text.format.DateUtils.formatElapsedTime

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.ExperimentalCoroutinesApi

import kotlinx.coroutines.cancelAndJoin

import kotlinx.coroutines.launch

import kotlinx.coroutines.test.advanceTimeBy

import kotlinx.coroutines.test.runTest

import org.junit.Before

import org.junit.Test

import org.junit.runner.RunWith

@OptIn(ExperimentalCoroutinesApi::class)

@SmallTest

@RunWith(AndroidJUnit4::class)

class ChronometerStateTest : SysuiTestCase() {

    private lateinit var mockTimeSource: MutableTimeSource

    @Before

    fun setup() {

        mockTimeSource = MutableTimeSource()

    }

    @Test

    fun initialText_isCorrect() = runTest {

        val state = ChronometerState(mockTimeSource, 0L)

        assertThat(state.currentTimeText).isEqualTo(formatElapsedTime(0))

    }

    @Test

    fun textUpdates_withTime() = runTest {

        val startTime = 1000L

        val state = ChronometerState(mockTimeSource, startTime)

        val job = launch { state.run() }

        val elapsedTime = 5000L

        mockTimeSource.time = startTime + elapsedTime

        advanceTimeBy(elapsedTime)

        assertThat(state.currentTimeText).isEqualTo(formatElapsedTime(elapsedTime / 1000))

        job.cancelAndJoin()

    }

    @Test

    fun textUpdates_toLargerValue() = runTest {

        val startTime = 1000L

        val state = ChronometerState(mockTimeSource, startTime)

        val job = launch { state.run() }

        val elapsedTime = 15000L

        mockTimeSource.time = startTime + elapsedTime

        advanceTimeBy(elapsedTime)

        assertThat(state.currentTimeText).isEqualTo(formatElapsedTime(elapsedTime / 1000))

        job.cancelAndJoin()

    }

    @Test

    fun textUpdates_afterResettingBase() = runTest {

        val initialElapsedTime = 30000L

        val startTime = 50000L

        val state = ChronometerState(mockTimeSource, startTime)

        val job = launch { state.run() }

        mockTimeSource.time = startTime + initialElapsedTime

        advanceTimeBy(initialElapsedTime)

        assertThat(state.currentTimeText).isEqualTo(formatElapsedTime(initialElapsedTime / 1000))

        job.cancelAndJoin()

        val newElapsedTime = 5000L

        val newStartTime = 100000L

        val newState = ChronometerState(mockTimeSource, newStartTime)

        val newJob = launch { newState.run() }

        mockTimeSource.time = newStartTime + newElapsedTime

        advanceTimeBy(newElapsedTime)

        assertThat(newState.currentTimeText).isEqualTo(formatElapsedTime(newElapsedTime / 1000))

        newJob.cancelAndJoin()

    }

}

/** A fake implementation of [TimeSource] that allows the caller to set the current time */

class MutableTimeSource(var time: Long = 0L) : TimeSource {

    override fun getCurrentTime(): Long {

        return time

    }

}

/*

 * 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.statusbar.chips.ui.compose

import android.os.SystemClock

import android.text.format.DateUtils.formatElapsedTime

import androidx.compose.material3.LocalTextStyle

import androidx.compose.material3.Text

import androidx.compose.runtime.Composable

import androidx.compose.runtime.LaunchedEffect

import androidx.compose.runtime.derivedStateOf

import androidx.compose.runtime.getValue

import androidx.compose.runtime.mutableLongStateOf

import androidx.compose.runtime.remember

import androidx.compose.runtime.setValue

import androidx.compose.ui.Modifier

import androidx.compose.ui.graphics.Color

import androidx.compose.ui.layout.Measurable

import androidx.compose.ui.layout.MeasureResult

import androidx.compose.ui.layout.MeasureScope

import androidx.compose.ui.node.LayoutModifierNode

import androidx.compose.ui.node.ModifierNodeElement

import androidx.compose.ui.text.TextStyle

import androidx.compose.ui.unit.Constraints

import androidx.compose.ui.unit.constrain

import androidx.lifecycle.Lifecycle

import androidx.lifecycle.compose.LocalLifecycleOwner

import androidx.lifecycle.repeatOnLifecycle

import kotlinx.coroutines.delay

/** Platform-optimized interface for getting current time */

fun interface TimeSource {

    fun getCurrentTime(): Long

}

/** Holds and manages the state for a Chronometer */

class ChronometerState(private val timeSource: TimeSource, private val startTimeMillis: Long) {

    private var currentTimeMillis by mutableLongStateOf(0L)

    private val elapsedTimeMillis: Long

        get() = maxOf(0L, currentTimeMillis - startTimeMillis)

    val currentTimeText: String by derivedStateOf { formatElapsedTime(elapsedTimeMillis / 1000) }

    suspend fun run() {

        while (true) {

            currentTimeMillis = timeSource.getCurrentTime()

            val delaySkewMillis = (currentTimeMillis - startTimeMillis) % 1000L

            delay(1000L - delaySkewMillis)

        }

    }

}

/** Remember and manage the ChronometerState */

@Composable

fun rememberChronometerState(timeSource: TimeSource, startTimeMillis: Long): ChronometerState {

    val state =

        remember(timeSource, startTimeMillis) { ChronometerState(timeSource, startTimeMillis) }

    val lifecycleOwner = LocalLifecycleOwner.current

    LaunchedEffect(lifecycleOwner, timeSource, startTimeMillis) {

        lifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) { state.run() }

    }

    return state

}

/**

 * A composable chronometer that displays elapsed time with constrained width. The width of the text

 * is only allowed to increase. This ensures there is no visual jitter when individual digits in the

 * text change due to the timer ticking.

 */

@Composable

fun ChronometerText(

    startTimeMillis: Long,

    modifier: Modifier = Modifier,

    color: Color = Color.Unspecified,

    style: TextStyle = LocalTextStyle.current,

    timeSource: TimeSource = remember { TimeSource { SystemClock.elapsedRealtime() } },

) {

    val state = rememberChronometerState(timeSource, startTimeMillis)

    Text(

        text = state.currentTimeText,

        style = style,

        color = color,

        modifier = modifier.neverDecreaseWidth(),

    )

}

/** A modifier that ensures the width of the content only increases and never decreases. */

private fun Modifier.neverDecreaseWidth(): Modifier {

    return this.then(neverDecreaseWidthElement)

}

private data object neverDecreaseWidthElement : ModifierNodeElement<NeverDecreaseWidthNode>() {

    override fun create(): NeverDecreaseWidthNode {

        return NeverDecreaseWidthNode()

    }

    override fun update(node: NeverDecreaseWidthNode) {

        error("This should never be called")

    }

}

private class NeverDecreaseWidthNode : Modifier.Node(), LayoutModifierNode {

    private var minWidth = 0

    override fun MeasureScope.measure(

        measurable: Measurable,

        constraints: Constraints,

    ): MeasureResult {

        val placeable = measurable.measure(Constraints(minWidth = minWidth).constrain(constraints))

        val width = placeable.width

        val height = placeable.height

        minWidth = maxOf(minWidth, width)

        return layout(width, height) { placeable.place(0, 0) }

    }

}