/*
 * Copyright (C) 2019 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.testutils

import android.os.Handler
import android.os.HandlerThread
import com.android.testutils.FunctionalUtils.ThrowingSupplier
import kotlin.random.Random
import kotlin.test.assertEquals
import kotlin.test.assertFailsWith
import kotlin.test.assertNull
import org.junit.Test
import org.junit.runner.RunWith

private const val ATTEMPTS = 50 // Causes testWaitForIdle to take about 150ms on aosp_crosshatch-eng
private const val TIMEOUT_MS = 1000

@DevSdkIgnoreRunner.MonitorThreadLeak
@RunWith(DevSdkIgnoreRunner::class)
class HandlerUtilsTest {
    @Test
    fun testWaitForIdle() {
        val handlerThread = HandlerThread("testHandler").apply { start() }
        tryTest {
            // Tests that waitForIdle can be called many times without ill impact if the service is
            // already idle.
            repeat(ATTEMPTS) {
                handlerThread.waitForIdle(TIMEOUT_MS)
            }

            // Tests that calling waitForIdle waits for messages to be processed. Use both an
            // inline runnable that's instantiated at each loop run and a runnable that's
            // instantiated once for all.
            val tempRunnable = object : Runnable {
                // Use StringBuilder preferentially to StringBuffer because StringBuilder is NOT
                // thread-safe. It's part of the point that both runnables run on the same thread
                // so if anything is wrong in that space it's better to opportunistically use a
                // class where things might go wrong, even if there is no guarantee of failure.
                var memory = StringBuilder()
                override fun run() {
                    memory.append("b")
                }
            }
            repeat(ATTEMPTS) { i ->
                handlerThread.threadHandler.post { tempRunnable.memory.append("a"); }
                handlerThread.threadHandler.post(tempRunnable)
                handlerThread.waitForIdle(TIMEOUT_MS)
                assertEquals(tempRunnable.memory.toString(), "ab".repeat(i + 1))
            }
        } cleanup {
            handlerThread.quitSafely()
            handlerThread.join()
        }
    }

    // Statistical test : even if visibleOnHandlerThread doesn't work this is likely to succeed,
    // but it will be at least flaky.
    @Test
    fun testVisibleOnHandlerThread() {
        val handlerThread = HandlerThread("testHandler").apply { start() }
        tryTest {
            val handler = Handler(handlerThread.looper)

            repeat(ATTEMPTS) { attempt ->
                var x = -10
                var y = -11
                y = visibleOnHandlerThread(handler, ThrowingSupplier<Int> { x = attempt; attempt })
                assertEquals(attempt, x)
                assertEquals(attempt, y)
                handler.post { assertEquals(attempt, x) }
            }

            assertFailsWith<IllegalArgumentException> {
                visibleOnHandlerThread(handler) { throw IllegalArgumentException() }
            }

            // Null values may be returned by the supplier
            assertNull(visibleOnHandlerThread(handler, ThrowingSupplier<Nothing?> { null }))
        } cleanup {
            handlerThread.quitSafely()
            handlerThread.join()
        }
    }

    @Test
    fun testPostAndWait() {
        val handlerThread = HandlerThread("testHandler").apply { start() }
        tryTest {
            val handler = Handler(handlerThread.looper)

            assertFailsWith<RuntimeException> {
                handler.postAndWait { throw RuntimeException() }
            }

            val result1 = Random.nextInt()
            val result = handler.postAndWait {
                assertEquals(handlerThread, Thread.currentThread())
                result1
            }
            assertEquals(result, result1)
        } cleanup {
            handlerThread.quitSafely()
            handlerThread.join()
        }
    }
}