package com.example.test

import android.os.SystemClock
import android.view.View
import android.view.ViewGroup
import androidx.test.espresso.PerformException
import androidx.test.espresso.UiController
import androidx.test.espresso.ViewAction
import androidx.test.espresso.matcher.ViewMatchers.isRoot
import org.hamcrest.Matcher
import java.util.ArrayDeque
import java.util.concurrent.TimeoutException

fun waitUntil(matcher: Matcher<View>, timeoutMs: Long = 5_000): ViewAction =
    WaitUntil(matcher, timeoutMs)

private class WaitUntil(
    private val matcher: Matcher<View>,
    private val timeoutMs: Long
) : ViewAction {
    override fun getConstraints(): Matcher<View> = isRoot()

    override fun getDescription(): String = "wait up to $timeoutMs ms for: $matcher"

    override fun perform(uiController: UiController, view: View) {
        val endTime = SystemClock.uptimeMillis() + timeoutMs

        do {
            if (findMatchingView(view, matcher) != null) {
                return
            }

            uiController.loopMainThreadForAtLeast(50)
        } while (SystemClock.uptimeMillis() < endTime)

        throw PerformException.Builder()
            .withActionDescription(getDescription())
            .withViewDescription(view.toString())
            .withCause(
                TimeoutException(
                    "No matching view appeared within $timeoutMs ms"
                )
            )
            .build()
    }

    private fun findMatchingView(root: View, matcher: Matcher<View>): View? {
        val queue = ArrayDeque<View>()
        queue.add(root)

        while (!queue.isEmpty()) {
            val current = queue.removeFirst()

            if (matcher.matches(current)) {
                return current
            }

            if (current is ViewGroup) {
                for (index in 0 until current.childCount) {
                    queue.add(current.getChildAt(index))
                }
            }
        }

        return null
    }
}