package com.projectsacrifice.game;

import android.app.Instrumentation;

import androidx.test.core.app.ActivityScenario;
import androidx.test.ext.junit.runners.AndroidJUnit4;
import androidx.test.platform.app.InstrumentationRegistry;

import org.junit.Test;
import org.junit.runner.RunWith;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

/** Device-level contract for leaving and returning to an active puzzle. */
@RunWith(AndroidJUnit4.class)
public final class GameLifecycleTest {
    @Test
    public void returningFromBackgroundKeepsPuzzleVisiblePausedAndClearsHeldInput() {
        Instrumentation instrumentation = InstrumentationRegistry.getInstrumentation();
        try (ActivityScenario<MainActivity> scenario = ActivityScenario.launch(MainActivity.class)) {
            final MainActivity[] activity = new MainActivity[1];
            final GameView[] view = new GameView[1];
            scenario.onActivity(current -> {
                activity[0] = current;
                view[0] = current.gameViewForAutomation();
            });
            createRetainedCorpse(instrumentation, view[0]);

            runOnGame(instrumentation, view[0], false, false, true, false);
            instrumentation.runOnMainSync(activity[0]::onPause);
            GameView.AutomationSnapshot backgroundStart = snapshot(instrumentation, view[0]);
            sleep(700L);
            GameView.AutomationSnapshot backgroundEnd = snapshot(instrumentation, view[0]);

            assertEquals(5, backgroundEnd.levelNumber());
            assertEquals(backgroundStart.deaths(), backgroundEnd.deaths());
            assertEquals(backgroundStart.corpseCount(), backgroundEnd.corpseCount());
            assertEquals(backgroundStart.playerX(), backgroundEnd.playerX(), 0.01f);
            assertEquals(backgroundStart.elapsedMilliseconds(), backgroundEnd.elapsedMilliseconds());

            instrumentation.runOnMainSync(activity[0]::onResume);
            GameView.AutomationSnapshot returned = snapshot(instrumentation, view[0]);
            assertTrue("Returning to an active puzzle must show the pause screen", returned.visiblyPaused());
            assertFalse("Held touch input must not survive backgrounding", returned.inputActive());
            assertEquals(backgroundEnd.deaths(), returned.deaths());
            assertEquals(backgroundEnd.corpseCount(), returned.corpseCount());

            scenario.onActivity(MainActivity::onBackPressed);
            sleep(80L);
            GameView.AutomationSnapshot resumed = snapshot(instrumentation, view[0]);
            assertFalse("Back from the visible pause screen must resume the puzzle", resumed.visiblyPaused());
            runOnGame(instrumentation, view[0], false, false, true, false);
            GameView.AutomationSnapshot moving = waitForMovement(
                    instrumentation, view[0], resumed.playerX(), 10_000L);
            runOnGame(instrumentation, view[0], false, false, false, false);
            assertTrue("The resumed simulation must accept movement", moving.playerX() > resumed.playerX() + 20f);
        }
    }

    private static GameView.AutomationSnapshot waitForMovement(
            Instrumentation instrumentation, GameView gameView, float startX, long timeoutMillis) {
        long deadline = System.currentTimeMillis() + timeoutMillis;
        GameView.AutomationSnapshot current = snapshot(instrumentation, gameView);
        while (System.currentTimeMillis() < deadline) {
            if (current.playerX() > startX + 20f) return current;
            sleep(24L);
            current = snapshot(instrumentation, gameView);
        }
        throw new AssertionError(
                "The resumed simulation did not move within " + timeoutMillis
                        + "ms; startX=" + startX
                        + ", finalX=" + current.playerX()
                        + ", alive=" + current.playerAlive()
                        + ", paused=" + current.visiblyPaused()
                        + ", inputActive=" + current.inputActive());
    }

    private static void createRetainedCorpse(Instrumentation instrumentation, GameView gameView) {
        runOnGame(instrumentation, gameView, true, false, true, false);
        long deadline = System.currentTimeMillis() + 8_000L;
        boolean died = false;
        while (System.currentTimeMillis() < deadline) {
            GameView.AutomationSnapshot value = snapshot(instrumentation, gameView);
            if (!value.playerAlive()) died = true;
            if (died && value.playerAlive() && value.corpseCount() >= 1) {
                runOnGame(instrumentation, gameView, false, false, false, false);
                return;
            }
            sleep(24L);
        }
        throw new AssertionError("Level 5 did not produce a retained corpse before lifecycle check");
    }

    private static void runOnGame(Instrumentation instrumentation, GameView gameView,
                                  boolean startLevelFive, boolean left, boolean right, boolean jump) {
        instrumentation.runOnMainSync(() -> {
            if (startLevelFive) gameView.startLevelForAutomation(5);
            gameView.setAutomationInput(left, right, jump);
        });
    }

    private static GameView.AutomationSnapshot snapshot(Instrumentation instrumentation, GameView gameView) {
        final GameView.AutomationSnapshot[] value = new GameView.AutomationSnapshot[1];
        instrumentation.runOnMainSync(() -> value[0] = gameView.automationSnapshot());
        return value[0];
    }

    private static void sleep(long millis) {
        try {
            Thread.sleep(millis);
        } catch (InterruptedException interrupted) {
            Thread.currentThread().interrupt();
            throw new AssertionError("Lifecycle test interrupted", interrupted);
        }
    }
}