dev/benchmarks/multiple_flutters/android/app/src/main/java/dev/flutter/multipleflutters/MainActivity.kt

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

package dev.flutter.multipleflutters

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.FrameLayout
import android.widget.LinearLayout
import android.widget.TextView
import androidx.fragment.app.FragmentActivity
import androidx.fragment.app.FragmentManager
import io.flutter.FlutterInjector
import io.flutter.embedding.android.FlutterFragment
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.embedding.engine.FlutterEngineCache
import io.flutter.embedding.engine.dart.DartExecutor

class MainActivity : FragmentActivity() {
    private val numberOfFlutters = 20

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val root = LinearLayout(this)
        root.layoutParams = LinearLayout.LayoutParams(
            LinearLayout.LayoutParams.MATCH_PARENT,
            LinearLayout.LayoutParams.MATCH_PARENT
        )
        root.orientation = LinearLayout.VERTICAL
        root.weightSum = numberOfFlutters.toFloat()

        val fragmentManager: FragmentManager = supportFragmentManager

        setContentView(root)

        val app = applicationContext as App
        val dartEntrypoint =
            DartExecutor.DartEntrypoint(
                FlutterInjector.instance().flutterLoader().findAppBundlePath(), "main"
            )
        val engines = generateSequence(0)  { it + 1 }
            .take(numberOfFlutters)
            .map { app.engines.createAndRunEngine(this, dartEntrypoint) }
            .toList()
        for (i in 0 until numberOfFlutters) {
            val flutterContainer = FrameLayout(this)
            root.addView(flutterContainer)
            flutterContainer.id = 12345 + i
            flutterContainer.layoutParams = LinearLayout.LayoutParams(
                FrameLayout.LayoutParams.MATCH_PARENT,
                FrameLayout.LayoutParams.MATCH_PARENT,
                1.0f
            )
            val engine = engines[i]
            FlutterEngineCache.getInstance().put(i.toString(), engine)
            val flutterFragment =
                FlutterFragment.withCachedEngine(i.toString()).build<FlutterFragment>()
            fragmentManager
                .beginTransaction()
                .add(
                    12345 + i,
                    flutterFragment
                )
                .commit()
        }
    }

    override fun onDestroy() {
        for (i in 0 until numberOfFlutters) {
            FlutterEngineCache.getInstance().remove(i.toString())
        }

        super.onDestroy()
    }
}