private var viewPager: ViewPager? = null
private var tabLayout: TabLayout? = null


override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    val toolbar = findViewById(R.id.toolbar) as Toolbar?
    setSupportActionBar(toolbar)





    supportActionBar!!.setDisplayHomeAsUpEnabled(true)
    supportActionBar!!.setDisplayShowHomeEnabled(true)

    setupWindowAnimations() // func for animation here

    viewPager = findViewById(R.id.viewpager) as ViewPager?
    tabLayout = findViewById(R.id.tabs1) as TabLayout?

    val fab = findViewById(R.id.fab) as FloatingActionButton?
    fab!!.setOnClickListener { view ->
        Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)

                .setAction("Retour") { Toast.makeText(this@MainActivity, "Retour", Toast.LENGTH_SHORT).show() }.show()
    }

    val drawer = findViewById(R.id.drawer_layout) as DrawerLayout?
    val toggle = ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close)
    drawer!!.setDrawerListener(toggle)
    toggle.syncState()

    val navigationView = findViewById(R.id.nav_view) as NavigationView?
    navigationView!!.setNavigationItemSelectedListener(this)

    //on remplit notre viewpager

    viewPager!!.adapter = object : FragmentPagerAdapter(supportFragmentManager) {
        override fun getItem(position: Int): Fragment? {

            var f: Fragment? = null
            when (position) {
                0 -> f = RecyclerViewFragment.newInstance()
                1 -> f = PlusOneFragment.newInstance()
                2 -> f = RecyclerViewFragment.newInstance()
                3 -> f = RecyclerViewFragment.newInstance()
            }

            return f
        }


        override fun getPageTitle(position: Int): CharSequence {
            var tab_name = ""

            when (position) {
                0 -> tab_name = "tab n 1"
                1 -> tab_name = "tab n 2"
                2 -> tab_name = "tab n 3"
                3 -> tab_name = "tab n 4"
            }
            return tab_name
        }

        override fun getCount(): Int {
            return 4
        }
    }

    //indique au tablayout quel est le viewpager à écouter
    tabLayout!!.setupWithViewPager(viewPager)


}

//animation for window
private fun setupWindowAnimations() {
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {

        val explode = Explode()
        window.exitTransition = explode

        val fade = Fade()
        window.reenterTransition = fade
    }
}

override fun onBackPressed() {
    val drawer = findViewById(R.id.drawer_layout) as DrawerLayout?
    if (drawer!!.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START)
    } else {
        super.onBackPressed()
    }
}

override fun onCreateOptionsMenu(menu: Menu): Boolean {
    // Inflate the menu; this adds items to the action bar if it is present.
    menuInflater.inflate(R.menu.main, menu)
    return true
}

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    val id = item.itemId


    if (id == R.id.action_settings) {
        return true
    }

    return super.onOptionsItemSelected(item)
}

override fun onNavigationItemSelected(item: MenuItem): Boolean {
    // Handle navigation view item clicks here.
    val id = item.itemId

    if (id == R.id.nav_camara) {
        // Handle the camera action
        Toast.makeText(this@MainActivity, "camera here", Toast.LENGTH_SHORT).show()
    } else if (id == R.id.nav_gallery) {

    } else if (id == R.id.nav_slideshow) {

    } else if (id == R.id.nav_manage) {

    } else if (id == R.id.nav_share) {

    } else if (id == R.id.nav_send) {

    }

    val drawer = findViewById(R.id.drawer_layout) as DrawerLayout?
    drawer!!.closeDrawer(GravityCompat.START)
    return true
}