PlayerAndroid/app/src/main/java/code/name/monkey/retromusic/fragments/base/AbsRecyclerViewFragment.kt

package code.name.monkey.retromusic.fragments.base

import android.os.Bundle
import android.view.View
import android.view.ViewGroup
import androidx.annotation.NonNull
import androidx.annotation.StringRes
import androidx.recyclerview.widget.RecyclerView
import code.name.monkey.retromusic.R
import code.name.monkey.retromusic.fragments.LibraryViewModel
import code.name.monkey.retromusic.helper.MusicPlayerRemote
import code.name.monkey.retromusic.util.DensityUtil
import code.name.monkey.retromusic.util.ThemedFastScroller.create
import code.name.monkey.retromusic.views.ScrollingViewOnApplyWindowInsetsListener
import com.google.android.material.appbar.AppBarLayout
import kotlinx.android.synthetic.main.fragment_main_activity_recycler_view.*
import me.zhanghai.android.fastscroll.FastScroller
import me.zhanghai.android.fastscroll.FastScrollerBuilder
import org.koin.androidx.viewmodel.ext.android.sharedViewModel

abstract class AbsRecyclerViewFragment<A : RecyclerView.Adapter<*>, LM : RecyclerView.LayoutManager> :
    AbsMusicServiceFragment(R.layout.fragment_main_activity_recycler_view),
    AppBarLayout.OnOffsetChangedListener {

    val libraryViewModel: LibraryViewModel by sharedViewModel()
    
    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        setHasOptionsMenu(true)
    }

    protected var adapter: A? = null
    protected var layoutManager: LM? = null


    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        initLayoutManager()
        initAdapter()
        setUpRecyclerView()
    }

    private fun setUpRecyclerView() {
        recyclerView.layoutManager = layoutManager
        recyclerView.adapter = adapter
        val fastScroller = create(recyclerView)
        recyclerView.setOnApplyWindowInsetsListener(
            ScrollingViewOnApplyWindowInsetsListener(
                recyclerView,
                fastScroller
            )
        )
        checkForPadding()
    }

    protected open fun createFastScroller(recyclerView: RecyclerView): FastScroller {
        return FastScrollerBuilder(recyclerView).useMd2Style().build()
    }

    private fun initAdapter() {
        adapter = createAdapter()
        adapter?.registerAdapterDataObserver(object : RecyclerView.AdapterDataObserver() {
            override fun onChanged() {
                super.onChanged()
                checkIsEmpty()
                checkForPadding()
            }
        })
    }

    protected open val emptyMessage: Int
        @StringRes get() = R.string.empty

    private fun getEmojiByUnicode(unicode: Int): String {
        return String(Character.toChars(unicode))
    }

    private fun checkIsEmpty() {
        emptyEmoji.text = getEmojiByUnicode(0x1F631)
        emptyText.setText(emptyMessage)
        empty.visibility = if (adapter!!.itemCount == 0) View.VISIBLE else View.GONE
    }

    private fun checkForPadding() {
        val itemCount: Int = adapter?.itemCount ?: 0
        val params = container.layoutParams as ViewGroup.MarginLayoutParams
        if (itemCount > 0 && MusicPlayerRemote.playingQueue.isNotEmpty()) {
            val height = DensityUtil.dip2px(requireContext(), 104f)
            params.bottomMargin = height
        } else {
            val height = DensityUtil.dip2px(requireContext(), 52f)
            params.bottomMargin = height
        }
    }


    private fun initLayoutManager() {
        layoutManager = createLayoutManager()
    }

    protected abstract fun createLayoutManager(): LM

    @NonNull
    protected abstract fun createAdapter(): A

    override fun onOffsetChanged(p0: AppBarLayout?, i: Int) {
        container.setPadding(
            container.paddingLeft,
            container.paddingTop,
            container.paddingRight,
            i
        )
    }

    override fun onQueueChanged() {
        super.onQueueChanged()
        checkForPadding()
    }

    override fun onServiceConnected() {
        super.onServiceConnected()
        checkForPadding()
    }

    protected fun invalidateLayoutManager() {
        initLayoutManager()
        recyclerView.layoutManager = layoutManager
    }

    protected fun invalidateAdapter() {
        initAdapter()
        checkIsEmpty()
        recyclerView.adapter = adapter
    }

    fun recyclerView(): RecyclerView {
        return recyclerView
    }
}