LibreTube/app/src/main/java/com/github/libretube/ChannelFragment.kt

package com.github.libretube


import android.os.Bundle
import android.util.Log
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.ScrollView
import android.widget.TextView
import androidx.lifecycle.lifecycleScope
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.github.libretube.adapters.ChannelAdapter
import com.squareup.picasso.Picasso
import retrofit2.HttpException
import java.io.IOException


class ChannelFragment : Fragment() {

    private var channel_id: String? = null
    private val TAG = "ChannelFragment"
    var nextPage: String? =null
    var channelAdapter: ChannelAdapter? = null
    var isLoading = true

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        arguments?.let {
            channel_id = it.getString("channel_id")
        }
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_channel, container, false)


    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        channel_id = channel_id!!.replace("/channel/","")
        view.findViewById<TextView>(R.id.channel_name).text=channel_id
        val recyclerView = view.findViewById<RecyclerView>(R.id.channel_recView)
        recyclerView.layoutManager = LinearLayoutManager(context)

        fetchChannel(view)
        val scrollView = view.findViewById<ScrollView>(R.id.channel_scrollView)
        scrollView.viewTreeObserver
            .addOnScrollChangedListener {
                if (scrollView.getChildAt(0).bottom
                    == (scrollView.height + scrollView.scrollY)) {
                    //scroll view is at bottom
                    if(nextPage!=null && !isLoading){
                        isLoading=true
                        fetchNextPage()
                    }

                }
            }

    }

    private fun fetchChannel(view: View){
        fun run() {
            lifecycleScope.launchWhenCreated {
                val response = try {
                    RetrofitInstance.api.getChannel(channel_id!!)
                }catch(e: IOException) {
                    println(e)
                    Log.e(TAG, "IOException, you might not have internet connection")
                    return@launchWhenCreated
                } catch (e: HttpException) {
                    Log.e(TAG, "HttpException, unexpected response")
                    return@launchWhenCreated
                }
                nextPage = response.nextpage
                isLoading=false
                runOnUiThread {
                    view.findViewById<TextView>(R.id.channel_name).text=response.name
                    view.findViewById<TextView>(R.id.channel_subs).text=response.subscriberCount.videoViews() + " subscribers"
                    view.findViewById<TextView>(R.id.channel_description).text=response.description
                    val bannerImage = view.findViewById<ImageView>(R.id.channel_banner)
                    val channelImage = view.findViewById<ImageView>(R.id.channel_image)
                    Picasso.get().load(response.bannerUrl).into(bannerImage)
                    Picasso.get().load(response.avatarUrl).into(channelImage)
                    channelAdapter = ChannelAdapter(response.relatedStreams!!.toMutableList())
                    view.findViewById<RecyclerView>(R.id.channel_recView).adapter = channelAdapter

                }
            }
        }
        run()
    }
    private fun fetchNextPage(){
        fun run() {

            lifecycleScope.launchWhenCreated {
                val response = try {
                    RetrofitInstance.api.getChannelNextPage(channel_id!!,nextPage!!)
                } catch (e: IOException) {
                    println(e)
                    Log.e(TAG, "IOException, you might not have internet connection")
                    return@launchWhenCreated
                } catch (e: HttpException) {
                    Log.e(TAG, "HttpException, unexpected response,"+e.response())
                    return@launchWhenCreated
                }
                nextPage = response.nextpage
                channelAdapter?.updateItems(response.relatedStreams!!)
                isLoading=false

            }
        }
        run()
    }
    private fun Fragment?.runOnUiThread(action: () -> Unit) {
        this ?: return
        if (!isAdded) return // Fragment not attached to an Activity
        activity?.runOnUiThread(action)
    }

    override fun onDestroyView() {
        val scrollView = view?.findViewById<ScrollView>(R.id.channel_scrollView)
        scrollView?.viewTreeObserver?.removeOnScrollChangedListener {
        }
        channelAdapter=null
        view?.findViewById<RecyclerView>(R.id.channel_recView)?.adapter=null
        super.onDestroyView()
    }
}