PixelDroid-App-Android/app/src/main/java/com/h/pixeldroid/fragments/feeds/HomeFragment.kt

package com.h.pixeldroid.fragments.feeds

import android.graphics.Color
import android.graphics.drawable.ColorDrawable
import android.graphics.drawable.Drawable
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.lifecycle.Observer
import androidx.paging.DataSource
import androidx.paging.ItemKeyedDataSource
import androidx.paging.LivePagedListBuilder
import androidx.paging.PagedList
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.Glide
import com.bumptech.glide.ListPreloader
import com.bumptech.glide.RequestBuilder
import com.bumptech.glide.integration.recyclerview.RecyclerViewPreloader
import com.bumptech.glide.util.ViewPreloadSizeProvider
import com.h.pixeldroid.R
import com.h.pixeldroid.objects.Status
import com.h.pixeldroid.utils.ImageConverter
import kotlinx.android.synthetic.main.fragment_home.*


class HomeFragment : FeedFragment<Status, HomeFragment.HomeRecyclerViewAdapter.ViewHolder>() {

    lateinit var picRequest: RequestBuilder<Drawable>


    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view = super.onCreateView(inflater, container, savedInstanceState)

        val config: PagedList.Config = PagedList.Config.Builder().setPageSize(10).build()
        val factory = HomeDataSourceFactory()

        content = LivePagedListBuilder(factory, config).build()

        picRequest = Glide.with(this)
            .asDrawable().fitCenter()
            .placeholder(ColorDrawable(Color.GRAY))

        adapter = HomeRecyclerViewAdapter()
        list.adapter = adapter

        content.observe(viewLifecycleOwner,
            Observer { c -> adapter.submitList(c); })

        val sizeProvider: ListPreloader.PreloadSizeProvider<Status> = ViewPreloadSizeProvider()
        val preloader: RecyclerViewPreloader<Status> = RecyclerViewPreloader(
            Glide.with(this), adapter, sizeProvider, 4
        )
        list.addOnScrollListener(preloader)

        return view
    }

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


        swipeRefreshLayout.setOnRefreshListener {
            val call = pixelfedAPI.timelineHome("Bearer $accessToken", limit = "20")
            //TODO
        }
    }

    /**
     * [RecyclerView.Adapter] that can display a list of Statuses
     */
    inner class HomeRecyclerViewAdapter: FeedsRecyclerViewAdapter<Status, HomeRecyclerViewAdapter.ViewHolder>() {

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
            val view = LayoutInflater.from(parent.context)
                .inflate(R.layout.post_fragment, parent, false)
            context = view.context
            return ViewHolder(view)
        }

        /**
         * Binds the different elements of the Post Model to the view holder
         */
        override fun onBindViewHolder(holder: ViewHolder, position: Int) {
            val post = getItem(position) ?: return
            val metrics = context.resources.displayMetrics
            //Limit the height of the different images
            holder.profilePic?.maxHeight = metrics.heightPixels
            holder.postPic.maxHeight = metrics.heightPixels

            //Set the two images
            ImageConverter.setRoundImageFromURL(
                holder.postView,
                post.getProfilePicUrl(),
                holder.profilePic!!
            )

            picRequest.load(post.getPostUrl()).into(holder.postPic)

            //Set the image back to a placeholder if the original is too big
            if(holder.postPic.height > metrics.heightPixels) {
                ImageConverter.setDefaultImage(holder.postView, holder.postPic)
            }

            //Set the the text views
            post.setupPost(holder.postView)
        }

        /**
         * Represents the posts that will be contained within the feed
         */
        inner class ViewHolder(val postView: View) : RecyclerView.ViewHolder(postView) {
            val profilePic  : ImageView? = postView.findViewById(R.id.profilePic)
            val postPic     : ImageView = postView.findViewById(R.id.postPicture)
            val username    : TextView = postView.findViewById(R.id.username)
            val usernameDesc: TextView = postView.findViewById(R.id.usernameDesc)
            val description : TextView = postView.findViewById(R.id.description)
            val nlikes      : TextView = postView.findViewById(R.id.nlikes)
            val nshares     : TextView = postView.findViewById(R.id.nshares)
        }

        override fun getPreloadItems(position: Int): MutableList<Status> {
            val status = getItem(position) ?: return mutableListOf()
            return mutableListOf(status)
        }

        override fun getPreloadRequestBuilder(item: Status): RequestBuilder<*>? {
            return picRequest.load(item.getPostUrl())
        }
    }


    inner class HomeDataSource: ItemKeyedDataSource<String, Status>() {

        override fun getKey(item: Status): String {
            return item.id
        }
        override fun loadInitial(
            params: LoadInitialParams<String>,
            callback: LoadInitialCallback<Status>
        ) {
            val call = pixelfedAPI
                .timelineHome("Bearer $accessToken", limit="${params.requestedLoadSize}")
            enqueueCall(call, callback)
        }

        override fun loadAfter(params: LoadParams<String>, callback: LoadCallback<Status>) {
            val call = pixelfedAPI
                .timelineHome("Bearer $accessToken", max_id=params.key,
                    limit="${params.requestedLoadSize}")
            enqueueCall(call, callback)
        }

        override fun loadBefore(params: LoadParams<String>, callback: LoadCallback<Status>) {
            //do nothing here, it is expected to pull to refresh to load newer notifications
        }

    }
    inner class HomeDataSourceFactory: DataSource.Factory<String, Status>() {
        override fun create(): DataSource<String, Status> {
            return HomeDataSource()
        }


    }
}