/* Copyright 2017 Andrew Dawson
 *
 * This file is a part of Tusky.
 *
 * This program is free software; you can redistribute it and/or modify it under the terms of the
 * GNU General Public License as published by the Free Software Foundation; either version 3 of the
 * License, or (at your option) any later version.
 *
 * Tusky is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
 * Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along with Tusky; if not,
 * see <http://www.gnu.org/licenses>. */

package com.keylesspalace.tusky.fragment

import android.graphics.Color
import android.os.Bundle
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import androidx.core.app.ActivityOptionsCompat
import androidx.core.content.ContextCompat
import androidx.core.view.ViewCompat
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.Glide
import com.bumptech.glide.load.resource.bitmap.DownsampleStrategy
import com.keylesspalace.tusky.R
import com.keylesspalace.tusky.ViewMediaActivity
import com.keylesspalace.tusky.di.Injectable
import com.keylesspalace.tusky.entity.Attachment
import com.keylesspalace.tusky.entity.Status
import com.keylesspalace.tusky.network.MastodonApi
import com.keylesspalace.tusky.util.ThemeUtils
import com.keylesspalace.tusky.util.hide
import com.keylesspalace.tusky.util.show
import com.keylesspalace.tusky.view.SquareImageView
import com.keylesspalace.tusky.viewdata.AttachmentViewData
import kotlinx.android.synthetic.main.fragment_timeline.*
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
import java.io.IOException
import java.util.*
import javax.inject.Inject

/**
 * Created by charlag on 26/10/2017.
 *
 * Fragment with multiple columns of media previews for the specified account.
 */

class AccountMediaFragment : BaseFragment(), Injectable {

    companion object {
        @JvmStatic
        fun newInstance(accountId: String): AccountMediaFragment {
            val fragment = AccountMediaFragment()
            val args = Bundle()
            args.putString(ACCOUNT_ID_ARG, accountId)
            fragment.arguments = args
            return fragment
        }

        private const val ACCOUNT_ID_ARG = "account_id"
        private const val TAG = "AccountMediaFragment"
    }

    @Inject
    lateinit var api: MastodonApi

    private val adapter = MediaGridAdapter()
    private var currentCall: Call<List<Status>>? = null
    private val statuses = mutableListOf<Status>()
    private var fetchingStatus = FetchingStatus.NOT_FETCHING
    private var isVisibleToUser: Boolean = false

    private val callback = object : Callback<List<Status>> {
        override fun onFailure(call: Call<List<Status>>?, t: Throwable?) {
            fetchingStatus = FetchingStatus.NOT_FETCHING

            if (isAdded) {
                swipeRefreshLayout.isRefreshing = false
                progressBar.visibility = View.GONE
                statusView.show()
                if (t is IOException) {
                    statusView.setup(R.drawable.elephant_offline, R.string.error_network) {
                        doInitialLoadingIfNeeded()
                    }
                } else {
                    statusView.setup(R.drawable.elephant_error, R.string.error_generic) {
                        doInitialLoadingIfNeeded()
                    }
                }
            }

            Log.d(TAG, "Failed to fetch account media", t)
        }

        override fun onResponse(call: Call<List<Status>>, response: Response<List<Status>>) {
            fetchingStatus = FetchingStatus.NOT_FETCHING
            if (isAdded) {
                swipeRefreshLayout.isRefreshing = false
                progressBar.visibility = View.GONE

                val body = response.body()
                body?.let { fetched ->
                    statuses.addAll(0, fetched)
                    // flatMap requires iterable but I don't want to box each array into list
                    val result = mutableListOf<AttachmentViewData>()
                    for (status in fetched) {
                        result.addAll(AttachmentViewData.list(status))
                    }
                    adapter.addTop(result)

                    if (statuses.isEmpty()) {
                        statusView.show()
                        statusView.setup(R.drawable.elephant_friend_empty, R.string.message_empty,
                                null)
                    }
                }
            }
        }
    }

    private val bottomCallback = object : Callback<List<Status>> {
        override fun onFailure(call: Call<List<Status>>?, t: Throwable?) {
            fetchingStatus = FetchingStatus.NOT_FETCHING

            Log.d(TAG, "Failed to fetch account media", t)
        }

        override fun onResponse(call: Call<List<Status>>, response: Response<List<Status>>) {
            fetchingStatus = FetchingStatus.NOT_FETCHING
            val body = response.body()
            body?.let { fetched ->
                Log.d(TAG, "fetched ${fetched.size} statuses")
                if (fetched.isNotEmpty()) Log.d(TAG, "first: ${fetched.first().id}, last: ${fetched.last().id}")
                statuses.addAll(fetched)
                Log.d(TAG, "now there are ${statuses.size} statuses")
                // flatMap requires iterable but I don't want to box each array into list
                val result = mutableListOf<AttachmentViewData>()
                for (status in fetched) {
                    result.addAll(AttachmentViewData.list(status))
                }
                adapter.addBottom(result)
            }
        }

    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
                              savedInstanceState: Bundle?): View? {
        return inflater.inflate(R.layout.fragment_timeline, container, false)
    }

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


        val columnCount = view.context.resources.getInteger(R.integer.profile_media_column_count)
        val layoutManager = GridLayoutManager(view.context, columnCount)

        val bgRes = ThemeUtils.getColorId(view.context, R.attr.window_background)

        adapter.baseItemColor = ContextCompat.getColor(recyclerView.context, bgRes)

        recyclerView.layoutManager = layoutManager
        recyclerView.adapter = adapter

        val accountId = arguments?.getString(ACCOUNT_ID_ARG)

        swipeRefreshLayout.setOnRefreshListener {
            statusView.hide()
            if (fetchingStatus != FetchingStatus.NOT_FETCHING) return@setOnRefreshListener
            currentCall = if (statuses.isEmpty()) {
                fetchingStatus = FetchingStatus.INITIAL_FETCHING
                api.accountStatuses(accountId, null, null, null, null, true, null)
            } else {
                fetchingStatus = FetchingStatus.REFRESHING
                api.accountStatuses(accountId, null, statuses[0].id, null, null, true, null)
            }
            currentCall?.enqueue(callback)

        }
        swipeRefreshLayout.setColorSchemeResources(R.color.tusky_blue)
        swipeRefreshLayout.setProgressBackgroundColorSchemeColor(ThemeUtils.getColor(view.context, android.R.attr.colorBackground))

        statusView.visibility = View.GONE

        recyclerView.addOnScrollListener(object : RecyclerView.OnScrollListener() {

            override fun onScrolled(recycler_view: RecyclerView, dx: Int, dy: Int) {
                if (dy > 0) {
                    val itemCount = layoutManager.itemCount
                    val lastItem = layoutManager.findLastCompletelyVisibleItemPosition()
                    if (itemCount <= lastItem + 3 && fetchingStatus == FetchingStatus.NOT_FETCHING) {
                        statuses.lastOrNull()?.let { last ->
                            Log.d(TAG, "Requesting statuses with max_id: ${last.id}, (bottom)")
                            fetchingStatus = FetchingStatus.FETCHING_BOTTOM
                            currentCall = api.accountStatuses(accountId, last.id, null, null, null, true, null)
                            currentCall?.enqueue(bottomCallback)
                        }
                    }
                }
            }
        })

        if (isVisibleToUser) doInitialLoadingIfNeeded()
    }

    // That's sort of an optimization to only load media once user has opened the tab
    // Attention: can be called before *any* lifecycle method!
    override fun setUserVisibleHint(isVisibleToUser: Boolean) {
        super.setUserVisibleHint(isVisibleToUser)
        this.isVisibleToUser = isVisibleToUser
        if (isVisibleToUser && isAdded) doInitialLoadingIfNeeded()
    }

    private fun doInitialLoadingIfNeeded() {
        if (isAdded) {
            statusView.hide()
        }
        val accountId = arguments?.getString(ACCOUNT_ID_ARG)
        if (fetchingStatus == FetchingStatus.NOT_FETCHING && statuses.isEmpty()) {
            fetchingStatus = FetchingStatus.INITIAL_FETCHING
            currentCall = api.accountStatuses(accountId, null, null, null, null, true, null)
            currentCall?.enqueue(callback)
        }
    }

    private fun viewMedia(items: List<AttachmentViewData>, currentIndex: Int, view: View?) {
        val type = items[currentIndex].attachment.type

        when (type) {
            Attachment.Type.IMAGE,
            Attachment.Type.GIFV,
            Attachment.Type.VIDEO -> {
                val intent = ViewMediaActivity.newIntent(context, items, currentIndex)
                if (view != null && activity != null) {
                    val url = items[currentIndex].attachment.url
                    ViewCompat.setTransitionName(view, url)
                    val options = ActivityOptionsCompat.makeSceneTransitionAnimation(activity!!, view, url)
                    startActivity(intent, options.toBundle())
                } else {
                    startActivity(intent)
                }
            }
            Attachment.Type.UNKNOWN -> {
            }/* Intentionally do nothing. This case is here is to handle when new attachment
                 * types are added to the API before code is added here to handle them. So, the
                 * best fallback is to just show the preview and ignore requests to view them. */

        }
    }

    private enum class FetchingStatus {
        NOT_FETCHING, INITIAL_FETCHING, FETCHING_BOTTOM, REFRESHING
    }

    inner class MediaGridAdapter :
            RecyclerView.Adapter<MediaGridAdapter.MediaViewHolder>() {

        var baseItemColor = Color.BLACK

        private val items = mutableListOf<AttachmentViewData>()
        private val itemBgBaseHSV = FloatArray(3)
        private val random = Random()

        fun addTop(newItems: List<AttachmentViewData>) {
            items.addAll(0, newItems)
            notifyItemRangeInserted(0, newItems.size)
        }

        fun addBottom(newItems: List<AttachmentViewData>) {
            if (newItems.isEmpty()) return

            val oldLen = items.size
            items.addAll(newItems)
            notifyItemRangeInserted(oldLen, newItems.size)
        }

        override fun onAttachedToRecyclerView(recycler_view: RecyclerView) {
            val hsv = FloatArray(3)
            Color.colorToHSV(baseItemColor, hsv)
            super.onAttachedToRecyclerView(recycler_view)
        }

        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MediaViewHolder {
            val view = SquareImageView(parent.context)
            view.scaleType = ImageView.ScaleType.CENTER_CROP
            return MediaViewHolder(view)
        }

        override fun getItemCount(): Int = items.size

        override fun onBindViewHolder(holder: MediaViewHolder, position: Int) {
            itemBgBaseHSV[2] = random.nextFloat() * (1f - 0.3f) + 0.3f
            holder.imageView.setBackgroundColor(Color.HSVToColor(itemBgBaseHSV))
            val item = items[position]

            Glide.with(holder.imageView)
                    .load(item.attachment.previewUrl)
                    .centerInside()
                    .into(holder.imageView)
        }


        inner class MediaViewHolder(val imageView: ImageView)
            : RecyclerView.ViewHolder(imageView),
                View.OnClickListener {
            init {
                itemView.setOnClickListener(this)
            }

            // saving some allocations
            override fun onClick(v: View?) {
                viewMedia(items, adapterPosition, imageView)
            }
        }
    }
}