Tusky-App-Android/app/src/main/java/com/keylesspalace/tusky/fragment/ViewImageFragment.kt

/* 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.animation.Animator
import android.animation.AnimatorListenerAdapter
import android.content.Context
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 com.bumptech.glide.Glide
import com.bumptech.glide.load.DataSource
import com.bumptech.glide.load.engine.GlideException
import com.bumptech.glide.request.RequestListener
import com.bumptech.glide.request.target.Target
import com.github.chrisbanes.photoview.PhotoViewAttacher
import com.keylesspalace.tusky.R
import com.keylesspalace.tusky.entity.Attachment
import com.keylesspalace.tusky.util.hide
import com.keylesspalace.tusky.util.visible
import io.reactivex.subjects.BehaviorSubject
import kotlinx.android.synthetic.main.activity_view_media.*
import kotlinx.android.synthetic.main.fragment_view_image.*
import kotlin.math.abs

class ViewImageFragment : ViewMediaFragment() {
    interface PhotoActionsListener {
        fun onBringUp()
        fun onDismiss()
        fun onPhotoTap()
    }

    private lateinit var attacher: PhotoViewAttacher
    private lateinit var photoActionsListener: PhotoActionsListener
    private lateinit var toolbar: View
    private var transition = BehaviorSubject.create<Unit>()

    override lateinit var descriptionView: TextView
    override fun onAttach(context: Context) {
        super.onAttach(context)
        photoActionsListener = context as PhotoActionsListener
    }

    override fun setupMediaView(url: String, previewUrl: String?) {
        descriptionView = mediaDescription
        photoView.transitionName = url
        attacher = PhotoViewAttacher(photoView).apply {
            // Clicking outside the photo closes the viewer.
            setOnOutsidePhotoTapListener { photoActionsListener.onDismiss() }
            setOnClickListener { onMediaTap() }

            /* A vertical swipe motion also closes the viewer. This is especially useful when the photo
             * mostly fills the screen so clicking outside is difficult. */
            setOnSingleFlingListener { _, _, velocityX, velocityY ->
                var result = false
                if (abs(velocityY) > abs(velocityX)) {
                    photoActionsListener.onDismiss()
                    result = true
                }
                result
            }
        }

        loadImageFromNetwork(url, previewUrl, photoView)
    }

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
        toolbar = activity!!.toolbar
        return inflater.inflate(R.layout.fragment_view_image, container, false)
    }

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

        val arguments = this.arguments!!
        val attachment = arguments.getParcelable<Attachment>(ARG_ATTACHMENT)
        val url: String?
        var description: String? = null

        if (attachment != null) {
            url = attachment.url
            description = attachment.description
        } else {
            url = arguments.getString(ARG_AVATAR_URL)
            if (url == null) {
                throw IllegalArgumentException("attachment or avatar url has to be set")
            }
        }

        finalizeViewSetup(url, attachment?.previewUrl, description)
    }

    private fun onMediaTap() {
        photoActionsListener.onPhotoTap()
    }

    override fun onToolbarVisibilityChange(visible: Boolean) {
        if (photoView == null || !userVisibleHint) {
            return
        }
        isDescriptionVisible = showingDescription && visible
        val alpha = if (isDescriptionVisible) 1.0f else 0.0f
        descriptionView.animate().alpha(alpha)
                .setListener(object : AnimatorListenerAdapter() {
                    override fun onAnimationEnd(animation: Animator) {
                        descriptionView.visible(isDescriptionVisible)
                        animation.removeListener(this)
                    }
                })
                .start()
    }

    override fun onDestroyView() {
        Glide.with(this).clear(photoView)
        super.onDestroyView()
    }

    private fun loadImageFromNetwork(url: String, previewUrl: String?, photoView: ImageView) {
        val glide = Glide.with(this)
        // Request image from the any cache
        glide
                .load(url)
                .dontAnimate()
                .onlyRetrieveFromCache(true)
                .let {
                    if (previewUrl != null)
                        it.thumbnail(glide
                                .load(previewUrl)
                                .dontAnimate()
                                .onlyRetrieveFromCache(true)
                                .centerInside()
                                .addListener(ImageRequestListener(true, isThumnailRequest = true)))
                    else it
                }
                //Request image from the network on fail load image from cache
                .error(glide.load(url)
                        .centerInside()
                        .addListener(ImageRequestListener(false, isThumnailRequest = false))
                )
                .centerInside()
                .addListener(ImageRequestListener(true, isThumnailRequest = false))
                .into(photoView)
    }

    /**
     * @param isCacheRequest - is this listener for request image from cache or from the network
     */
    private inner class ImageRequestListener(
            private val isCacheRequest: Boolean,
            private val isThumnailRequest: Boolean) : RequestListener<Drawable> {

        override fun onLoadFailed(e: GlideException?, model: Any, target: Target<Drawable>,
                                  isFirstResource: Boolean): Boolean {
            // If cache for full image failed, complete transition
            if (isCacheRequest && !isThumnailRequest) photoActionsListener.onBringUp()
            // Hide progress bar only on fail request from internet
            if (!isCacheRequest) progressBar?.hide()
            return false
        }

        override fun onResourceReady(resource: Drawable, model: Any, target: Target<Drawable>,
                                     dataSource: DataSource, isFirstResource: Boolean): Boolean {
            progressBar?.hide() // Always hide the progress bar on success
                if (isThumnailRequest) {
                    photoView.post {
                        target.onResourceReady(resource, null)
                        photoActionsListener.onBringUp()
                    }
                } else {
                    transition
                            .take(1)
                            .subscribe {
                                target.onResourceReady(resource, null)
                                photoActionsListener.onBringUp()
                            }
                }
                return true
        }

    }

    override fun onTransitionEnd() {
        this.transition.onNext(Unit)
    }
}