/*
 *  Copyright 2017 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the
 * License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package com.example.playgamesshadows

import android.app.LoaderManager
import android.content.AsyncTaskLoader
import android.content.Context
import android.content.Intent
import android.content.Loader
import android.graphics.drawable.Drawable
import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.support.v7.widget.LinearSnapHelper
import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        carousel.setHasFixedSize(true)
        LinearSnapHelper().attachToRecyclerView(carousel)
        carousel.addOnScrollListener(object : RecyclerView.OnScrollListener() {
            override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
                val center = recyclerView.width / 2
                (0 until recyclerView.childCount).forEach { i ->
                    val child = recyclerView.getChildAt(i) as? IconView ?: return@forEach
                    val cx = (child.left + child.right) / 2
                    val offsetPx = Math.abs(center - cx)
                    child.offset = offsetPx / center.toFloat()
                }
            }
        })

        loaderManager.initLoader(0, Bundle.EMPTY,
                object : LoaderManager.LoaderCallbacks<List<Drawable>> {
            override fun onCreateLoader(id: Int, args: Bundle?) = AppIconLoader(applicationContext)

            override fun onLoadFinished(loader: Loader<List<Drawable>>, icons: List<Drawable>) {
                loading.visibility = View.GONE
                carousel.adapter = AppAdapter(icons)
            }

            override fun onLoaderReset(loader: Loader<List<Drawable>>?) {}
        })
    }

    private class AppIconLoader(context: Context) : AsyncTaskLoader<List<Drawable>>(context) {

        private val icons = mutableListOf<Drawable>()

        override fun onStartLoading() {
            if (icons.isNotEmpty()) {
                deliverResult(icons)
            } else {
                forceLoad()
            }
        }

        override fun loadInBackground(): List<Drawable>? {
            val pm = context.packageManager
            val launchableAppIcons = mutableListOf<Drawable>()
            val launcherIntent = Intent().apply { addCategory(Intent.CATEGORY_LAUNCHER) }
            pm.getInstalledApplications(0).forEach { appInfo ->
                launcherIntent.`package` = appInfo.packageName
                // only show launch-able apps
                if (pm.queryIntentActivities(launcherIntent, 0).isNotEmpty()) {
                    launchableAppIcons += appInfo.loadUnbadgedIcon(pm)
                }
            }
            return launchableAppIcons
        }

        override fun deliverResult(data: List<Drawable>) {
            icons += data
            super.deliverResult(data)
        }
    }

    class AppAdapter(private val icons: List<Drawable>) : RecyclerView.Adapter<AppViewHolder>() {
        override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): AppViewHolder {
            return AppViewHolder(LayoutInflater.from(parent.context)
                    .inflate(R.layout.app_item, parent, false) as IconView)
        }

        override fun onBindViewHolder(holder: AppViewHolder, position: Int) {
            holder.iconView.icon = icons[position]
        }

        override fun getItemCount() = icons.size
    }

    class AppViewHolder(val iconView: IconView) : RecyclerView.ViewHolder(iconView)
}