AboutActivity: use ViewModel

package at.bitfire.davdroid.ui

import android.content.Context

import android.app.Application

import android.os.Bundle

import android.text.Spanned

import android.view.*

import androidx.fragment.app.Fragment

import androidx.fragment.app.FragmentManager

import androidx.fragment.app.FragmentPagerAdapter

import androidx.loader.app.LoaderManager

import androidx.loader.content.AsyncTaskLoader

import androidx.loader.content.Loader

import androidx.lifecycle.AndroidViewModel

import androidx.lifecycle.MutableLiveData

import androidx.lifecycle.Observer

import androidx.lifecycle.ViewModelProviders

import at.bitfire.davdroid.App

import at.bitfire.davdroid.BuildConfig

import at.bitfire.davdroid.R

import at.bitfire.davdroid.log.Logger

import com.mikepenz.aboutlibraries.LibsBuilder

import kotlinx.android.synthetic.main.about_davdroid.*

import kotlinx.android.synthetic.main.about.*

import kotlinx.android.synthetic.main.activity_about.*

import org.apache.commons.io.IOUtils

import java.text.SimpleDateFormat

import java.util.*

import kotlin.concurrent.thread

class AboutActivity: AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {

        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_about)

        setSupportActionBar(toolbar)

                            .withFields(R.string::class.java.fields)

                            .withLicenseShown(true)

                            .supportFragment()

                    else -> DavdroidFragment()

                    else -> AppFragment()

                }!!

    }

    class DavdroidFragment: Fragment(), LoaderManager.LoaderCallbacks<Spanned> {

    class AppFragment: Fragment() {

        override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?) =

                inflater.inflate(R.layout.about_davdroid, container, false)!!

                inflater.inflate(R.layout.about, container, false)!!

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

            app_name.text = getString(R.string.app_name)

            if (true /* open-source version */) {

                warranty.setText(R.string.about_license_info_no_warranty)

                LoaderManager.getInstance(this).initLoader(0, null, this)

            }

        }

        override fun onCreateLoader(id: Int, args: Bundle?) =

                HtmlAssetLoader(requireActivity(), "gplv3.html")

        override fun onLoadFinished(loader: Loader<Spanned>, license: Spanned?) {

            Logger.log.info("LOAD FINISHED")

            license_text.text = license

                val model = ViewModelProviders.of(this).get(LicenseModel::class.java)

                model.htmlText.observe(this, Observer { spanned ->

                    license_text.text = spanned

                })

            }

        override fun onLoaderReset(loader: Loader<Spanned>) {

        }

    }

    class HtmlAssetLoader(

            context: Context,

            val fileName: String

    ): AsyncTaskLoader<Spanned>(context) {

    class LicenseModel(

            application: Application

    ): AndroidViewModel(application) {

        override fun onStartLoading() {

            forceLoad()

        }

        val htmlText = MutableLiveData<Spanned>()

        override fun loadInBackground(): Spanned =

                context.resources.assets.open(fileName).use {

                    HtmlCompat.fromHtml(IOUtils.toString(it, Charsets.UTF_8), HtmlCompat.FROM_HTML_MODE_LEGACY)

        init {

            thread {

                getApplication<Application>().resources.assets.open("gplv3.html").use {

                    val spanned = HtmlCompat.fromHtml(IOUtils.toString(it, Charsets.UTF_8), HtmlCompat.FROM_HTML_MODE_LEGACY)

                    htmlText.postValue(spanned)

                }

            }

        }

    }