LibreTube/app/src/main/java/com/github/libretube/util/NotificationHelper.kt

package com.github.libretube.util

import android.app.NotificationManager
import android.app.PendingIntent
import android.content.Context
import android.content.Intent
import androidx.core.app.NotificationCompat
import androidx.core.app.NotificationManagerCompat
import androidx.work.Constraints
import androidx.work.ExistingPeriodicWorkPolicy
import androidx.work.NetworkType
import androidx.work.PeriodicWorkRequest
import androidx.work.WorkManager
import com.github.libretube.NOTIFICATION_WORK_NAME
import com.github.libretube.PUSH_CHANNEL_ID
import com.github.libretube.R
import com.github.libretube.activities.MainActivity
import com.github.libretube.api.RetrofitInstance
import com.github.libretube.api.SubscriptionHelper
import com.github.libretube.preferences.PreferenceHelper
import com.github.libretube.preferences.PreferenceKeys
import kotlinx.coroutines.async
import kotlinx.coroutines.runBlocking
import java.util.concurrent.TimeUnit

class NotificationHelper(
    private val context: Context
) {
    val NotificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager

    // the id where notification channels start
    private var notificationId = NotificationManager.activeNotifications.size + 5

    /**
     * Enqueue the work manager task
     */
    fun enqueueWork(
        existingPeriodicWorkPolicy: ExistingPeriodicWorkPolicy
    ) {
        // get the notification preferences
        PreferenceHelper.initialize(context)
        val notificationsEnabled = PreferenceHelper.getBoolean(
            PreferenceKeys.NOTIFICATION_ENABLED,
            true
        )

        val checkingFrequency = PreferenceHelper.getString(
            PreferenceKeys.CHECKING_FREQUENCY,
            "60"
        ).toLong()

        // schedule the work manager request if logged in and notifications enabled
        if (notificationsEnabled && PreferenceHelper.getToken() != "") {
            // required network type for the work
            val networkType = when (
                PreferenceHelper.getString(PreferenceKeys.REQUIRED_NETWORK, "all")
            ) {
                "all" -> NetworkType.CONNECTED
                "wifi" -> NetworkType.UNMETERED
                "metered" -> NetworkType.METERED
                else -> NetworkType.CONNECTED
            }

            // requirements for the work
            // here: network needed to run the task
            val constraints = Constraints.Builder()
                .setRequiredNetworkType(networkType)
                .build()

            // create the worker
            val notificationWorker = PeriodicWorkRequest.Builder(
                NotificationWorker::class.java,
                checkingFrequency,
                TimeUnit.MINUTES
            )
                .setConstraints(constraints)
                .build()

            // enqueue the task
            WorkManager.getInstance(context)
                .enqueueUniquePeriodicWork(
                    NOTIFICATION_WORK_NAME,
                    existingPeriodicWorkPolicy,
                    notificationWorker
                )
        } else {
            // cancel the work if notifications are disabled or the user is not logged in
            WorkManager.getInstance(context)
                .cancelUniqueWork(NOTIFICATION_WORK_NAME)
        }
    }

    /**
     * check whether new streams are available in subscriptions
     */
    fun checkForNewStreams(): Boolean {
        var success = true

        val token = PreferenceHelper.getToken()
        runBlocking {
            val task = async {
                if (token != "") {
                    RetrofitInstance.authApi.getFeed(token)
                } else {
                    RetrofitInstance.authApi.getUnauthenticatedFeed(
                        SubscriptionHelper.getFormattedLocalSubscriptions()
                    )
                }
            }
            // fetch the users feed
            val videoFeed = try {
                task.await()
            } catch (e: Exception) {
                success = false
                return@runBlocking
            }

            val lastSeenStreamId = PreferenceHelper.getLatestVideoId()
            val latestFeedStreamId = videoFeed[0].url.toID()

            // first time notifications enabled or no new video available
            if (lastSeenStreamId == "" || lastSeenStreamId == latestFeedStreamId) {
                PreferenceHelper.setLatestVideoId(lastSeenStreamId)
                return@runBlocking
            }

            // filter the new videos out
            val lastSeenStreamItem = videoFeed.filter { it.url.toID() == lastSeenStreamId }

            // previous video not found
            if (lastSeenStreamItem.isEmpty()) return@runBlocking

            val lastStreamIndex = videoFeed.indexOf(lastSeenStreamItem[0])
            val newVideos = videoFeed.filterIndexed { index, _ ->
                index < lastStreamIndex
            }

            // group the new streams by the uploader
            val channelGroups = newVideos.groupBy { it.uploaderUrl }
            // create a notification for each new stream
            channelGroups.forEach { (_, streams) ->
                createNotification(
                    group = streams[0].uploaderUrl.toID(),
                    title = streams[0].uploaderName.toString(),
                    isSummary = true
                )

                streams.forEach { streamItem ->
                    notificationId += 1
                    createNotification(
                        title = streamItem.title.toString(),
                        description = streamItem.uploaderName.toString(),
                        group = streamItem.uploaderUrl.toID()
                    )
                }
            }
            // save the latest streams that got notified about
            PreferenceHelper.setLatestVideoId(videoFeed[0].url.toID())
        }
        // return whether the work succeeded
        return success
    }

    /**
     * Notification that is created when new streams are found
     */
    private fun createNotification(
        title: String,
        group: String,
        description: String? = null,
        isSummary: Boolean = false
    ) {
        val intent = Intent(context, MainActivity::class.java).apply {
            flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
        }
        val pendingIntent: PendingIntent = PendingIntent.getActivity(
            context,
            0,
            intent,
            PendingIntent.FLAG_IMMUTABLE
        )

        val builder = NotificationCompat.Builder(context, PUSH_CHANNEL_ID)
            .setContentTitle(title)
            .setGroup(group)
            .setSmallIcon(R.drawable.ic_notification)
            .setPriority(NotificationCompat.PRIORITY_DEFAULT)
            // Set the intent that will fire when the user taps the notification
            .setContentIntent(pendingIntent)
            .setAutoCancel(true)

        if (isSummary) builder.setGroupSummary(true)
        else builder.setContentText(description)

        with(NotificationManagerCompat.from(context)) {
            // notificationId is a unique int for each notification that you must define
            notify(notificationId, builder.build())
        }
    }
}