package us.beckmeyer.autobrightnessdelay

import android.app.Service
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.os.IBinder
import android.provider.Settings
import androidx.core.app.NotificationChannelCompat
import androidx.core.app.NotificationCompat
import androidx.core.app.NotificationManagerCompat
import kotlin.time.Duration.Companion.milliseconds
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.Job
import kotlinx.coroutines.SupervisorJob
import kotlinx.coroutines.cancel
import kotlinx.coroutines.delay
import kotlinx.coroutines.launch

class AutoBrightnessDelayService : Service() {
  companion object {
    private const val CHANNEL_ID = "guard_channel"
    private const val NOTIFICATION_ID = 42
    private val SCREEN_ON_DELAY = 500.milliseconds
  }

  private val scope = CoroutineScope(Dispatchers.Main + SupervisorJob())
  private var pendingJob: Job? = null

  private val screenReceiver =
    object : BroadcastReceiver() {
      override fun onReceive(ctx: Context, intent: Intent) {
        pendingJob?.cancel() // cancel any "mid-flight" task
        when (intent.action) {
          Intent.ACTION_SCREEN_OFF -> {
            disableAutoBrightness()
          }
          Intent.ACTION_SCREEN_ON,
          Intent.ACTION_USER_PRESENT -> {
            pendingJob =
              scope.launch {
                delay(SCREEN_ON_DELAY)
                enableAutoBrightness()
                pendingJob = null
              }
          }
        }
      }
    }

  override fun onCreate() {
    super.onCreate()
    createNotificationChannel()
    startForeground(
      NOTIFICATION_ID,
      NotificationCompat.Builder(this, CHANNEL_ID)
        .setContentTitle("AutoBrightnessDelay running")
        .setSmallIcon(R.drawable.brightness_auto)
        .setOngoing(true)
        .build(),
    )
    IntentFilter().apply {
      addAction(Intent.ACTION_SCREEN_OFF)
      addAction(Intent.ACTION_SCREEN_ON)
      addAction(Intent.ACTION_USER_PRESENT)
      registerReceiver(screenReceiver, this, RECEIVER_NOT_EXPORTED)
    }
  }

  override fun onDestroy() {
    pendingJob?.cancel()
    scope.cancel()
    unregisterReceiver(screenReceiver)
    super.onDestroy()
  }

  override fun onBind(intent: Intent?): IBinder? = null

  private fun disableAutoBrightness() {
    if (!Settings.System.canWrite(this)) return
    Settings.System.putInt(
      contentResolver,
      Settings.System.SCREEN_BRIGHTNESS_MODE,
      Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL,
    )
  }

  private fun enableAutoBrightness() {
    if (!Settings.System.canWrite(this)) return
    Settings.System.putInt(
      contentResolver,
      Settings.System.SCREEN_BRIGHTNESS_MODE,
      Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC,
    )
  }

  private fun createNotificationChannel() {
    NotificationManagerCompat.from(this)
      .createNotificationChannel(
        NotificationChannelCompat.Builder(CHANNEL_ID, NotificationManagerCompat.IMPORTANCE_MIN)
          .setName("AutoBrightnessDelay Service")
          .setSound(null, null)
          .build()
      )
  }
}