vpnhotspotmod/mobile/src/main/java/be/mygod/vpnhotspot/manage/BluetoothTethering.kt

package be.mygod.vpnhotspot.manage

import android.annotation.SuppressLint
import android.annotation.TargetApi
import android.bluetooth.BluetoothAdapter
import android.bluetooth.BluetoothManager
import android.bluetooth.BluetoothProfile
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.os.Build
import androidx.annotation.RequiresApi
import androidx.core.content.getSystemService
import androidx.core.os.BuildCompat
import be.mygod.vpnhotspot.App.Companion.app
import be.mygod.vpnhotspot.net.TetheringManager
import be.mygod.vpnhotspot.util.broadcastReceiver
import be.mygod.vpnhotspot.util.readableMessage
import be.mygod.vpnhotspot.widget.SmartSnackbar
import timber.log.Timber
import java.lang.reflect.InvocationTargetException

class BluetoothTethering(context: Context, val stateListener: () -> Unit) :
        BluetoothProfile.ServiceListener, AutoCloseable {
    companion object : BroadcastReceiver() {
        /**
         * PAN Profile
         */
        private const val PAN = 5
        private val clazz by lazy { Class.forName("android.bluetooth.BluetoothPan") }
        private val constructor by lazy {
            (if (BuildCompat.isAtLeastS()) {
                clazz.getDeclaredConstructor(Context::class.java, BluetoothProfile.ServiceListener::class.java,
                    BluetoothAdapter::class.java)
            } else {
                clazz.getDeclaredConstructor(Context::class.java, BluetoothProfile.ServiceListener::class.java)
            }).apply {
                isAccessible = true
            }
        }
        private val isTetheringOn by lazy { clazz.getDeclaredMethod("isTetheringOn") }

        private val adapter = app.getSystemService<BluetoothManager>()?.adapter
        fun pan(context: Context, serviceListener: BluetoothProfile.ServiceListener) = (if (BuildCompat.isAtLeastS()) {
            constructor.newInstance(context, serviceListener, adapter)
        } else constructor.newInstance(context, serviceListener)) as BluetoothProfile
        val BluetoothProfile.isTetheringOn get() = isTetheringOn(this) as Boolean
        fun BluetoothProfile.closePan() = adapter!!.closeProfileProxy(PAN, this)

        private fun registerBluetoothStateListener(receiver: BroadcastReceiver) =
                app.registerReceiver(receiver, IntentFilter(BluetoothAdapter.ACTION_STATE_CHANGED))

        private var pendingCallback: TetheringManager.StartTetheringCallback? = null

        /**
         * https://android.googlesource.com/platform/packages/apps/Settings/+/b1af85d/src/com/android/settings/TetherSettings.java#215
         */
        @TargetApi(24)
        override fun onReceive(context: Context?, intent: Intent?) {
            when (intent?.getIntExtra(BluetoothAdapter.EXTRA_STATE, BluetoothAdapter.ERROR)) {
                BluetoothAdapter.STATE_ON -> {
                    TetheringManager.startTethering(TetheringManager.TETHERING_BLUETOOTH, true, pendingCallback!!)
                }
                BluetoothAdapter.STATE_OFF, BluetoothAdapter.ERROR -> { }
                else -> return  // ignore transition states
            }
            pendingCallback = null
            app.unregisterReceiver(this)
        }
    }

    private var connected = false
    private var pan: BluetoothProfile? = null
    private var stoppedByUser = false
    var activeFailureCause: Throwable? = null
    /**
     * Based on: https://android.googlesource.com/platform/packages/apps/Settings/+/78d5efd/src/com/android/settings/TetherSettings.java
     */
    val active: Boolean? get() {
        val pan = pan ?: return null
        if (!connected) return null
        activeFailureCause = null
        val on = adapter?.state == BluetoothAdapter.STATE_ON && try {
            pan.isTetheringOn
        } catch (e: InvocationTargetException) {
            activeFailureCause = e.cause ?: e
            if (e.cause is SecurityException && Build.VERSION.SDK_INT >= 30) Timber.d(e.readableMessage)
            else Timber.w(e)
            return null
        }
        return if (stoppedByUser) {
            if (!on) stoppedByUser = false
            false
        } else on
    }

    private val receiver = broadcastReceiver { _, _ -> stateListener() }

    fun ensureInit(context: Context) {
        activeFailureCause = null
        if (pan == null) try {
            pan = pan(context, this)
        } catch (e: ReflectiveOperationException) {
            if (e.cause is SecurityException && BuildCompat.isAtLeastS()) Timber.d(e.readableMessage)
            else Timber.w(e)
            activeFailureCause = e
        }
    }
    init {
        ensureInit(context)
        registerBluetoothStateListener(receiver)
    }

    override fun onServiceDisconnected(profile: Int) {
        connected = false
        stoppedByUser = false
    }
    override fun onServiceConnected(profile: Int, proxy: BluetoothProfile) {
        connected = true
        stateListener()
    }

    /**
     * https://android.googlesource.com/platform/packages/apps/Settings/+/b1af85d/src/com/android/settings/TetherSettings.java#384
     */
    @SuppressLint("MissingPermission")
    @RequiresApi(24)
    fun start(callback: TetheringManager.StartTetheringCallback) {
        if (pendingCallback == null) try {
            if (adapter?.state == BluetoothAdapter.STATE_OFF) {
                registerBluetoothStateListener(BluetoothTethering)
                pendingCallback = callback
                adapter.enable()
            } else TetheringManager.startTethering(TetheringManager.TETHERING_BLUETOOTH, true, callback)
        } catch (e: SecurityException) {
            SmartSnackbar.make(e.readableMessage).shortToast().show()
            pendingCallback = null
        }
    }
    @RequiresApi(24)
    fun stop(callback: (Exception) -> Unit) {
        TetheringManager.stopTethering(TetheringManager.TETHERING_BLUETOOTH, callback)
        stoppedByUser = true
    }

    override fun close() {
        app.unregisterReceiver(receiver)
        pan?.closePan()
    }
}