/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

package org.amnezia.vpn.qt;

import android.Manifest
import android.content.ComponentName
import android.content.ContentResolver
import android.content.Context
import android.content.Intent
import android.content.ServiceConnection
import android.content.pm.PackageManager
import android.net.Uri
import android.os.*
import android.provider.MediaStore
import android.util.Log
import android.view.KeyEvent
import android.widget.Toast
import androidx.core.app.ActivityCompat
import androidx.core.content.ContextCompat
import org.amnezia.vpn.VPNService
import org.amnezia.vpn.VPNServiceBinder
import org.amnezia.vpn.IMPORT_COMMAND_CODE
import org.amnezia.vpn.IMPORT_ACTION_CODE
import org.amnezia.vpn.IMPORT_CONFIG_KEY
import org.qtproject.qt.android.bindings.QtActivity
import java.io.*

class VPNActivity : org.qtproject.qt.android.bindings.QtActivity() {

    private var configString: String? = null
    private var vpnServiceBinder: IBinder? = null
    private var isBound = false

    private val TAG = "VPNActivity"
    private val STORAGE_PERMISSION_CODE = 42

    private val CAMERA_ACTION_CODE = 101

    companion object {
        private lateinit var instance: VPNActivity

        @JvmStatic fun getInstance(): VPNActivity {
            return instance
        }

        @JvmStatic fun connectService() {
            VPNActivity.getInstance().initServiceConnection()
        }

        @JvmStatic fun startQrCodeReader() {
            VPNActivity.getInstance().startQrCodeActivity()
        }

        @JvmStatic fun sendToService(actionCode: Int, body: String) {
            VPNActivity.getInstance().dispatchParcel(actionCode, body)
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        val newIntent = intent
        val newIntentAction = newIntent.action

        if (newIntent != null && newIntentAction != null) {
            configString = processIntent(newIntent, newIntentAction)
        }

        super.onCreate(savedInstanceState)

        instance = this
    }

    private fun startQrCodeActivity() {
        val intent = Intent(this, CameraActivity::class.java)
        startActivityForResult(intent, CAMERA_ACTION_CODE)
    }

    override fun getSystemService(name: String): Any? {
        return if (Build.VERSION.SDK_INT >= 29 && name == "clipboard") {
            // QT will always attempt to read the clipboard if content is there.
            // since we have no use of the clipboard in android 10+
            // we _can_  return null
            // And we defnitly should since android 12 displays clipboard access.
            null
        } else {
            super.getSystemService(name)
        }
    }

    external fun handleBackButton(): Boolean

    external fun onServiceMessage(actionCode: Int, body: String?)
    external fun qtOnServiceConnected()
    external fun qtOnServiceDisconnected()
    external fun onActivityMessage(actionCode: Int, body: String?)

    private fun dispatchParcel(actionCode: Int, body: String) {
        if (!isBound) {
            Log.d(TAG, "dispatchParcel: not bound")
            return
        } else {
            Log.d(TAG, "dispatchParcel: bound")
        }

        val out: Parcel = Parcel.obtain()
        out.writeByteArray(body.toByteArray())

        try {
            vpnServiceBinder?.transact(actionCode, out, Parcel.obtain(), 0)
        } catch (e: DeadObjectException) {
            isBound = false
            vpnServiceBinder = null
            qtOnServiceDisconnected()
        } catch (e: RemoteException) {
            e.printStackTrace()
        }
    }

    override fun onNewIntent(newIntent: Intent) {
        intent = newIntent

        val newIntentAction = newIntent.action

        if (newIntent != null && newIntentAction != null && newIntentAction != Intent.ACTION_MAIN) {
            if (isReadStorageAllowed()) {
                configString = processIntent(newIntent, newIntentAction)
            } else {
                requestStoragePermission()
            }
        }

        super.onNewIntent(intent)
    }

    override fun onResume() {
        super.onResume()

        if (configString != null && isBound) {
            sendImportConfigCommand()
        }
    }

    private fun isReadStorageAllowed(): Boolean {
        val permissionStatus = ContextCompat.checkSelfPermission(this, Manifest.permission.READ_EXTERNAL_STORAGE)
        return permissionStatus == PackageManager.PERMISSION_GRANTED
    }

    private fun requestStoragePermission() {
        ActivityCompat.requestPermissions(this, arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE), STORAGE_PERMISSION_CODE)
    }

    override fun onRequestPermissionsResult(requestCode: Int, permissions: Array<String?>, grantResults: IntArray) {
        if (requestCode == STORAGE_PERMISSION_CODE) {
            if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                Log.d(TAG, "Storage read permission granted")

                if (configString == null) {
                    configString = processIntent(intent, intent.action!!)
                }

                if (configString != null) {
                    Log.d(TAG, "not empty")
                    sendImportConfigCommand()
                } else {
                    Log.d(TAG, "empty")
                }
            } else {
                Toast.makeText(this, "Oops you just denied the permission", Toast.LENGTH_LONG).show()
            }
        }
    }

    private fun processIntent(intent: Intent, action: String): String? {
        val scheme = intent.scheme

        if (scheme == null) {
            return null
        }

        if (action.compareTo(Intent.ACTION_VIEW) == 0) {
            val resolver = contentResolver

            if (scheme.compareTo(ContentResolver.SCHEME_CONTENT) == 0) {
                val uri = intent.data
                val name: String? = getContentName(resolver, uri)

                Log.d(TAG, "Content intent detected: " + action + " : " + intent.dataString + " : " + intent.type + " : " + name)

                val input = resolver.openInputStream(uri!!)

                return input?.bufferedReader()?.use(BufferedReader::readText)
            } else if (scheme.compareTo(ContentResolver.SCHEME_FILE) == 0) {
                val uri = intent.data
                val name = uri!!.lastPathSegment

                Log.d(TAG, "File intent detected: " + action + " : " + intent.dataString + " : " + intent.type + " : " + name)

                val input = resolver.openInputStream(uri)

                return input?.bufferedReader()?.use(BufferedReader::readText)
            }
        }

        return null
    }

    private fun getContentName(resolver: ContentResolver?, uri: Uri?): String? {
        val cursor = resolver!!.query(uri!!, null, null, null, null)

        cursor.use {
            cursor!!.moveToFirst()
            val nameIndex = cursor.getColumnIndex(MediaStore.MediaColumns.DISPLAY_NAME)
            return if (nameIndex >= 0) {
                return cursor.getString(nameIndex)
            } else {
                null
            }
        }
    }

    private fun sendImportConfigCommand() {
        if (configString != null) {
            val msg: Parcel = Parcel.obtain()
            msg.writeString(configString!!)

            try {
                vpnServiceBinder?.transact(ACTION_IMPORT_CONFIG, msg, Parcel.obtain(), 0)
            } catch (e: RemoteException) {
                e.printStackTrace()
            }

            configString = null
        }
    }

    private var connection: ServiceConnection = object : ServiceConnection {
        override fun onServiceConnected(className: ComponentName, binder: IBinder) {
            vpnServiceBinder = binder

            // This is called when the connection with the service has been
            // established, giving us the object we can use to
            // interact with the service.  We are communicating with the
            // service using a Messenger, so here we get a client-side
            // representation of that from the raw IBinder object.
            if (registerBinder()){
                qtOnServiceConnected();
            } else {
                qtOnServiceDisconnected();
                return
            }

            isBound = true
        }

        override fun onServiceDisconnected(className: ComponentName) {
            vpnServiceBinder = null
            isBound = false
            qtOnServiceDisconnected();
        }
    }

    private fun registerBinder(): Boolean {
        val binder = VPNClientBinder()
        val out: Parcel = Parcel.obtain()
        out.writeStrongBinder(binder)

        try {
            // Register our IBinder Listener
            vpnServiceBinder?.transact(ACTION_REGISTER_LISTENER, out, Parcel.obtain(), 0)
            return true
        } catch (e: DeadObjectException) {
            isBound = false
            vpnServiceBinder = null
        } catch (e: RemoteException) {
            e.printStackTrace()
        }
        return false
    }

    private fun initServiceConnection() {
        // We already have a connection to the service,
        // just need to re-register the binder
        if (isBound && vpnServiceBinder!!.isBinderAlive() && registerBinder()) {
            qtOnServiceConnected()
            return
        }

        bindService(Intent(this, VPNService::class.java), connection, Context.BIND_AUTO_CREATE)
    }

    // TODO: Move all ipc codes into a shared lib.
    // this is getting out of hand.
    private val PERMISSION_TRANSACTION = 1337
    private val ACTION_REGISTER_LISTENER = 3
    private val ACTION_RESUME_ACTIVATE = 7
    private val ACTION_IMPORT_CONFIG = 11
    private val EVENT_PERMISSION_REQURED = 6
    private val EVENT_DISCONNECTED = 2

    private val UI_EVENT_QR_CODE_RECEIVED = 0

    fun onPermissionRequest(code: Int, data: Parcel?) {
        if (code != EVENT_PERMISSION_REQURED) {
            return
        }

        val x = Intent()
        x.readFromParcel(data)

        startActivityForResult(x, PERMISSION_TRANSACTION)
    }

    override protected fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        if (requestCode == PERMISSION_TRANSACTION) {
            // THATS US!
            if (resultCode == RESULT_OK) {
                // Prompt accepted, tell service to retry.
                dispatchParcel(ACTION_RESUME_ACTIVATE, "")
            } else {
                // Tell the Client we've disconnected
                onServiceMessage(EVENT_DISCONNECTED, "")
            }
            return
        }

        super.onActivityResult(requestCode, resultCode, data)

        if (requestCode == CAMERA_ACTION_CODE && resultCode == RESULT_OK) {
            val extra = data?.getStringExtra("result") ?: ""
            onActivityMessage(UI_EVENT_QR_CODE_RECEIVED, extra)
        }
    }

    override fun onKeyDown(keyCode: Int, event: KeyEvent): Boolean {
        if (keyCode == KeyEvent.KEYCODE_BACK && event.repeatCount == 0) {
            onBackPressed()
            return true
        }
        return super.onKeyDown(keyCode, event)
    }
}