package com.geeksville.mesh.service

import android.bluetooth.BluetoothAdapter
import android.bluetooth.BluetoothGattCharacteristic
import android.bluetooth.BluetoothManager
import android.content.Context
import android.content.Intent
import androidx.core.app.JobIntentService
import com.geeksville.mesh.android.Logging
import com.geeksville.mesh.MainActivity
import com.geeksville.mesh.R
import com.geeksville.mesh.model.DeviceVersion
import com.geeksville.mesh.util.exceptionReporter
import java.util.*
import java.util.zip.CRC32

/**
 * Some misformatted ESP32s have problems
 */
class DeviceRejectedException : BLEException("Device rejected filesize")

/**
 * Move this somewhere as a generic network byte order function
 */
fun toNetworkByteArray(value: Int, formatType: Int): ByteArray {

    val len = when (formatType) {
        BluetoothGattCharacteristic.FORMAT_UINT8 -> 1
        BluetoothGattCharacteristic.FORMAT_UINT32 -> 4
        else -> TODO()
    }

    val mValue = ByteArray(len)

    when (formatType) {
        /* BluetoothGattCharacteristic.FORMAT_SINT8 -> {
            value = intToSignedBits(value, 8)
            mValue.get(offset) = (value and 0xFF).toByte()
        }
        BluetoothGattCharacteristic.FORMAT_UINT8 -> mValue.get(offset) =
            (value and 0xFF).toByte()
        BluetoothGattCharacteristic.FORMAT_SINT16 -> {
            value = intToSignedBits(value, 16)
            mValue.get(offset++) = (value and 0xFF).toByte()
            mValue.get(offset) = (value shr 8 and 0xFF).toByte()
        }
        BluetoothGattCharacteristic.FORMAT_UINT16 -> {
            mValue.get(offset++) = (value and 0xFF).toByte()
            mValue.get(offset) = (value shr 8 and 0xFF).toByte()
        }
        BluetoothGattCharacteristic.FORMAT_SINT32 -> {
            value = intToSignedBits(value, 32)
            mValue.get(offset++) = (value and 0xFF).toByte()
            mValue.get(offset++) = (value shr 8 and 0xFF).toByte()
            mValue.get(offset++) = (value shr 16 and 0xFF).toByte()
            mValue.get(offset) = (value shr 24 and 0xFF).toByte()
        } */
        BluetoothGattCharacteristic.FORMAT_UINT8 ->
            mValue[0] = (value and 0xFF).toByte()

        BluetoothGattCharacteristic.FORMAT_UINT32 -> {
            mValue[0] = (value and 0xFF).toByte()
            mValue[1] = (value shr 8 and 0xFF).toByte()
            mValue[2] = (value shr 16 and 0xFF).toByte()
            mValue[3] = (value shr 24 and 0xFF).toByte()
        }
        else -> TODO()
    }
    return mValue
}


data class UpdateFilenames(val appLoad: String?, val littlefs: String?)

/**
 * typical flow
 *
 * startScan
 * startUpdate
 *
 * stopScan
 *
 * FIXME - if we don't find a device stop our scan
 * FIXME - broadcast when we found devices, made progress sending blocks or when the update is complete
 * FIXME - make the user decide to start an update on a particular device
 */
class SoftwareUpdateService : JobIntentService(), Logging {


    private val bluetoothAdapter: BluetoothAdapter by lazy(LazyThreadSafetyMode.NONE) {
        val bluetoothManager = getSystemService(Context.BLUETOOTH_SERVICE) as BluetoothManager
        bluetoothManager.adapter!!
    }


    private fun startUpdate(macaddr: String) {
        info("starting update to $macaddr")

        val device = bluetoothAdapter.getRemoteDevice(macaddr)

        val sync =
            SafeBluetooth(
                this@SoftwareUpdateService,
                device
            )

        sync.connect()
        sync.use { _ ->
            // we begin by setting our MTU size as high as it can go
            sync.requestMtu(512)

            sync.discoverServices() // Get our services

            val updateFilename = getUpdateFilename(this, sync)
            if (updateFilename != null) {
                doUpdate(this, sync, updateFilename)
            } else
                warn("Device is already up-to-date no update needed.")
        }
    }


    override fun onHandleWork(intent: Intent) {
        // We have received work to do.  The system or framework is already
// holding a wake lock for us at this point, so we can just go.

        // Report failures but do not crash the app
        exceptionReporter {
            debug("Executing work: $intent")
            when (intent.action) {
                ACTION_START_UPDATE -> {
                    val addr = intent.getStringExtra(EXTRA_MACADDR)
                        ?: throw Exception("EXTRA_MACADDR not specified")
                    startUpdate(addr) // FIXME, pass in as an intent arg instead
                }
                else -> TODO("Unhandled case")
            }
        }
    }

    companion object : Logging {
        /**
         * Unique job ID for this service.  Must be the same for all work.
         */
        private const val JOB_ID = 1000

        fun startUpdateIntent(macAddress: String): Intent {
            val i = Intent(ACTION_START_UPDATE)
            i.putExtra(EXTRA_MACADDR, macAddress)

            return i
        }

        const val ACTION_START_UPDATE = "$prefix.START_UPDATE"

        const val ACTION_UPDATE_PROGRESS = "$prefix.UPDATE_PROGRESS"

        const val EXTRA_MACADDR = "macaddr"

        private const val SCAN_PERIOD: Long = 10000

        private val TAG =
            MainActivity::class.java.simpleName // FIXME - use my logging class instead

        private val SW_UPDATE_UUID = UUID.fromString("cb0b9a0b-a84c-4c0d-bdbb-442e3144ee30")
        private val SW_UPDATE_TOTALSIZE_CHARACTER =
            UUID.fromString("e74dd9c0-a301-4a6f-95a1-f0e1dbea8e1e") // write|read          total image size, 32 bit, write this first, then read read back to see if it was acceptable (0 mean not accepted)
        private val SW_UPDATE_DATA_CHARACTER =
            UUID.fromString("e272ebac-d463-4b98-bc84-5cc1a39ee517") //  write               data, variable sized, recommended 512 bytes, write one for each block of file
        private val SW_UPDATE_CRC32_CHARACTER =
            UUID.fromString("4826129c-c22a-43a3-b066-ce8f0d5bacc6") //  write               crc32, write last - writing this will complete the OTA operation, now you can read result
        private val SW_UPDATE_RESULT_CHARACTER =
            UUID.fromString("5e134862-7411-4424-ac4a-210937432c77") // read|notify         result code, readable but will notify when the OTA operation completes
        private val SW_UPDATE_REGION_CHARACTER =
            UUID.fromString("5e134862-7411-4424-ac4a-210937432c67") // write - used to set the region we are setting (appload vs littlefs)

        private val SW_VERSION_CHARACTER = longBLEUUID("2a28")
        private val MANUFACTURE_CHARACTER = longBLEUUID("2a29")
        private val HW_VERSION_CHARACTER = longBLEUUID("2a27")

        const val ProgressSuccess = -1
        const val ProgressUpdateFailed = -2
        const val ProgressBleException = -3
        const val ProgressNotStarted = -4

        /**
         * % progress through the update
         */
        var progress = ProgressNotStarted

        /**
         * Convenience method for enqueuing work in to this service.
         */
        fun enqueueWork(context: Context, work: Intent) {
            enqueueWork(
                context,
                SoftwareUpdateService::class.java,
                JOB_ID, work
            )
        }


        /**
         * true if we are busy with an update right now
         */
        val isUpdating get() = progress >= 0

        /**
         * Update our progress indication for GUIs
         *
         * @param isAppload if false, we don't report failure indications (because we consider littlefs non critical for now).  But do report to analytics
         */
        fun sendProgress(context: Context, p: Int, isAppload: Boolean) {
            if (!isAppload && p < 0)
                errormsg("Error while writing littlefs $p") // treat errors writing littlefs as non fatal for now (user partition probably missized and most people don't need it)
            else
                if (progress != p) {
                    progress = p

                    val intent = Intent(ACTION_UPDATE_PROGRESS).putExtra(
                        EXTRA_PROGRESS,
                        p
                    )
                    context.sendBroadcast(intent)
                }
        }

        /** Return true if we thing the firmwarte shoulde be updated
         *
         * @param swVer the version of the software running on the target
         */
        fun shouldUpdate(
            context: Context,
            deviceVersion: DeviceVersion
        ): Boolean = try {
            val curVer = DeviceVersion(context.getString(R.string.cur_firmware_version))
            val minVer =
                DeviceVersion("0.7.8") // The oldest device version with a working software update service

            ((curVer > deviceVersion) && (deviceVersion >= minVer))
        } catch (ex: Exception) {
            errormsg("Error finding swupdate info", ex)
            false // If we fail parsing our update info
        }

        /** Return a Pair of appload filename, littlefs filename this device needs to use as an update (or null if no update needed)
         */
        fun getUpdateFilename(
            context: Context,
            mfg: String
        ): UpdateFilenames {
            val curVer = context.getString(R.string.cur_firmware_version)

            // Check to see if the file exists (some builds might not include update files for size reasons)
            val firmwareFiles = context.assets.list("firmware") ?: arrayOf()

            val appLoad = "firmware-$mfg-$curVer.bin"
            val littlefs = "littlefs-$curVer.bin"

            return UpdateFilenames(
                if (firmwareFiles.contains(appLoad))
                    "firmware/$appLoad"
                else
                    null,
                if (firmwareFiles.contains(littlefs))
                    "firmware/$littlefs"
                else
                    null
            )
        }

        /** Return the filename this device needs to use as an update (or null if no update needed)
         * No longer used, because we get update info inband from our radio API
         */
        fun getUpdateFilename(context: Context, sync: SafeBluetooth): UpdateFilenames? {
            val service = sync.gatt!!.services.find { it.uuid == SW_UPDATE_UUID }!!

            //val hwVerDesc = service.getCharacteristic(HW_VERSION_CHARACTER)
            val mfgDesc = service.getCharacteristic(MANUFACTURE_CHARACTER)
            //val swVerDesc = service.getCharacteristic(SW_VERSION_CHARACTER)

            // looks like HELTEC
            val mfg = sync.readCharacteristic(mfgDesc).getStringValue(0)

            return getUpdateFilename(context, mfg)
        }

        /**
         * A public function so that if you have your own SafeBluetooth connection already open
         * you can use it for the software update.
         */
        fun doUpdate(context: Context, sync: SafeBluetooth, assets: UpdateFilenames) {
            // calculate total firmware size (littlefs + appLoad)
            var totalFirmwareSize = 0
            if (assets.appLoad != null && assets.littlefs != null) {
                totalFirmwareSize += context.assets.open(assets.appLoad).available()
                totalFirmwareSize += context.assets.open(assets.littlefs).available()
            }
            // we must attempt littlefs first, because if we update the appload the device will reboot afterwards
            try {
                assets.littlefs?.let { doUpdate(context, sync, it, FLASH_REGION_LITTLEFS, totalFirmwareSize) }
            } catch (_: BLECharacteristicNotFoundException) {
                // If we can't update littlefs (because not supported by target), do not fail
                errormsg("Ignoring failure to update littlefs on old appload")
            } catch (_: DeviceRejectedException) {
                // the spi filesystem of this device is malformatted, fail silently because most users don't need the web server
                errormsg("Device rejected invalid littlefs partition")
            }

            assets.appLoad?.let { doUpdate(context, sync, it, FLASH_REGION_APPLOAD, totalFirmwareSize) }
            sendProgress(context, ProgressSuccess, true)
        }

        // writable region codes in the ESP32 update code
        private val FLASH_REGION_APPLOAD = 0
        private val FLASH_REGION_LITTLEFS = 100

        /**
         * A public function so that if you have your own SafeBluetooth connection already open
         * you can use it for the software update.
         */
        private fun doUpdate(
            context: Context,
            sync: SafeBluetooth,
            assetName: String,
            flashRegion: Int = FLASH_REGION_APPLOAD,
            totalFirmwareSize: Int = 0
        ) {
            val isAppload = flashRegion == FLASH_REGION_APPLOAD

            try {
                val g = sync.gatt!!
                val service = g.services.find { it.uuid == SW_UPDATE_UUID }
                    ?: throw BLEException("Couldn't find update service")

                /**
                 * Get a chracteristic, but in a safe manner because some buggy BLE implementations might return null
                 */
                fun getCharacteristic(uuid: UUID) =
                    service.getCharacteristic(uuid)
                        ?: throw BLECharacteristicNotFoundException(uuid)

                info("Starting firmware update for $assetName, flash region $flashRegion")

                sendProgress(context, 0, isAppload)
                val totalSizeDesc = getCharacteristic(SW_UPDATE_TOTALSIZE_CHARACTER)
                val dataDesc = getCharacteristic(SW_UPDATE_DATA_CHARACTER)
                val crc32Desc = getCharacteristic(SW_UPDATE_CRC32_CHARACTER)
                val updateResultDesc = getCharacteristic(SW_UPDATE_RESULT_CHARACTER)

                /// Try to set the destination region for programming (littlefs vs appload etc)
                /// Old apploads don't have this feature, but we only fail if the user was trying to set a
                /// littlefs - otherwise we assume appload.
                try {
                    val updateRegionDesc = getCharacteristic(SW_UPDATE_REGION_CHARACTER)
                    sync.writeCharacteristic(
                        updateRegionDesc,
                        toNetworkByteArray(flashRegion, BluetoothGattCharacteristic.FORMAT_UINT8)
                    )
                } catch (ex: BLECharacteristicNotFoundException) {
                    errormsg("Can't set flash programming region (old appload?")
                    if (flashRegion != FLASH_REGION_APPLOAD) {
                        throw ex
                    }
                    warn("Ignoring setting appload flashRegion")
                }

                context.assets.open(assetName).use { firmwareStream ->
                    val firmwareCrc = CRC32()
                    var firmwareNumSent = 0
                    val firmwareSize = firmwareStream.available()

                    // Start the update by writing the # of bytes in the image
                    sync.writeCharacteristic(
                        totalSizeDesc,
                        toNetworkByteArray(firmwareSize, BluetoothGattCharacteristic.FORMAT_UINT32)
                    )

                    // Our write completed, queue up a readback
                    val totalSizeReadback = sync.readCharacteristic(totalSizeDesc)
                        .getIntValue(BluetoothGattCharacteristic.FORMAT_UINT32, 0)
                    if (totalSizeReadback == 0)
                        throw DeviceRejectedException()

                    // Send all the blocks
                    var oldProgress = -1 // used to limit # of log spam
                    while (firmwareNumSent < firmwareSize) {
                        // If we are doing the littlefs partition, we limit progress to a max of maxProgress
                        //  when updating the appload partition, progress from (100 - maxProgress) to 100%
                        //  maxProgress = littlefs% = 100% - appLoad%; (int * 10 + 5) / 10 used for rounding
                        val maxProgress = ((firmwareSize * 1000 / totalFirmwareSize) + 5) / 10
                        val minProgress = if (flashRegion != FLASH_REGION_APPLOAD)
                            0 else (100 - maxProgress)
                        sendProgress(
                            context,
                            minProgress + firmwareNumSent * maxProgress / firmwareSize,
                            isAppload
                        )
                        if (progress != oldProgress) {
                            debug("sending block ${progress}%")
                            oldProgress = progress
                        }
                        var blockSize = 512 - 3 // Max size MTU excluding framing

                        if (blockSize > firmwareStream.available())
                            blockSize = firmwareStream.available()
                        val buffer = ByteArray(blockSize)

                        // slightly expensive to keep reallocing this buffer, but whatever
                        logAssert(firmwareStream.read(buffer) == blockSize)
                        firmwareCrc.update(buffer)

                        sync.writeCharacteristic(dataDesc, buffer)
                        firmwareNumSent += blockSize
                    }

                    try {
                        // We have finished sending all our blocks, so post the CRC so our state machine can advance
                        val c = firmwareCrc.value
                        info("Sent all blocks, crc is $c")
                        sync.writeCharacteristic(
                            crc32Desc,
                            toNetworkByteArray(c.toInt(), BluetoothGattCharacteristic.FORMAT_UINT32)
                        )

                        // we just read the update result if !0 we have an error
                        val updateResult =
                            sync.readCharacteristic(updateResultDesc)
                                .getIntValue(BluetoothGattCharacteristic.FORMAT_UINT8, 0)
                        if (updateResult != 0) {
                            sendProgress(context, ProgressUpdateFailed, isAppload)
                            throw Exception("Device update failed, reason=$updateResult")
                        }

                        // Device will now reboot
                    } catch (ex: BLEException) {
                        // We might get SyncContinuation timeout on the final write, assume the device simply rebooted to run the new load and we missed it
                        errormsg("Assuming successful update", ex)
                    }
                }
            } catch (ex: BLEException) {
                sendProgress(context, ProgressBleException, isAppload)
                throw ex // Unexpected BLE exception
            }
        }
    }
}