class Utils {

    /**
     * Waits for the provided milliseconds, and then resolves.
     * @param millis
     * @returns {Promise<void>}
     */
    static async sleepMillis(millis) {
        await new Promise((resolve) => {
            setTimeout(resolve, millis);
        });
    }

    static bytesToHex(bytes) {
        for(var hex = [], i = 0; i < bytes.length; i++){
            var current = bytes[i] < 0 ? bytes[i] + 256 : bytes[i];
            hex.push((current >>> 4).toString(16));
            hex.push((current & 0xF).toString(16));
        }
        return hex.join("");
    }

    static md5(data) {
        var bytes = [];
        const hash = CryptoJS.MD5(CryptoJS.enc.Hex.parse(this.bytesToHex(data)));
        for(var i = 0; i < hash.sigBytes; i++){
            bytes.push((hash.words[i >>> 2] >>> (24 - (i % 4) * 8)) & 0xff);
        }
        return bytes;
    }

    static packUInt32BE(value) {
        const buffer = new ArrayBuffer(4);
        const view = new DataView(buffer);
        view.setUint32(0, value, false);
        return new Uint8Array(buffer);
    }

    static unpackUInt32BE(byteArray) {
        const buffer = new Uint8Array(byteArray).buffer;
        const view = new DataView(buffer);
        return view.getUint32(0, false);
    }

}

class RNode {

    KISS_FEND = 0xC0;
    KISS_FESC = 0xDB;
    KISS_TFEND = 0xDC;
    KISS_TFESC = 0xDD;

    CMD_FREQUENCY = 0x01;
    CMD_BANDWIDTH = 0x02;
    CMD_TXPOWER = 0x03;
    CMD_SF = 0x04;
    CMD_CR = 0x05;
    CMD_RADIO_STATE = 0x06;

    CMD_STAT_RX = 0x21;
    CMD_STAT_TX = 0x22
    CMD_STAT_RSSI = 0x23;
    CMD_STAT_SNR = 0x24;

    CMD_BOARD = 0x47;
    CMD_PLATFORM = 0x48;
    CMD_MCU = 0x49;
    CMD_RESET = 0x55;
    CMD_RESET_BYTE = 0xF8;
    CMD_DEV_HASH = 0x56;
    CMD_FW_VERSION = 0x50;
    CMD_ROM_READ = 0x51;
    CMD_ROM_WRITE = 0x52;
    CMD_CONF_SAVE = 0x53;
    CMD_CONF_DELETE = 0x54;
    CMD_FW_HASH = 0x58;
    CMD_UNLOCK_ROM = 0x59;
    ROM_UNLOCK_BYTE = 0xF8;
    CMD_HASHES = 0x60;
    CMD_FW_UPD = 0x61;

    CMD_BT_CTRL = 0x46;
    CMD_BT_PIN = 0x62;

    CMD_DISP_READ = 0x66;

    CMD_DETECT = 0x08;
    DETECT_REQ = 0x73;
    DETECT_RESP = 0x46;

    RADIO_STATE_OFF = 0x00;
    RADIO_STATE_ON = 0x01;
    RADIO_STATE_ASK = 0xFF;

    CMD_ERROR = 0x90
    ERROR_INITRADIO = 0x01
    ERROR_TXFAILED = 0x02
    ERROR_EEPROM_LOCKED = 0x03

    PLATFORM_AVR = 0x90;
    PLATFORM_ESP32 = 0x80;
    PLATFORM_NRF52 = 0x70;

    MCU_1284P = 0x91;
    MCU_2560 = 0x92;
    MCU_ESP32 = 0x81;
    MCU_NRF52 = 0x71;

    BOARD_RNODE = 0x31;
    BOARD_HMBRW = 0x32;
    BOARD_TBEAM = 0x33;
    BOARD_HUZZAH32 = 0x34;
    BOARD_GENERIC_ESP32 = 0x35;
    BOARD_LORA32_V2_0 = 0x36;
    BOARD_LORA32_V2_1 = 0x37;
    BOARD_RAK4631 = 0x51;

    HASH_TYPE_TARGET_FIRMWARE = 0x01;
    HASH_TYPE_FIRMWARE = 0x02;

    constructor(serialPort) {
        this.serialPort = serialPort;
        this.readable = serialPort.readable;
        this.writable = serialPort.writable;
    }

    static async fromSerialPort(serialPort) {

        // open port
        await serialPort.open({
            baudRate: 115200,
        });

        return new RNode(serialPort);

    }

    async close() {
        try {
            await this.serialPort.close();
        } catch(e) {
            console.log("failed to close serial port, ignoring...", e);
        }
    }

    async write(bytes) {
        const writer = this.writable.getWriter();
        try {
            await writer.write(new Uint8Array(bytes));
        } finally {
            writer.releaseLock();
        }
    }

    async readFromSerialPort(timeoutMillis) {
        return new Promise(async (resolve, reject) => {

            // create reader
            const reader = this.readable.getReader();

            // timeout after provided millis
            if(timeoutMillis != null){
                setTimeout(() => {
                    reader.releaseLock();
                    reject("timeout");
                }, timeoutMillis);
            }

            // attempt to read kiss frame
            try {
                let buffer = [];
                while(true){
                    const { value, done } = await reader.read();
                    if(done){
                        break;
                    }
                    if(value){
                        for(let byte of value){
                            buffer.push(byte);
                            if(byte === this.KISS_FEND){
                                if(buffer.length > 1){
                                    resolve(this.handleKISSFrame(buffer));
                                    return;
                                }
                                buffer = [this.KISS_FEND]; // Start new frame
                            }
                        }
                    }
                }
            } catch (error) {
                console.error('Error reading from serial port: ', error);
            } finally {
                reader.releaseLock();
            }

        });
    }

    handleKISSFrame(frame) {

        let data = [];
        let escaping = false;

        // Skip the initial 0xC0 and process the rest
        for(let i = 1; i < frame.length; i++){
            let byte = frame[i];
            if (escaping) {
                if (byte === this.KISS_TFEND) {
                    data.push(this.KISS_FEND);
                } else if (byte === this.KISS_TFESC) {
                    data.push(this.KISS_FESC);
                }
                escaping = false;
            } else {
                if (byte === this.KISS_FESC) {
                    escaping = true;
                } else if (byte === this.KISS_FEND) {
                    // Ignore the end frame delimiter
                    break;
                } else {
                    data.push(byte);
                }
            }
        }

        //console.log('Received KISS frame data:', new Uint8Array(data));
        return data;

    }

    createKissFrame(data) {
        let frame = [this.KISS_FEND];
        for(let byte of data){
            if(byte === this.KISS_FEND){
                frame.push(this.KISS_FESC, this.KISS_TFEND);
            } else if(byte === this.KISS_FESC){
                frame.push(this.KISS_FESC, this.KISS_TFESC);
            } else {
                frame.push(byte);
            }
        }
        frame.push(this.KISS_FEND);
        return new Uint8Array(frame);
    }

    async sendKissCommand(data) {
        await this.write(this.createKissFrame(data));
    }

    async reset() {
        await this.sendKissCommand([
            this.CMD_RESET,
            this.CMD_RESET_BYTE,
        ]);
    }

    async detect() {

        // ask if device is rnode
        await this.sendKissCommand([
            this.CMD_DETECT,
            this.DETECT_REQ,
        ]);

        // read response from device
        const [ command, responseByte ] = await this.readFromSerialPort();

        // device is an rnode if response is as expected
        return command === this.CMD_DETECT && responseByte === this.DETECT_RESP;

    }

    async getFirmwareVersion() {

        await this.sendKissCommand([
            this.CMD_FW_VERSION,
            0x00,
        ]);

        // read response from device
        var [ command, majorVersion, minorVersion ] = await this.readFromSerialPort();
        if(minorVersion.length === 1){
            minorVersion = "0" + minorVersion;
        }

        // 1.23
        return majorVersion + "." + minorVersion;

    }

    async getPlatform() {

        await this.sendKissCommand([
            this.CMD_PLATFORM,
            0x00,
        ]);

        // read response from device
        const [ command, platformByte ] = await this.readFromSerialPort();
        return platformByte;

    }

    async getMcu() {

        await this.sendKissCommand([
            this.CMD_MCU,
            0x00,
        ]);

        // read response from device
        const [ command, mcuByte ] = await this.readFromSerialPort();
        return mcuByte;

    }

    async getBoard() {

        await this.sendKissCommand([
            this.CMD_BOARD,
            0x00,
        ]);

        // read response from device
        const [ command, boardByte ] = await this.readFromSerialPort();
        return boardByte;

    }

    async getDeviceHash() {

        await this.sendKissCommand([
            this.CMD_DEV_HASH,
            0x01, // anything != 0x00
        ]);

        // read response from device
        const [ command, ...deviceHash ] = await this.readFromSerialPort();
        return deviceHash;

    }

    async getTargetFirmwareHash() {

        await this.sendKissCommand([
            this.CMD_HASHES,
            this.HASH_TYPE_TARGET_FIRMWARE,
        ]);

        // read response from device
        const [ command, hashType, ...targetFirmwareHash ] = await this.readFromSerialPort();
        return targetFirmwareHash;

    }

    async getFirmwareHash() {

        await this.sendKissCommand([
            this.CMD_HASHES,
            this.HASH_TYPE_FIRMWARE,
        ]);

        // read response from device
        const [ command, hashType, ...firmwareHash ] = await this.readFromSerialPort();
        return firmwareHash;

    }

    async getRom() {

        await this.sendKissCommand([
            this.CMD_ROM_READ,
            0x00,
        ]);

        // read response from device
        const [ command, ...eepromBytes ] = await this.readFromSerialPort();
        return eepromBytes;

    }

    async getFrequency() {

        await this.sendKissCommand([
            this.CMD_FREQUENCY,
            // request frequency by sending zero as 4 bytes
            0x00,
            0x00,
            0x00,
            0x00,
        ]);

        // read response from device
        const [ command, ...frequencyBytes ] = await this.readFromSerialPort();

        // convert 4 bytes to 32bit integer representing frequency in hertz
        const frequencyInHz = frequencyBytes[0] << 24 | frequencyBytes[1] << 16 | frequencyBytes[2] << 8 | frequencyBytes[3];
        return frequencyInHz;

    }

    async getBandwidth() {

        await this.sendKissCommand([
            this.CMD_BANDWIDTH,
            // request bandwidth by sending zero as 4 bytes
            0x00,
            0x00,
            0x00,
            0x00,
        ]);

        // read response from device
        const [ command, ...bandwidthBytes ] = await this.readFromSerialPort();

        // convert 4 bytes to 32bit integer representing bandwidth in hertz
        const bandwidthInHz = bandwidthBytes[0] << 24 | bandwidthBytes[1] << 16 | bandwidthBytes[2] << 8 | bandwidthBytes[3];
        return bandwidthInHz;

    }

    async getTxPower() {

        await this.sendKissCommand([
            this.CMD_TXPOWER,
            0xFF, // request tx power
        ]);

        // read response from device
        const [ command, txPower ] = await this.readFromSerialPort();

        return txPower;

    }

    async getSpreadingFactor() {

        await this.sendKissCommand([
            this.CMD_SF,
            0xFF, // request spreading factor
        ]);

        // read response from device
        const [ command, spreadingFactor ] = await this.readFromSerialPort();

        return spreadingFactor;

    }

    async getCodingRate() {

        await this.sendKissCommand([
            this.CMD_CR,
            0xFF, // request coding rate
        ]);

        // read response from device
        const [ command, codingRate ] = await this.readFromSerialPort();

        return codingRate;

    }

    async getRadioState() {

        await this.sendKissCommand([
            this.CMD_RADIO_STATE,
            0xFF, // request radio state
        ]);

        // read response from device
        const [ command, radioState ] = await this.readFromSerialPort();

        return radioState;

    }

    async getRxStat() {

        await this.sendKissCommand([
            this.CMD_STAT_RX,
            0x00,
        ]);

        // read response from device
        const [ command, ...statBytes ] = await this.readFromSerialPort();

        // convert 4 bytes to 32bit integer
        const stat = statBytes[0] << 24 | statBytes[1] << 16 | statBytes[2] << 8 | statBytes[3];
        return stat;

    }

    async getTxStat() {

        await this.sendKissCommand([
            this.CMD_STAT_TX,
            0x00,
        ]);

        // read response from device
        const [ command, ...statBytes ] = await this.readFromSerialPort();

        // convert 4 bytes to 32bit integer
        const stat = statBytes[0] << 24 | statBytes[1] << 16 | statBytes[2] << 8 | statBytes[3];
        return stat;

    }

    async getRssiStat() {

        await this.sendKissCommand([
            this.CMD_STAT_RSSI,
            0x00,
        ]);

        // read response from device
        const [ command, rssi ] = await this.readFromSerialPort();

        return rssi;

    }

    async disableBluetooth() {
        await this.sendKissCommand([
            this.CMD_BT_CTRL,
            0x00, // stop
        ]);
    }

    async enableBluetooth() {
        await this.sendKissCommand([
            this.CMD_BT_CTRL,
            0x01, // start
        ]);
    }

    async startBluetoothPairing() {

        // enable pairing
        await this.sendKissCommand([
            this.CMD_BT_CTRL,
            0x02, // enable pairing
        ]);

        // attempt to get bluetooth pairing pin
        try {

            // read response from device
            const [ command, ...pinBytes ] = await this.readFromSerialPort(5000);
            if(command !== this.CMD_BT_PIN){
                throw `unexpected command response: ${command}`;
            }

            // convert 4 bytes to 32bit integer
            const pin = pinBytes[0] << 24 | pinBytes[1] << 16 | pinBytes[2] << 8 | pinBytes[3];

            // todo: remove logs
            console.log(pinBytes);
            console.log(pin);

            // todo: convert to string
            return pin;

        } catch(error) {
            throw `failed to get bluetooth pin: ${error}`;
        }

    }

    async readDisplay() {

        await this.sendKissCommand([
            this.CMD_DISP_READ,
            0x01,
        ]);

        // read response from device
        const [ command, ...displayBuffer ] = await this.readFromSerialPort();

        return displayBuffer;

    }

    async setFrequency(frequencyInHz) {

        const c1 = frequencyInHz >> 24;
        const c2 = frequencyInHz >> 16 & 0xFF;
        const c3 = frequencyInHz >> 8 & 0xFF;
        const c4 = frequencyInHz & 0xFF;

        await this.sendKissCommand([
            this.CMD_FREQUENCY,
            c1,
            c2,
            c3,
            c4,
        ]);

    }

    async setBandwidth(bandwidthInHz) {

        const c1 = bandwidthInHz >> 24;
        const c2 = bandwidthInHz >> 16 & 0xFF;
        const c3 = bandwidthInHz >> 8 & 0xFF;
        const c4 = bandwidthInHz & 0xFF;

        await this.sendKissCommand([
            this.CMD_BANDWIDTH,
            c1,
            c2,
            c3,
            c4,
        ]);

    }

    async setTxPower(db) {
        await this.sendKissCommand([
            this.CMD_TXPOWER,
            db,
        ]);
    }

    async setSpreadingFactor(spreadingFactor) {
        await this.sendKissCommand([
            this.CMD_SF,
            spreadingFactor,
        ]);
    }

    async setCodingRate(codingRate) {
        await this.sendKissCommand([
            this.CMD_CR,
            codingRate,
        ]);
    }

    async setRadioStateOn() {
        await this.sendKissCommand([
            this.CMD_RADIO_STATE,
            this.RADIO_STATE_ON,
        ]);
    }

    async setRadioStateOff() {
        await this.sendKissCommand([
            this.CMD_RADIO_STATE,
            this.RADIO_STATE_OFF,
        ]);
    }

    // setTNCMode
    async saveConfig() {
        await this.sendKissCommand([
            this.CMD_CONF_SAVE,
            0x00,
        ]);
    }

    // setNormalMode
    async deleteConfig() {
        await this.sendKissCommand([
            this.CMD_CONF_DELETE,
            0x00,
        ]);
    }

    async indicateFirmwareUpdate() {
        await this.sendKissCommand([
            this.CMD_FW_UPD,
            0x01,
        ]);
    }

    async setFirmwareHash(hash) {
        await this.sendKissCommand([
            this.CMD_FW_HASH,
            ...hash,
        ]);
    }

    async writeRom(address, value) {

        // write to rom
        await this.sendKissCommand([
            this.CMD_ROM_WRITE,
            address,
            value,
        ]);

        // wait a bit to allow device to write to rom
        await Utils.sleepMillis(85);

    }

    async wipeRom() {

        await this.sendKissCommand([
            this.CMD_UNLOCK_ROM,
            this.ROM_UNLOCK_BYTE,
        ]);

        // wiping can take up to 30 seconds
        await Utils.sleepMillis(30000);

    }

    async getRomAsObject() {
        const rom = await this.getRom();
        return new ROM(rom);
    }

}

class ROM {

    static PLATFORM_AVR   = 0x90
    static PLATFORM_ESP32 = 0x80
    static PLATFORM_NRF52 = 0x70

    static MCU_1284P      = 0x91
    static MCU_2560       = 0x92
    static MCU_ESP32      = 0x81
    static MCU_NRF52      = 0x71

    static PRODUCT_RAK4631 = 0x10
    static MODEL_11       = 0x11
    static MODEL_12       = 0x12

    static PRODUCT_RNODE  = 0x03
    static MODEL_A1       = 0xA1
    static MODEL_A6       = 0xA6
    static MODEL_A4       = 0xA4
    static MODEL_A9       = 0xA9
    static MODEL_A3       = 0xA3
    static MODEL_A8       = 0xA8
    static MODEL_A2       = 0xA2
    static MODEL_A7       = 0xA7
    static MODEL_A5       = 0xA5;
    static MODEL_AA       = 0xAA;

    static PRODUCT_T32_10 = 0xB2
    static MODEL_BA       = 0xBA
    static MODEL_BB       = 0xBB

    static PRODUCT_T32_20 = 0xB0
    static MODEL_B3       = 0xB3
    static MODEL_B8       = 0xB8

    static PRODUCT_T32_21 = 0xB1
    static MODEL_B4       = 0xB4
    static MODEL_B9       = 0xB9
    static MODEL_B4_TCXO  = 0x04 // The TCXO model codes are only used here to select the
    static MODEL_B9_TCXO  = 0x09 // correct firmware, actual model codes in firmware is still 0xB4 and 0xB9.

    static PRODUCT_H32_V2 = 0xC0
    static MODEL_C4       = 0xC4
    static MODEL_C9       = 0xC9

    static PRODUCT_H32_V3 = 0xC1
    static MODEL_C5       = 0xC5
    static MODEL_CA       = 0xCA

    static PRODUCT_TBEAM  = 0xE0
    static MODEL_E4       = 0xE4
    static MODEL_E9       = 0xE9
    static MODEL_E3       = 0xE3
    static MODEL_E8       = 0xE8

    static PRODUCT_TBEAM_S_V1 = 0xEA;
    static MODEL_DB           = 0xDB
    static MODEL_DC           = 0xDC

    static PRODUCT_TDECK  = 0xD0;
    static MODEL_D4       = 0xD4;
    static MODEL_D9       = 0xD9;

    static PRODUCT_TECHO  = 0x15;
    static MODEL_T4       = 0x16;
    static MODEL_T9       = 0x17;

    static PRODUCT_HMBRW  = 0xF0
    static MODEL_FF       = 0xFF
    static MODEL_FE       = 0xFE

    static ADDR_PRODUCT   = 0x00
    static ADDR_MODEL     = 0x01
    static ADDR_HW_REV    = 0x02
    static ADDR_SERIAL    = 0x03
    static ADDR_MADE      = 0x07
    static ADDR_CHKSUM    = 0x0B
    static ADDR_SIGNATURE = 0x1B
    static ADDR_INFO_LOCK = 0x9B
    static ADDR_CONF_SF   = 0x9C
    static ADDR_CONF_CR   = 0x9D
    static ADDR_CONF_TXP  = 0x9E
    static ADDR_CONF_BW   = 0x9F
    static ADDR_CONF_FREQ = 0xA3
    static ADDR_CONF_OK   = 0xA7

    static INFO_LOCK_BYTE = 0x73
    static CONF_OK_BYTE   = 0x73

    static BOARD_RNODE         = 0x31
    static BOARD_HMBRW         = 0x32
    static BOARD_TBEAM         = 0x33
    static BOARD_HUZZAH32      = 0x34
    static BOARD_GENERIC_ESP32 = 0x35
    static BOARD_LORA32_V2_0   = 0x36
    static BOARD_LORA32_V2_1   = 0x37
    static BOARD_RAK4631       = 0x51

    static MANUAL_FLASH_MODELS = [ROM.MODEL_A1, ROM.MODEL_A6]

    constructor(eeprom) {
        this.eeprom = eeprom;
    }

    getProduct() {
        return this.eeprom[ROM.ADDR_PRODUCT];
    }

    getModel() {
        return this.eeprom[ROM.ADDR_MODEL];
    }

    getHardwareRevision() {
        return this.eeprom[ROM.ADDR_HW_REV];
    }

    getSerialNumber() {
        return [
            this.eeprom[ROM.ADDR_SERIAL],
            this.eeprom[ROM.ADDR_SERIAL + 1],
            this.eeprom[ROM.ADDR_SERIAL + 2],
            this.eeprom[ROM.ADDR_SERIAL + 3],
        ];
    }

    getMade() {
        return [
            this.eeprom[ROM.ADDR_MADE],
            this.eeprom[ROM.ADDR_MADE + 1],
            this.eeprom[ROM.ADDR_MADE + 2],
            this.eeprom[ROM.ADDR_MADE + 3],
        ];
    }

    getChecksum() {
        const checksum = [];
        for(var i = 0; i < 16; i++){
            checksum.push(this.eeprom[ROM.ADDR_CHKSUM + i]);
        }
        return checksum;
    }

    getSignature() {
        const signature = [];
        for(var i = 0; i < 128; i++){
            signature.push(this.eeprom[ROM.ADDR_SIGNATURE + i]);
        }
        return signature;
    }

    getCalculatedChecksum() {
        return Utils.md5([
            this.getProduct(),
            this.getModel(),
            this.getHardwareRevision(),
            ...this.getSerialNumber(),
            ...this.getMade(),
        ]);
    }

    getConfiguredSpreadingFactor() {
        return this.eeprom[ROM.ADDR_CONF_SF];
    }

    getConfiguredCodingRate() {
        return this.eeprom[ROM.ADDR_CONF_CR];
    }

    getConfiguredTxPower() {
        return this.eeprom[ROM.ADDR_CONF_TXP];
    }

    getConfiguredFrequency() {
        return this.eeprom[ROM.ADDR_CONF_FREQ] << 24
            | this.eeprom[ROM.ADDR_CONF_FREQ + 1] << 16
            | this.eeprom[ROM.ADDR_CONF_FREQ + 2] << 8
            | this.eeprom[ROM.ADDR_CONF_FREQ + 3];
    }

    getConfiguredBandwidth() {
        return this.eeprom[ROM.ADDR_CONF_BW] << 24
            | this.eeprom[ROM.ADDR_CONF_BW + 1] << 16
            | this.eeprom[ROM.ADDR_CONF_BW + 2] << 8
            | this.eeprom[ROM.ADDR_CONF_BW + 3];
    }

    isInfoLocked() {
        return this.eeprom[ROM.ADDR_INFO_LOCK] === ROM.INFO_LOCK_BYTE;
    }

    isConfigured() {
        return this.eeprom[ROM.ADDR_CONF_OK] === ROM.CONF_OK_BYTE;
    }

    parse() {

        // ensure info lock byte is set
        if(!this.isInfoLocked()){
            return null;
        }

        // convert to hex
        const checksumHex = Utils.bytesToHex(this.getChecksum());
        const calculatedChecksumHex = Utils.bytesToHex(this.getCalculatedChecksum());
        const signatureHex = Utils.bytesToHex(this.getSignature());

        // add details
        var details = {
            is_provisioned: true,
            is_configured: this.isConfigured(),
            product: this.getProduct(),
            model: this.getModel(),
            hardware_revision: this.getHardwareRevision(),
            serial_number: Utils.unpackUInt32BE(this.getSerialNumber()),
            made: Utils.unpackUInt32BE(this.getMade()),
            checksum: checksumHex,
            calculated_checksum: calculatedChecksumHex,
            signature: signatureHex,
        }

        // if configured, add configuration to details
        if(details.is_configured){
            details = {
                ...details,
                configured_spreading_factor: this.getConfiguredSpreadingFactor(),
                configured_coding_rate: this.getConfiguredCodingRate(),
                configured_tx_power: this.getConfiguredTxPower(),
                configured_frequency: this.getConfiguredFrequency(),
                configured_bandwidth: this.getConfiguredBandwidth(),
            };
        }

        // if checksum in eeprom does not match checksum calculated from info, it is not provisioned
        if(details.checksum !== details.calculated_checksum){
            details.is_provisioned = false;
        }

        return details;

    }

}