// Licence: MIT
#include <Arduino.h>
#include <RadioLib.h>
#include <Wire.h>
#include <TinyGPS++.h>
#include <SD.h>
#include "compression.h"

// Date Type Codes defined in aprs434.github.io
constexpr int DATA_TYPE_CODE_GEOLOCATION = 0;
constexpr int DATA_TYPE_CODE_STATUS_REPORT = 1;

// TODO: read these settings from the SD Card
constexpr char CALLSIGN[] = "HB9EGM";
constexpr int SSID = 7;
constexpr int PATH_CODE = 2; // metropolitan mobile
constexpr char SYMBOL_TABLE_IDENTIFIER = '/';
constexpr char SYMBOL_CODE_BICYCLE = 'b';
constexpr char SYMBOL_CODE_FOOT = '[';
constexpr long REPORT_TX_INTERVAL = 15000;

constexpr long TEXT_TX_INTERVAL = 47000;
constexpr char TEXT_REPORT[] = "mpb.li/git/lora-aprs-hb9egm"; // Max length=28

#if 0
File myFile;
constexpr int SD_CS = 17;
#endif

// SX1278 has the following connections:
// NSS pin:   PD14 (Arduino 10)
// DIO0 pin:  PF3 (Arduino 8)
// RESET pin: PF15 (Arduino 9)
RFM96 radio = new Module(10, 8, 9);

HardwareSerial serialGNSS(PA10, PA9);
TinyGPSPlus    gps;

long lastGnssPoll = 0;
long lastPositionReport = 0;
long lastTextReport = 0;

constexpr size_t MAX_REPORT_LEN = 32;
size_t report_len = 0;
uint8_t report[MAX_REPORT_LEN];

static char letterize(int x) {
    return (char) x + 65;
}

void setup() {
    Serial.begin(9600);
    pinMode(LED_BUILTIN, OUTPUT);

#if 0
    pinMode(SD_CS, OUTPUT);

    if (!SD.begin(SD_CS)) {
        Serial.println("SD init failed!");
        return;
    }
#endif

    Wire.begin();


    serialGNSS.begin(9600);

    Serial.print(F("[RFM] Init "));
    int state = radio.begin(433.900);
    if (state == RADIOLIB_ERR_NONE) {
        Serial.println(F("success!"));
    } else {
        Serial.print(F("failed, code "));
        Serial.println(state);
        while (true);
    }

    if (radio.setBandwidth(125.0) == RADIOLIB_ERR_INVALID_BANDWIDTH) {
        Serial.println(F("Selected bandwidth is invalid for this module!"));
        while (true);
    }

    if (radio.setSpreadingFactor(12) == RADIOLIB_ERR_INVALID_SPREADING_FACTOR) {
        Serial.println(F("Selected spreading factor is invalid for this module!"));
        while (true);
    }

    if (radio.setCodingRate(5) == RADIOLIB_ERR_INVALID_CODING_RATE) {
        Serial.println(F("Selected coding rate is invalid for this module!"));
        while (true);
    }

    // NOTE: value 0x34 is reserved for LoRaWAN networks and should not be used
    if (radio.setSyncWord(0x14) != RADIOLIB_ERR_NONE) {
        Serial.println(F("Unable to set sync word!"));
        while (true);
    }

    if (radio.setOutputPower(16) == RADIOLIB_ERR_INVALID_OUTPUT_POWER) {
        Serial.println(F("Selected output power is invalid for this module!"));
        while (true);
    }

    if (radio.setPreambleLength(8) == RADIOLIB_ERR_INVALID_PREAMBLE_LENGTH) {
        Serial.println(F("Selected preamble length is invalid for this module!"));
        while (true);
    }

    // radio.setRfSwitchPins(4, 5);
}

static void handle_radio_error(int state)
{
    if (state == RADIOLIB_ERR_NONE) {
        Serial.print(F(" RFM OK Datarate: "));
        Serial.print(radio.getDataRate());
        Serial.println(F(" bps"));

    }
    else if (state == RADIOLIB_ERR_PACKET_TOO_LONG) {
        Serial.println(F(" too long!"));

    }
    else if (state == RADIOLIB_ERR_TX_TIMEOUT) {
        Serial.println(F(" timeout!"));

    }
    else {
        Serial.print(F(" failed, code "));
        Serial.println(state);
    }
}

void loop()
{
    while (serialGNSS.available() > 0) {
        gps.encode(serialGNSS.read());
    }

    const auto now = millis();
    if (now - lastGnssPoll > 1000) {
        lastGnssPoll = now;

        // longitude and latitude are in degrees*1e7
        const long latitude = gps.location.lat();
        Serial.print(F("Lat: "));
        Serial.print(latitude);

        const long longitude = gps.location.lng();
        Serial.print(F(" Long: "));
        Serial.print(longitude);

        const long altitude = gps.altitude.feet();

        const int speed = gps.speed.kmph();
        Serial.print(F(" Speed: "));
        Serial.print(speed);
        Serial.print(F(" (mm/s)"));
        // 1m/s = 900/463 knots
        const double speed_kn  = gps.speed.knots();

        const long heading = gps.course.deg();
        Serial.print(F(" Heading: "));
        Serial.print(heading);
        Serial.print(F(" (degrees * 10^-5)"));

        const byte SIV = gps.satellites.value();
        Serial.print(F(" SIV: "));
        Serial.print(SIV);

        Serial.print(F(" TX in: "));
        Serial.print(REPORT_TX_INTERVAL - (now - lastPositionReport));

        Serial.println();

        if (now - lastPositionReport > REPORT_TX_INTERVAL) {
            lastPositionReport = now;

            digitalWrite(LED_BUILTIN, HIGH);

            // Encode Compressed Geolocation Frame according to aprs434.github.io
            const uint32_t callsign_EEEE = encodeCallsign(CALLSIGN);

            report_len = 0;
            // Callsign encoded as CCCC
            report[report_len++] = (callsign_EEEE >> 24) & 0xFF;
            report[report_len++] = (callsign_EEEE >> 16) & 0xFF;
            report[report_len++] = (callsign_EEEE >> 8) & 0xFF;
            report[report_len++] = callsign_EEEE & 0xFF;

            // D SSID Path Code and Data Type Code
            report[report_len++] = SSID * 16 + PATH_CODE * 4 + DATA_TYPE_CODE_GEOLOCATION;

            // / Symbol Table Identifier
            report[report_len++] = SYMBOL_TABLE_IDENTIFIER;

            // XXXX Base91 Longitude
            // YYYY Base91 Latitude
            uint32_t aprs_lat = 900000000 - latitude;
            aprs_lat = aprs_lat / 26 - aprs_lat / 2710 + aprs_lat / 15384615;
            uint32_t aprs_lon = 900000000 + longitude / 2;
            aprs_lon = aprs_lon / 26 - aprs_lon / 2710 + aprs_lon / 15384615;

            char tmp_base91[5];
            ax25_base91enc(tmp_base91, 4, aprs_lat);
            for (int i=0; i<4; i++) {
                report[report_len++] = tmp_base91[i];
            }
            ax25_base91enc(tmp_base91, 4, aprs_lon);
            for (int i=0; i<4; i++) {
                report[report_len++] = tmp_base91[i];
            }

            // $ Symbol Code
            report[report_len++] = SYMBOL_CODE_FOOT;

            // cs Course and Speed
            ax25_base91enc(tmp_base91, 1, heading * 10000 / 4);
            report[report_len++] = tmp_base91[0];

            ax25_base91enc(tmp_base91, 1, (uint32_t)(log1p(speed_kn) / 0.07696));
            report[report_len++] = tmp_base91[0];

            // Debug print
            Serial.println(F("Bytes: "));
            for (int i = 0; i < report_len; i++) {
                Serial.print((uint32_t)report[i]);
            }
            Serial.println(F(""));

            int state = radio.transmit(report, report_len);
            handle_radio_error(state);

            digitalWrite(LED_BUILTIN, LOW);
        }

        if (now - lastTextReport > TEXT_TX_INTERVAL) {
            lastTextReport = now;
            digitalWrite(LED_BUILTIN, HIGH);

            // Encode Compressed Status Report Frame according to aprs434.github.io
            const uint32_t callsign_EEEE = encodeCallsign(CALLSIGN);

            report_len = 0;
            // Callsign encoded as CCCC
            report[report_len++] = (callsign_EEEE >> 24) & 0xFF;
            report[report_len++] = (callsign_EEEE >> 16) & 0xFF;
            report[report_len++] = (callsign_EEEE >> 8) & 0xFF;
            report[report_len++] = callsign_EEEE & 0xFF;

            // D SSID Path Code and Data Type Code
            report[report_len++] = SSID * 16 + PATH_CODE * 4 + DATA_TYPE_CODE_STATUS_REPORT;

            // t(t...) text
            const auto bignum = encodetttt(TEXT_REPORT);
            for (int i = 0; i <= 512; i += 8) {
                auto v = static_cast<uint8_t>((bignum >> (512-i)) & 0xFF);
                if (v) {
                    report[report_len++] = v;
                }
            }

            Serial.print(F("TX length "));
            Serial.print(report_len);
            Serial.print(F(" bytes: "));
            Serial.println(TEXT_REPORT);

            int state = radio.transmit(report, report_len);
            handle_radio_error(state);

            digitalWrite(LED_BUILTIN, LOW);
        }
    }
}