/*

TTN module
Wrapper to use TTN with the LMIC library

Copyright (C) 2018 by Xose Pérez <xose dot perez at gmail dot com>

This code requires the MCCI LoRaWAN LMIC library
by IBM, Matthis Kooijman, Terry Moore, ChaeHee Won, Frank Rose
https://github.com/mcci-catena/arduino-lmic

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

#include "ttn.h"

#include <Arduino.h>
#include <Preferences.h>
#include <SPI.h>
#include <hal/hal.h>
#include <lmic.h>

#include <vector>

#include "configuration.h"
#include "credentials.h"
#include "screen.h"

dr_t ttn_tx_sf = LORAWAN_SF;
void ttn_sf(dr_t sf);

// -----------------------------------------------------------------------------
// Globals
// -----------------------------------------------------------------------------

// LMIC GPIO configuration
const lmic_pinmap lmic_pins = {
    .nss = NSS_GPIO,
    .rxtx = LMIC_UNUSED_PIN,
    .rst = RESET_GPIO,
    .dio = {DIO0_GPIO, DIO1_GPIO, DIO2_GPIO},
};

// Message counter, stored in RTC memory, survives deep sleep.
static RTC_DATA_ATTR uint32_t count = 0;

#ifdef USE_ABP
// These callbacks are only used in over-the-air activation, so they are
// left empty here (we cannot leave them out completely unless
// DISABLE_JOIN is set in config.h, otherwise the linker will complain).
void os_getArtEui(u1_t* buf) {}
void os_getDevEui(u1_t* buf) {}
void os_getDevKey(u1_t* buf) {}
#endif

#ifdef USE_OTAA
void os_getArtEui(u1_t* buf) {
  memcpy_P(buf, APPEUI, 8);
}
void os_getDevEui(u1_t* buf) {
  memcpy(buf, DEVEUI, 8);
}
void os_getDevKey(u1_t* buf) {
  memcpy_P(buf, APPKEY, 16);
}
#endif

std::vector<void (*)(uint8_t message)> _lmic_callbacks;

// -----------------------------------------------------------------------------
// Private methods
// -----------------------------------------------------------------------------

void _ttn_callback(uint8_t message) {
  for (uint8_t i = 0; i < _lmic_callbacks.size(); i++) {
    (_lmic_callbacks[i])(message);
  }
}

void forceTxSingleChannelDr() {
// Disables all channels, except for the one defined by SINGLE_CHANNEL_GATEWAY
// This only affects uplinks; for downlinks the default
// channels or the configuration from the OTAA Join Accept are used.
#ifdef SINGLE_CHANNEL_GATEWAY
  for (int i = 0; i < 9; i++) {  // For EU; for US use i<71
    if (i != SINGLE_CHANNEL_GATEWAY) {
      LMIC_disableChannel(i);
    }
  }
#endif

  // Set data rate (SF) and transmit power for uplink
  ttn_sf(ttn_tx_sf);
}

// DevEUI generator using devices's MAC address - from
// https://github.com/cyberman54/ESP32-Paxcounter/blob/master/src/lorawan.cpp
void gen_lora_deveui(uint8_t* pdeveui) {
  uint8_t *p = pdeveui, dmac[6];
  int i = 0;
  esp_efuse_mac_get_default(dmac);
  // deveui is LSB, we reverse it so TTN DEVEUI display
  // will remain the same as MAC address
  // MAC is 6 bytes, devEUI 8, set first 2 ones
  // with an arbitrary value
  *p++ = 0xFF;
  *p++ = 0xFE;
  // Then next 6 bytes are mac address reversed
  for (i = 0; i < 6; i++) {
    *p++ = dmac[5 - i];
  }
}

static void printHex2(unsigned v) {
  v &= 0xff;
  if (v < 16)
    Serial.print('0');
  Serial.print(v, HEX);
}

#ifdef USE_OTAA
// generate DevEUI from macaddr if it's all zero
void initDevEUI() {
  bool needInit = true;
  for (int i = 0; i < sizeof(DEVEUI); i++)
    if (DEVEUI[i])
      needInit = false;

  if (needInit)
    gen_lora_deveui(DEVEUI);
}
#endif

// LMIC library will call this method when an event is fired
// *** MAGIC FUNCTION NAME ***
// *** DO NOT CHANGE ***
void onEvent(ev_t event) {  // <<<< Very Specific Name here for lmic.c
  switch (event) {
    case EV_JOINED: {
#ifdef SINGLE_CHANNEL_GATEWAY
      forceTxSingleChannelDr();
#endif

      // Disable link check validation (automatically enabled
      // during join, but because slow data rates change max TX
      // size, we don't use it in this example.
      if (!LORAWAN_ADR) {
        LMIC_setLinkCheckMode(0);  // Link check problematic if not using ADR. Must be set after join
      }

      Serial.println(F("EV_JOINED"));

      u4_t netid = 0;
      devaddr_t devaddr = 0;
      u1_t nwkKey[16];
      u1_t artKey[16];
      LMIC_getSessionKeys(&netid, &devaddr, nwkKey, artKey);
      Serial.print("netid: ");
      Serial.println(netid, DEC);
      Serial.print("devaddr: ");
      Serial.println(devaddr, HEX);
      Serial.print("AppSKey: ");
      for (size_t i = 0; i < sizeof(artKey); ++i) {
        if (i != 0)
          Serial.print("-");
        printHex2(artKey[i]);
      }
      Serial.println("");
      Serial.print("NwkSKey: ");
      for (size_t i = 0; i < sizeof(nwkKey); ++i) {
        if (i != 0)
          Serial.print("-");
        printHex2(nwkKey[i]);
      }
      Serial.println();

      Preferences p;
      if (p.begin("lora", false)) {
        p.putUInt("netId", netid);
        p.putUInt("devAddr", devaddr);
        p.putBytes("nwkKey", nwkKey, sizeof(nwkKey));
        p.putBytes("artKey", artKey, sizeof(artKey));
        p.end();
      }
      break;
    }
    case EV_TXCOMPLETE:
      //        Serial.println(F("EV_TXCOMPLETE"));
      if (LMIC.txrxFlags & TXRX_ACK) {
        //           Serial.println(F("Received ack"));
        _ttn_callback(EV_ACK);
      }
      if (LMIC.dataLen) {
        //            Serial.print(F("Data Received: "));
        //            Serial.write(LMIC.frame+LMIC.dataBeg, LMIC.dataLen);
        //            Serial.println();
        _ttn_callback(EV_RESPONSE);
      }
      break;
    default:
      break;
  }

  // Send message callbacks
  _ttn_callback(event);
}

// -----------------------------------------------------------------------------
// Public methods
// -----------------------------------------------------------------------------

void ttn_register(void (*callback)(uint8_t message)) {
  _lmic_callbacks.push_back(callback);
}

size_t ttn_response_len() {
  return LMIC.dataLen;
}

void ttn_response(uint8_t* port, uint8_t* buffer, size_t len) {
  if (port)
    *port = LMIC.frame[LMIC.dataBeg - 1];
  for (uint8_t i = 0; i < LMIC.dataLen; i++) {
    buffer[i] = LMIC.frame[LMIC.dataBeg + i];
  }
}

// If the value for LORA packet counts is unknown, restore from flash
static void initCount() {
  if (count == 0) {
    Preferences p;
    if (p.begin("lora", true)) {
      count = p.getUInt("count", 0);
      p.end();
    }
  }
}

bool ttn_setup() {
  initCount();

#if defined(USE_OTAA)
  initDevEUI();
#endif

  // Print out DevEUI, AppEUI, APPKEY suitable for Helium Console
  Serial.println();
  Serial.print("DevEUI (msb): ");
  for (int i = 0; i < sizeof(DEVEUI); i++) printHex2(DEVEUI[sizeof(DEVEUI) - 1 - i]);
  Serial.println();

  Serial.print("APPEUI (msb): ");
  for (int i = 0; i < sizeof(APPEUI); i++) printHex2(APPEUI[sizeof(APPEUI) - 1 - i]);
  Serial.println();

  Serial.print("APPKEY (msb): ");
  for (int i = 0; i < sizeof(APPKEY); i++) printHex2(APPKEY[i]);
  Serial.println();

  // SPI interface
  SPI.begin(SCK_GPIO, MISO_GPIO, MOSI_GPIO, NSS_GPIO);

  // LMIC init
  return (1 == os_init_ex((const void*)&lmic_pins));
}

void ttn_join(void) {
  // Reset the MAC state. Session and pending data transfers will be discarded.
  LMIC_reset();

#ifdef CLOCK_ERROR
  LMIC_setClockError(MAX_CLOCK_ERROR * CLOCK_ERROR / 100);
#endif

#if defined(CFG_eu868)

  // Set up the channels used by the Things Network, which corresponds
  // to the defaults of most gateways. Without this, only three base
  // channels from the LoRaWAN specification are used, which certainly
  // works, so it is good for debugging, but can overload those
  // frequencies, so be sure to configure the full frequency range of
  // your network here (unless your network autoconfigures them).
  // Setting up channels should happen after LMIC_setSession, as that
  // configures the minimal channel set.
  LMIC_setupChannel(0, 868100000, DR_RANGE_MAP(DR_SF12, DR_SF7),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(1, 868300000, DR_RANGE_MAP(DR_SF12, DR_SF7B),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(2, 868500000, DR_RANGE_MAP(DR_SF12, DR_SF7),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(3, 867100000, DR_RANGE_MAP(DR_SF12, DR_SF7),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(4, 867300000, DR_RANGE_MAP(DR_SF12, DR_SF7),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(5, 867500000, DR_RANGE_MAP(DR_SF12, DR_SF7),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(6, 867700000, DR_RANGE_MAP(DR_SF12, DR_SF7),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(7, 867900000, DR_RANGE_MAP(DR_SF12, DR_SF7),
                    BAND_CENTI);  // g-band
  LMIC_setupChannel(8, 868800000, DR_RANGE_MAP(DR_FSK, DR_FSK),
                    BAND_MILLI);  // g2-band

#elif defined(CFG_us915)

  // NA-US channels 0-71 are configured automatically
  // but only one group of 8 should (a subband) should be active
  // TTN recommends the second sub band, 1 in a zero based count.
  // https://github.com/TheThingsNetwork/gateway-conf/blob/master/US-global_conf.json
  // in the US, with TTN, it saves join time if we start on subband 1
  // (channels 8-15). This will get overridden after the join by
  // parameters from the network. If working with other networks or in
  // other regions, this will need to be changed.
  LMIC_selectSubBand(1);

#elif defined(CFG_au915)

  // set sub band for AU915
  // https://github.com/TheThingsNetwork/gateway-conf/blob/master/AU-global_conf.json
  LMIC_selectSubBand(1);

#endif

  // TTN defines an additional channel at 869.525Mhz using SF9 for class B
  // devices' ping slots. LMIC does not have an easy way to define set this
  // frequency and support for class B is spotty and untested, so this
  // frequency is not configured here.

  // Disable link check validation
  LMIC_setLinkCheckMode(0);

#ifdef SINGLE_CHANNEL_GATEWAY
  forceTxSingleChannelDr();
#else
  // Set default rate and transmit power for uplink (note: txpow seems to be
  // ignored by the library)
  ttn_sf(LORAWAN_SF);
#endif

#if defined(USE_ABP)

  // Set static session parameters. Instead of dynamically establishing a
  // session by joining the network, precomputed session parameters are be
  // provided.
  uint8_t appskey[sizeof(APPSKEY)];
  uint8_t nwkskey[sizeof(NWKSKEY)];
  memcpy_P(appskey, APPSKEY, sizeof(APPSKEY));
  memcpy_P(nwkskey, NWKSKEY, sizeof(NWKSKEY));
  LMIC_setSession(0x1, DEVADDR, nwkskey, appskey);

  // TTN uses SF9 for its RX2 window.
  LMIC.dn2Dr = DR_SF9;

  // Trigger a false joined
  _ttn_callback(EV_JOINED);

#elif defined(USE_OTAA)

  // Make LMiC initialize the default channels, choose a channel, and
  // schedule the OTAA join
  LMIC_startJoining();

#ifdef SINGLE_CHANNEL_GATEWAY
  // LMiC will already have decided to send on one of the 3 default
  // channels; ensure it uses the one we want
  LMIC.txChnl = SINGLE_CHANNEL_GATEWAY;
#endif

  Preferences p;
  p.begin("lora", true);  // we intentionally ignore failure here
  uint32_t netId = p.getUInt("netId", UINT32_MAX);
  uint32_t devAddr = p.getUInt("devAddr", UINT32_MAX);
  uint8_t nwkKey[16], artKey[16];
  bool keysgood = devAddr != UINT32_MAX && netId != UINT32_MAX &&
                  p.getBytes("nwkKey", nwkKey, sizeof(nwkKey)) == sizeof(nwkKey) &&
                  p.getBytes("artKey", artKey, sizeof(artKey)) == sizeof(artKey);
  p.end();  // close our prefs

  if (!keysgood) {
    // We have not yet joined a network, start a full join attempt
    // Make LMiC initialize the default channels, choose a channel, and
    // schedule the OTAA join
    Serial.println("Joining from scratch");
    screen_print("Joining...\n");
    LMIC_startJoining();
  } else {
    Serial.println("Reusing saved session");
    LMIC_setSession(netId, devAddr, nwkKey, artKey);

    // Trigger a false joined
    screen_print("(re-used join)\n");
    _ttn_callback(EV_JOINED);
  }

#endif
}

void ttn_get_sf_name(char* b, size_t len) {
  rps_t txrps = dndr2rps(ttn_tx_sf);

  u1_t sf, bw;
  sf = getSf(txrps) + 6;  // 1 == SF7
  bw = getBw(txrps);

  /*
  snprintf(b, len, "%3d.%02d SF%d BW%d",
           LMIC.freq / 1000000,
           (LMIC.freq % 1000000) / 10000,
           sf,
           bw == BW125 ? 125 : (bw == BW250 ? 250 : 500)
           );
  Serial.println(b);
  */
  snprintf(b, len, "SF%d BW%d", sf, bw == BW125 ? 125 : (bw == BW250 ? 250 : 500));
  // Serial.println(b);
}

void ttn_set_sf(dr_t sf) {
  ttn_tx_sf = sf;
  ttn_sf(ttn_tx_sf);
}

void ttn_sf(dr_t sf) {
  // Serial.printf("Setting SF to %d\n", sf);
  LMIC_setDrTxpow(sf, 14);
}

void ttn_adr(bool enabled) {
  LMIC_setAdrMode(enabled);
  LMIC_setLinkCheckMode(!enabled);
}

uint32_t ttn_get_count() {
  return count;
}

void ttn_write_prefs() {
  Preferences p;
  if (p.begin("lora", false)) {
    p.putUInt("count", count);
    p.end();
  }
}

static void ttn_set_cnt() {
  LMIC_setSeqnoUp(count);

  // We occasionally mirror our count to flash, to ensure that if we lose power we will at least start with a count that
  // is almost correct (otherwise the TNN network will discard packets until count once again reaches the value they've
  // seen).  We limit these writes to a max rate of one write every 5 minutes.  Which should let the FLASH last for 300
  // years (given the ESP32 NVS algoritm)
  static uint32_t lastWriteMsec = UINT32_MAX;  // Ensure we write at least once
  uint32_t now = millis();
  if (now < lastWriteMsec || (now - lastWriteMsec) > 5 * 60 * 1000L) {  // write if we roll over (50 days) or 5 mins
    lastWriteMsec = now;
    ttn_write_prefs();
  }
}

/// Blow away our prefs (i.e. to rejoin from scratch)
void ttn_erase_prefs() {
  Preferences p;
  if (p.begin("lora", false)) {
    p.clear();
    p.end();
  }
}

boolean ttn_send(uint8_t* data, uint8_t data_size, uint8_t port, bool confirmed) {
  ttn_set_cnt();  // we are about to send using the current packet count

  // Check if there is not a current TX/RX job running
  if (LMIC.opmode & OP_TXRXPEND) {
    _ttn_callback(EV_PENDING);
    return false;
  }

  // Set data rate (SF) for Uplink, as it might have changed during last Tx
  ttn_sf(ttn_tx_sf);

  // Prepare upstream data transmission at the next possible time.
  // Parameters are port, data, length, confirmed
  LMIC_setTxData2(port, data, data_size, confirmed ? 1 : 0);

  _ttn_callback(EV_QUEUED);
  count++;
  return true;
}

void ttn_loop() {
  os_runloop_once();
}