#if BOARD_MODEL == BOARD_TBEAM
  #include <XPowersLib.h>
  XPowersLibInterface* PMU = NULL;

  #ifndef PMU_WIRE_PORT
    #define PMU_WIRE_PORT   Wire
  #endif

  #define BAT_V_MIN       3.15
  #define BAT_V_MAX       4.14

  void disablePeripherals() {
    if (PMU) {
      // GNSS RTC PowerVDD
      PMU->enablePowerOutput(XPOWERS_VBACKUP);

      // LoRa VDD
      PMU->disablePowerOutput(XPOWERS_ALDO2);

      // GNSS VDD
      PMU->disablePowerOutput(XPOWERS_ALDO3);
    }
  }

  bool pmuInterrupt;
  void setPmuFlag()
  {
      pmuInterrupt = true;
  }
#elif BOARD_MODEL == BOARD_RNODE_NG_21 || BOARD_MODEL == BOARD_LORA32_V2_1
  #define BAT_C_SAMPLES   7
  #define BAT_D_SAMPLES   2
  #define BAT_V_MIN       3.15
  #define BAT_V_MAX       4.3
  #define BAT_V_CHG       4.48
  #define BAT_V_FLOAT     4.33
  #define BAT_SAMPLES     5
  const uint8_t pin_vbat = 35;
  float bat_p_samples[BAT_SAMPLES];
  float bat_v_samples[BAT_SAMPLES];
  uint8_t bat_samples_count = 0;
  int bat_discharging_samples = 0;
  int bat_charging_samples = 0;
  int bat_charged_samples = 0;
  bool bat_voltage_dropping = false;
  float bat_delay_v = 0;
#elif BOARD_MODEL == BOARD_RAK4631
#include "nrfx_power.h"
#define BAT_C_SAMPLES   7
#define BAT_D_SAMPLES   2
#define BAT_V_MIN       2.75
#define BAT_V_MAX       4.2
#define BAT_V_FLOAT     4.22
#define BAT_SAMPLES     5
#define VBAT_MV_PER_LSB (0.73242188F) // 3.0V ADC range and 12 - bit ADC resolution = 3000mV / 4096
#define VBAT_DIVIDER_COMP (1.73)      // Compensation factor for the VBAT divider
#define VBAT_MV_PER_LSB_FIN (VBAT_DIVIDER_COMP * VBAT_MV_PER_LSB)
#define PIN_VBAT WB_A0
float bat_p_samples[BAT_SAMPLES];
float bat_v_samples[BAT_SAMPLES];
uint8_t bat_samples_count = 0;
int bat_discharging_samples = 0;
int bat_charging_samples = 0;
int bat_charged_samples = 0;
bool bat_voltage_dropping = false;
float bat_delay_v = 0;
#endif

uint32_t last_pmu_update = 0;
uint8_t pmu_target_pps = 1;
int pmu_update_interval = 1000/pmu_target_pps;
uint8_t pmu_rc = 0;
#define PMU_R_INTERVAL 5
void kiss_indicate_battery();

void measure_battery() {
  #if BOARD_MODEL == BOARD_RNODE_NG_21 || BOARD_MODEL == BOARD_LORA32_V2_1
    battery_installed = true;
    battery_indeterminate = true;
    bat_v_samples[bat_samples_count%BAT_SAMPLES] = (float)(analogRead(pin_vbat)) / 4095*2*3.3*1.1;
    bat_p_samples[bat_samples_count%BAT_SAMPLES] = ((battery_voltage-BAT_V_MIN) / (BAT_V_MAX-BAT_V_MIN))*100.0;
    
    bat_samples_count++;
    if (!battery_ready && bat_samples_count >= BAT_SAMPLES) {
      battery_ready = true;
    }

    if (battery_ready) {

      battery_percent = 0;
      for (uint8_t bi = 0; bi < BAT_SAMPLES; bi++) {
        battery_percent += bat_p_samples[bi];
      }
      battery_percent = battery_percent/BAT_SAMPLES;
      
      battery_voltage = 0;
      for (uint8_t bi = 0; bi < BAT_SAMPLES; bi++) {
        battery_voltage += bat_v_samples[bi];
      }
      battery_voltage = battery_voltage/BAT_SAMPLES;
      
      if (bat_delay_v == 0) bat_delay_v = battery_voltage;
      if (battery_percent > 100.0) battery_percent = 100.0;
      if (battery_percent < 0.0) battery_percent = 0.0;

      if (bat_samples_count%BAT_SAMPLES == 0) {
        if (battery_voltage < bat_delay_v && battery_voltage < BAT_V_FLOAT) {
          bat_voltage_dropping = true;
        } else {
          bat_voltage_dropping = false;
        }
        bat_samples_count = 0;
      }

      if (bat_voltage_dropping && battery_voltage < BAT_V_FLOAT) {
        battery_state = BATTERY_STATE_DISCHARGING;
      } else {
        #if BOARD_MODEL == BOARD_RNODE_NG_21
          battery_state = BATTERY_STATE_CHARGING;
        #else
          battery_state = BATTERY_STATE_DISCHARGING;
        #endif
      }



      // if (bt_state == BT_STATE_CONNECTED) {
      //   SerialBT.printf("Bus voltage %.3fv. Unfiltered %.3fv.", battery_voltage, bat_v_samples[BAT_SAMPLES-1]);
      //   if (bat_voltage_dropping) {
      //     SerialBT.printf(" Voltage is dropping. Percentage %.1f%%.\n", battery_percent);
      //   } else {
      //     SerialBT.print(" Voltage is not dropping.\n");
      //   }
      // }
    }

  #elif BOARD_MODEL == BOARD_TBEAM
    if (PMU) {
      float discharge_current = 0;
      float charge_current    = 0;
      float ext_voltage       = 0;
      float ext_current       = 0;
      if (PMU->getChipModel() == XPOWERS_AXP192) {
        discharge_current       = ((XPowersAXP192*)PMU)->getBattDischargeCurrent();
        charge_current          = ((XPowersAXP192*)PMU)->getBatteryChargeCurrent();
        battery_voltage         = PMU->getBattVoltage()/1000.0;
        // battery_percent         = PMU->getBattPercentage()*1.0;
        battery_installed       = PMU->isBatteryConnect();
        external_power          = PMU->isVbusIn();
        ext_voltage             = PMU->getVbusVoltage()/1000.0;
        ext_current             = ((XPowersAXP192*)PMU)->getVbusCurrent();
      }
      else if (PMU->getChipModel() == XPOWERS_AXP2101) {
        battery_voltage         = PMU->getBattVoltage()/1000.0;
        // battery_percent         = PMU->getBattPercentage()*1.0;
        battery_installed       = PMU->isBatteryConnect();
        external_power          = PMU->isVbusIn();
        ext_voltage             = PMU->getVbusVoltage()/1000.0;
      }

      if (battery_installed) {
        if (PMU->isCharging()) {
          battery_state = BATTERY_STATE_CHARGING;
          battery_percent = ((battery_voltage-BAT_V_MIN) / (BAT_V_MAX-BAT_V_MIN))*100.0;
        } else {
          if (PMU->isDischarge()) {
            battery_state = BATTERY_STATE_DISCHARGING;
            battery_percent = ((battery_voltage-BAT_V_MIN) / (BAT_V_MAX-BAT_V_MIN))*100.0;
          } else {
            battery_state = BATTERY_STATE_CHARGED;
            battery_percent = 100.0;
          }
        }
      } else {
        battery_state = BATTERY_STATE_DISCHARGING;
        battery_percent = 0.0;
        battery_voltage = 0.0;
      }

      if (battery_percent > 100.0) battery_percent = 100.0;
      if (battery_percent < 0.0) battery_percent = 0.0;

      float charge_watts    = battery_voltage*(charge_current/1000.0);
      float discharge_watts = battery_voltage*(discharge_current/1000.0);
      float ext_watts       = ext_voltage*(ext_current/1000.0);

      battery_ready = true;

      // if (bt_state == BT_STATE_CONNECTED) {
      //   if (battery_installed) {
      //     if (external_power) {
      //       SerialBT.printf("External power connected, drawing %.2fw, %.1fmA at %.1fV\n", ext_watts, ext_current, ext_voltage);
      //     } else {
      //       SerialBT.println("Running on battery");
      //     }
      //     SerialBT.printf("Battery percentage %.1f%%\n", battery_percent);
      //     SerialBT.printf("Battery voltage %.2fv\n", battery_voltage);
      //     // SerialBT.printf("Temperature %.1f%\n", auxillary_temperature);

      //     if (battery_state == BATTERY_STATE_CHARGING) {
      //       SerialBT.printf("Charging with %.2fw, %.1fmA at %.1fV\n", charge_watts, charge_current, battery_voltage);
      //     } else if (battery_state == BATTERY_STATE_DISCHARGING) {
      //       SerialBT.printf("Discharging at %.2fw, %.1fmA at %.1fV\n", discharge_watts, discharge_current, battery_voltage);
      //     } else if (battery_state == BATTERY_STATE_CHARGED) {
      //       SerialBT.printf("Battery charged\n");
      //     }
      //   } else {
      //     SerialBT.println("No battery installed");
      //   }
      //   SerialBT.println("");
      // }
    }
    else {
      battery_ready = false;
    }

  #elif BOARD_MODEL == BOARD_RAK4631
    battery_installed = true;
    battery_indeterminate = false;

    bat_v_samples[bat_samples_count%BAT_SAMPLES] = (float)(analogRead(PIN_VBAT)) * VBAT_MV_PER_LSB_FIN;

    if (bat_v_samples[bat_samples_count%BAT_SAMPLES] < 3300) {
        bat_p_samples[bat_samples_count%BAT_SAMPLES] = 0;
    }
    else if (bat_v_samples[bat_samples_count%BAT_SAMPLES] < 3600)
    {
        bat_v_samples[bat_samples_count%BAT_SAMPLES] -= 3300;
        bat_p_samples[bat_samples_count%BAT_SAMPLES] = bat_v_samples[bat_samples_count%BAT_SAMPLES] / 30;
    } else {
        bat_v_samples[bat_samples_count%BAT_SAMPLES] -= 3600;
    }
    bat_p_samples[bat_samples_count%BAT_SAMPLES] = 10 + (bat_v_samples[bat_samples_count%BAT_SAMPLES] * 0.15F);

    bat_samples_count++;
    if (!battery_ready && bat_samples_count >= BAT_SAMPLES) {
      battery_ready = true;
    }

    battery_percent = 0;
    for (uint8_t bi = 0; bi < BAT_SAMPLES; bi++) {
        battery_percent += bat_p_samples[bi];
    }
    battery_percent = battery_percent/BAT_SAMPLES;

    battery_voltage = 0;
    for (uint8_t bi = 0; bi < BAT_SAMPLES; bi++) {
        battery_voltage += bat_v_samples[bi];
    }
    battery_voltage = battery_voltage/BAT_SAMPLES;

    if (bat_delay_v == 0) bat_delay_v = battery_voltage;
    if (battery_percent > 100.0) battery_percent = 100.0;
    if (battery_percent < 0.0) battery_percent = 0.0;

    if (bat_samples_count%BAT_SAMPLES == 0) {
        if (battery_voltage < bat_delay_v && battery_voltage < BAT_V_FLOAT) {
            bat_voltage_dropping = true;
        } else {
            bat_voltage_dropping = false;
        }
        bat_samples_count = 0;
    }

    nrfx_power_usb_state_t usbstate = nrfx_power_usbstatus_get();
    if (usbstate == NRFX_POWER_USB_STATE_CONNECTED || usbstate == NRFX_POWER_USB_STATE_READY) {
        // charging
        battery_state = BATTERY_STATE_CHARGING;
    } else {
        battery_state = BATTERY_STATE_DISCHARGING;
    }

    if (battery_percent >= 98) {
        battery_state = BATTERY_STATE_CHARGED;
    }
  #endif

  if (battery_ready) {
    pmu_rc++;
    if (pmu_rc%PMU_R_INTERVAL == 0) {
      kiss_indicate_battery();
    }
  }
}

void update_pmu() {
  if (millis()-last_pmu_update >= pmu_update_interval) {
    measure_battery();
    last_pmu_update = millis();
  }
}

bool init_pmu() {
  #if BOARD_MODEL == BOARD_RNODE_NG_21 || BOARD_MODEL == BOARD_LORA32_V2_1
    pinMode(pin_vbat, INPUT);
    return true;
  #elif BOARD_MODEL == BOARD_TBEAM
    Wire.begin(I2C_SDA, I2C_SCL);

    if (!PMU) {
        PMU = new XPowersAXP2101(PMU_WIRE_PORT);
        if (!PMU->init()) {
            Serial.println("Warning: Failed to find AXP2101 power management");
            delete PMU;
            PMU = NULL;
        } else {
            Serial.println("AXP2101 PMU init succeeded, using AXP2101 PMU");
        }
    }

    if (!PMU) {
        PMU = new XPowersAXP192(PMU_WIRE_PORT);
        if (!PMU->init()) {
            Serial.println("Warning: Failed to find AXP192 power management");
            delete PMU;
            PMU = NULL;
        } else {
            Serial.println("AXP192 PMU init succeeded, using AXP192 PMU");
        }
    }

    if (!PMU) {
        return false;
    }

    // Configure charging indicator
    PMU->setChargingLedMode(XPOWERS_CHG_LED_OFF);

    pinMode(PMU_IRQ, INPUT_PULLUP);
    attachInterrupt(PMU_IRQ, setPmuFlag, FALLING);

    if (PMU->getChipModel() == XPOWERS_AXP192) {

      // Turn off unused power sources to save power
      PMU->disablePowerOutput(XPOWERS_DCDC1);
      PMU->disablePowerOutput(XPOWERS_DCDC2);
      PMU->disablePowerOutput(XPOWERS_LDO2);
      PMU->disablePowerOutput(XPOWERS_LDO3);

      // Set the power of LoRa and GPS module to 3.3V
      // LoRa
      PMU->setPowerChannelVoltage(XPOWERS_LDO2, 3300);
      // GPS
      PMU->setPowerChannelVoltage(XPOWERS_LDO3, 3300);
      // OLED
      PMU->setPowerChannelVoltage(XPOWERS_DCDC1, 3300);

      // Turn on LoRa
      PMU->enablePowerOutput(XPOWERS_LDO2);

      // Turn on GPS
      //PMU->enablePowerOutput(XPOWERS_LDO3);

      // protected oled power source
      PMU->setProtectedChannel(XPOWERS_DCDC1);
      // protected esp32 power source
      PMU->setProtectedChannel(XPOWERS_DCDC3);
      // enable oled power
      PMU->enablePowerOutput(XPOWERS_DCDC1);

      PMU->disableIRQ(XPOWERS_AXP192_ALL_IRQ);

      PMU->enableIRQ(XPOWERS_AXP192_VBUS_REMOVE_IRQ |
                      XPOWERS_AXP192_VBUS_INSERT_IRQ |
                      XPOWERS_AXP192_BAT_CHG_DONE_IRQ |
                      XPOWERS_AXP192_BAT_CHG_START_IRQ |
                      XPOWERS_AXP192_BAT_REMOVE_IRQ |
                      XPOWERS_AXP192_BAT_INSERT_IRQ |
                      XPOWERS_AXP192_PKEY_SHORT_IRQ
                    );

    }
    else if (PMU->getChipModel() == XPOWERS_AXP2101) {

      // Turn off unused power sources to save power
      PMU->disablePowerOutput(XPOWERS_DCDC2);
      PMU->disablePowerOutput(XPOWERS_DCDC3);
      PMU->disablePowerOutput(XPOWERS_DCDC4);
      PMU->disablePowerOutput(XPOWERS_DCDC5);
      PMU->disablePowerOutput(XPOWERS_ALDO1);
      PMU->disablePowerOutput(XPOWERS_ALDO2);
      PMU->disablePowerOutput(XPOWERS_ALDO3);
      PMU->disablePowerOutput(XPOWERS_ALDO4);
      PMU->disablePowerOutput(XPOWERS_BLDO1);
      PMU->disablePowerOutput(XPOWERS_BLDO2);
      PMU->disablePowerOutput(XPOWERS_DLDO1);
      PMU->disablePowerOutput(XPOWERS_DLDO2);
      PMU->disablePowerOutput(XPOWERS_VBACKUP);

      // Set the power of LoRa and GPS module to 3.3V
      // LoRa
      PMU->setPowerChannelVoltage(XPOWERS_ALDO2, 3300);
      // GPS
      PMU->setPowerChannelVoltage(XPOWERS_ALDO3, 3300);
      PMU->setPowerChannelVoltage(XPOWERS_VBACKUP, 3300);

      // ESP32 VDD
      // ! No need to set, automatically open , Don't close it
      // PMU->setPowerChannelVoltage(XPOWERS_DCDC1, 3300);
      // PMU->setProtectedChannel(XPOWERS_DCDC1);
      PMU->setProtectedChannel(XPOWERS_DCDC1);

      // LoRa VDD
      PMU->enablePowerOutput(XPOWERS_ALDO2);

      // GNSS VDD
      //PMU->enablePowerOutput(XPOWERS_ALDO3);

      // GNSS RTC PowerVDD
      //PMU->enablePowerOutput(XPOWERS_VBACKUP);
    }

    PMU->enableSystemVoltageMeasure();
    PMU->enableVbusVoltageMeasure();
    PMU->enableBattVoltageMeasure();
    // It is necessary to disable the detection function of the TS pin on the board
    // without the battery temperature detection function, otherwise it will cause abnormal charging
    PMU->disableTSPinMeasure();

    // Set the time of pressing the button to turn off
    PMU->setPowerKeyPressOffTime(XPOWERS_POWEROFF_4S);

    return true; 
  #elif BOARD_MODEL == BOARD_RAK4631
    // board doesn't have PMU but we can measure batt voltage

    // prep ADC for reading battery level
    analogReference(AR_INTERNAL_3_0);

    // Set the resolution to 12-bit (0..4095)
    analogReadResolution(12);

    // Let the ADC settle
    delay(1);

    // Get a single ADC sample and throw it away
    float raw = analogRead(PIN_VBAT);
    return true;
  #else
    return false;
  #endif
}