/*
 * This file 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 file 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/>.
 *
 * Code by Charlie Johnson
 */

#include <AP_HAL/AP_HAL.h>
#include <AP_Math/AP_Math.h>
#include "AP_BattMonitor_FuelLevel_Analog.h"

extern const AP_HAL::HAL& hal;

const AP_Param::GroupInfo AP_BattMonitor_FuelLevel_Analog::var_info[] = {

    // @Param: FL_VLT_MIN
    // @DisplayName: Empty fuel level voltage
    // @Description: The voltage seen on the analog pin when the fuel tank is empty. Note: For this type of battery monitor, the voltage seen by the analog pin is displayed as battery voltage on a GCS.
    // @Range: 0.01 10
    // @Units: V
    // @User: Advanced
    AP_GROUPINFO("FL_VLT_MIN", 40, AP_BattMonitor_FuelLevel_Analog, _fuel_level_empty_voltage, 0.5),

    // @Param: FL_V_MULT
    // @DisplayName: Fuel level voltage multiplier
    // @Description: Voltage multiplier to determine what the full tank voltage reading is. This is calculated as 1 / (Voltage_Full - Voltage_Empty) Note: For this type of battery monitor, the voltage seen by the analog pin is displayed as battery voltage on a GCS.
    // @Range: 0.01 10
    // @User: Advanced
    AP_GROUPINFO("FL_V_MULT", 41, AP_BattMonitor_FuelLevel_Analog, _fuel_level_voltage_mult, 0.5),

    // @Param: FL_FLTR
    // @DisplayName: Fuel level filter frequency
    // @Description: Filter frequency in Hertz where a low pass filter is used. This is used to filter out tank slosh from the fuel level reading. A value of -1 disables the filter and unfiltered voltage is used to determine the fuel level. The suggested values at in the range of 0.2 Hz to 0.5 Hz.
    // @Range: -1 1
    // @User: Advanced
    // @Units: Hz
    // @RebootRequired: True
    AP_GROUPINFO("FL_FLTR", 42, AP_BattMonitor_FuelLevel_Analog, _fuel_level_filter_frequency, 0.3),

    // @Param: FL_PIN
    // @DisplayName: Fuel level analog pin number
    // @Description: Analog input pin that fuel level sensor is connected to. Airspeed ports can be used for Analog input. When using analog pin 103, the maximum value of the input in 3.3V.
    // @Values: -1:Not Used,11:Pixracer,13:Pixhawk ADC4,14:Pixhawk ADC3,15:Pixhawk ADC6/Pixhawk2 ADC,103:Pixhawk SBUS
    AP_GROUPINFO("FL_PIN", 43, AP_BattMonitor_FuelLevel_Analog, _pin, -1),

    // Param indexes must be between 40 and 49 to avoid conflict with other battery monitor param tables loaded by pointer

    AP_GROUPEND
};

// Constructor
AP_BattMonitor_FuelLevel_Analog::AP_BattMonitor_FuelLevel_Analog(AP_BattMonitor &mon, AP_BattMonitor::BattMonitor_State &mon_state, AP_BattMonitor_Params &params) :
    AP_BattMonitor_Backend(mon, mon_state, params)
{
    AP_Param::setup_object_defaults(this, var_info);
    _state.var_info = var_info;

    _analog_source = hal.analogin->channel(_pin);

    // create a low pass filter
    // use a pole at 0.3 Hz if the filter is not being used
    _voltage_filter.set_cutoff_frequency((_fuel_level_filter_frequency >= 0) ? _fuel_level_filter_frequency : 0.3f);
}

/*
  read - read the "voltage" and "current"
*/
void AP_BattMonitor_FuelLevel_Analog::read()
{
    if (_analog_source == nullptr) {
        return;
    }

    if (!_analog_source->set_pin(_pin)) {
        _state.healthy = false;
        return;
    }
    _state.healthy = true;

    // get a dt and a timestamp
    const uint32_t tnow = AP_HAL::micros();
    const uint32_t dt_us = tnow - _state.last_time_micros;

    // get voltage from an ADC pin and filter it
    const float voltage = _analog_source->voltage_average();
    const float filtered_voltage = _voltage_filter.apply(voltage, float(dt_us) * 1.0e-6f);
    const float &voltage_used = (_fuel_level_filter_frequency >= 0) ? filtered_voltage : voltage;

    // output the ADC voltage to the voltage field for easier calibration of sensors
    // also output filtered voltage as a measure of tank slosh filtering
    // this could be useful for tuning the LPF
    _state.voltage = voltage;
    _state.current_amps = filtered_voltage;

    // this driver assumes that CAPACITY is set to tank volume in millilitres.
    // _fuel_level_voltage_mult is calculated by the user as 1 / (full_voltage - empty_voltage)
    const float fuel_level_ratio = (voltage_used - _fuel_level_empty_voltage) * _fuel_level_voltage_mult;
    const float fuel_level_used_ratio = 1.0 - fuel_level_ratio;

    // map consumed_mah to consumed millilitres
    _state.consumed_mah = fuel_level_used_ratio * _params._pack_capacity;

    // map consumed_wh using fixed voltage of 1
    _state.consumed_wh = _state.consumed_mah;

    // record time
    _state.last_time_micros = tnow;
}
