#include "fs3000.h"
#include "esphome/core/log.h"

namespace esphome::fs3000 {

static const char *const TAG = "fs3000";

void FS3000Component::setup() {
  if (model_ == FIVE) {
    // datasheet gives 9 points to interpolate from for the 1005 model
    static const uint16_t RAW_DATA_POINTS_1005[9] = {409, 915, 1522, 2066, 2523, 2908, 3256, 3572, 3686};
    static const float MPS_DATA_POINTS_1005[9] = {0.0, 1.07, 2.01, 3.0, 3.97, 4.96, 5.98, 6.99, 7.23};

    std::copy(RAW_DATA_POINTS_1005, RAW_DATA_POINTS_1005 + 9, this->raw_data_points_);
    std::copy(MPS_DATA_POINTS_1005, MPS_DATA_POINTS_1005 + 9, this->mps_data_points_);
  } else if (model_ == FIFTEEN) {
    // datasheet gives 13 points to extrapolate from for the 1015 model
    static const uint16_t RAW_DATA_POINTS_1015[13] = {409,  1203, 1597, 1908, 2187, 2400, 2629,
                                                      2801, 3006, 3178, 3309, 3563, 3686};
    static const float MPS_DATA_POINTS_1015[13] = {0.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 13.0, 15.0};

    std::copy(RAW_DATA_POINTS_1015, RAW_DATA_POINTS_1015 + 13, this->raw_data_points_);
    std::copy(MPS_DATA_POINTS_1015, MPS_DATA_POINTS_1015 + 13, this->mps_data_points_);
  }
}

void FS3000Component::update() {
  // 5 bytes of data read from fs3000 sensor
  //  byte 1 - checksum
  //  byte 2 - (lower 4 bits) high byte of sensor reading
  //  byte 3 - (8 bits) low byte of sensor reading
  //  byte 4 - generic checksum data
  //  byte 5 - generic checksum data

  uint8_t data[5];

  if (!this->read_bytes_raw(data, 5)) {
    this->status_set_warning();
    ESP_LOGW(TAG, "Error reading data from FS3000");
    this->publish_state(NAN);
    return;
  }

  // checksum passes if the modulo 256 sum of the five bytes is 0
  uint8_t checksum = 0;
  for (uint8_t i : data) {
    checksum += i;
  }

  if (checksum != 0) {
    this->status_set_warning();
    ESP_LOGW(TAG, "Checksum failure when reading from FS3000");
    return;
  }

  // raw value information is 12 bits
  uint16_t raw_value = (data[1] << 8) | data[2];
  ESP_LOGV(TAG, "Got raw reading=%i", raw_value);

  // convert and publish the raw value into m/s using the table of data points in the datasheet
  this->publish_state(fit_raw_(raw_value));

  this->status_clear_warning();
}

void FS3000Component::dump_config() {
  ESP_LOGCONFIG(TAG, "FS3000:");
  LOG_I2C_DEVICE(this);
  LOG_UPDATE_INTERVAL(this);
  LOG_SENSOR("  ", "Air Velocity", this);
}

float FS3000Component::fit_raw_(uint16_t raw_value) {
  // converts a raw value read from the FS3000 into a speed in m/s based on the
  // reference data points given in the datasheet
  // fits raw reading using a linear interpolation between each data point

  uint8_t end = 8;  // assume model 1005, which has 9 data points
  if (this->model_ == FIFTEEN)
    end = 12;  // model 1015 has 13 data points

  if (raw_value <= this->raw_data_points_[0]) {  // less than smallest data point returns first data point
    return this->mps_data_points_[0];
  } else if (raw_value >= this->raw_data_points_[end]) {  // greater than largest data point returns max speed
    return this->mps_data_points_[end];
  } else {
    uint8_t i = 0;

    // determine between which data points does the reading fall, i-1 and i
    while (raw_value > this->raw_data_points_[i]) {
      ++i;
    }

    // calculate the slope of the secant line between the two data points that surrounds the reading
    float slope = (this->mps_data_points_[i] - this->mps_data_points_[i - 1]) /
                  (this->raw_data_points_[i] - this->raw_data_points_[i - 1]);

    // return the interpolated value for the reading
    return (float(raw_value - this->raw_data_points_[i - 1])) * slope + this->mps_data_points_[i - 1];
  }
}

}  // namespace esphome::fs3000
