#include "ads1115_int.h"
#include "esphome/core/hal.h"
#include "esphome/core/log.h"

namespace esphome {
namespace ads1115_int {

static const char *const TAG = "ads1115_int";
static const uint8_t ADS1115_REGISTER_CONVERSION = 0x00;
static const uint8_t ADS1115_REGISTER_CONFIG = 0x01;
static const uint8_t ADS1115_REGISTER_LO_TRESH = 0x02;
static const uint8_t ADS1115_REGISTER_HI_TRESH = 0x03;

void ADS1115Component::setup() {
  uint16_t value;
  this->alert_pin_->setup();
  this->alert_pin_->attach_interrupt(&ADS1115Component::isr, this, gpio::INTERRUPT_FALLING_EDGE);
  if (!this->read_byte_16(ADS1115_REGISTER_CONVERSION, &value)) {
    this->mark_failed();
    return;
  }
  uint16_t config = 0;
  // Clear single-shot bit
  //        0b0xxxxxxxxxxxxxxx
  config |= 0b0000000000000000;
  // Setup multiplexer
  //        0bx000xxxxxxxxxxxx
  config |= ADS1115_MULTIPLEXER_P0_N1 << 12;

  // Setup Gain
  //        0bxxxx000xxxxxxxxx
  config |= ADS1115_GAIN_6P144 << 9;

  if (this->continuous_mode_) {
    // Set continuous mode
    //        0bxxxxxxx0xxxxxxxx
    config |= 0b0000000000000000;
  } else {
    // Set singleshot mode
    //        0bxxxxxxx1xxxxxxxx
    config |= 0b0000000100000000;
  }

  // Set data rate - 860 samples per second
  //        0bxxxxxxxx100xxxxx
  config |= ADS1115_860SPS << 5;

  // Set comparator mode - hysteresis
  //        0bxxxxxxxxxxx0xxxx
  config |= 0b0000000000000000;

  // Set comparator polarity - active low
  //        0bxxxxxxxxxxxx0xxx
  config |= 0b0000000000000000;

  // Set comparator latch enabled - false
  //        0bxxxxxxxxxxxxx0xx
  config |= 0b0000000000000000;

  // Set comparator que mode - disabled
  //        0bxxxxxxxxxxxxxx11
  config |= 0b0000000000000011;

  if (!this->write_byte_16(ADS1115_REGISTER_CONFIG, config)) {
    this->mark_failed();
    return;
  }
  this->prev_config_ = config;
  if(!this->set_data_ready_mode()) {
    this->mark_failed();
    return;
  }
}
bool ADS1115Component::set_data_ready_mode() 
{
  uint16_t config = this->prev_config_;
  // Set comparator que mode - assert after one conversion
  //        0bxxxxxxxxxxxxxx00
  config &= 0b1111111111111100;

  if (!this->write_byte_16(ADS1115_REGISTER_CONFIG, config)) {
    return false;
  }
  this->prev_config_ = config;
  if(!this->write_byte_16(ADS1115_REGISTER_HI_TRESH, 0x8000)) {
    return false;
  }
  if(!this->write_byte_16(ADS1115_REGISTER_LO_TRESH, 0x0000)) {
    return false;
  }
  // also clear all data_ready_ flags
  for (int i = 0; i < 8; i++)
    this->data_ready_[i] = false; 
  return true;
}
// ISR function to handle interrupt from alert pin  
// only function that sets data_ready_ flags
void IRAM_ATTR ADS1115Component::isr(ADS1115Component *arg) 
{
  for (int i = 0; i < 8; i++)
    arg->data_ready_[i] = true; 
}
bool ADS1115Component::is_data_ready(ADS1115Multiplexer multiplexer)
{
  int index = static_cast<int>(multiplexer);
  if(index < 0 || index >= 8)
    return false;
  return this->data_ready_[index];
}
void ADS1115Component::clear_data_ready(ADS1115Multiplexer multiplexer)
{
  int index = static_cast<int>(multiplexer);
  if(index < 0 || index >= 8)
    return;
  this->data_ready_[index] = false;
}

// call only when data_ready_ is true
double ADS1115Component::read_data(int16_t& raw_value, ADS1115Multiplexer multiplexer, ADS1115Gain gain, ADS1115Resolution resolution, ADS1115Samplerate samplerate) 
{
  uint16_t config = this->prev_config_;
  // Multiplexer
  //        0bxBBBxxxxxxxxxxxx
  config &= 0b1000111111111111;
  config |= (multiplexer & 0b111) << 12;

  // Gain
  //        0bxxxxBBBxxxxxxxxx
  config &= 0b1111000111111111;
  config |= (gain & 0b111) << 9;

  // Sample rate
  //        0bxxxxxxxxBBBxxxxx
  config &= 0b1111111100011111;
  config |= (samplerate & 0b111) << 5;

  if (!this->continuous_mode_) {
    // Start conversion
    config |= 0b1000000000000000;
  }

  this->clear_data_ready(multiplexer);
  //ESP_LOGI(TAG, "'mux:%d': Gain=%d, Res=%d, CONF=<0x%04X>", static_cast<int>(multiplexer), static_cast<int>(gain), static_cast<int>(resolution), config);
  // write config if in single-shot mode or config has changed
  if (!this->continuous_mode_ || this->prev_config_ != config) {
    if (!this->write_byte_16(ADS1115_REGISTER_CONFIG, config)) {
      this->status_set_warning();
      return false;
    }
    this->prev_config_ = config;
    //
    // removed delay
    //
    if (!this->continuous_mode_) {
      uint32_t start = millis();
      // wait for conversion to complete
      while (this->read_byte_16(ADS1115_REGISTER_CONFIG, &config) && (config >> 15) == 0) {
        if (millis() - start > 100) {
          ESP_LOGW(TAG, "Reading ADS1115 timed out");
          this->status_set_warning();
          return NAN;
        }
        yield();
      }
    }
  }
  uint16_t raw_conversion;
  if (!this->read_byte_16(ADS1115_REGISTER_CONVERSION, &raw_conversion)) {
    this->status_set_warning();
    return NAN;
  }
  //ESP_LOGI(TAG, "'mux:%d': raw=<0x%04X>", static_cast<int>(multiplexer), raw_conversion);

  if (resolution == ADS1015_12_BITS) {
    bool negative = (raw_conversion >> 15) == 1;

    // shift raw_conversion as it's only 12-bits, left justified
    raw_conversion = raw_conversion >> (16 - ADS1015_12_BITS);

    // check if number was negative in order to keep the sign
    if (negative) {
      // the number was negative
      // 1) set the negative bit back
      raw_conversion |= 0x8000;
      // 2) reset the former (shifted) negative bit
      raw_conversion &= 0xF7FF;
    }
  }
  auto signed_conversion = static_cast<int16_t>(raw_conversion);
  raw_value = signed_conversion;
  double millivolts;
  double divider = (resolution == ADS1115_16_BITS) ? 32768.0f : 2048.0f;
  switch (gain) {
    case ADS1115_GAIN_6P144:
      millivolts = (signed_conversion * 6144) / divider;
      break;
    case ADS1115_GAIN_4P096:
      millivolts = (signed_conversion * 4096) / divider;
      break;
    case ADS1115_GAIN_2P048:
      millivolts = (signed_conversion * 2048) / divider;
      break;
    case ADS1115_GAIN_1P024:
      millivolts = (signed_conversion * 1024) / divider;
      break;
    case ADS1115_GAIN_0P512:
      millivolts = (signed_conversion * 512) / divider;
      break;
    case ADS1115_GAIN_0P256:
      millivolts = (signed_conversion * 256) / divider;
      break;
    default:
      millivolts = NAN;
  }

  this->status_clear_warning();
  return millivolts / 1e3f;
}

void ADS1115Component::dump_config()
{
  ESP_LOGCONFIG(TAG, "ADS1115_INT:");
  LOG_I2C_DEVICE(this);
  LOG_PIN("  ALERT Pin:", this->alert_pin_);    
  if (this->is_failed()) {
    ESP_LOGE(TAG, ESP_LOG_MSG_COMM_FAIL);
  }
}


}  // namespace ads1115_int
}  // namespace esphome