#include "mcp9808.h"
#include "esphome/core/log.h"

namespace esphome {
namespace mcp9808 {

static const uint8_t MCP9808_REG_AMBIENT_TEMP = 0x05;
static const uint8_t MCP9808_REG_MANUF_ID = 0x06;
static const uint8_t MCP9808_REG_DEVICE_ID = 0x07;

static const uint16_t MCP9808_MANUF_ID = 0x0054;
static const uint16_t MCP9808_DEV_ID = 0x0400;

static const uint8_t MCP9808_AMBIENT_CLEAR_FLAGS = 0x1F;
static const uint8_t MCP9808_AMBIENT_CLEAR_SIGN = 0x0F;
static const uint8_t MCP9808_AMBIENT_TEMP_NEGATIVE = 0x10;

static const char *const TAG = "mcp9808";

void MCP9808Sensor::setup() {
  uint16_t manu = 0;
  if (!this->read_byte_16(MCP9808_REG_MANUF_ID, &manu) || manu != MCP9808_MANUF_ID) {
    this->mark_failed();
    ESP_LOGE(TAG, "Incorrect manufacturer ID (%X) for '%s'", manu, this->name_.c_str());
    return;
  }
  uint16_t dev_id = 0;
  if (!this->read_byte_16(MCP9808_REG_DEVICE_ID, &dev_id) || dev_id != MCP9808_DEV_ID) {
    this->mark_failed();
    ESP_LOGE(TAG, "Incorrect device ID (%X) for '%s'", dev_id, this->name_.c_str());
    return;
  }
}
void MCP9808Sensor::dump_config() {
  ESP_LOGCONFIG(TAG, "%s:", this->name_.c_str());
  LOG_I2C_DEVICE(this);
  if (this->is_failed()) {
    ESP_LOGE(TAG, ESP_LOG_MSG_COMM_FAIL_FOR, this->name_.c_str());
  }
  LOG_UPDATE_INTERVAL(this);
  LOG_SENSOR("  ", "Temperature", this);
}
void MCP9808Sensor::update() {
  uint16_t raw_temp;
  if (!this->read_byte_16(MCP9808_REG_AMBIENT_TEMP, &raw_temp)) {
    this->status_set_warning();
    return;
  }
  if (raw_temp == 0xFFFF) {
    this->status_set_warning();
    return;
  }

  float temp = NAN;
  uint8_t msb = (uint8_t) ((raw_temp & 0xff00) >> 8);
  uint8_t lsb = raw_temp & 0x00ff;

  msb = msb & MCP9808_AMBIENT_CLEAR_FLAGS;

  if ((msb & MCP9808_AMBIENT_TEMP_NEGATIVE) == MCP9808_AMBIENT_TEMP_NEGATIVE) {
    msb = msb & MCP9808_AMBIENT_CLEAR_SIGN;
    temp = (256 - ((uint16_t) (msb) *16 + lsb / 16.0f)) * -1;
  } else {
    temp = (uint16_t) (msb) *16 + lsb / 16.0f;
  }

  if (std::isnan(temp)) {
    this->status_set_warning();
    return;
  }

  ESP_LOGD(TAG, "%s: Got temperature=%.4f°C", this->name_.c_str(), temp);
  this->publish_state(temp);
  this->status_clear_warning();
}

}  // namespace mcp9808
}  // namespace esphome
