#include "MQ-2.h"

#include "esp_adc/adc_oneshot.h"
#include "esp_check.h"

#define MQ2_ADC_UNIT ADC_UNIT_1
#define MQ2_ADC_CHANNEL ADC_CHANNEL_7
#define MQ2_SAMPLE_COUNT 8

static const char *TAG = "MQ2";
static adc_oneshot_unit_handle_t s_adc_handle = NULL;
static bool s_inited = false;

esp_err_t mq2_init(void)
{
	if (s_inited) {
		return ESP_OK;
	}

	adc_oneshot_unit_init_cfg_t init_cfg = {
		.unit_id = MQ2_ADC_UNIT,
		.ulp_mode = ADC_ULP_MODE_DISABLE,
	};
	ESP_RETURN_ON_ERROR(adc_oneshot_new_unit(&init_cfg, &s_adc_handle), TAG, "adc new unit failed");

	adc_oneshot_chan_cfg_t chan_cfg = {
		.atten = ADC_ATTEN_DB_12,
		.bitwidth = ADC_BITWIDTH_DEFAULT,
	};
	ESP_RETURN_ON_ERROR(adc_oneshot_config_channel(s_adc_handle, MQ2_ADC_CHANNEL, &chan_cfg),
						TAG, "adc channel config failed");

	s_inited = true;
	return ESP_OK;
}

esp_err_t mq2_read_raw(int *raw_out)
{
	ESP_RETURN_ON_FALSE(raw_out != NULL, ESP_ERR_INVALID_ARG, TAG, "raw_out is null");
	ESP_RETURN_ON_FALSE(s_inited, ESP_ERR_INVALID_STATE, TAG, "mq2 not inited");

	int sum = 0;
	for (int i = 0; i < MQ2_SAMPLE_COUNT; ++i) {
		int sample = 0;
		ESP_RETURN_ON_ERROR(adc_oneshot_read(s_adc_handle, MQ2_ADC_CHANNEL, &sample),
							TAG, "adc read failed");
		sum += sample;
	}

	*raw_out = sum / MQ2_SAMPLE_COUNT;
	return ESP_OK;
}

esp_err_t mq2_read_percent(float *percent_out)
{
	ESP_RETURN_ON_FALSE(percent_out != NULL, ESP_ERR_INVALID_ARG, TAG, "percent_out is null");

	int raw = 0;
	ESP_RETURN_ON_ERROR(mq2_read_raw(&raw), TAG, "read raw failed");
	*percent_out = (raw * 100.0f) / 4095.0f;
	return ESP_OK;
}

bool mq2_is_alarm(float percent, float threshold_percent)
{
	return percent >= threshold_percent;
}