#include "Arduino.h"

#include "HermitCrab.h"
#include "NTC_10K.h"
#include "Config.h"

const float resistance[] = {
		3360850.37, // -40°C
		1973470.32, // -35°C
		1179560.43, // -30°C
		718858.73, // -25°C
		445267.47, // -20°C
		281046.96, // -15°C
		180321.36, // -10°C
		117081.11, //  -5°C
		77147.90, //   0°C
		51471.97, //   5°C
		34838.43, //  10°C
		23847.63, //  15°C

		16594.38, //  20°C
		12307.39, //  21°C
		11739.87, //  22°C
		11203.64, //  23°C
		10696.86, //  24°C
		10217.84, //  25°C
		9527.52, //  26°C
		9076.66, //  27°C
		8656.02, //  28°C
		8263.81, //  29°C
		7897.84, //  30°C
		
		5868.86, //  35°C
		4383.72, //  40°C
		3315.12, //  45°C
		2527.73, //  50°C
		1942.15, //  55°C
		1505.11, //  60°C
		1174.71, //  65°C
		926.23, //  70°C
		735.99, //  75°C
		588.91, //  80°C
		474.43, //  85°C
		384.48, //  90°C
		313.88, //  95°C
		258.87, // 100°C
		215.64, // 105°C
		181.10, // 110°C
		153.01, // 115°C
		129.77, // 120°C
		110.27, // 125°C
		94.03, // 130°C
		80.13, // 135°C
		68.18, // 140°C
		57.99, // 145°C
		49.30  // 150°C
		};

const int16_t	temp_C[] = {
		-40, -35, -30, -25, -20, -15, -10, -5, 0, 5, 10, 15,
		20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
		35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100,
		105, 110, 115, 120, 125, 130, 135, 140, 145, 150 };

NTC_10K ntc;

void NTC_10K::setup(bool bNegativePolarity) {
	m_bNegativePolarity = bNegativePolarity;
	_vRef = 3.3f;
	_RESO = 4095;
	for (int i = 0; i < 16; i++) temps[i] = 0;
	temp_idx = 0;
	temp_sum = 0;

	pinMode(PIN_NTC, INPUT);          // Set PIN_NTC as input
    analogReadResolution(12);        // Set ADC resolution to 12 bits (0-4095)
    analogSetAttenuation(ADC_11db);  // Set attenuation for full-scale 3.3V
}

void NTC_10K::readSensor() {
    float Vin;
	int16_t temp;
	static int16_t lastTemp = 0;

    int adcValue = analogRead(PIN_NTC); // Read ADC value from PIN_NTC

    // Calculate the input voltage from the ADC reading
    Vin = (float)adcValue * _vRef / _RESO; 

    // Calculate the resistance of the thermistor
    // Calculate the resistance of the thermistor (adjusted for inverted ADC behavior)
	
	float r;
	if (m_bNegativePolarity) {
		// NTC is connected to Negative
		r = (Vin / (_vRef - Vin)) * rRef;
	} else {
		// NTC is connected to Positive
		r = ((_vRef - Vin) / Vin) * rRef;
	}

    // Find the index of the resistance in the table where r is between resistance[i-1] and resistance[i]
    int i = 0;
    while (i < sizeof(resistance) / sizeof(resistance[0]) - 1 && resistance[i] > r) {
        i++;
    }

    // If r is out of range, return the closest extreme temperature
    if (i == 0 || i == sizeof(resistance) / sizeof(resistance[0]) - 1) {
		if (lastTemp != 0) temp = lastTemp;
        else temp = 0;
    }
	else {
		// Interpolate between resistance[i-1] and resistance[i]
		float m = (temp_C[i] - temp_C[i - 1]) / (resistance[i] - resistance[i - 1]); // Slope
		float b = temp_C[i - 1] - (m * resistance[i - 1]);                          // Intercept
		temp = (int16_t) roundf((m * r + b) * 10.0f);
	}

    // Return the temperature as an integer scaled by 10 (e.g., 25.3°C => 253)
	temp_sum -= temps[temp_idx];
	temps[temp_idx++] = temp; 
	temp_idx &= NTC_MASK;
	temp_sum += temp;
	lastTemp = temp;
	m_nTemp = temp_sum / NTC_COUNT;
}