/*
 * @file rsense.cpp
 * @brief Radiation sensor implementation
 *
 * Created: 21.09.2025
 * Author: ThePetrovich
 *
 * Copyright YKSA - Sakha Aerospace Systems, LLC.
 * See the LICENSE file for details.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include <Arduino.h>
#include <Event.h>
#include <Logic.h>
#include <SPI.h>
#include <stdint.h>
#include <util/atomic.h>

#include "config.h"
#include "eeprom.h"
#include "iodefs.h"
#include "rsense.h"
#include "utils.h"

static volatile union __attribute__((packed)) {
	uint16_t channels_16[DETECTOR_CHANNEL_COUNT];
	uint32_t channels_32[DETECTOR_CHANNEL_32_COUNT];
} g_detector_counts = {0};

static uint8_t g_spectrum_mode = 0; // 0 = 16-bit, 1 = 32-bit

static uint16_t g_read_pointer = 0;
static uint32_t g_total_counts = 0;
static uint32_t g_total_time = 0;
static uint32_t g_flush_time = 0;
static volatile uint16_t g_counts_cpm = 0;

static uint32_t g_cpm_time = 0;
static uint16_t g_cpm_last = 0;

static potentiometer_settings_t g_current_pot_settings;

static void apply_potentiometer_settings(const potentiometer_settings_t *settings);
static void initialize_event_system(void);
static void enable_fast_adc(void);
static void restore_default_adc(void);
static inline void handle_analog_read_interrupt(void);
static void clear_detector_counters(void);
static void clear_channel_data(void);
static void set_potentiometer_values(uint8_t hv, uint8_t amp, uint8_t det);
static void send_temperature_data(void);

void rsense_init(void)
{
	eeprom_load_pot_settings(&g_current_pot_settings);

	pinMode(HV_EN, OUTPUT);
	pinMode(DET_EN, OUTPUT);
	pinMode(DET_RST, OUTPUT);

	// Disable HV and Detector on startup
	digitalWrite(HV_EN, LOW);
	digitalWrite(DET_EN, LOW);

	pinMode(HV_CS, OUTPUT);
	pinMode(DET_CS, OUTPUT);
	pinMode(AMP_CS, OUTPUT);

	digitalWrite(HV_CS, HIGH);
	digitalWrite(DET_CS, HIGH);
	digitalWrite(AMP_CS, HIGH);

	apply_potentiometer_settings(&g_current_pot_settings);

	pinMode(DET_TRIG_PIN, INPUT);

	initialize_event_system();
}

/**
 * @brief Initialize event system for radiation detection
 */
static void initialize_event_system(void)
{
	// Enable event on DET_TRIG_PIN
	Event2.set_generator(event::gen2::pin_pc7);
	Event2.set_user(event::user::adc0_start);

	// Pin events are async, level; convert to sync, edge via CCL
	// Logic0.enable = true;
	// Logic0.input0 = logic::in::event_a;
	// Logic0.input1 = logic::in::masked;
	// Logic0.input2 = logic::in::masked;
	// Logic0.output = logic::out::enable;
	// Logic0.output_swap = logic::out::no_swap;
	// Logic0.filter = logic::filter::synchronizer;
	// Logic0.edgedetect = logic::edgedetect::enable;
	// Logic0.clocksource = logic::clocksource::clk_per;
	// Logic0.sequencer = logic::sequencer::disable;
	// Logic0.truth = 0b00000010; // A and not previous A
	// Logic0.init();

	// Route CCL output to ADC
	// Event0.set_generator(event::gen::ccl0_out);
	// Event0.set_user(event::user::adc0_start);

	//Event0.start();
	Event2.start();
}

/**
 * @brief Enable ADC for fast radiation detection
 */
static void enable_fast_adc(void)
{
	ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
	{
		ADC0.CTRLA |= ADC_ENABLE_bm;

		// Enable oversampling x16 for 12-bit result
		#if ADC_OVERSAMPLING_BITS == 1
			ADC0.CTRLB |= ADC_SAMPNUM_ACC4_gc;
		#elif ADC_OVERSAMPLING_BITS == 2
			ADC0.CTRLB |= ADC_SAMPNUM_ACC16_gc;
		#elif ADC_OVERSAMPLING_BITS == 3
			ADC0.CTRLB |= ADC_SAMPNUM_ACC64_gc;
		#else 
			#error "Unsupported ADC oversampling setting"
		#endif

		ADC0.CTRLC = 0;						 // reset
		ADC0.CTRLC |= ADC_PRESC_DIV32_gc | ADC_REFSEL_VDDREF_gc; // CLK_PER/32, VDD as reference

		// Enable interrupt on conversion complete
		ADC0.EVCTRL |= ADC_STARTEI_bm; // Start event input
		ADC0.INTCTRL |= ADC_RESRDY_bm;

		// Configure VREF, Microchip DS40002015B page 424
		VREF.CTRLA |= VREF_ADC0REFSEL_4V34_gc;

		// Select ADC channel
		ADC0.MUXPOS = ADC_MUXPOS_AIN3_gc; // DET_SIG_PIN
	}
}

/**
 * @brief Restore ADC to default settings
 */
static void restore_default_adc(void)
{
	ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
	{
		// Disable oversampling
		ADC0.CTRLB &= ~ADC_SAMPNUM_gm;

		// Set reference back to VREFA
		ADC0.CTRLC &= ~ADC_REFSEL_gm;
		ADC0.CTRLC |= ADC_REFSEL_VREFA_gc; // VREFA as reference

		// Disable interrupt on conversion complete
		ADC0.EVCTRL &= ~ADC_STARTEI_bm; // Start event input
		ADC0.INTCTRL &= ~ADC_RESRDY_bm;
	}
}

/**
 * @brief Handle ADC conversion results for radiation detection
 */
static inline void handle_analog_read_interrupt(void)
{
	digitalWriteFast(DET_RST, HIGH);
	uint16_t channel = ADC0.RES; // read result to clear flag
	digitalWriteFast(STATUS_LED, LOW);

	if (g_spectrum_mode == 0) {
		// 16-bit spectrum mode
		// 2 extra bits from oversampling + averaging
		// shift down to equiv. 11 bits
		#if ADC_OVERSAMPLING_BITS == 1
			channel = channel >> 1;
		#elif ADC_OVERSAMPLING_BITS == 2
			channel = channel >> (ADC_OVERSAMPLING_BITS + 1);
		#elif ADC_OVERSAMPLING_BITS == 3
			channel = channel >> (ADC_OVERSAMPLING_BITS + 2);
		#else 
			#error "Unsupported ADC oversampling setting"
		#endif

		g_detector_counts.channels_16[channel & ADC_CHANNEL_16_MASK]++;
	} else {
		// 32-bit spectrum mode
		// 2 extra bits from oversampling + averaging x2
		// shift down to equiv. 10 bits
		#if ADC_OVERSAMPLING_BITS == 1
			channel = channel >> 2;
		#elif ADC_OVERSAMPLING_BITS == 2
			channel = channel >> (ADC_OVERSAMPLING_BITS + 2);
		#elif ADC_OVERSAMPLING_BITS == 3
			channel = channel >> (ADC_OVERSAMPLING_BITS + 3);
		#else 
			#error "Unsupported ADC oversampling setting"
		#endif

		g_detector_counts.channels_32[channel & ADC_CHANNEL_32_MASK]++;
	}

	g_total_counts++;
	g_counts_cpm++;
	digitalWriteFast(DET_RST, LOW);
}

/**
 * @brief Clear all detector counters
 */
static void clear_detector_counters(void)
{
	ATOMIC_BLOCK(ATOMIC_RESTORESTATE)
	{
		g_total_counts = 0;
		g_total_time = 0;
		g_flush_time = millis();
		g_counts_cpm = 0;
		g_cpm_time = millis();
	}
}

/**
 * @brief Clear channel data
 */
static void clear_channel_data(void)
{
	for (int i = 0; i < DETECTOR_CHANNEL_COUNT; i++) {
		g_detector_counts.channels_16[i] = 0;
	}
}

/**
 * @brief Apply potentiometer settings to hardware
 * @param settings Pointer to potentiometer settings
 */
static void apply_potentiometer_settings(const potentiometer_settings_t *settings)
{
	if (settings == nullptr)
		return;

	// HV potentiometer setup
	digitalWrite(HV_CS, LOW);
	SPI.transfer(settings->hv_pot);
	digitalWrite(HV_CS, HIGH);
	delay(1);

	// SiPM Pre-amp gain potentiometer setup
	digitalWrite(AMP_CS, LOW);
	SPI.transfer(settings->amp_pot);
	digitalWrite(AMP_CS, HIGH);
	delay(1);

	// Detection threshold potentiometer setup
	digitalWrite(DET_CS, LOW);
	SPI.transfer(settings->det_pot);
	digitalWrite(DET_CS, HIGH);
	delay(1);
}

/**
 * @brief Set new potentiometer values
 * @param hv High voltage potentiometer value (0-255)
 * @param amp Amplifier potentiometer value (0-255)
 * @param det Detector potentiometer value (0-255)
 */
static void set_potentiometer_values(uint8_t hv, uint8_t amp, uint8_t det)
{
	digitalWrite(DET_EN, LOW);
	digitalWrite(HV_EN, LOW);
	delay(5);

	// Update current settings and save to EEPROM
	g_current_pot_settings.hv_pot = hv;
	g_current_pot_settings.amp_pot = amp;
	g_current_pot_settings.det_pot = det;

	apply_potentiometer_settings(&g_current_pot_settings);

	eeprom_save_pot_settings(&g_current_pot_settings);
}

/*******************************************************************************/
/*******************************************************************************/
/*                             Command handlers                                */
/*******************************************************************************/
/*******************************************************************************/

void rsense_cmd_telemetry(void)
{
	restore_default_adc();

	// Send total counts as 4 bytes
	Serial.write(g_total_counts & 0xFF);
	Serial.write((g_total_counts >> 8) & 0xFF);
	Serial.write((g_total_counts >> 16) & 0xFF);
	Serial.write((g_total_counts >> 24) & 0xFF);

	// 2 bytes of voltage in mV
	uint16_t voltage_raw = read_adc_oversampled(V28V0_FB_PIN, 16);
	uint16_t voltage_mv = adc_to_voltage_mv(voltage_raw);
	Serial.write(voltage_mv & 0xFF);
	Serial.write(voltage_mv >> 8);

	// 6 bytes of temperature data
	send_temperature_data();

	// 3 bytes of potentiometer settings
	Serial.write(g_current_pot_settings.hv_pot);
	Serial.write(g_current_pot_settings.amp_pot);
	Serial.write(g_current_pot_settings.det_pot);

	Serial.flush();
	SERIAL_BUFFER_CLEAR();
	enable_fast_adc();
}

/**
 * @brief Send temperature sensor data
 */
static void send_temperature_data(void)
{
	int16_t hv_temp_c = adc_to_temperature_c(read_adc_oversampled(HV_TEMP_PIN, 16));
	int16_t amp_temp_c = adc_to_temperature_c(read_adc_oversampled(AMP_TEMP_PIN, 16));
	int16_t det_temp_c = adc_to_temperature_c(read_adc_oversampled(DET_TEMP_PIN, 16));

	Serial.write(hv_temp_c & 0xFF);
	Serial.write(hv_temp_c >> 8);
	Serial.write(amp_temp_c & 0xFF);
	Serial.write(amp_temp_c >> 8);
	Serial.write(det_temp_c & 0xFF);
	Serial.write(det_temp_c >> 8);
}

/* TODO: CRC for parameters */
void rsense_cmd_set_potentiometers(void)
{
	// Wait for HV, AMP, DET potentiometer values
	while (Serial.available() < 3)
		;

	uint8_t hv = Serial.read();
	uint8_t amp = Serial.read();
	uint8_t det = Serial.read();

	set_potentiometer_values(hv, amp, det);

	SERIAL_SEND_OK();
}

void rsense_cmd_enable(void)
{
	digitalWrite(HV_EN, HIGH);
	digitalWrite(DET_EN, HIGH);

	enable_fast_adc();

	SERIAL_SEND_OK();
}

void rsense_cmd_disable(void)
{
	digitalWrite(DET_EN, LOW);
	digitalWrite(HV_EN, LOW);

	restore_default_adc();

	SERIAL_SEND_OK();
}

void rsense_cmd_flush(void)
{
	clear_detector_counters();
	clear_channel_data();
	SERIAL_SEND_OK();
}

void rsense_cmd_dump_channels(void)
{
	restore_default_adc();

	uint16_t read_from = 0;

	// Wait for 2 bytes specifying read position
	while (Serial.available() < 2)
		;
	read_from = Serial.read();
	read_from |= (uint16_t)Serial.read() << 8;

	// Send 2 bytes of read position
	Serial.write(g_read_pointer & 0xFF);
	Serial.write(g_read_pointer >> 8);

	g_read_pointer = read_from;
	if (g_read_pointer >= (DETECTOR_CHANNEL_32_COUNT - 32)) {
		g_read_pointer = DETECTOR_CHANNEL_32_COUNT - 32;
	}

	// Send 2 bytes of CRC16 checksum for the 32 channels
	uint16_t crc16 = calculate_crc16_xmodem((uint8_t *)(&g_detector_counts.channels_32[g_read_pointer]), 32 * 4);
	Serial.write(crc16 & 0xFF);
	Serial.write(crc16 >> 8);

	// Send 32 channel values (128 bytes total)
	for (uint16_t i = 0; i < 32 && g_read_pointer < DETECTOR_CHANNEL_32_COUNT; i++, g_read_pointer++) {
		uint32_t channel_value = g_detector_counts.channels_32[g_read_pointer];
		Serial.write(channel_value & 0xFF);
		Serial.write((channel_value >> 8) & 0xFF);
		Serial.write((channel_value >> 16) & 0xFF);
		Serial.write((channel_value >> 24) & 0xFF);

		Serial.flush();
		SERIAL_BUFFER_CLEAR();
		delay(1);
	}

	Serial.flush();
	SERIAL_BUFFER_CLEAR();
	enable_fast_adc();
}

void rsense_cmd_get_cpm(void)
{
	Serial.write(g_cpm_last & 0xFF);
	Serial.write(g_cpm_last >> 8);
	Serial.flush();
	SERIAL_BUFFER_CLEAR();
}

void rsense_cmd_set_mode(void)
{
	// Wait for 1 byte specifying mode
	while (Serial.available() < 1)
		;
	uint8_t mode = Serial.read();

	if (mode <= 1) {
		g_spectrum_mode = mode;
		clear_channel_data();
		SERIAL_SEND_OK();
	}

	Serial.flush();
	SERIAL_BUFFER_CLEAR();
}

void rsense_periodic(void)
{
	if (millis() - g_cpm_time > CPM_UPDATE_PERIOD) {
		uint32_t elapsed_time = millis() - g_cpm_time;
		g_cpm_last = (uint16_t)(((uint32_t)g_counts_cpm * 60UL * 1000UL) / elapsed_time);
		g_counts_cpm = 0;
		g_cpm_time = millis();
	}
}

/**
 * @brief ADC conversion complete interrupt handler
 */
ISR(ADC0_RESRDY_vect) { handle_analog_read_interrupt(); }