/*
 * @file config.h
 * @brief System configuration, persisted-config struct definition, and
 *        compile-time constants shared between modules.
 *
 * Created: 21.09.2025
 * Author: ThePetrovich
 *
 * Copyright YKSA - Sakha Aerospace Systems, LLC.
 * See the LICENSE file for details.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

#ifndef CONFIG_H
#define CONFIG_H

#include <stdint.h>

/* Firmware version */
#define FIRMWARE_VERSION_MAJOR 3
#define FIRMWARE_VERSION_MINOR 00

/* Serial communication */
#define SERIAL_BAUD_RATE 38400

/* Timing constants */
#define STATUS_LED_BLINK_PERIOD 500U
#define MAIN_LOOP_DELAY 10
#define RSENSE_UPDATE_PERIOD 1000U

/* Spectrum channel masks and counts */
#define RSENSE_CHANNEL_MASK 0x3FFU /* 10-bit channel mask */
#define RSENSE_CHANNEL_COUNT 1024

/* MCP9700 temperature sensor calibration constants */
#define MCP9700_OFFSET_MV 500L	/* 500 mV at 0 °C */
#define MCP9700_SCALE_MV 10L	/* 10 mV per °C */
#define ADC_OVERSAMPLING_BITS 2 /* 16x oversampling -> 2 extra bits */
#define ADC_VREF_MV 3000L	/* 3.0 V reference */
#define ADC_RESOLUTION 1024L	/* 10-bit ADC */

/* Voltage divider constants */
#define VOLTAGE_DIVIDER_RATIO 20.0f	/* 200k and 10k resistors */
#define VOLTAGE_MV_PER_STEP 14.6484375f /* (3.0 * 20) / 4096 */

/* Default potentiometer wiper value (mid-scale, 127/255) */
#define DEFAULT_POT_VALUE 127

/* Light sensor I2C constants */
#define LSENSE_I2C_BASE_ADDR 0x38
#define LSENSE_EXPECTED_ID 0xE0
#define LSENSE_DATA_SIZE 12

/**
 * @brief AD5160 wiper settings for the three digital potentiometers.
 */
typedef struct potentiometers_t {
	uint8_t pot_hv;	 /**< HV regulator wiper. */
	uint8_t pot_amp; /**< Amplifier gain wiper. */
	uint8_t pot_det; /**< Detector threshold wiper. */
} __attribute__((packed)) potentiometers_t;

/**
 * @brief ADC and temperature-sensor calibration coefficients.
 *        Reused as the payload of #CMD_SET_CALIBRATION.
 */
typedef struct calibration_t {
	uint16_t adccal0; /**< ADC reading at GND (offset). */
	uint16_t adccal3; /**< ADC reading at 3.0 V reference. */
	uint16_t tempcal; /**< Temperature offset correction. */
} __attribute__((packed)) calibration_t;

/**
 * @brief Runtime feature flags packed into a single byte.
 *        Reused as the payload of #CMD_SET_FLAGS.
 */
typedef union config_flags_t {
	struct __attribute__((packed)) {
		/** Spectrum oversampling: 0/1/2/3 = 1x/4x/16x/64x. */
		uint8_t spectrum_oversample_bits : 2;
		uint8_t reserved1 : 1;
		/** 0 = disable, 1 = enable temperature drift compensation. */
		uint8_t temperature_drift_compensation : 1;
		/** ADC oversampling for temperature/voltage: 0/1/2/3 = 1x/4x/16x/64x. */
		uint8_t adc_oversample_bits : 2;
		uint8_t reserved2 : 2;
	} fields;
	uint8_t value;
} __attribute__((packed)) config_flags_t;

/**
 * @brief Temperature drift compensation parameters.
 *        Reused as the payload of #CMD_SET_TEMP_DRIFT_COMPENSATION.
 *
 * Drift coefficients are in pot_units/255 per °C. When @c pot_X_low equals
 * @c pot_X_high, drift compensation for that channel is disabled.
 *
 * Sensor → potentiometer mapping:
 *   - temp_drift      : DET_TEMP (SiPM carrier) → pot_hv
 *   - vbias_drift     : HV_TEMP  (+28V supply)  → pot_hv
 *   - gain_drift      : AMP_TEMP (amplifier)    → pot_amp
 *   - threshold_drift : AMP_TEMP (amplifier)    → pot_det
 */
typedef struct temp_drift_compensation_t {
	int16_t temp_drift;
	int16_t vbias_drift;
	int16_t gain_drift;
	int16_t threshold_drift;
	uint32_t drift_period_ms; /**< Minimum interval between adjustments, in ms. */
	uint8_t pot_hv_low;
	uint8_t pot_hv_high;
	uint8_t pot_amp_low;
	uint8_t pot_amp_high;
	uint8_t pot_det_low;
	uint8_t pot_det_high;
} __attribute__((packed)) temp_drift_compensation_t;

/**
 * @brief Persistent device configuration.
 *
 * Stored in EEPROM with dual-partition wear leveling (see eeprom.cpp).
 * The pair @c magic1 / @c magic2 (0xA5 / 0x5A) marks a partition as valid.
 */
typedef struct config_t {
	uint8_t magic1; /**< 0xA5 — valid-partition marker, byte 1. */
	uint8_t magic2; /**< 0x5A — valid-partition marker, byte 2. */
	potentiometers_t pots;
	calibration_t calibration;
	config_flags_t flags;
	temp_drift_compensation_t temp_drift_compensation;
} __attribute__((packed)) config_t;

extern config_t config;

#endif /* CONFIG_H */