/**
 * @file adc_sensor.c
 * @brief Implementation of the ADC sensor library.
 *
 * This file contains the implementation for initializing and reading from ADC
 * sensors. It currently provides simulated values for voltage and current, with
 * placeholders for real hardware ADC implementation including GPIO control.
 */

#include <lib/adc_sensor.h>
#include <zephyr/devicetree.h>
#include <zephyr/drivers/adc.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(adc_sensor, LOG_LEVEL_INF);

// Simulated values
#define SIMULATED_VOLTAGE_MV 12000
#define SIMULATED_CURRENT_MA 45

// Devicetree node checks
#define VOLTAGE_SENSOR_NODE DT_NODELABEL(supply_voltage)
#define CURRENT_SENSOR_NODE DT_NODELABEL(motor_current)

#ifndef CONFIG_ADC_SENSOR_SIMULATED
// ADC device reference
#if DT_NODE_EXISTS(VOLTAGE_SENSOR_NODE)
#define ADC_NODE DT_PHANDLE(VOLTAGE_SENSOR_NODE, io_channels)
#define ADC_CHANNEL DT_PHA(VOLTAGE_SENSOR_NODE, io_channels, input)
#define ADC_RESOLUTION 12
#define ADC_REFERENCE_MV DT_PROP(VOLTAGE_SENSOR_NODE, reference_mv)
#define VOLTAGE_DIVIDER_RATIO \
  DT_PROP(VOLTAGE_SENSOR_NODE, voltage_divider_ratio)

static const struct device *adc_dev;
static struct adc_channel_cfg adc_channel_cfg = {
    .gain = ADC_GAIN_1,
    .reference = ADC_REF_INTERNAL,
    .acquisition_time = ADC_ACQ_TIME_DEFAULT,
    .channel_id = ADC_CHANNEL,
    .differential = 0};

static struct adc_sequence adc_sequence = {
    .channels = BIT(ADC_CHANNEL),
    .buffer_size = sizeof(uint16_t),
    .resolution = ADC_RESOLUTION,
};

static uint16_t adc_buffer;
#endif
#endif

static bool initialized = false;

#ifndef CONFIG_ADC_SENSOR_SIMULATED
// GPIO specs for voltage sensor (if devicetree nodes exist)
#if DT_NODE_EXISTS(VOLTAGE_SENSOR_NODE)
static const struct gpio_dt_spec voltage_sen_gpio =
    GPIO_DT_SPEC_GET(VOLTAGE_SENSOR_NODE, sen_gpios);
static const struct gpio_dt_spec voltage_s0_gpio =
    GPIO_DT_SPEC_GET(VOLTAGE_SENSOR_NODE, s0_gpios);
static const struct gpio_dt_spec voltage_s1_gpio =
    GPIO_DT_SPEC_GET(VOLTAGE_SENSOR_NODE, s1_gpios);
#endif

// GPIO specs for current sensor (if devicetree nodes exist)
#if DT_NODE_EXISTS(CURRENT_SENSOR_NODE)
static const struct gpio_dt_spec current_sen_gpio =
    GPIO_DT_SPEC_GET(CURRENT_SENSOR_NODE, sen_gpios);
static const struct gpio_dt_spec current_s0_gpio =
    GPIO_DT_SPEC_GET(CURRENT_SENSOR_NODE, s0_gpios);
static const struct gpio_dt_spec current_s1_gpio =
    GPIO_DT_SPEC_GET(CURRENT_SENSOR_NODE, s1_gpios);
#endif

/**
 * @brief Configure GPIO pins for ADC sensor control
 */
static int configure_sensor_gpios(void) {
  int ret = 0;

#if DT_NODE_EXISTS(VOLTAGE_SENSOR_NODE)
  // Configure voltage sensor GPIOs
  if (gpio_is_ready_dt(&voltage_sen_gpio)) {
    ret = gpio_pin_configure_dt(&voltage_sen_gpio, GPIO_OUTPUT_INACTIVE);
    if (ret < 0) {
      LOG_ERR("Failed to configure voltage sen GPIO: %d", ret);
      return ret;
    }
  }

  if (gpio_is_ready_dt(&voltage_s0_gpio)) {
    ret = gpio_pin_configure_dt(&voltage_s0_gpio, GPIO_OUTPUT_INACTIVE);
    if (ret < 0) {
      LOG_ERR("Failed to configure voltage s0 GPIO: %d", ret);
      return ret;
    }
  }

  if (gpio_is_ready_dt(&voltage_s1_gpio)) {
    ret = gpio_pin_configure_dt(&voltage_s1_gpio, GPIO_OUTPUT_INACTIVE);
    if (ret < 0) {
      LOG_ERR("Failed to configure voltage s1 GPIO: %d", ret);
      return ret;
    }
  }
#endif

#if DT_NODE_EXISTS(CURRENT_SENSOR_NODE)
  // Configure current sensor GPIOs
  if (gpio_is_ready_dt(&current_sen_gpio)) {
    ret = gpio_pin_configure_dt(&current_sen_gpio, GPIO_OUTPUT_INACTIVE);
    if (ret < 0) {
      LOG_ERR("Failed to configure current sen GPIO: %d", ret);
      return ret;
    }
  }

  if (gpio_is_ready_dt(&current_s0_gpio)) {
    ret = gpio_pin_configure_dt(&current_s0_gpio, GPIO_OUTPUT_INACTIVE);
    if (ret < 0) {
      LOG_ERR("Failed to configure current s0 GPIO: %d", ret);
      return ret;
    }
  }

  if (gpio_is_ready_dt(&current_s1_gpio)) {
    ret = gpio_pin_configure_dt(&current_s1_gpio, GPIO_OUTPUT_INACTIVE);
    if (ret < 0) {
      LOG_ERR("Failed to configure current s1 GPIO: %d", ret);
      return ret;
    }
  }
#endif

  return 0;
}

/**
 * @brief Set GPIO pins for voltage measurement
 * @param s0_state State for S0 pin (multiplexer bit 0)
 * @param s1_state State for S1 pin (multiplexer bit 1)
 */
static int set_voltage_sensor_gpios(bool enable, bool s0_state, bool s1_state) {
#if DT_NODE_EXISTS(VOLTAGE_SENSOR_NODE)
  if (gpio_is_ready_dt(&voltage_sen_gpio)) {
    gpio_pin_set_dt(&voltage_sen_gpio, enable ? 1 : 0);
  }
  if (gpio_is_ready_dt(&voltage_s0_gpio)) {
    gpio_pin_set_dt(&voltage_s0_gpio, s0_state ? 1 : 0);
  }
  if (gpio_is_ready_dt(&voltage_s1_gpio)) {
    gpio_pin_set_dt(&voltage_s1_gpio, s1_state ? 1 : 0);
  }

  // Delay for GPIO settling (from devicetree or default)
#if DT_NODE_HAS_PROP(VOLTAGE_SENSOR_NODE, measurement_delay_ms)
  k_msleep(DT_PROP(VOLTAGE_SENSOR_NODE, measurement_delay_ms));
#else
  k_msleep(5);  // Default 5ms delay
#endif
#endif
  return 0;
}

/**
 * @brief Set GPIO pins for current measurement
 * @param s0_state State for S0 pin (multiplexer bit 0)
 * @param s1_state State for S1 pin (multiplexer bit 1)
 */
static int set_current_sensor_gpios(bool enable, bool s0_state, bool s1_state) {
#if DT_NODE_EXISTS(CURRENT_SENSOR_NODE)
  if (gpio_is_ready_dt(&current_sen_gpio)) {
    gpio_pin_set_dt(&current_sen_gpio, enable ? 1 : 0);
  }
  if (gpio_is_ready_dt(&current_s0_gpio)) {
    gpio_pin_set_dt(&current_s0_gpio, s0_state ? 1 : 0);
  }
  if (gpio_is_ready_dt(&current_s1_gpio)) {
    gpio_pin_set_dt(&current_s1_gpio, s1_state ? 1 : 0);
  }

  // Delay for GPIO settling (from devicetree or default)
#if DT_NODE_HAS_PROP(CURRENT_SENSOR_NODE, measurement_delay_ms)
  k_msleep(DT_PROP(CURRENT_SENSOR_NODE, measurement_delay_ms));
#else
  k_msleep(10);  // Default 10ms delay
#endif
#endif
  return 0;
}
#endif /* !CONFIG_ADC_SENSOR_SIMULATED */

#ifndef CONFIG_ADC_SENSOR_SIMULATED
/**
 * @brief Read ADC value and convert to millivolts
 * @return ADC reading in millivolts, or 0 on error
 */
static uint16_t read_adc_voltage_mv(void) {
#if DT_NODE_EXISTS(VOLTAGE_SENSOR_NODE)
  int ret = adc_read(adc_dev, &adc_sequence);
  if (ret < 0) {
    LOG_ERR("ADC read failed: %d", ret);
    return 0;
  }

  // Convert ADC reading to millivolts
  // ADC reading is 12-bit (0-4095) representing 0 to ADC_REFERENCE_MV
  uint32_t adc_value = adc_buffer;
  uint32_t voltage_mv = (adc_value * ADC_REFERENCE_MV) / 4095;

  // Apply voltage divider scaling
  voltage_mv *= VOLTAGE_DIVIDER_RATIO;

  LOG_DBG("ADC raw: %u, voltage: %u mV", adc_value, (uint16_t)voltage_mv);

  return (uint16_t)voltage_mv;
#else
  return 0;
#endif
}

/**
 * @brief Read ADC value and convert to milliamps (for current sensor)
 * @return ADC reading in milliamps, or 0 on error
 */
static uint16_t read_adc_current_ma(void) {
#if DT_NODE_EXISTS(CURRENT_SENSOR_NODE)
  int ret = adc_read(adc_dev, &adc_sequence);
  if (ret < 0) {
    LOG_ERR("ADC read failed: %d", ret);
    return 0;
  }

  // Convert ADC reading to millivolts first
  uint32_t adc_value = adc_buffer;
  uint32_t voltage_mv = (adc_value * ADC_REFERENCE_MV) / 4095;

  // Convert voltage to current based on current sensor characteristics
  // Assuming a linear current sensor with specific mV/mA ratio
  // This will need to be calibrated for your specific current sensor
  uint32_t current_ma = voltage_mv / 10;  // Example: 10mV per mA

  LOG_DBG("ADC raw: %u, current: %u mA", adc_value, (uint16_t)current_ma);

  return (uint16_t)current_ma;
#else
  return 0;
#endif
}
#endif

int adc_sensor_init(void) {
  if (initialized) {
    return 0;
  }

#ifdef CONFIG_ADC_SENSOR_SIMULATED
  LOG_INF("ADC sensor initialized (simulated mode)");
  LOG_INF("Simulated values: %dmV, %dmA", SIMULATED_VOLTAGE_MV,
          SIMULATED_CURRENT_MA);
#else
  // Initialize GPIO pins for sensor control
  int ret = configure_sensor_gpios();
  if (ret < 0) {
    LOG_ERR("Failed to configure sensor GPIOs: %d", ret);
    return ret;
  }

  // Initialize ADC hardware
#if DT_NODE_EXISTS(VOLTAGE_SENSOR_NODE)
  adc_dev = DEVICE_DT_GET(ADC_NODE);
  if (!device_is_ready(adc_dev)) {
    LOG_ERR("ADC device not ready");
    return -ENODEV;
  }

  adc_sequence.buffer = &adc_buffer;

  ret = adc_channel_setup(adc_dev, &adc_channel_cfg);
  if (ret < 0) {
    LOG_ERR("Failed to setup ADC channel: %d", ret);
    return ret;
  }

  LOG_INF("ADC device ready: %s", adc_dev->name);
#endif

  LOG_INF("ADC sensor initialized (real ADC mode with GPIO control)");

#if DT_NODE_EXISTS(VOLTAGE_SENSOR_NODE)
  LOG_INF("Voltage sensor found in devicetree");
#endif
#if DT_NODE_EXISTS(CURRENT_SENSOR_NODE)
  LOG_INF("Current sensor found in devicetree");
#endif
#endif

  initialized = true;
  return 0;
}

uint16_t adc_sensor_get_voltage_mv(void) {
  if (!initialized) {
    LOG_WRN("ADC sensor not initialized, calling adc_sensor_init()");
    adc_sensor_init();
  }

#ifdef CONFIG_ADC_SENSOR_SIMULATED
  return SIMULATED_VOLTAGE_MV;
#else
  // Set GPIOs for voltage measurement (example: s0=0, s1=0 for channel 0)
  set_voltage_sensor_gpios(true, false, false);

  // Read real ADC value for voltage
  uint16_t voltage = read_adc_voltage_mv();

  // Disable sensor after measurement to save power
  set_voltage_sensor_gpios(false, false, false);

  return voltage;
#endif
}

uint16_t adc_sensor_get_current_ma(void) {
  if (!initialized) {
    LOG_WRN("ADC sensor not initialized, calling adc_sensor_init()");
    adc_sensor_init();
  }

#ifdef CONFIG_ADC_SENSOR_SIMULATED
  return SIMULATED_CURRENT_MA;
#else
  // Set GPIOs for current measurement (example: s0=1, s1=0 for channel 1)
  set_current_sensor_gpios(true, true, false);

  // Read real ADC value for current
  uint16_t current = read_adc_current_ma();

  // Disable sensor after measurement to save power
  set_current_sensor_gpios(false, false, false);

  return current;
#endif
}