#include <zephyr/device.h>
#include <zephyr/drivers/adc.h>
#include <zephyr/drivers/gpio.h>
#include <zephyr/init.h>
#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>

#include <errno.h>
#include <stdbool.h>

#include "batt_mgmt.h"
#include "usb_mgmt.h"

LOG_MODULE_REGISTER(batt_mgmt, CONFIG_BATT_MGMT_LOG_LEVEL);

#define BATT_VDDH_DIVIDER_FACTOR 5

#define BATT_VDDH_ADC_NODE DT_PATH(zephyr_user)
static const struct adc_dt_spec batt_vddh_adc = ADC_DT_SPEC_GET_BY_NAME(BATT_VDDH_ADC_NODE, vddh);

#define BATT_CHG_STATUS_NODE DT_ALIAS(chg_status)
static const struct gpio_dt_spec batt_chg_status = GPIO_DT_SPEC_GET(BATT_CHG_STATUS_NODE, gpios);

static bool batt_mgmt_ready;
static int64_t batt_mgmt_last_chg_change_ms;
static bool batt_mgmt_chg_interrupt_enabled;
static K_THREAD_STACK_DEFINE(batt_monitor_stack, CONFIG_BATT_MGMT_MONITOR_THREAD_STACK_SIZE);
static struct k_thread batt_monitor_thread_data;

static int batt_mgmt_to_adc_oversampling(uint8_t oversampling, uint8_t *adc_oversampling)
{
	if (adc_oversampling == NULL)
	{
		return -EINVAL;
	}

	switch (oversampling)
	{
	case BATT_MGMT_OVERSAMPLING_8X:
		*adc_oversampling = 3U;
		return 0;
	case BATT_MGMT_OVERSAMPLING_16X:
		*adc_oversampling = 4U;
		return 0;
	default:
		return -EINVAL;
	}
}

int batt_mgmt_measure_vddh_mv(uint8_t oversampling, int32_t *vddh_mv)
{
	int rc;
	uint8_t adc_oversampling;
	int16_t raw_sample;
	int32_t input_mv;
	struct adc_sequence sequence = {
		.buffer = &raw_sample,
		.buffer_size = sizeof(raw_sample),
	};

	if (vddh_mv == NULL)
	{
		return -EINVAL;
	}

	if (!batt_mgmt_ready)
	{
		return -EAGAIN;
	}

	rc = batt_mgmt_to_adc_oversampling(oversampling, &adc_oversampling);
	if (rc < 0)
	{
		return rc;
	}

	rc = adc_sequence_init_dt(&batt_vddh_adc, &sequence);
	if (rc < 0)
	{
		return rc;
	}

	sequence.oversampling = adc_oversampling;

	rc = adc_read_dt(&batt_vddh_adc, &sequence);
	if (rc < 0)
	{
		return rc;
	}

	input_mv = raw_sample;
	rc = adc_raw_to_millivolts_dt(&batt_vddh_adc, &input_mv);
	if (rc < 0)
	{
		return rc;
	}

	*vddh_mv = input_mv * BATT_VDDH_DIVIDER_FACTOR;

	LOG_DBG("Battery VDDH: %d mV (raw=%d, os=%ux)", *vddh_mv, raw_sample, oversampling);
	return 0;
}

static void batt_mgmt_chg_interrupt_handler(const struct device *dev,
											struct gpio_callback *cb,
											uint32_t pins)
{
	int64_t now_ms = k_uptime_get();
	int64_t delta_ms = now_ms - batt_mgmt_last_chg_change_ms;

#ifdef CONFIG_BATT_MGMT_BLINK_INTERVAL_LOGGING
	LOG_DBG("CHG interrupt: delta=%lld ms", delta_ms);
#endif

	batt_mgmt_last_chg_change_ms = now_ms;
}

static int batt_mgmt_enable_chg_interrupt(void)
{
	int rc;
	static struct gpio_callback batt_chg_cb;

	if (batt_mgmt_chg_interrupt_enabled)
	{
		return 0;
	}

	if (!gpio_is_ready_dt(&batt_chg_status))
	{
		LOG_ERR("CHG GPIO device not ready");
		return -ENODEV;
	}

	rc = gpio_pin_configure_dt(&batt_chg_status, GPIO_INPUT);
	if (rc < 0)
	{
		LOG_ERR("Failed to configure CHG GPIO: %d", rc);
		return rc;
	}

	gpio_init_callback(&batt_chg_cb, batt_mgmt_chg_interrupt_handler, BIT(batt_chg_status.pin));
	rc = gpio_add_callback(batt_chg_status.port, &batt_chg_cb);
	if (rc < 0)
	{
		LOG_ERR("Failed to add CHG callback: %d", rc);
		return rc;
	}

	rc = gpio_pin_interrupt_configure_dt(&batt_chg_status, GPIO_INT_EDGE_BOTH);
	if (rc < 0)
	{
		LOG_ERR("Failed to configure CHG interrupt: %d", rc);
		return rc;
	}

	batt_mgmt_chg_interrupt_enabled = true;
	batt_mgmt_last_chg_change_ms = k_uptime_get();
	LOG_INF("CHG interrupt enabled");

	return 0;
}

static int batt_mgmt_disable_chg_interrupt(void)
{
	int rc;

	if (!batt_mgmt_chg_interrupt_enabled)
	{
		return 0;
	}

	rc = gpio_pin_interrupt_configure_dt(&batt_chg_status, GPIO_INT_DISABLE);
	if (rc < 0)
	{
		LOG_WRN("Failed to disable CHG interrupt: %d", rc);
		return rc;
	}

	rc = gpio_pin_configure(batt_chg_status.port, batt_chg_status.pin, GPIO_DISCONNECTED);
	if (rc < 0)
	{
		LOG_WRN("Failed to disconnect CHG GPIO: %d", rc);
		return rc;
	}

	batt_mgmt_chg_interrupt_enabled = false;
	LOG_DBG("CHG interrupt disabled");

	return 0;
}

bool batt_mgmt_get_charger_status(void)
{
	if (!batt_mgmt_chg_interrupt_enabled)
	{
		return false;
	}

	return gpio_pin_get_dt(&batt_chg_status);
}

batt_mgmt_state_t batt_mgmt_get_battery_state(void)
{
	int64_t now_ms = k_uptime_get();
	int64_t delta_ms = now_ms - batt_mgmt_last_chg_change_ms;
	bool chg_high = batt_mgmt_get_charger_status();
	bool usb_present = usb_mgmt_is_vbus_present();

	/* Blinking detection: state change within window */
	if (delta_ms < CONFIG_BATT_MGMT_CHG_BLINKING_WINDOW_MS)
	{
		LOG_DBG("Blinking detected (delta=%lld ms)", delta_ms);
		return BATT_STATE_ERROR;
	}

	/* Stable states */
	if (chg_high)
	{
		return BATT_STATE_CHARGING;
	}

	if (usb_present)
	{
		return BATT_STATE_FULL;
	}

	return BATT_STATE_DISCHARGING;
}

static void batt_mgmt_monitor_thread(void *unused1, void *unused2, void *unused3)
{
	(void)unused1;
	(void)unused2;
	(void)unused3;

	if (!usb_mgmt_wait_ready(K_SECONDS(2)))
	{
		LOG_WRN("usb_mgmt not ready after timeout; using current VBUS state");
	}

	/* Sync initial state in case VBUS was already present before this thread started. */
	bool vbus_present = usb_mgmt_is_vbus_present();

	if (vbus_present)
	{
		(void)batt_mgmt_enable_chg_interrupt();
	}
	else
	{
		(void)batt_mgmt_disable_chg_interrupt();
	}

	while (1)
	{
		uint32_t events = k_event_wait(&usb_mgmt_events,
									   USB_MGMT_VBUS_CONNECTED | USB_MGMT_VBUS_DISCONNECTED,
									   false, K_FOREVER);

		if (events & USB_MGMT_VBUS_CONNECTED)
		{
			(void)batt_mgmt_enable_chg_interrupt();
		}

		if (events & USB_MGMT_VBUS_DISCONNECTED)
		{
			(void)batt_mgmt_disable_chg_interrupt();
		}

		k_event_clear(&usb_mgmt_events, USB_MGMT_VBUS_CONNECTED | USB_MGMT_VBUS_DISCONNECTED);
	}
}

static int batt_mgmt_init(void)
{
	int32_t boot_vddh_mv;
	int rc;

	if (!adc_is_ready_dt(&batt_vddh_adc))
	{
		LOG_ERR("VDDH ADC device not ready");
		return -ENODEV;
	}

	rc = adc_channel_setup_dt(&batt_vddh_adc);
	if (rc < 0)
	{
		LOG_ERR("VDDH ADC channel setup failed: %d", rc);
		return rc;
	}

	batt_mgmt_ready = true;

	rc = batt_mgmt_measure_vddh_mv(BATT_MGMT_OVERSAMPLING_16X, &boot_vddh_mv);
	if (rc < 0)
	{
		LOG_WRN("Initial battery measurement failed: %d", rc);
		return 0;
	}

	LOG_DBG("Initial battery VDDH: %d mV", boot_vddh_mv);

	k_thread_create(&batt_monitor_thread_data,
					batt_monitor_stack,
					K_THREAD_STACK_SIZEOF(batt_monitor_stack),
					batt_mgmt_monitor_thread,
					NULL, NULL, NULL,
					K_PRIO_COOP(CONFIG_BATT_MGMT_MONITOR_THREAD_PRIORITY),
					0, K_NO_WAIT);

	return 0;
}

SYS_INIT(batt_mgmt_init, APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY);