#include <errno.h>

#include <zephyr/kernel.h>
#include <zephyr/bluetooth/gatt.h>

#include <app_event_manager.h>

#define MODULE ble_battery
#include <caf/events/module_state_event.h>

#include "battery_status_event.h"

#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(MODULE, LOG_LEVEL_INF);

static bool notify_enabled;
static uint8_t battery_level = 100U;

static void bas_ccc_cfg_changed(const struct bt_gatt_attr *attr, uint16_t value)
{
	ARG_UNUSED(attr);
	notify_enabled = (value == BT_GATT_CCC_NOTIFY);
}

static ssize_t read_battery_level(struct bt_conn *conn,
				  const struct bt_gatt_attr *attr,
				  void *buf,
				  uint16_t len,
				  uint16_t offset)
{
	const uint8_t *value = attr->user_data;

	return bt_gatt_attr_read(conn, attr, buf, len, offset, value, sizeof(*value));
}

BT_GATT_SERVICE_DEFINE(ble_battery_svc,
	BT_GATT_PRIMARY_SERVICE(BT_UUID_BAS),
	BT_GATT_CHARACTERISTIC(BT_UUID_BAS_BATTERY_LEVEL,
			       BT_GATT_CHRC_READ | BT_GATT_CHRC_NOTIFY,
			       BT_GATT_PERM_READ_ENCRYPT,
			       read_battery_level, NULL, &battery_level),
	BT_GATT_CCC(bas_ccc_cfg_changed,
		    BT_GATT_PERM_READ_ENCRYPT | BT_GATT_PERM_WRITE_ENCRYPT),
);

static bool handle_battery_status_event(const struct battery_status_event *event)
{
	battery_level = battery_status_event_get_soc(event);

	if (!notify_enabled) {
		return false;
	}

	int err = bt_gatt_notify(NULL, &ble_battery_svc.attrs[1], &battery_level, sizeof(battery_level));

	if (err == -ENOTCONN) {
		LOG_WRN("BAS notify skipped: peer disconnecting");
	} else if (err) {
		LOG_ERR("BAS notify failed: %d", err);
	}

	return false;
}

static bool handle_module_state_event(const struct module_state_event *event)
{
	if (!check_state(event, MODULE_ID(ble_state), MODULE_STATE_READY)) {
		return false;
	}

	module_set_state(MODULE_STATE_READY);
	return false;
}

static bool app_event_handler(const struct app_event_header *aeh)
{
	if (is_battery_status_event(aeh)) {
		return handle_battery_status_event(cast_battery_status_event(aeh));
	}

	if (is_module_state_event(aeh)) {
		return handle_module_state_event(cast_module_state_event(aeh));
	}

	__ASSERT_NO_MSG(false);
	return false;
}

APP_EVENT_LISTENER(MODULE, app_event_handler);
APP_EVENT_SUBSCRIBE(MODULE, battery_status_event);
APP_EVENT_SUBSCRIBE(MODULE, module_state_event);