/*
 * Copyright (c) 2023 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/drivers/emul.h>
#include <zephyr/drivers/sensor.h>
#include <zephyr/drivers/sensor_attribute_types.h>

#include <stdint.h>

/**
 * @brief Sensor emulator backend API
 * @defgroup sensor_emulator_backend Sensor emulator backend API
 * @ingroup io_interfaces
 * @{
 */

/**
 * @cond INTERNAL_HIDDEN
 *
 * These are for internal use only, so skip these in public documentation.
 */

/**
 * @brief Collection of function pointers implementing a common backend API for sensor emulators
 */
__subsystem struct emul_sensor_backend_api {
	/** Sets a given fractional value for a given sensor channel. */
	int (*set_channel)(const struct emul *target, enum sensor_channel ch, const q31_t *value,
			   int8_t shift);
	/** Retrieve a range of sensor values to use with test. */
	int (*get_sample_range)(const struct emul *target, enum sensor_channel ch, q31_t *lower,
				q31_t *upper, q31_t *epsilon, int8_t *shift);
	/** Set the attribute value(s) of a given chanel. */
	int (*set_attribute)(const struct emul *target, enum sensor_channel ch,
			     enum sensor_attribute attribute, const void *value);
	/** Get metadata about an attribute. */
	int (*get_attribute_metadata)(const struct emul *target, enum sensor_channel ch,
				      enum sensor_attribute attribute, q31_t *min, q31_t *max,
				      q31_t *increment, int8_t *shift);
};
/**
 * @endcond
 */

/**
 * @brief Check if a given sensor emulator supports the backend API
 *
 * @param target Pointer to emulator instance to query
 *
 * @return True if supported, false if unsupported or if \p target is NULL.
 */
static inline bool emul_sensor_backend_is_supported(const struct emul *target)
{
	return target && target->backend_api;
}

/**
 * @brief Set an expected value for a given channel on a given sensor emulator
 *
 * @param target Pointer to emulator instance to operate on
 * @param ch Sensor channel to set expected value for
 * @param value Expected value in fixed-point format using standard SI unit for sensor type
 * @param shift Shift value (scaling factor) applied to \p value
 *
 * @return 0 if successful
 * @return -ENOTSUP if no backend API or if channel not supported by emul
 * @return -ERANGE if provided value is not in the sensor's supported range
 */
static inline int emul_sensor_backend_set_channel(const struct emul *target, enum sensor_channel ch,
						  const q31_t *value, int8_t shift)
{
	if (!target || !target->backend_api) {
		return -ENOTSUP;
	}

	struct emul_sensor_backend_api *api = (struct emul_sensor_backend_api *)target->backend_api;

	if (api->set_channel) {
		return api->set_channel(target, ch, value, shift);
	}
	return -ENOTSUP;
}

/**
 * @brief Query an emulator for a channel's supported sample value range and tolerance
 *
 * @param target Pointer to emulator instance to operate on
 * @param ch The channel to request info for. If \p ch is unsupported, return `-ENOTSUP`
 * @param[out] lower Minimum supported sample value in SI units, fixed-point format
 * @param[out] upper Maximum supported sample value in SI units, fixed-point format
 * @param[out] epsilon Tolerance to use comparing expected and actual values to account for rounding
 *             and sensor precision issues. This can usually be set to the minimum sample value step
 *             size. Uses SI units and fixed-point format.
 * @param[out] shift The shift value (scaling factor) associated with \p lower, \p upper, and
 *             \p epsilon.
 *
 * @return 0 if successful
 * @return -ENOTSUP if no backend API or if channel not supported by emul
 *
 */
static inline int emul_sensor_backend_get_sample_range(const struct emul *target,
						       enum sensor_channel ch, q31_t *lower,
						       q31_t *upper, q31_t *epsilon, int8_t *shift)
{
	if (!target || !target->backend_api) {
		return -ENOTSUP;
	}

	struct emul_sensor_backend_api *api = (struct emul_sensor_backend_api *)target->backend_api;

	if (api->get_sample_range) {
		return api->get_sample_range(target, ch, lower, upper, epsilon, shift);
	}
	return -ENOTSUP;
}

/**
 * @brief Set the emulator's attribute values
 *
 * @param[in] target Pointer to emulator instance to operate on
 * @param[in] ch The channel to request info for. If \p ch is unsupported, return `-ENOTSUP`
 * @param[in] attribute The attribute to set
 * @param[in] value the value to use (cast according to the channel/attribute pair)
 * @return 0 is successful
 * @return < 0 on error
 */
static inline int emul_sensor_backend_set_attribute(const struct emul *target,
						    enum sensor_channel ch,
						    enum sensor_attribute attribute,
						    const void *value)
{
	if (!target || !target->backend_api) {
		return -ENOTSUP;
	}

	struct emul_sensor_backend_api *api = (struct emul_sensor_backend_api *)target->backend_api;

	if (api->set_attribute == NULL) {
		return -ENOTSUP;
	}
	return api->set_attribute(target, ch, attribute, value);
}

/**
 * @brief Get metadata about an attribute.
 *
 * Information provided by this function includes the minimum/maximum values of the attribute as
 * well as the increment (value per LSB) which can be used as an epsilon when comparing results.
 *
 * @param[in] target Pointer to emulator instance to operate on
 * @param[in] ch The channel to request info for. If \p ch is unsupported, return '-ENOTSUP'
 * @param[in] attribute The attribute to request info for. If \p attribute is unsupported, return
 *   '-ENOTSUP'
 * @param[out] min The minimum value the attribute can be set to
 * @param[out] max The maximum value the attribute can be set to
 * @param[out] increment The value that the attribute increses by for every LSB
 * @param[out] shift The shift for \p min, \p max, and \p increment
 * @return 0 on SUCCESS
 * @return < 0 on error
 */
static inline int emul_sensor_backend_get_attribute_metadata(const struct emul *target,
							     enum sensor_channel ch,
							     enum sensor_attribute attribute,
							     q31_t *min, q31_t *max,
							     q31_t *increment, int8_t *shift)
{
	if (!target || !target->backend_api) {
		return -ENOTSUP;
	}

	struct emul_sensor_backend_api *api = (struct emul_sensor_backend_api *)target->backend_api;

	if (api->get_attribute_metadata == NULL) {
		return -ENOTSUP;
	}
	return api->get_attribute_metadata(target, ch, attribute, min, max, increment, shift);
}

/**
 * @}
 */