//! Inertial measurement unit observations.

use kaptan_time::Timestamp;

/// Coherent IMU observation in the board body frame.
///
/// Acceleration is milligravity, angular rate is milliradians per second, and
/// temperature is centidegrees Celsius. The board-frame transform is complete
/// before this value is published.
///
/// Current MPU6000 and ICM-42688-P decoders round integer conversions toward
/// zero. Across their configured ranges, decoded acceleration is within
/// ±16,000 mg and angular rate within ±34,871 mrad/s, including mounting sign
/// changes. Temperature is within -22,234..=27,233 cdegC. These are backend
/// representation bounds over every raw i16 value, not physical operating
/// limits or validation performed by this public snapshot type.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct ImuSnapshot {
    /// Host monotonic acquisition-request time, captured immediately before the
    /// accepted register read is submitted by the worker. This is neither DRDY
    /// ISR entry nor the sensor's physical sampling epoch. Register updates,
    /// filtering and deferred/coalesced interrupts prevent that inference.
    pub timestamp: Timestamp,
    /// Body-frame acceleration in milligravity.
    pub acceleration_milligravity: [i16; 3],
    /// Body-frame angular rate in milliradians per second.
    pub angular_rate_milliradians_per_second: [i32; 3],
    /// Sensor temperature in centidegrees Celsius.
    pub temperature_centidegrees_celsius: i16,
}

impl ImuSnapshot {
    /// Creates one accepted IMU observation.
    pub const fn new(
        timestamp: Timestamp,
        acceleration_milligravity: [i16; 3],
        angular_rate_milliradians_per_second: [i32; 3],
        temperature_centidegrees_celsius: i16,
    ) -> Self {
        Self {
            timestamp,
            acceleration_milligravity,
            angular_rate_milliradians_per_second,
            temperature_centidegrees_celsius,
        }
    }
}