osdp 0.3.1

//! `osdp_MFG` (`0x80`) — manufacturer-specific command.
//!
//! # Spec: §6.22
//!
//! Body is `OUI (3 bytes)` + opaque vendor data.

use crate::error::Error;
use crate::payload_util::require_at_least;
use alloc::vec::Vec;

/// `osdp_MFG` body.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Mfg {
    /// IEEE-assigned OUI for the vendor.
    pub oui: [u8; 3],
    /// Vendor-specific payload.
    pub payload: Vec<u8>,
}

impl Mfg {
    /// Encode.
    pub fn encode(&self) -> Result<Vec<u8>, Error> {
        let mut out = Vec::with_capacity(3 + self.payload.len());
        out.extend_from_slice(&self.oui);
        out.extend_from_slice(&self.payload);
        Ok(out)
    }

    /// Decode.
    pub fn decode(data: &[u8]) -> Result<Self, Error> {
        require_at_least(data, 3, 0x80)?;
        let mut oui = [0u8; 3];
        oui.copy_from_slice(&data[..3]);
        Ok(Self {
            oui,
            payload: data[3..].to_vec(),
        })
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn roundtrip() {
        let body = Mfg {
            oui: [0x00, 0x06, 0x8E],
            payload: alloc::vec![0xCA, 0xFE],
        };
        let bytes = body.encode().unwrap();
        assert_eq!(bytes, [0x00, 0x06, 0x8E, 0xCA, 0xFE]);
        assert_eq!(Mfg::decode(&bytes).unwrap(), body);
    }

    #[test]
    fn empty_payload_is_valid() {
        let body = Mfg {
            oui: [0xAA, 0xBB, 0xCC],
            payload: alloc::vec::Vec::new(),
        };
        let bytes = body.encode().unwrap();
        assert_eq!(bytes, [0xAA, 0xBB, 0xCC]);
        assert_eq!(Mfg::decode(&bytes).unwrap(), body);
    }

    #[test]
    fn decode_rejects_short_oui() {
        assert!(matches!(
            Mfg::decode(&[0x00, 0x06]),
            Err(Error::PayloadTooShort { code: 0x80, .. })
        ));
    }
}