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use crate::common::{get_status_code, get_status_description, PduError, GENERIC_NACK, HEADER_LEN};
use std::io::{Cursor, Read, Write};
/// Represents a Generic NACK PDU.
///
/// Sent when a PDU cannot be identified or is malformed (e.g., invalid Command ID).
#[derive(Debug, Clone, PartialEq)]
pub struct GenericNack {
/// Sequence number of the PDU
pub sequence_number: u32,
/// The error code explaining why the NACK was sent
pub command_status: u32, // The error code explaining why the NACK was sent
/// Human-readable status name
pub status_name: String,
}
impl GenericNack {
/// Create a new Generic NACK.
///
/// # Examples
///
/// ```
/// use smpp_codec::pdus::GenericNack;
///
/// let sequence_number: u32 = 1;
/// let nack = GenericNack::new("ESME_RINVCMDID", sequence_number);
/// ```
pub fn new(status_name: &str, sequence_number: u32) -> Self {
let command_status = get_status_code(status_name);
Self {
sequence_number,
command_status,
status_name: status_name.to_string(),
}
}
/// Encode the struct into raw bytes for the network.
///
/// # Errors
///
/// Returns a [`PduError`] if an I/O error occurs while writing.
///
/// # Examples
///
/// ```
/// # use smpp_codec::pdus::GenericNack;
/// # let sequence_number: u32 = 1;
/// # let nack = GenericNack::new("ESME_RINVCMDID", sequence_number);
/// let mut buffer = Vec::new();
/// nack.encode(&mut buffer).expect("Encoding failed");
/// ```
pub fn encode(&self, writer: &mut impl Write) -> Result<(), PduError> {
let command_len = HEADER_LEN as u32;
writer.write_all(&command_len.to_be_bytes())?;
writer.write_all(&GENERIC_NACK.to_be_bytes())?;
writer.write_all(&self.command_status.to_be_bytes())?;
writer.write_all(&self.sequence_number.to_be_bytes())?;
Ok(())
}
/// Decode raw bytes from the network into the struct.
///
/// # Errors
///
/// Returns a [`PduError`] if the buffer is too short.
///
/// # Examples
///
/// ```
/// # use smpp_codec::pdus::GenericNack;
/// # let sequence_number: u32 = 1;
/// # let nack = GenericNack::new("ESME_RINVCMDID", sequence_number);
/// # let mut buffer = Vec::new();
/// # nack.encode(&mut buffer).unwrap();
/// let decoded = GenericNack::decode(&buffer).expect("Decoding failed");
/// assert_eq!(decoded.status_name, "ESME_RINVCMDID");
/// ```
pub fn decode(buffer: &[u8]) -> Result<Self, PduError> {
if buffer.len() < HEADER_LEN {
return Err(PduError::BufferTooShort);
}
let mut cursor = Cursor::new(buffer);
// Skip Length (4) and ID (4)
cursor.set_position(8);
let mut bytes = [0u8; 4];
// Status
cursor.read_exact(&mut bytes)?;
let command_status = u32::from_be_bytes(bytes);
// Sequence
cursor.read_exact(&mut bytes)?;
let sequence_number = u32::from_be_bytes(bytes);
Ok(Self {
sequence_number,
command_status,
status_name: get_status_description(command_status),
})
}
}