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use crate::dns::{CharacterString, DnsPacketContent};

/// HINFO records are used to acquire general information about a host.  
/// The main use is for protocols such as FTP that can use special procedures
/// when talking between machines or operating systems of the same type.
#[derive(Debug, PartialEq, Eq, Hash)]
pub struct HINFO<'a> {
    /// A [CharacterString](`CharacterString`) which specifies the CPU type.
    pub cpu: CharacterString<'a>,
    /// A [CharacterString](`CharacterString`) which specifies the operating system type.
    pub os: CharacterString<'a>,
}

impl<'a> DnsPacketContent<'a> for HINFO<'a> {
    fn parse(data: &'a [u8], position: usize) -> crate::Result<Self>
    where
        Self: Sized,
    {
        let cpu = CharacterString::parse(data, position)?;
        let os = CharacterString::parse(data, position + cpu.len())?;

        Ok(Self { cpu, os })
    }

    fn append_to_vec(&self, out: &mut Vec<u8>) -> crate::Result<()> {
        self.cpu.append_to_vec(out)?;
        self.os.append_to_vec(out)
    }

    fn len(&self) -> usize {
        self.cpu.len() + self.os.len()
    }
}

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

    #[test]
    fn parse_and_write_hinfo() {
        let hinfo = HINFO {
            cpu: CharacterString::new(b"\"some cpu\"").unwrap(),
            os: CharacterString::new(b"\"some os\"").unwrap(),
        };

        let mut data = Vec::new();
        assert!(hinfo.append_to_vec(&mut data).is_ok());

        let hinfo = HINFO::parse(&data, 0);
        assert!(hinfo.is_ok());
        let hinfo = hinfo.unwrap();

        assert_eq!(data.len(), hinfo.len());
        assert_eq!("\"some cpu\"", hinfo.cpu.to_string());
        assert_eq!("\"some os\"", hinfo.os.to_string());
    }
}