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use crate::{util, BitRead, BitWrite, ByteOrder, Error, Protocol};
use core::any::Any;
use std::ffi::CString;

impl Protocol for CString {
    fn read(
        read: &mut dyn BitRead,
        byte_order: ByteOrder,
        ctx: &mut dyn Any,
    ) -> Result<Self, Error> {
        let mut result = Vec::new();
        // this logic is susceptible to DoS attacks by never providing
        //   a null character and will be fixed by
        //   https://github.com/dylanmckay/bin_proto/issues/14
        loop {
            let c: u8 = Protocol::read(read, byte_order, ctx)?;
            if c == 0x00 {
                return Ok(CString::new(result)?);
            }
            result.push(c);
        }
    }

    fn write(
        &self,
        write: &mut dyn BitWrite,
        byte_order: ByteOrder,
        ctx: &mut dyn Any,
    ) -> Result<(), Error> {
        util::write_items(
            self.clone().into_bytes_with_nul().iter(),
            write,
            byte_order,
            ctx,
        )
    }
}

#[cfg(test)]
mod test {
    use bitstream_io::{BigEndian, BitReader, BitWriter};

    use crate::{ByteOrder, Protocol};
    use std::ffi::CString;

    #[test]
    fn can_read_cstring() {
        let mut data = BitReader::endian([0x41u8, 0x42, 0x43, 0].as_slice(), BigEndian);
        let read_back: CString = Protocol::read(&mut data, ByteOrder::BigEndian, &mut ()).unwrap();
        assert_eq!(read_back, CString::new("ABC").unwrap());
    }

    #[test]
    fn can_write_cstring() {
        let mut data: Vec<u8> = Vec::new();
        CString::new("ABC")
            .unwrap()
            .write(
                &mut BitWriter::endian(&mut data, BigEndian),
                ByteOrder::BigEndian,
                &mut (),
            )
            .unwrap();
        assert_eq!(data, vec![0x41, 0x42, 0x43, 0]);
    }
}