use crate::net::codec::data_type::DataType;
use crate::net::codec::{varint::Varint, byte::Byte};

pub struct JString;

impl DataType for JString {
    type Value = String;

    async fn read<R: tokio::io::AsyncReadExt + Unpin>(stream: &mut R) -> anyhow::Result<Self::Value> {
        let length = Varint::read(stream).await? as usize;
        let mut buf = vec![0u8; length];
        stream.read_exact(&mut buf).await?;
        let string = String::from_utf8(buf)?;
        Ok(string)   
    }

    async fn write<R: tokio::io::AsyncWriteExt + Unpin>(stream: &mut R, value: Self::Value) -> anyhow::Result<()> {
        let len = value.len() as i32;
        let bytes = value.bytes();
        Varint::write(stream, len).await?;

        for byte in bytes {
            Byte::write(stream, byte).await?;
        };
        Ok(())
    }
}

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

    #[tokio::test]
    async fn write_string() {
        let mut data: Vec<u8> = Vec::new();
        JString::write(&mut data, "hello!".to_string()).await.unwrap();
        assert_eq!(vec![6, 104, 101, 108, 108, 111, 33], data);
    }

    #[tokio::test]
    async fn read_string() {
        let mut data: &[u8] = &[6, 104, 101, 108, 108, 111, 33];
        assert_eq!("hello!", JString::read(&mut data).await.unwrap());
    }
}