btp 0.1.4

A rust library of, a lightweight protocol, Blog Transfer Protocol.
Documentation 
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use tokio::fs::File;
use tokio::io::AsyncReadExt;

type Error = Box<dyn std::error::Error + Send + Sync>;

#[repr(u8)]
#[derive(Debug, PartialEq)]
pub enum StatusCode {
    OkieDokie = 0,
    Message = 1,
    File = 2,
    Success = 3,
    Error = 4,
}

#[derive(Clone)]
pub struct BtpPackage {
    pub header: BtpHeader,
    pub body1: String,
    pub body2: Option<String>,
}

#[derive(Clone)]
pub struct BtpHeader {
    pub file_size: [u8; 4],
    pub file_name_size: [u8; 2],
    pub sc: [u8; 1],
    pub version: [u8; 3],
}

impl BtpHeader {
    /// To create [`BtpHeader`] from its building blocks.
    ///
    /// [`BtpHeader`]: crate::message::BtpHeader
    pub fn from(
        file_size: [u8; 4],
        file_name_size: [u8; 2],
        sc: [u8; 1],
        version: [u8; 3],
    ) -> Self {
        BtpHeader {
            file_size,
            file_name_size,
            sc,
            version,
        }
    }

    pub fn from_raw(raw: [u8; 10]) -> Result<Self, Error> {
        let res = BtpHeader {
            file_size: raw[..4].try_into()?,
            sc: raw[4..5].try_into()?,
            version: raw[5..8].try_into()?,
            file_name_size: raw[8..].try_into()?,
        };
        Ok(res)
    }

    pub fn get_sc(&self) -> StatusCode {
        match self.sc {
            [0] => StatusCode::OkieDokie,
            [1] => StatusCode::Message,
            [2] => StatusCode::File,
            [3] => StatusCode::Success,
            [4] => StatusCode::Error,
            _ => StatusCode::Error,
        }
    }

    pub fn get_len(&self) -> usize {
        u32::from_be_bytes(self.file_size) as usize
    }

    pub fn get_file_name_len(&self) -> usize {
        u16::from_be_bytes(self.file_name_size) as usize
    }

    pub fn as_raw(self: Self) -> [u8; 10] {
        let mut header = [0u8; 10];
        header[..4].copy_from_slice(&self.file_size);
        header[4..5].copy_from_slice(&self.sc);
        header[5..8].copy_from_slice(&self.version);
        header[8..].copy_from_slice(&self.file_name_size);

        header
    }
}

impl BtpPackage {
    pub fn from(
        len: [u8; 4],
        sc: [u8; 1],
        version: [u8; 3],
        body1: String,
        body2: Option<String>,
    ) -> Self {
        let header = BtpHeader::from(len, [0, 0], sc, version);
        BtpPackage::from_header(header, body1, body2)
    }

    pub fn from_header(header: BtpHeader, body1: String, body2: Option<String>) -> Self {
        BtpPackage {
            header,
            body1,
            body2,
        }
    }

    pub fn from_str(body: &str) -> Self {
        let len = body.len() as u32;
        BtpPackage::from(
            len.to_be_bytes(),
            [StatusCode::Message as u8],
            super::VERSION,
            body.to_string(),
            None,
        )
    }

    pub async fn from_file(file: &mut File, filename: String) -> Result<Self, Error> {
        let mut file_content = String::new();
        let file_len = file.read_to_string(&mut file_content).await? as u32;

        Ok(BtpPackage {
            header: BtpHeader::from(
                file_len.to_be_bytes(),
                (filename.len() as u16).to_be_bytes(),
                [StatusCode::File as u8],
                super::VERSION,
            ),
            body1: file_content,
            body2: Some(filename),
        })
    }

    pub fn as_vec(self: Self) -> Vec<u8> {
        let mut raw = Vec::new();
        raw.extend_from_slice(&self.header.as_raw());
        raw.extend_from_slice(self.body1.as_bytes());
        match self.body2 {
            Some(body2) => raw.extend_from_slice(body2.as_bytes()),
            None => {}
        }
        raw
    }

    pub fn okie(ver: [u8; 3]) -> Self {
        let okie = String::from("okie");
        let len = (okie.len() as u32).to_be_bytes();
        let header = BtpHeader::from(len, [0, 0], [0], ver);
        BtpPackage::from_header(header, okie, None)
    }

    pub fn dokie(ver: [u8; 3]) -> Self {
        let dokie = String::from("dokie");
        let len = (dokie.len() as u32).to_be_bytes();
        let header = BtpHeader::from(len, [0, 0], [0], ver);
        BtpPackage::from_header(header, dokie, None)
    }
}