pub const CODE: &[u8] = b"20";

pub struct Meta {
    pub mime: String,
}

impl Meta {
    /// Build `Self` from UTF-8 meta bytes
    /// * expected buffer includes leading status code, message, CRLF
    pub fn from_bytes(buffer: &[u8]) -> Result<Self> {
        use crate::tool::Header;
        use regex::Regex;
        use std::str::from_utf8;
        let h = buffer.header_bytes()?;
        if h.get(..2)
            .is_none_or(|c| c[0] != CODE[0] || c[1] != CODE[1])
        {
            bail!("Invalid status code")
        }
        Ok(Self {
            mime: match Regex::new(r"^([^\/]+\/[^\s;]+)")?.captures(from_utf8(&h[3..])?) {
                Some(c) => match c.get(1) {
                    Some(m) => m.as_str().to_string(),
                    None => bail!("Content type required"),
                },
                None => bail!("Could not parse content type"),
            },
        })
    }

    /// Convert `Self` into UTF-8 bytes presentation
    pub fn into_bytes(self) -> Vec<u8> {
        self.to_bytes()
    }

    pub fn to_bytes(&self) -> Vec<u8> {
        let mut bytes = Vec::with_capacity(3 + self.mime.len() + 2);
        bytes.extend(CODE);
        bytes.push(b' ');
        bytes.extend(self.mime.as_bytes());
        bytes.extend([b'\r', b'\n']);
        bytes
    }
}

#[test]
fn test() {
    const BYTES: &[u8] = "20 text/gemini\r\nDATA".as_bytes();
    let meta = Meta::from_bytes(BYTES).unwrap();

    assert_eq!(meta.mime, "text/gemini".to_string());
    assert_eq!(meta.into_bytes(), BYTES[..BYTES.len() - 4]); // skip DATA
}

use anyhow::{bail, Result};