use crate::{mutable::SPACE, Time};
use bstr::{BStr, BString, ByteSlice};
use quick_error::quick_error;
use std::io;

/// A mutable signature is created by an actor at a certain time.
///
/// Note that this is not a cryptographical signature.
#[derive(PartialEq, Eq, Debug, Hash, Ord, PartialOrd, Clone)]
#[cfg_attr(feature = "serde1", derive(serde::Serialize, serde::Deserialize))]
pub struct Signature {
    /// The actors name.
    pub name: BString,
    /// The actor's email.
    pub email: BString,
    /// The time stamp at which the signature is performed.
    pub time: Time,
}

quick_error! {
    /// The Error produced in by [`Signature::write_to()`].
    #[derive(Debug)]
    #[allow(missing_docs)]
    pub enum Error {
        IllegalCharacter {
            display("Signature name or email must not contain '<', '>' or \\n")
        }
    }
}

impl From<Error> for io::Error {
    fn from(err: Error) -> Self {
        io::Error::new(io::ErrorKind::Other, err)
    }
}

/// Output
impl Signature {
    /// Serialize this instance to `out` in the git serialization format for actors.
    pub fn write_to(&self, mut out: impl io::Write) -> io::Result<()> {
        out.write_all(validated_token(self.name.as_bstr())?)?;
        out.write_all(SPACE)?;
        out.write_all(&b"<"[..])?;
        out.write_all(validated_token(self.email.as_bstr())?)?;
        out.write_all(&b"> "[..])?;
        self.time.write_to(out)?;
        Ok(())
    }
}

fn validated_token(name: &BStr) -> Result<&BStr, Error> {
    if name.find_byteset(b"<>\n").is_some() {
        return Err(Error::IllegalCharacter);
    }
    Ok(name)
}