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use ring::hmac;
use serde::{Deserialize, Serialize};
use std::{fmt, str::FromStr};

#[derive(Debug, Eq, PartialEq, Clone, Copy, Serialize, Deserialize)]
pub enum Algorithm {
    SHA1,
    SHA256,
    SHA512,
}

impl From<Algorithm> for hmac::Algorithm {
    fn from(h: Algorithm) -> Self {
        match h {
            Algorithm::SHA1 => hmac::HMAC_SHA1_FOR_LEGACY_USE_ONLY,
            Algorithm::SHA256 => hmac::HMAC_SHA256,
            Algorithm::SHA512 => hmac::HMAC_SHA512,
        }
    }
}

impl fmt::Display for Algorithm {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        let s = match *self {
            Algorithm::SHA1 => "sha1",
            Algorithm::SHA256 => "sha256",
            Algorithm::SHA512 => "sha512",
        };
        write!(f, "{}", s)
    }
}

impl Default for Algorithm {
    fn default() -> Self {
        Self::SHA1
    }
}

impl FromStr for Algorithm {
    type Err = anyhow::Error;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s.to_lowercase().as_ref() {
            "sha1" | "otp" => Ok(Self::SHA1),
            "sha256" => Ok(Self::SHA256),
            "sha512" => Ok(Self::SHA512),
            _ => anyhow::bail!("Unsupported HMAC-algorithm"),
        }
    }
}