use super::BASE32;

#[derive(Debug)]
pub enum Error {
    ReadHash(String),
    InvalidBytes,
}

pub const BLAKE3_BYTES: usize = 32;

#[derive(Clone, Copy, Eq, PartialEq, Hash, PartialOrd, Ord)]
pub enum Hash {
    Blake3([u8; BLAKE3_BYTES]),
}

pub enum Hasher {
    Blake3(blake3::Hasher),
}

impl Default for Hasher {
    fn default() -> Self {
        Hasher::Blake3(blake3::Hasher::new())
    }
}

impl Hasher {
    pub fn update(&mut self, bytes: &[u8]) {
        match self {
            Hasher::Blake3(ref mut h) => {
                h.update(bytes);
            }
        }
    }

    pub fn finish(&self) -> Hash {
        match self {
            Hasher::Blake3(ref h) => {
                let result = h.finalize();
                let mut hash = [0; BLAKE3_BYTES];
                hash.clone_from_slice(result.as_bytes());
                Hash::Blake3(hash)
            }
        }
    }
}

impl std::fmt::Debug for Hash {
    fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
        write!(fmt, "{}", self.to_base32())
    }
}

#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
enum Algo {
    Blake3 = 1,
}

impl Hash {
    pub fn to_bytes(self) -> [u8; 1 + BLAKE3_BYTES] {
        match self {
            Hash::Blake3(ref s) => {
                let mut out = [0; 1 + BLAKE3_BYTES];
                out[0] = Algo::Blake3 as u8;
                out[1..].clone_from_slice(s);
                out
            }
        }
    }

    pub fn from_bytes(s: &[u8]) -> Option<Self> {
        if s.len() >= 1 + BLAKE3_BYTES && s[0] == Algo::Blake3 as u8 {
            let mut out = [0; BLAKE3_BYTES];
            out.clone_from_slice(&s[1..]);
            Some(Hash::Blake3(out))
        } else {
            None
        }
    }

    pub fn validate(s: &[u8]) -> Result<(), Error> {
        if s.len() >= 1 + BLAKE3_BYTES && s[0] == Algo::Blake3 as u8 {
            Ok(())
        } else {
            Err(Error::InvalidBytes)
        }
    }

    pub fn to_base32(self) -> String {
        let hash = self.to_bytes();
        BASE32.encode(&hash)
    }

    pub fn from_base32(s: &[u8]) -> Option<Self> {
        let bytes = BASE32.decode(s).ok()?;
        Self::from_bytes(&bytes)
    }
}

impl std::str::FromStr for Hash {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        if let Some(b) = Self::from_base32(s.as_bytes()) {
            Ok(b)
        } else {
            Err(Error::ReadHash(s.to_string()))
        }
    }
}