use crate::{extended_key::private_key::Error as XPrvError, DerivationPath, ExtendedPrivateKey, PrivateKey};
use keyfork_mnemonic_util::Mnemonic;
use serde::{Deserialize, Serialize};

#[derive(Debug, thiserror::Error)]
pub enum DerivationError {
    #[error("algorithm not supported")]
    Algorithm,

    #[error("{0}")]
    ExtendedPrivateKey(#[from] XPrvError),
}

pub type Result<T, E = DerivationError> = std::result::Result<T, E>;

#[derive(Serialize, Deserialize, Clone, Debug)]
pub enum DerivationAlgorithm {
    Ed25519,
    Secp256k1,
}

impl DerivationAlgorithm {
    pub fn derive(&self, seed: Vec<u8>, path: &DerivationPath) -> Result<DerivationResponse> {
        match self {
            #[cfg(feature = "ed25519")]
            Self::Ed25519 => {
                let key = ExtendedPrivateKey::<ed25519_dalek::SigningKey>::new(seed)?;
                let derived_key = key.derive_path(path)?;
                Ok(DerivationResponse {
                    algorithm: self.clone(),
                    data: PrivateKey::to_bytes(&derived_key.private_key).to_vec(),
                })
            }
            #[cfg(feature = "secp256k1")]
            Self::Secp256k1 => {
                let key = ExtendedPrivateKey::<k256::SecretKey>::new(seed)?;
                let derived_key = key.derive_path(path)?;
                Ok(DerivationResponse {
                    algorithm: self.clone(),
                    data: PrivateKey::to_bytes(&derived_key.private_key).to_vec(),
                })
            }
            #[allow(unreachable_patterns)]
            _ => Err(DerivationError::Algorithm),
        }
    }
}

#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct DerivationRequest {
    algorithm: DerivationAlgorithm,
    path: DerivationPath,
}

impl DerivationRequest {
    pub fn new(algorithm: DerivationAlgorithm, path: DerivationPath) -> Self {
        Self { algorithm, path }
    }

    pub fn derive_with_mnemonic(&self, mnemonic: &Mnemonic) -> Result<DerivationResponse> {
        self.derive_with_master_seed(mnemonic.seed())
    }

    pub fn derive_with_master_seed(&self, seed: Vec<u8>) -> Result<DerivationResponse> {
        self.algorithm.derive(seed, &self.path)
    }
}

#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct DerivationResponse {
    pub algorithm: DerivationAlgorithm,
    pub data: Vec<u8>,
}