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use alloc::boxed::Box;
use alloc::string::String;

use serde::{Deserialize, Serialize};
use umbral_pre::{PublicKey, Signature, Signer};

use crate::address::Address;
use crate::key_frag::EncryptedKeyFrag;
use crate::versioning::{
    messagepack_deserialize, messagepack_serialize, ProtocolObject, ProtocolObjectInner,
};
use crate::VerificationError;

/// Represents a string used by characters to perform a revocation on a specific Ursula.
#[derive(PartialEq, Debug, Clone, Serialize, Deserialize)]
pub struct RevocationOrder {
    /// The address of the Ursula that is being revoked.
    staking_provider_address: Address,
    encrypted_kfrag: EncryptedKeyFrag,
    signature: Signature,
}

impl RevocationOrder {
    /// Create and sign a new revocation order.
    pub fn new(
        signer: &Signer,
        staking_provider_address: &Address,
        encrypted_kfrag: &EncryptedKeyFrag,
    ) -> Self {
        Self {
            staking_provider_address: *staking_provider_address,
            encrypted_kfrag: encrypted_kfrag.clone(),
            signature: signer.sign(
                &[
                    staking_provider_address.as_ref(),
                    &encrypted_kfrag.to_bytes(),
                ]
                .concat(),
            ),
        }
    }

    /// Verifies the revocation order against Alice's key.
    /// On success, returns the staking provider address and the encrypted keyfrag.
    pub fn verify(
        self,
        alice_verifying_key: &PublicKey,
    ) -> Result<(Address, EncryptedKeyFrag), VerificationError> {
        let message = [
            self.staking_provider_address.as_ref(),
            &self.encrypted_kfrag.to_bytes(),
        ]
        .concat();
        if self.signature.verify(alice_verifying_key, &message) {
            Ok((self.staking_provider_address, self.encrypted_kfrag))
        } else {
            Err(VerificationError)
        }
    }
}

impl<'a> ProtocolObjectInner<'a> for RevocationOrder {
    fn brand() -> [u8; 4] {
        *b"Revo"
    }

    fn version() -> (u16, u16) {
        (1, 0)
    }

    fn unversioned_to_bytes(&self) -> Box<[u8]> {
        messagepack_serialize(&self)
    }

    fn unversioned_from_bytes(minor_version: u16, bytes: &[u8]) -> Option<Result<Self, String>> {
        if minor_version == 0 {
            Some(messagepack_deserialize(bytes))
        } else {
            None
        }
    }
}

impl<'a> ProtocolObject<'a> for RevocationOrder {}