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// Copyright (C) 2019-2023 Aleo Systems Inc.
// This file is part of the Aleo SDK library.

// The Aleo SDK library is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// The Aleo SDK library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with the Aleo SDK library. If not, see <https://www.gnu.org/licenses/>.

use crate::account::{Address, PrivateKey};

use crate::types::native::SignatureNative;
use core::{fmt, ops::Deref, str::FromStr};
use rand::{rngs::StdRng, SeedableRng};
use wasm_bindgen::prelude::*;

/// Cryptographic signature of a message signed by an Aleo account
#[wasm_bindgen]
pub struct Signature(SignatureNative);

#[wasm_bindgen]
impl Signature {
    /// Sign a message with a private key
    ///
    /// @param {PrivateKey} private_key The private key to sign the message with
    /// @param {Uint8Array} message Byte representation of the message to sign
    /// @returns {Signature} Signature of the message
    pub fn sign(private_key: &PrivateKey, message: &[u8]) -> Self {
        Self(SignatureNative::sign_bytes(private_key, message, &mut StdRng::from_entropy()).unwrap())
    }

    /// Verify a signature of a message with an address
    ///
    /// @param {Address} address The address to verify the signature with
    /// @param {Uint8Array} message Byte representation of the message to verify
    /// @returns {boolean} True if the signature is valid, false otherwise
    pub fn verify(&self, address: &Address, message: &[u8]) -> bool {
        self.0.verify_bytes(address, message)
    }

    /// Get a signature from a string representation of a signature
    ///
    /// @param {string} signature String representation of a signature
    /// @returns {Signature} Signature
    pub fn from_string(signature: &str) -> Self {
        Self::from_str(signature).unwrap()
    }

    /// Get a string representation of a signature
    ///
    /// @returns {string} String representation of a signature
    #[allow(clippy::inherent_to_string_shadow_display)]
    pub fn to_string(&self) -> String {
        self.0.to_string()
    }
}

impl FromStr for Signature {
    type Err = anyhow::Error;

    fn from_str(signature: &str) -> Result<Self, Self::Err> {
        Ok(Self(SignatureNative::from_str(signature).unwrap()))
    }
}

impl fmt::Display for Signature {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "{}", self.0)
    }
}

impl Deref for Signature {
    type Target = SignatureNative;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use rand::{rngs::StdRng, Rng, SeedableRng};
    use wasm_bindgen_test::*;

    const ITERATIONS: u64 = 1_000;

    #[wasm_bindgen_test]
    pub fn test_sign_and_verify() {
        for _ in 0..ITERATIONS {
            // Sample a new private key and message.
            let private_key = PrivateKey::new();
            let message: [u8; 32] = StdRng::from_entropy().gen();

            // Sign the message.
            let signature = Signature::sign(&private_key, &message);
            // Check the signature is valid.
            assert!(signature.verify(&private_key.to_address(), &message));

            // Sample a different message.
            let bad_message: [u8; 32] = StdRng::from_entropy().gen();
            // Check the signature is invalid.
            assert!(!signature.verify(&private_key.to_address(), &bad_message));
        }
    }
}