// Copyright 2015-2020 Parity Technologies (UK) Ltd.
// This file is part of OpenEthereum.

// OpenEthereum 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.

// OpenEthereum 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 OpenEthereum.  If not, see <http://www.gnu.org/licenses/>.

use ethereum_types::{Address, H256};
/// Preconfigured validator list.
use parity_util_mem::MallocSizeOf;

use super::{SystemCall, ValidatorSet};
use bytes::Bytes;
use error::Error as EthcoreError;
use machine::{AuxiliaryData, Call, EthereumMachine};
use types::{header::Header, BlockNumber};

/// Validator set containing a known set of addresses.
#[derive(Clone, Debug, PartialEq, Eq, Default, MallocSizeOf)]
pub struct SimpleList {
    validators: Vec<Address>,
}

impl SimpleList {
    /// Create a new `SimpleList`.
    pub fn new(validators: Vec<Address>) -> Self {
        SimpleList {
            validators: validators,
        }
    }

    /// Convert into inner representation.
    pub fn into_inner(self) -> Vec<Address> {
        self.validators
    }
}

impl ::std::ops::Deref for SimpleList {
    type Target = [Address];

    fn deref(&self) -> &[Address] {
        &self.validators
    }
}

impl From<Vec<Address>> for SimpleList {
    fn from(validators: Vec<Address>) -> Self {
        SimpleList {
            validators: validators,
        }
    }
}

impl ValidatorSet for SimpleList {
    fn default_caller(&self, _block_id: ::types::ids::BlockId) -> Box<Call> {
        Box::new(|_, _| Err("Simple list doesn't require calls.".into()))
    }

    fn generate_engine_transactions(
        &self,
        _first: bool,
        _header: &Header,
        _call: &mut SystemCall,
    ) -> Result<Vec<(Address, Bytes)>, EthcoreError> {
        Ok(Vec::new())
    }

    fn on_close_block(&self, _header: &Header, _address: &Address) -> Result<(), EthcoreError> {
        Ok(())
    }

    fn is_epoch_end(&self, first: bool, _chain_head: &Header) -> Option<Vec<u8>> {
        match first {
            true => Some(Vec::new()), // allow transition to fixed list, and instantly
            false => None,
        }
    }

    fn signals_epoch_end(
        &self,
        _: bool,
        _: &Header,
        _: AuxiliaryData,
    ) -> ::engines::EpochChange<EthereumMachine> {
        ::engines::EpochChange::No
    }

    fn epoch_set(
        &self,
        _first: bool,
        _: &EthereumMachine,
        _: BlockNumber,
        _: &[u8],
    ) -> Result<(SimpleList, Option<H256>), ::error::Error> {
        Ok((self.clone(), None))
    }

    fn contains_with_caller(&self, _bh: &H256, address: &Address, _: &Call) -> bool {
        self.validators.contains(address)
    }

    fn get_with_caller(&self, _bh: &H256, nonce: usize, _: &Call) -> Address {
        let validator_n = self.validators.len();

        if validator_n == 0 {
            panic!("Cannot operate with an empty validator set.");
        }

        self.validators.get(nonce % validator_n).expect("There are validator_n authorities; taking number modulo validator_n gives number in validator_n range; qed").clone()
    }

    fn count_with_caller(&self, _bh: &H256, _: &Call) -> usize {
        self.validators.len()
    }
}

impl AsRef<dyn ValidatorSet> for SimpleList {
    fn as_ref(&self) -> &dyn ValidatorSet {
        self
    }
}

#[cfg(test)]
mod tests {
    use super::{super::ValidatorSet, SimpleList};
    use ethereum_types::Address;
    use std::str::FromStr;

    #[test]
    fn simple_list() {
        let a1 = Address::from_str("cd1722f3947def4cf144679da39c4c32bdc35681").unwrap();
        let a2 = Address::from_str("0f572e5295c57f15886f9b263e2f6d2d6c7b5ec6").unwrap();
        let list = SimpleList::new(vec![a1.clone(), a2.clone()]);
        assert!(list.contains(&Default::default(), &a1));
        assert_eq!(list.get(&Default::default(), 0), a1);
        assert_eq!(list.get(&Default::default(), 1), a2);
        assert_eq!(list.get(&Default::default(), 2), a1);
    }
}