// Copyright 2019 Conflux Foundation. All rights reserved.
// Conflux is free software and distributed under GNU General Public License.
// See http://www.gnu.org/licenses/

use std::convert::TryInto;

use cfx_math::power_two_fractional;
use cfx_parameters::consensus_internal::DAO_MIN_VOTE_PERCENTAGE;
use cfx_statedb::Result as DbResult;
use cfx_types::{Address, U256, U512};
use cfx_vm_types::{self as vm, ActionParams, Spec};
use lazy_static::lazy_static;

use super::super::{
    components::{InternalRefContext, SolidityEventTrait},
    contracts::params_control::*,
    impls::staking::get_vote_power,
};
use crate::{internal_bail, state::State};

use self::system_storage_key::{
    current_pos_staking_for_votes, settled_pos_staking_for_votes,
};
pub use system_storage_key::storage_point_prop;

pub fn cast_vote(
    address: Address, version: u64, votes: Vec<Vote>, params: &ActionParams,
    context: &mut InternalRefContext,
) -> vm::Result<()> {
    // If this is called, `env.number` must be larger than the activation
    // number. And version starts from 1 to tell if an account has ever voted in
    // the first version.
    let current_voting_version = (context.env.number
        - context.spec.cip94_activation_block_number)
        / context.spec.params_dao_vote_period
        + 1;
    if version != current_voting_version {
        internal_bail!(
            "vote version unmatch: current={} voted={}",
            current_voting_version,
            version
        );
    }
    let old_version =
        context.storage_at(params, &storage_key::versions(&address))?;
    let is_new_vote = old_version.as_u64() != version;

    let mut vote_counts = [None; PARAMETER_INDEX_MAX];
    for vote in votes {
        if vote.index >= params_index_max(context.spec) as u16 {
            internal_bail!("invalid vote index or opt_index");
        }
        let entry = &mut vote_counts[vote.index as usize];
        match entry {
            None => {
                *entry = Some(vote.votes);
            }
            Some(_) => {
                internal_bail!(
                    "Parameter voted twice: vote.index={}",
                    vote.index
                );
            }
        }
    }
    if is_new_vote {
        // If this is the first vote in the version, even for the not-voted
        // parameters, we still reset the account's votes from previous
        // versions.
        for index in 0..params_index_max(context.spec) {
            if vote_counts[index].is_none() {
                vote_counts[index] = Some([U256::zero(); OPTION_INDEX_MAX]);
            }
        }
    }

    let vote_power = get_vote_power(
        address,
        U256::from(context.env.number),
        context.env.number,
        context.state,
    )?;
    debug!("vote_power:{}", vote_power);
    for index in 0..params_index_max(context.spec) {
        if vote_counts[index].is_none() {
            continue;
        }
        let param_vote = vote_counts[index].unwrap();
        let total_counts = param_vote[0]
            .saturating_add(param_vote[1])
            .saturating_add(param_vote[2]);
        if total_counts > vote_power {
            internal_bail!(
                "not enough vote power: power={} votes={}",
                vote_power,
                total_counts
            );
        }
        let mut old_votes = [U256::zero(); 3];
        for opt_index in 0..OPTION_INDEX_MAX {
            let vote_slot = storage_key::votes(&address, index, opt_index);
            let old_vote = if is_new_vote {
                U256::zero()
            } else {
                context.storage_at(params, &vote_slot)?
            };
            old_votes[opt_index] = old_vote;
            debug!(
                "index:{}, opt_index{}, old_vote: {}, new_vote: {}",
                index, opt_index, old_vote, param_vote[opt_index]
            );

            // Update the global votes if the account vote changes.
            if param_vote[opt_index] != old_vote {
                let old_total_votes = context.state.get_system_storage(
                    &CURRENT_VOTES_ENTRIES[index][opt_index],
                )?;
                // Should not overflow since we checked the efficiency of voting
                // power.
                let new_total_votes =
                    old_total_votes + param_vote[opt_index] - old_vote;

                debug!(
                    "old_total_vote: {}, new_total_vote:{}",
                    old_total_votes, new_total_votes
                );
                context.state.set_system_storage(
                    CURRENT_VOTES_ENTRIES[index][opt_index].to_vec(),
                    new_total_votes,
                )?;
            }

            // Overwrite the account vote entry.
            context.set_storage(
                params,
                vote_slot.to_vec(),
                param_vote[opt_index],
            )?;
        }
        if !is_new_vote {
            RevokeEvent::log(
                &(version, address, index as u16),
                &old_votes,
                params,
                context,
            )?;
        }
        VoteEvent::log(
            &(version, address, index as u16),
            &vote_counts[index].as_ref().unwrap(),
            params,
            context,
        )?;
    }
    if is_new_vote {
        context.set_storage(
            params,
            storage_key::versions(&address).to_vec(),
            U256::from(version),
        )?;
    }
    Ok(())
}

pub fn cast_vote_gas(length: usize, spec: &Spec) -> usize {
    let version_gas =
        2 * spec.sload_gas + spec.sha3_gas + spec.sstore_reset_gas;

    let io_gas_per_topic = 3
        * (2 * spec.sload_gas + 2 * spec.sstore_reset_gas + 2 * spec.sha3_gas);

    let log_gas_per_topic = 2 * spec.log_gas
        + 8 * spec.log_topic_gas
        + 32 * 3 * 2 * spec.log_data_gas;

    version_gas + length * (io_gas_per_topic + log_gas_per_topic)
}

pub fn read_vote(
    address: Address, params: &ActionParams, context: &mut InternalRefContext,
) -> vm::Result<Vec<Vote>> {
    let current_voting_version = (context.env.number
        - context.spec.cip94_activation_block_number)
        / context.spec.params_dao_vote_period
        + 1;
    let version = context
        .storage_at(params, &storage_key::versions(&address))?
        .as_u64();
    let deprecated_vote = version != current_voting_version;

    let mut votes_list = Vec::new();
    for index in 0..params_index_max(context.spec) {
        let mut param_vote = [U256::zero(); OPTION_INDEX_MAX];
        if !deprecated_vote {
            for opt_index in 0..OPTION_INDEX_MAX {
                let votes = context.storage_at(
                    params,
                    &storage_key::votes(&address, index, opt_index),
                )?;
                param_vote[opt_index] = votes;
            }
        }
        votes_list.push(Vote {
            index: index as u16,
            votes: param_vote,
        })
    }
    Ok(votes_list)
}

pub fn total_votes(
    version: u64, context: &mut InternalRefContext,
) -> vm::Result<Vec<Vote>> {
    let current_voting_version = (context.env.number
        - context.spec.cip94_activation_block_number)
        / context.spec.params_dao_vote_period
        + 1;

    let state = &context.state;

    let votes_entries = if version + 1 == current_voting_version {
        SETTLED_VOTES_ENTRIES.as_ref()
    } else if version == current_voting_version {
        CURRENT_VOTES_ENTRIES.as_ref()
    } else {
        internal_bail!(
            "Unsupport version {} (current {})",
            version,
            current_voting_version
        );
    };

    let mut answer = vec![];
    for x in 0..params_index_max(context.spec) {
        let slot_entry = &votes_entries[x];
        answer.push(Vote {
            index: x as u16,
            votes: [
                state.get_system_storage(
                    slot_entry[OPTION_UNCHANGE_INDEX as usize].as_ref(),
                )?,
                state.get_system_storage(
                    slot_entry[OPTION_INCREASE_INDEX as usize].as_ref(),
                )?,
                state.get_system_storage(
                    slot_entry[OPTION_DECREASE_INDEX as usize].as_ref(),
                )?,
            ],
        });
    }

    Ok(answer)
}

pub fn pos_stake_for_votes(
    version: u64, context: &mut InternalRefContext,
) -> vm::Result<U256> {
    let current_voting_version = (context.env.number
        - context.spec.cip94_activation_block_number)
        / context.spec.params_dao_vote_period
        + 1;

    let state = &context.state;
    let pos_stake_entry = if version + 1 == current_voting_version {
        settled_pos_staking_for_votes()
    } else if version == current_voting_version {
        current_pos_staking_for_votes()
    } else {
        internal_bail!(
            "Unsupport version {} (current {})",
            version,
            current_voting_version
        );
    };
    Ok(state.get_system_storage(&pos_stake_entry)?)
}

lazy_static! {
    static ref CURRENT_VOTES_ENTRIES: [[[u8; 32]; OPTION_INDEX_MAX]; PARAMETER_INDEX_MAX] = {
        let mut answer: [[[u8; 32]; OPTION_INDEX_MAX]; PARAMETER_INDEX_MAX] =
            Default::default();
        for index in 0..PARAMETER_INDEX_MAX {
            for opt_index in 0..OPTION_INDEX_MAX {
                answer[index][opt_index] =
                    system_storage_key::current_votes(index, opt_index);
            }
        }
        answer
    };
    static ref SETTLED_VOTES_ENTRIES: [[[u8; 32]; OPTION_INDEX_MAX]; PARAMETER_INDEX_MAX] = {
        let mut answer: [[[u8; 32]; OPTION_INDEX_MAX]; PARAMETER_INDEX_MAX] =
            Default::default();
        for index in 0..PARAMETER_INDEX_MAX {
            for opt_index in 0..OPTION_INDEX_MAX {
                answer[index][opt_index] =
                    system_storage_key::settled_votes(index, opt_index);
            }
        }
        answer
    };
}

#[derive(Clone, Copy, Debug, Default)]
pub struct ParamVoteCount {
    unchange: U256,
    increase: U256,
    decrease: U256,
}

impl ParamVoteCount {
    pub fn new(unchange: U256, increase: U256, decrease: U256) -> Self {
        Self {
            unchange,
            increase,
            decrease,
        }
    }

    pub fn from_state<U: AsRef<[u8]>>(
        state: &State, slot_entry: &[U; 3],
    ) -> DbResult<Self> {
        Ok(ParamVoteCount {
            unchange: state.get_system_storage(
                slot_entry[OPTION_UNCHANGE_INDEX as usize].as_ref(),
            )?,
            increase: state.get_system_storage(
                &slot_entry[OPTION_INCREASE_INDEX as usize].as_ref(),
            )?,
            decrease: state.get_system_storage(
                &slot_entry[OPTION_DECREASE_INDEX as usize].as_ref(),
            )?,
        })
    }

    pub fn compute_next_params(
        &self, old_value: U256, pos_staking_for_votes: U256,
    ) -> U256 {
        if self.should_update(pos_staking_for_votes) {
            let answer = self.compute_next_params_inner(old_value);
            // The return value should be in `[2^8, 2^192]`
            let min_value = U256::from(256u64);
            let max_value = U256::one() << 192usize;
            if answer < min_value {
                min_value
            } else if answer > max_value {
                max_value
            } else {
                answer
            }
        } else {
            debug!("params unchanged with pos token {}", pos_staking_for_votes);
            old_value
        }
    }

    fn compute_next_params_inner(&self, old_value: U256) -> U256 {
        // `VoteCount` only counts valid votes, so this will not overflow.
        let total = self.unchange + self.increase + self.decrease;

        if total == U256::zero() || self.increase == self.decrease {
            // If no one votes, we just keep the value unchanged.
            return old_value;
        } else if self.increase == total {
            return old_value * 2u64;
        } else if self.decrease == total {
            return old_value / 2u64;
        };

        let weight = if self.increase > self.decrease {
            self.increase - self.decrease
        } else {
            self.decrease - self.increase
        };
        let increase = self.increase > self.decrease;

        let frac_power = (U512::from(weight) << 64u64) / U512::from(total);
        assert!(frac_power < (U512::one() << 64u64));
        let frac_power = frac_power.as_u64();

        let ratio = power_two_fractional(frac_power, increase, 96);
        let new_value = (U512::from(old_value) * U512::from(ratio)) >> 96u64;

        if new_value > (U512::one() << 192u64) {
            return U256::one() << 192u64;
        } else {
            return new_value.try_into().unwrap();
        }
    }

    fn should_update(&self, pos_staking_for_votes: U256) -> bool {
        (self.decrease + self.increase + self.unchange)
            >= pos_staking_for_votes * DAO_MIN_VOTE_PERCENTAGE / 100
    }
}

#[derive(Clone, Copy, Debug, Default)]
pub struct AllParamsVoteCount {
    pub pow_base_reward: ParamVoteCount,
    pub pos_reward_interest: ParamVoteCount,
    pub storage_point_prop: ParamVoteCount,
    pub base_fee_prop: ParamVoteCount,
}

/// If the vote counts are not initialized, all counts will be zero, and the
/// parameters will be unchanged.
pub fn get_settled_param_vote_count(
    state: &State,
) -> DbResult<AllParamsVoteCount> {
    let pow_base_reward = ParamVoteCount::from_state(
        state,
        &SETTLED_VOTES_ENTRIES[POW_BASE_REWARD_INDEX as usize],
    )?;
    let pos_reward_interest = ParamVoteCount::from_state(
        state,
        &SETTLED_VOTES_ENTRIES[POS_REWARD_INTEREST_RATE_INDEX as usize],
    )?;
    let storage_point_prop = ParamVoteCount::from_state(
        state,
        &SETTLED_VOTES_ENTRIES[STORAGE_POINT_PROP_INDEX as usize],
    )?;
    let base_fee_prop = ParamVoteCount::from_state(
        state,
        &SETTLED_VOTES_ENTRIES[BASEFEE_PROP_INDEX as usize],
    )?;
    Ok(AllParamsVoteCount {
        pow_base_reward,
        pos_reward_interest,
        storage_point_prop,
        base_fee_prop,
    })
}

pub fn get_settled_pos_staking_for_votes(state: &State) -> DbResult<U256> {
    state.get_system_storage(&settled_pos_staking_for_votes())
}

/// Move the next vote counts into settled and reset the counts.
/// `set_pos_staking` is for compatibility with the Testnet.
pub fn settle_current_votes(state: &mut State, cip105: bool) -> DbResult<()> {
    // Here using `PARAMETER_INDEX_MAX` without knowing the block_number is okay
    // because if the new parameters have not been enabled, their votes will
    // be zero and setting them will be no-op.
    for index in 0..PARAMETER_INDEX_MAX {
        for opt_index in 0..OPTION_INDEX_MAX {
            let vote_count = state
                .get_system_storage(&CURRENT_VOTES_ENTRIES[index][opt_index])?;
            state.set_system_storage(
                SETTLED_VOTES_ENTRIES[index][opt_index].to_vec(),
                vote_count,
            )?;
            state.set_system_storage(
                CURRENT_VOTES_ENTRIES[index][opt_index].to_vec(),
                U256::zero(),
            )?;
        }
    }
    if cip105 {
        let pos_staking =
            state.get_system_storage(&current_pos_staking_for_votes())?;
        state.set_system_storage(
            settled_pos_staking_for_votes().to_vec(),
            pos_staking,
        )?;
        state.set_system_storage(
            current_pos_staking_for_votes().to_vec(),
            state.total_pos_staking_tokens(),
        )?;
    }
    Ok(())
}

pub fn params_index_max(spec: &Spec) -> usize {
    let mut max = PARAMETER_INDEX_MAX;
    if !spec.cip1559 {
        max -= 1;
    }
    if !spec.cip107 {
        max -= 1;
    }
    max
}

/// Solidity variable sequences.
/// ```solidity
/// struct VoteInfo {
///     uint version,
///     uint[3] pow_base_reward dynamic,
///     uint[3] pos_interest_rate dynamic,
/// }
/// mapping(address => VoteInfo) votes;
/// ```
mod storage_key {
    use cfx_types::{Address, BigEndianHash, H256, U256};

    use super::super::super::components::storage_layout::*;

    const VOTES_SLOT: usize = 0;

    // TODO: add cache to avoid duplicated hash computing
    pub fn versions(address: &Address) -> [u8; 32] {
        // Position of `votes`
        let base = U256::from(VOTES_SLOT);

        // Position of `votes[address]`
        let address_slot = mapping_slot(base, H256::from(*address).into_uint());

        // Position of `votes[address].version`
        let version_slot = address_slot;

        return u256_to_array(version_slot);
    }

    pub fn votes(
        address: &Address, index: usize, opt_index: usize,
    ) -> [u8; 32] {
        const TOPIC_OFFSET: [usize; 4] = [1, 2, 3, 4];

        // Position of `votes`
        let base = U256::from(VOTES_SLOT);

        // Position of `votes[address]`
        let address_slot = mapping_slot(base, H256::from(*address).into_uint());

        // Position of `votes[address].<topic>` (static slot)
        let topic_slot = address_slot + TOPIC_OFFSET[index];

        // Position of `votes[address].<topic>` (dynamic slot)
        let topic_slot = dynamic_slot(topic_slot);

        // Position of `votes[address].<topic>[opt_index]`
        let opt_slot = array_slot(topic_slot, opt_index, 1);

        return u256_to_array(opt_slot);
    }
}

/// Solidity variable sequences.
/// ```solidity
/// struct VoteStats {
///     uint[3] pow_base_reward dynamic,
///     uint[3] pos_interest_rate dynamic,
/// }
/// VoteStats current_votes dynamic;
/// VoteStats settled_votes dynamic;
/// uint current_pos_staking;
/// uint settled_pos_staking;
/// ```
mod system_storage_key {
    use cfx_parameters::internal_contract_addresses::PARAMS_CONTROL_CONTRACT_ADDRESS;
    use cfx_types::U256;

    use super::super::super::{
        components::storage_layout::*, contracts::system_storage::base_slot,
    };

    const CURRENT_VOTES_SLOT: usize = 0;
    const SETTLED_VOTES_SLOT: usize = 1;
    const CURRENT_POS_STAKING_SLOT: usize = 2;
    const SETTLED_POS_STAKING_SLOT: usize = 3;
    const STORAGE_POINT_PROP_SLOT: usize = 4;

    fn vote_stats(base: U256, index: usize, opt_index: usize) -> U256 {
        // Position of `.<topic>` (static slot)
        let topic_slot = base + index;

        // Position of `.<topic>` (dynamic slot)
        let topic_slot = dynamic_slot(topic_slot);

        // Position of `.<topic>[opt_index]`
        return array_slot(topic_slot, opt_index, 1);
    }

    pub(super) fn current_votes(index: usize, opt_index: usize) -> [u8; 32] {
        // Position of `current_votes` (static slot)
        let base = base_slot(PARAMS_CONTROL_CONTRACT_ADDRESS)
            + U256::from(CURRENT_VOTES_SLOT);

        // Position of `current_votes` (dynamic slot)
        let base = dynamic_slot(base);

        u256_to_array(vote_stats(base, index, opt_index))
    }

    pub(super) fn settled_votes(index: usize, opt_index: usize) -> [u8; 32] {
        // Position of `settled_votes` (static slot)
        let base = base_slot(PARAMS_CONTROL_CONTRACT_ADDRESS)
            + U256::from(SETTLED_VOTES_SLOT);

        // Position of `settled_votes` (dynamic slot)
        let base = dynamic_slot(base);

        u256_to_array(vote_stats(base, index, opt_index))
    }

    pub(super) fn current_pos_staking_for_votes() -> [u8; 32] {
        // Position of `current_pos_staking` (static slot)
        let base = base_slot(PARAMS_CONTROL_CONTRACT_ADDRESS)
            + U256::from(CURRENT_POS_STAKING_SLOT);
        u256_to_array(base)
    }

    pub(super) fn settled_pos_staking_for_votes() -> [u8; 32] {
        // Position of `settled_pos_staking` (static slot)
        let base = base_slot(PARAMS_CONTROL_CONTRACT_ADDRESS)
            + U256::from(SETTLED_POS_STAKING_SLOT);
        u256_to_array(base)
    }

    pub fn storage_point_prop() -> [u8; 32] {
        // Position of `storage_point_prop` (static slot)
        let base = base_slot(PARAMS_CONTROL_CONTRACT_ADDRESS)
            + U256::from(STORAGE_POINT_PROP_SLOT);
        u256_to_array(base)
    }
}