package importer

import (
	"math/big"

	"github.com/ethereum/go-ethereum/consensus/ethash"
	ethstate "github.com/ethereum/go-ethereum/core/state"
	ethtypes "github.com/ethereum/go-ethereum/core/types"
	ethparams "github.com/ethereum/go-ethereum/params"
)

// Some weird constants to avoid constant memory allocs for them.
var (
	big8  = big.NewInt(8)
	big32 = big.NewInt(32)
)

// accumulateRewards credits the coinbase of the given block with the mining
// reward. The total reward consists of the static block reward and rewards for
// included uncles. The coinbase of each uncle block is also rewarded.
func accumulateRewards(config *ethparams.ChainConfig, state *ethstate.StateDB, header *ethtypes.Header, uncles []*ethtypes.Header) {
	// select the correct block reward based on chain progression
	blockReward := ethash.FrontierBlockReward
	if config.IsByzantium(header.Number) {
		blockReward = ethash.ByzantiumBlockReward
	}

	// accumulate the rewards for the miner and any included uncles
	reward := new(big.Int).Set(blockReward)
	r := new(big.Int)

	for _, uncle := range uncles {
		r.Add(uncle.Number, big8)
		r.Sub(r, header.Number)
		r.Mul(r, blockReward)
		r.Div(r, big8)
		state.AddBalance(uncle.Coinbase, r)
		r.Div(blockReward, big32)
		reward.Add(reward, r)
	}

	state.AddBalance(header.Coinbase, reward)
}