// CalcBlockWorkSubsidy calculates the proof of work subsidy for a block as a
// proportion of the total subsidy.
func CalcBlockWorkSubsidy(height int64, voters uint16,
	params *chaincfg.Params) int64 {
	subsidy := calcBlockSubsidy(height, params)
	proportionWork := int64(params.WorkRewardProportion)
	proportions := int64(params.TotalSubsidyProportions())
	subsidy *= proportionWork
	subsidy /= proportions

	// Ignore the voters field of the header before we're at a point
	// where there are any voters.
	if height < params.StakeValidationHeight {
		return subsidy
	}

	// If there are no voters, subsidy is 0. The block will fail later anyway.
	if voters == 0 {
		return 0
	}

	// Adjust for the number of voters. This shouldn't ever overflow if you start
	// with 50 * 10^8 Atoms and voters and potentialVoters are uint16.
	potentialVoters := params.TicketsPerBlock
	actual := (int64(voters) * subsidy) / int64(potentialVoters)

	return actual
}

// CalcBlockTaxSubsidy calculates the subsidy for the organization address in the
// coinbase.
//
// Safe for concurrent access.
func CalcBlockTaxSubsidy(height int64, voters uint16,
	params *chaincfg.Params) int64 {
	if params.BlockTaxProportion == 0 {
		return 0
	}

	subsidy := calcBlockSubsidy(int64(height), params)
	proportionTax := int64(params.BlockTaxProportion)
	proportions := int64(params.TotalSubsidyProportions())
	subsidy *= proportionTax
	subsidy /= proportions

	// Assume all voters 'present' before stake voting is turned on.
	if height < params.StakeValidationHeight {
		voters = 5
	}

	// If there are no voters, subsidy is 0. The block will fail later anyway.
	if voters == 0 && height >= params.StakeValidationHeight {
		return 0
	}

	// Adjust for the number of voters. This shouldn't ever overflow if you start
	// with 50 * 10^8 Atoms and voters and potentialVoters are uint16.
	potentialVoters := params.TicketsPerBlock
	adjusted := (int64(voters) * subsidy) / int64(potentialVoters)

	return adjusted
}

// CalcStakeVoteSubsidy calculates the subsidy for a stake vote based on the height
// of its input SStx.
//
// Safe for concurrent access.
func CalcStakeVoteSubsidy(height int64, params *chaincfg.Params) int64 {
	// Calculate the actual reward for this block, then further reduce reward
	// proportional to StakeRewardProportion.
	// Note that voters/potential voters is 1, so that vote reward is calculated
	// irrespective of block reward.
	subsidy := calcBlockSubsidy(height, params)
	proportionStake := int64(params.StakeRewardProportion)
	proportions := int64(params.TotalSubsidyProportions())
	subsidy *= proportionStake
	subsidy /= (proportions * int64(params.TicketsPerBlock))

	return subsidy
}

// CalcBlockSubsidy returns the subsidy amount a block at the provided height
// should have. This is mainly used for determining how much the coinbase for
// newly generated blocks awards as well as validating the coinbase for blocks
// has the expected value.
//
// Subsidy calculation for exponential reductions:
// 0 for i in range (0, height / ReductionInterval):
// 1     subsidy *= MulSubsidy
// 2     subsidy /= DivSubsidy
//
// Safe for concurrent access.
func calcBlockSubsidy(height int64, params *chaincfg.Params) int64 {
	// Block height 1 subsidy is 'special' and used to
	// distribute initial tokens, if any.
	if height == 1 {
		return params.BlockOneSubsidy()
	}

	iterations := height / params.ReductionInterval
	subsidy := params.BaseSubsidy

	// You could stick all these values in a LUT for faster access if you
	// wanted to, but this calculation is already really fast until you
	// get very very far into the blockchain. The other method you could
	// use is storing the total subsidy in a block node and do the
	// multiplication and division when needed when adding a block.
	if iterations > 0 {
		for i := int64(0); i < iterations; i++ {
			subsidy *= params.MulSubsidy
			subsidy /= params.DivSubsidy
		}
	}

	return subsidy
}