package v2

import (
	"github.com/prysmaticlabs/prysm/beacon-chain/core/time"
	"github.com/prysmaticlabs/prysm/beacon-chain/state/stateutil"
)

// CurrentEpochParticipation corresponding to participation bits on the beacon chain.
func (b *BeaconState) CurrentEpochParticipation() ([]byte, error) {
	if !b.hasInnerState() {
		return nil, ErrNilInnerState
	}
	if b.state.CurrentEpochParticipation == nil {
		return nil, nil
	}

	b.lock.RLock()
	defer b.lock.RUnlock()

	return b.currentEpochParticipation(), nil
}

// PreviousEpochParticipation corresponding to participation bits on the beacon chain.
func (b *BeaconState) PreviousEpochParticipation() ([]byte, error) {
	if !b.hasInnerState() {
		return nil, ErrNilInnerState
	}
	if b.state.PreviousEpochParticipation == nil {
		return nil, nil
	}

	b.lock.RLock()
	defer b.lock.RUnlock()

	return b.previousEpochParticipation(), nil
}

// UnrealizedCheckpointBalances returns the total balances: active, target attested in
// current epoch and target attested in previous epoch. This function is used to
// compute the "unrealized justification" that a synced Beacon Block will have.
func (b *BeaconState) UnrealizedCheckpointBalances() (uint64, uint64, uint64, error) {
	if !b.hasInnerState() {
		return 0, 0, 0, ErrNilInnerState
	}
	b.lock.RLock()
	defer b.lock.RUnlock()

	cp := b.state.CurrentEpochParticipation
	pp := b.state.PreviousEpochParticipation
	if cp == nil || pp == nil {
		return 0, 0, 0, ErrNilParticipation
	}
	currentEpoch := time.CurrentEpoch(b)
	return stateutil.UnrealizedCheckpointBalances(cp, pp, b.state.Validators, currentEpoch)

}

// currentEpochParticipation corresponding to participation bits on the beacon chain.
// This assumes that a lock is already held on BeaconState.
func (b *BeaconState) currentEpochParticipation() []byte {
	if !b.hasInnerState() {
		return nil
	}
	tmp := make([]byte, len(b.state.CurrentEpochParticipation))
	copy(tmp, b.state.CurrentEpochParticipation)
	return tmp
}

// previousEpochParticipation corresponding to participation bits on the beacon chain.
// This assumes that a lock is already held on BeaconState.
func (b *BeaconState) previousEpochParticipation() []byte {
	if !b.hasInnerState() {
		return nil
	}
	tmp := make([]byte, len(b.state.PreviousEpochParticipation))
	copy(tmp, b.state.PreviousEpochParticipation)
	return tmp
}