package blockchain

import (
	"context"
	"errors"
	"testing"

	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/helpers"
	"github.com/prysmaticlabs/prysm/v3/beacon-chain/core/time"
	testDB "github.com/prysmaticlabs/prysm/v3/beacon-chain/db/testing"
	doublylinkedtree "github.com/prysmaticlabs/prysm/v3/beacon-chain/forkchoice/doubly-linked-tree"
	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state"
	"github.com/prysmaticlabs/prysm/v3/beacon-chain/state/stategen"
)

func testServiceOptsWithDB(t *testing.T) []Option {
	beaconDB := testDB.SetupDB(t)
	fcs := doublylinkedtree.New()
	return []Option{
		WithDatabase(beaconDB),
		WithStateGen(stategen.New(beaconDB, fcs)),
		WithForkChoiceStore(fcs),
	}
}

// WARNING: only use these opts when you are certain there are no db calls
// in your code path. this is a lightweight way to satisfy the stategen/beacondb
// initialization requirements w/o the overhead of db init.
func testServiceOptsNoDB() []Option {
	return []Option{
		withStateBalanceCache(satisfactoryStateBalanceCache()),
	}
}

type mockBalanceByRooter struct {
	state state.BeaconState
	err   error
}

var _ balanceByRooter = &mockBalanceByRooter{}

func (m mockBalanceByRooter) BalancesByRoot(_ context.Context, _ [32]byte) ([]uint64, error) {
	st := m.state
	if st == nil || st.IsNil() {
		return nil, errors.New("nil state")
	}
	epoch := time.CurrentEpoch(st)

	balances := make([]uint64, st.NumValidators())
	var balanceAccretor = func(idx int, val state.ReadOnlyValidator) error {
		if helpers.IsActiveValidatorUsingTrie(val, epoch) {
			balances[idx] = val.EffectiveBalance()
		} else {
			balances[idx] = 0
		}
		return nil
	}
	if err := st.ReadFromEveryValidator(balanceAccretor); err != nil {
		return nil, err
	}
	return balances, nil
}

// returns an instance of the state balance cache that can be used
// to satisfy the requirement for one in NewService, but which will
// always return an error if used.
func satisfactoryStateBalanceCache() *stateBalanceCache {
	err := errors.New("satisfactoryStateBalanceCache doesn't perform real caching")
	return &stateBalanceCache{stateGen: mockBalanceByRooter{err: err}}
}