package bor

import (
	"math/rand"
	"sort"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"pgregory.net/rapid"

	"github.com/ethereum/go-ethereum/common"
	unique "github.com/ethereum/go-ethereum/common/set"
	"github.com/ethereum/go-ethereum/consensus/bor/valset"
)

const (
	numVals = 100
)

func TestGetSignerSuccessionNumber_ProposerIsSigner(t *testing.T) {
	t.Parallel()

	validators := buildRandomValidatorSet(numVals)
	validatorSet := valset.NewValidatorSet(validators)
	snap := Snapshot{
		ValidatorSet: validatorSet,
	}

	// proposer is signer
	signer := validatorSet.Proposer.Address
	successionNumber, err := snap.GetSignerSuccessionNumber(signer)
	if err != nil {
		t.Fatalf("%s", err)
	}

	assert.Equal(t, 0, successionNumber)
}

func TestGetSignerSuccessionNumber_SignerIndexIsLarger(t *testing.T) {
	t.Parallel()

	validators := buildRandomValidatorSet(numVals)

	// sort validators by address, which is what NewValidatorSet also does
	sort.Sort(valset.ValidatorsByAddress(validators))

	proposerIndex := 32
	signerIndex := 56
	// give highest ProposerPriority to a particular val, so that they become the proposer
	validators[proposerIndex].VotingPower = 200
	snap := Snapshot{
		ValidatorSet: valset.NewValidatorSet(validators),
	}

	// choose a signer at an index greater than proposer index
	signer := snap.ValidatorSet.Validators[signerIndex].Address
	successionNumber, err := snap.GetSignerSuccessionNumber(signer)
	if err != nil {
		t.Fatalf("%s", err)
	}

	assert.Equal(t, signerIndex-proposerIndex, successionNumber)
}

func TestGetSignerSuccessionNumber_SignerIndexIsSmaller(t *testing.T) {
	t.Parallel()

	validators := buildRandomValidatorSet(numVals)
	proposerIndex := 98
	signerIndex := 11
	// give highest ProposerPriority to a particular val, so that they become the proposer
	validators[proposerIndex].VotingPower = 200
	snap := Snapshot{
		ValidatorSet: valset.NewValidatorSet(validators),
	}

	// choose a signer at an index greater than proposer index
	signer := snap.ValidatorSet.Validators[signerIndex].Address
	successionNumber, err := snap.GetSignerSuccessionNumber(signer)
	if err != nil {
		t.Fatalf("%s", err)
	}

	assert.Equal(t, signerIndex+numVals-proposerIndex, successionNumber)
}

func TestGetSignerSuccessionNumber_ProposerNotFound(t *testing.T) {
	t.Parallel()

	validators := buildRandomValidatorSet(numVals)
	snap := Snapshot{
		ValidatorSet: valset.NewValidatorSet(validators),
	}

	dummyProposerAddress := randomAddress()
	snap.ValidatorSet.Proposer = &valset.Validator{Address: dummyProposerAddress}

	// choose any signer
	signer := snap.ValidatorSet.Validators[3].Address

	_, err := snap.GetSignerSuccessionNumber(signer)
	assert.NotNil(t, err)

	e, ok := err.(*UnauthorizedProposerError)
	assert.True(t, ok)
	assert.Equal(t, dummyProposerAddress.Bytes(), e.Proposer)
}

func TestGetSignerSuccessionNumber_SignerNotFound(t *testing.T) {
	t.Parallel()

	validators := buildRandomValidatorSet(numVals)
	snap := Snapshot{
		ValidatorSet: valset.NewValidatorSet(validators),
	}
	dummySignerAddress := randomAddress()
	_, err := snap.GetSignerSuccessionNumber(dummySignerAddress)
	assert.NotNil(t, err)
	e, ok := err.(*UnauthorizedSignerError)
	assert.True(t, ok)
	assert.Equal(t, dummySignerAddress.Bytes(), e.Signer)
}

// nolint: unparam
func buildRandomValidatorSet(numVals int) []*valset.Validator {
	rand.Seed(time.Now().Unix())

	validators := make([]*valset.Validator, numVals)
	valAddrs := randomAddresses(numVals)

	for i := 0; i < numVals; i++ {
		validators[i] = &valset.Validator{
			Address: valAddrs[i],
			// cannot process validators with voting power 0, hence +1
			VotingPower: int64(rand.Intn(99) + 1),
		}
	}

	// sort validators by address, which is what NewValidatorSet also does
	sort.Sort(valset.ValidatorsByAddress(validators))

	return validators
}

func randomAddress() common.Address {
	bytes := make([]byte, 32)
	rand.Read(bytes)

	return common.BytesToAddress(bytes)
}

func randomAddresses(n int) []common.Address {
	if n <= 0 {
		return []common.Address{}
	}

	addrs := make([]common.Address, 0, n)
	addrsSet := make(map[common.Address]struct{}, n)

	var (
		addr  common.Address
		exist bool
	)

	bytes := make([]byte, 32)

	for {
		rand.Read(bytes)

		addr = common.BytesToAddress(bytes)

		_, exist = addrsSet[addr]
		if !exist {
			addrs = append(addrs, addr)

			addrsSet[addr] = struct{}{}
		}

		if len(addrs) == n {
			return addrs
		}
	}
}

func TestRandomAddresses(t *testing.T) {
	t.Parallel()

	rapid.Check(t, func(t *rapid.T) {
		length := rapid.IntMax(100).Draw(t, "length").(int)

		addrs := randomAddresses(length)
		addressSet := unique.New(addrs)

		if len(addrs) != len(addressSet) {
			t.Fatalf("length of unique addresses %d, expected %d", len(addressSet), len(addrs))
		}
	})
}