// Copyright 2018 The dexon-consensus-core Authors
// This file is part of the dexon-consensus-core library.
//
// The dexon-consensus-core library is free software: you can redistribute it
// and/or modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
//
// The dexon-consensus-core library is distributed in the hope that it will be
// useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
// General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the dexon-consensus-core library. If not, see
// <http://www.gnu.org/licenses/>.

package core

import (
	"testing"

	"github.com/stretchr/testify/suite"

	"github.com/dexon-foundation/dexon-consensus-core/common"
	"github.com/dexon-foundation/dexon-consensus-core/core/crypto/ecdsa"
	"github.com/dexon-foundation/dexon-consensus-core/core/types"
)

type LeaderSelectorTestSuite struct {
	suite.Suite
}

func (s *LeaderSelectorTestSuite) newLeader() *leaderSelector {
	return newLeaderSelector(common.NewRandomHash())
}

func (s *LeaderSelectorTestSuite) TestDistance() {
	leader := s.newLeader()
	hash := common.NewRandomHash()
	prv, err := ecdsa.NewPrivateKey()
	s.Require().Nil(err)
	sig, err := prv.Sign(hash)
	s.Require().Nil(err)
	dis := leader.distance(sig)
	s.True(dis.Cmp(maxHash) == -1)
}

func (s *LeaderSelectorTestSuite) TestProbability() {
	leader := s.newLeader()
	prv1, err := ecdsa.NewPrivateKey()
	s.Require().Nil(err)
	prv2, err := ecdsa.NewPrivateKey()
	s.Require().Nil(err)
	for {
		hash := common.NewRandomHash()
		sig1, err := prv1.Sign(hash)
		s.Require().Nil(err)
		sig2, err := prv2.Sign(hash)
		s.Require().Nil(err)
		dis1 := leader.distance(sig1)
		dis2 := leader.distance(sig2)
		prob1 := leader.probability(sig1)
		prob2 := leader.probability(sig2)
		s.True(prob1 <= 1 && prob1 >= 0)
		s.True(prob2 <= 1 && prob2 >= 0)
		cmp := dis1.Cmp(dis2)
		if cmp == 0 {
			s.True(dis1.Cmp(dis2) == 0)
			continue
		}
		if cmp == 1 {
			s.True(prob2 > prob1)
		} else if cmp == -1 {
			s.True(prob2 < prob1)
		}
		break
	}
}

func (s *LeaderSelectorTestSuite) TestLeaderBlockHash() {
	leader := s.newLeader()
	blocks := make(map[common.Hash]*types.Block)
	for i := 0; i < 10; i++ {
		prv, err := ecdsa.NewPrivateKey()
		s.Require().Nil(err)
		block := &types.Block{
			ProposerID: types.NewNodeID(prv.PublicKey()),
			Hash:       common.NewRandomHash(),
		}
		s.Require().NoError(
			NewAuthenticator(prv).SignCRS(block, leader.hashCRS))
		s.Require().Nil(leader.processBlock(block))
		blocks[block.Hash] = block
	}
	blockHash := leader.leaderBlockHash()
	leaderBlock, exist := blocks[blockHash]
	s.Require().True(exist)
	leaderDist := leader.distance(leaderBlock.CRSSignature)
	for _, block := range blocks {
		if block == leaderBlock {
			continue
		}
		dist := leader.distance(block.CRSSignature)
		s.True(leaderDist.Cmp(dist) == -1)
	}
}

func TestLeaderSelector(t *testing.T) {
	suite.Run(t, new(LeaderSelectorTestSuite))
}