package shardingconfig

import (
	"math/big"

	"github.com/harmony-one/harmony/internal/genesis"
)

const (
	mainnetEpochBlock1 = 344064 // 21 * 2^14
	blocksPerShard     = 16384  // 2^14

	mainnetVdfDifficulty  = 50000 // This takes about 100s to finish the vdf
	mainnetConsensusRatio = float64(0.66)

	mainnetFirstCrossLinkBlock = 524288 // 32 * 2^14

	// TODO: remove it after randomness feature turned on mainnet
	mainnetRandomnessStartingEpoch = 100000

	mainnetV0_1Epoch = 1
	mainnetV0_2Epoch = 5
	mainnetV0_3Epoch = 8
	mainnetV0_4Epoch = 10
)

// MainnetSchedule is the mainnet sharding configuration schedule.
var MainnetSchedule mainnetSchedule

type mainnetSchedule struct{}

func (mainnetSchedule) InstanceForEpoch(epoch *big.Int) Instance {
	switch {
	case epoch.Cmp(big.NewInt(mainnetV0_4Epoch)) >= 0:
		// tenth resharding epoch around 08/13/2019 9:00pm PDT
		return mainnetV0_4
	case epoch.Cmp(big.NewInt(mainnetV0_3Epoch)) >= 0:
		// eighth resharding epoch around 08/10/2019 6:00pm PDT
		return mainnetV0_3
	case epoch.Cmp(big.NewInt(mainnetV0_2Epoch)) >= 0:
		// fifth resharding epoch around 08/06/2019 2:30am PDT
		return mainnetV0_2
	case epoch.Cmp(big.NewInt(mainnetV0_1Epoch)) >= 0:
		// first resharding epoch around 07/30/2019 10:30pm PDT
		return mainnetV0_1
	default: // genesis
		return mainnetV0
	}
}

func (mainnetSchedule) BlocksPerEpoch() uint64 {
	return blocksPerShard
}

func (ms mainnetSchedule) CalcEpochNumber(blockNum uint64) *big.Int {
	blocks := ms.BlocksPerEpoch()
	switch {
	case blockNum >= mainnetEpochBlock1:
		return big.NewInt(int64((blockNum-mainnetEpochBlock1)/blocks) + 1)
	default:
		return big.NewInt(0)
	}
}

func (ms mainnetSchedule) IsLastBlock(blockNum uint64) bool {
	blocks := ms.BlocksPerEpoch()
	switch {
	case blockNum < mainnetEpochBlock1-1:
		return false
	case blockNum == mainnetEpochBlock1-1:
		return true
	default:
		return ((blockNum-mainnetEpochBlock1)%blocks == blocks-1)
	}
}

func (ms mainnetSchedule) VdfDifficulty() int {
	return mainnetVdfDifficulty
}

func (ms mainnetSchedule) FirstCrossLinkBlock() uint64 {
	return mainnetFirstCrossLinkBlock
}

// ConsensusRatio ratio of new nodes vs consensus total nodes
func (ms mainnetSchedule) ConsensusRatio() float64 {
	return mainnetConsensusRatio
}

// TODO: remove it after randomness feature turned on mainnet
//RandonnessStartingEpoch returns starting epoch of randonness generation
func (ms mainnetSchedule) RandomnessStartingEpoch() uint64 {
	return mainnetRandomnessStartingEpoch
}

var mainnetReshardingEpoch = []*big.Int{big.NewInt(0), big.NewInt(mainnetV0_1Epoch), big.NewInt(mainnetV0_2Epoch), big.NewInt(mainnetV0_3Epoch), big.NewInt(mainnetV0_4Epoch)}
var mainnetV0 = MustNewInstance(4, 150, 112, genesis.HarmonyAccounts, genesis.FoundationalNodeAccounts, mainnetReshardingEpoch)
var mainnetV0_1 = MustNewInstance(4, 152, 112, genesis.HarmonyAccounts, genesis.FoundationalNodeAccountsV0_1, mainnetReshardingEpoch)
var mainnetV0_2 = MustNewInstance(4, 200, 148, genesis.HarmonyAccounts, genesis.FoundationalNodeAccountsV0_2, mainnetReshardingEpoch)
var mainnetV0_3 = MustNewInstance(4, 210, 148, genesis.HarmonyAccounts, genesis.FoundationalNodeAccountsV0_3, mainnetReshardingEpoch)
var mainnetV0_4 = MustNewInstance(4, 216, 148, genesis.HarmonyAccounts, genesis.FoundationalNodeAccountsV0_4, mainnetReshardingEpoch)