// Copyright 2017 The go-ethereum Authors
// This file is part of go-ethereum.
//
// go-ethereum is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// go-ethereum 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.

package main

import (
	"bytes"
	"fmt"
	"math/big"
	"math/rand"
	"time"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/log"
	"github.com/ethereum/go-ethereum/params"
)

// makeGenesis creates a new genesis struct based on some user input.
func (w *wizard) makeGenesis() {
	// Construct a default genesis block
	genesis := &core.Genesis{
		Timestamp:  uint64(time.Now().Unix()),
		GasLimit:   4700000,
		Difficulty: big.NewInt(1048576),
		Alloc:      make(core.GenesisAlloc),
		Config: &params.ChainConfig{
			HomesteadBlock: big.NewInt(1),
			EIP150Block:    big.NewInt(2),
			EIP155Block:    big.NewInt(3),
			EIP158Block:    big.NewInt(3),
		},
	}
	// Figure out which consensus engine to choose
	fmt.Println()
	fmt.Println("Which consensus engine to use? (default = clique)")
	fmt.Println(" 1. Ethash - proof-of-work")
	fmt.Println(" 2. Clique - proof-of-authority")

	choice := w.read()
	switch {
	case choice == "1":
		// In case of ethash, we're pretty much done
		genesis.Config.Ethash = new(params.EthashConfig)
		genesis.ExtraData = make([]byte, 32)

	case choice == "" || choice == "2":
		// In the case of clique, configure the consensus parameters
		genesis.Difficulty = big.NewInt(1)
		genesis.Config.Clique = &params.CliqueConfig{
			Period: 15,
			Epoch:  30000,
		}
		fmt.Println()
		fmt.Println("How many seconds should blocks take? (default = 15)")
		genesis.Config.Clique.Period = uint64(w.readDefaultInt(15))

		// We also need the initial list of signers
		fmt.Println()
		fmt.Println("Which accounts are allowed to seal? (mandatory at least one)")

		var signers []common.Address
		for {
			if address := w.readAddress(); address != nil {
				signers = append(signers, *address)
				continue
			}
			if len(signers) > 0 {
				break
			}
		}
		// Sort the signers and embed into the extra-data section
		for i := 0; i < len(signers); i++ {
			for j := i + 1; j < len(signers); j++ {
				if bytes.Compare(signers[i][:], signers[j][:]) > 0 {
					signers[i], signers[j] = signers[j], signers[i]
				}
			}
		}
		genesis.ExtraData = make([]byte, 32+len(signers)*common.AddressLength+65)
		for i, signer := range signers {
			copy(genesis.ExtraData[32+i*common.AddressLength:], signer[:])
		}

	default:
		log.Crit("Invalid consensus engine choice", "choice", choice)
	}
	// Consensus all set, just ask for initial funds and go
	fmt.Println()
	fmt.Println("Which accounts should be pre-funded? (advisable at least one)")
	for {
		// Read the address of the account to fund
		if address := w.readAddress(); address != nil {
			genesis.Alloc[*address] = core.GenesisAccount{
				Balance: new(big.Int).Lsh(big.NewInt(1), 256-7), // 2^256 / 128 (allow many pre-funds without balance overflows)
			}
			continue
		}
		break
	}
	// Add a batch of precompile balances to avoid them getting deleted
	for i := int64(0); i < 256; i++ {
		genesis.Alloc[common.BigToAddress(big.NewInt(i))] = core.GenesisAccount{Balance: big.NewInt(1)}
	}
	fmt.Println()

	// Query the user for some custom extras
	fmt.Println()
	fmt.Println("Specify your chain/network ID if you want an explicit one (default = random)")
	genesis.Config.ChainId = new(big.Int).SetUint64(uint64(w.readDefaultInt(rand.Intn(65536))))

	fmt.Println()
	fmt.Println("Anything fun to embed into the genesis block? (max 32 bytes)")

	extra := w.read()
	if len(extra) > 32 {
		extra = extra[:32]
	}
	genesis.ExtraData = append([]byte(extra), genesis.ExtraData[len(extra):]...)

	// All done, store the genesis and flush to disk
	w.conf.genesis = genesis
}
