// Copyright (C) 2019-2025, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.
//
// This file is a derived work, based on the go-ethereum library whose original
// notices appear below.
//
// It is distributed under a license compatible with the licensing terms of the
// original code from which it is derived.
//
// Much love to the original authors for their work.
// **********
// Copyright 2014 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum 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 go-ethereum 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 go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package core

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"math/big"

	"github.com/ava-labs/avalanchego/vms/evm/acp226"
	"github.com/ava-labs/coreth/core/extstate"
	"github.com/ava-labs/coreth/params"
	"github.com/ava-labs/coreth/plugin/evm/customtypes"
	"github.com/ava-labs/coreth/plugin/evm/upgrade/ap3"
	"github.com/ava-labs/coreth/triedb/pathdb"
	"github.com/ava-labs/libevm/common"
	"github.com/ava-labs/libevm/common/hexutil"
	"github.com/ava-labs/libevm/common/math"
	"github.com/ava-labs/libevm/core/rawdb"
	"github.com/ava-labs/libevm/core/state"
	"github.com/ava-labs/libevm/core/types"
	"github.com/ava-labs/libevm/ethdb"
	"github.com/ava-labs/libevm/libevm/stateconf"
	"github.com/ava-labs/libevm/log"
	ethparams "github.com/ava-labs/libevm/params"
	"github.com/ava-labs/libevm/trie"
	"github.com/ava-labs/libevm/triedb"
	"github.com/holiman/uint256"
)

//go:generate go tool -modfile=../tools/go.mod gencodec -type Genesis -field-override genesisSpecMarshaling -out gen_genesis.go

var errGenesisNoConfig = errors.New("genesis has no chain configuration")

// Deprecated: use types.Account instead.
type GenesisAccount = types.Account

// Deprecated: use types.GenesisAlloc instead.
type GenesisAlloc = types.GenesisAlloc

// Genesis specifies the header fields, state of a genesis block. It also defines hard
// fork switch-over blocks through the chain configuration.
type Genesis struct {
	Config     *params.ChainConfig `json:"config"`
	Nonce      uint64              `json:"nonce"`
	Timestamp  uint64              `json:"timestamp"`
	ExtraData  []byte              `json:"extraData"`
	GasLimit   uint64              `json:"gasLimit"   gencodec:"required"`
	Difficulty *big.Int            `json:"difficulty" gencodec:"required"`
	Mixhash    common.Hash         `json:"mixHash"`
	Coinbase   common.Address      `json:"coinbase"`
	Alloc      types.GenesisAlloc  `json:"alloc"      gencodec:"required"`

	// These fields are used for consensus tests. Please don't use them
	// in actual genesis blocks.
	Number        uint64      `json:"number"`
	GasUsed       uint64      `json:"gasUsed"`
	ParentHash    common.Hash `json:"parentHash"`
	BaseFee       *big.Int    `json:"baseFeePerGas"` // EIP-1559
	ExcessBlobGas *uint64     `json:"excessBlobGas"` // EIP-4844
	BlobGasUsed   *uint64     `json:"blobGasUsed"`   // EIP-4844
}

// GenesisAccount is an account in the state of the genesis block.
// field type overrides for gencodec
type genesisSpecMarshaling struct {
	Nonce         math.HexOrDecimal64
	Timestamp     math.HexOrDecimal64
	ExtraData     hexutil.Bytes
	GasLimit      math.HexOrDecimal64
	GasUsed       math.HexOrDecimal64
	Number        math.HexOrDecimal64
	Difficulty    *math.HexOrDecimal256
	Alloc         map[common.UnprefixedAddress]types.Account
	BaseFee       *math.HexOrDecimal256
	ExcessBlobGas *math.HexOrDecimal64
	BlobGasUsed   *math.HexOrDecimal64
}

// GenesisMismatchError is raised when trying to overwrite an existing
// genesis block with an incompatible one.
type GenesisMismatchError struct {
	Stored, New common.Hash
}

func (e *GenesisMismatchError) Error() string {
	return fmt.Sprintf("database contains incompatible genesis (have %x, new %x)", e.Stored, e.New)
}

// SetupGenesisBlock writes or updates the genesis block in db.
// The block that will be used is:
//
//	                     genesis == nil       genesis != nil
//	                  +------------------------------------------
//	db has no genesis |  main-net default  |  genesis
//	db has genesis    |  from DB           |  genesis (if compatible)

// The argument [genesis] must be specified and must contain a valid chain config.
// If the genesis block has already been set up, then we verify the hash matches the genesis passed in
// and that the chain config contained in genesis is backwards compatible with what is stored in the database.
//
// The stored chain configuration will be updated if it is compatible (i.e. does not
// specify a fork block below the local head block). In case of a conflict, the
// error is a *params.ConfigCompatError and the new, unwritten config is returned.
func SetupGenesisBlock(
	db ethdb.Database, triedb *triedb.Database, genesis *Genesis, lastAcceptedHash common.Hash, skipChainConfigCheckCompatible bool,
) (*params.ChainConfig, common.Hash, error) {
	if genesis == nil {
		return nil, common.Hash{}, ErrNoGenesis
	}
	if genesis.Config == nil {
		return nil, common.Hash{}, errGenesisNoConfig
	}
	// Just commit the new block if there is no stored genesis block.
	stored := rawdb.ReadCanonicalHash(db, 0)
	if (stored == common.Hash{}) {
		log.Info("Writing genesis to database")
		block, err := genesis.Commit(db, triedb)
		if err != nil {
			return genesis.Config, common.Hash{}, err
		}
		return genesis.Config, block.Hash(), nil
	}
	// The genesis block is present(perhaps in ancient database) while the
	// state database is not initialized yet. It can happen that the node
	// is initialized with an external ancient store. Commit genesis state
	// in this case.
	header := rawdb.ReadHeader(db, stored, 0)
	if header.Root != types.EmptyRootHash && !triedb.Initialized(header.Root) {
		// Ensure the stored genesis matches with the given one.
		hash := genesis.ToBlock().Hash()
		if hash != stored {
			return genesis.Config, common.Hash{}, &GenesisMismatchError{stored, hash}
		}
		_, err := genesis.Commit(db, triedb)
		return genesis.Config, common.Hash{}, err
	}
	// Check whether the genesis block is already written.
	hash := genesis.ToBlock().Hash()
	if hash != stored {
		return genesis.Config, common.Hash{}, &GenesisMismatchError{stored, hash}
	}
	// Get the existing chain configuration.
	newcfg := genesis.Config
	if err := newcfg.CheckConfigForkOrder(); err != nil {
		return newcfg, common.Hash{}, err
	}
	storedcfg := rawdb.ReadChainConfig(db, stored)
	if storedcfg == nil {
		log.Warn("Found genesis block without chain config")
		rawdb.WriteChainConfig(db, stored, newcfg)
		return newcfg, stored, nil
	}
	if err := params.SetEthUpgrades(storedcfg); err != nil {
		return genesis.Config, common.Hash{}, err
	}
	storedData, _ := json.Marshal(storedcfg)
	// Check config compatibility and write the config. Compatibility errors
	// are returned to the caller unless we're already at block zero.
	// we use last accepted block for cfg compatibility check. Note this allows
	// the node to continue if it previously halted due to attempting to process blocks with
	// an incorrect chain config.
	lastBlock := ReadBlockByHash(db, lastAcceptedHash)
	// this should never happen, but we check anyway
	// when we start syncing from scratch, the last accepted block
	// will be genesis block
	if lastBlock == nil {
		return newcfg, common.Hash{}, errors.New("missing last accepted block")
	}
	height := lastBlock.NumberU64()
	timestamp := lastBlock.Time()
	if skipChainConfigCheckCompatible {
		log.Info("skipping verifying activated network upgrades on chain config")
	} else {
		compatErr := storedcfg.CheckCompatible(newcfg, height, timestamp)
		if compatErr != nil && ((height != 0 && compatErr.RewindToBlock != 0) || (timestamp != 0 && compatErr.RewindToTime != 0)) {
			return newcfg, stored, compatErr
		}
	}
	// Don't overwrite if the old is identical to the new
	if newData, _ := json.Marshal(newcfg); !bytes.Equal(storedData, newData) {
		rawdb.WriteChainConfig(db, stored, newcfg)
	}
	return newcfg, stored, nil
}

// IsVerkle indicates whether the state is already stored in a verkle
// tree at genesis time.
func (g *Genesis) IsVerkle() bool {
	return g.Config.IsVerkle(new(big.Int).SetUint64(g.Number), g.Timestamp)
}

// ToBlock returns the genesis block according to genesis specification.
func (g *Genesis) ToBlock() *types.Block {
	db := rawdb.NewMemoryDatabase()
	return g.toBlock(db, triedb.NewDatabase(db, g.trieConfig()))
}

func (g *Genesis) trieConfig() *triedb.Config {
	if !g.IsVerkle() {
		return nil
	}
	return &triedb.Config{
		DBOverride: pathdb.Defaults.BackendConstructor,
		IsVerkle:   true,
	}
}

// TODO: migrate this function to "flush" for more similarity with upstream.
func (g *Genesis) toBlock(db ethdb.Database, triedb *triedb.Database) *types.Block {
	statedb, err := state.New(types.EmptyRootHash, extstate.NewDatabaseWithNodeDB(db, triedb), nil)
	if err != nil {
		panic(err)
	}

	head := &types.Header{
		Number:     new(big.Int).SetUint64(g.Number),
		Nonce:      types.EncodeNonce(g.Nonce),
		Time:       g.Timestamp,
		ParentHash: g.ParentHash,
		Extra:      g.ExtraData,
		GasLimit:   g.GasLimit,
		GasUsed:    g.GasUsed,
		BaseFee:    g.BaseFee,
		Difficulty: g.Difficulty,
		MixDigest:  g.Mixhash,
		Coinbase:   g.Coinbase,
	}

	// Configure any stateful precompiles that should be enabled in the genesis.
	blockContext := NewBlockContext(head.Number, head.Time)
	err = ApplyPrecompileActivations(g.Config, nil, blockContext, statedb)
	if err != nil {
		panic(fmt.Sprintf("unable to configure precompiles in genesis block: %v", err))
	}

	for addr, account := range g.Alloc {
		statedb.SetBalance(addr, uint256.MustFromBig(account.Balance))
		statedb.SetCode(addr, account.Code)
		statedb.SetNonce(addr, account.Nonce)
		for key, value := range account.Storage {
			statedb.SetState(addr, key, value)
		}
	}
	root := statedb.IntermediateRoot(false)
	head.Root = root

	if g.GasLimit == 0 {
		head.GasLimit = ethparams.GenesisGasLimit
	}
	if g.Difficulty == nil {
		head.Difficulty = ethparams.GenesisDifficulty
	}
	if g.ExtraData == nil {
		head.Extra = []byte{}
	}
	if conf := g.Config; conf != nil {
		num := new(big.Int).SetUint64(g.Number)
		confExtra := params.GetExtra(conf)
		if confExtra.IsApricotPhase3(g.Timestamp) {
			if g.BaseFee != nil {
				head.BaseFee = g.BaseFee
			} else {
				head.BaseFee = big.NewInt(ap3.InitialBaseFee)
			}
		}
		headerExtra := customtypes.GetHeaderExtra(head)

		// When Etna/Cancun is active, `BlockGasCost` and `ExtDataGasUsed` are decoded to 0 if it's nil.
		// This is because these fields come before the other optional Cancun fields in RLP order.
		// This only occurs with a serialized and written genesis block, and then reading it back.
		// While this does not affect anything (because we don't use `ToBlock` to retrieve the genesis block),
		// it's still confusing and breaking few tests. So we set it here to 0 to make it consistent.
		if confExtra.IsEtna(g.Timestamp) {
			if headerExtra.ExtDataGasUsed == nil {
				headerExtra.ExtDataGasUsed = new(big.Int)
			}
			if headerExtra.BlockGasCost == nil {
				headerExtra.BlockGasCost = new(big.Int)
			}
		}
		if conf.IsCancun(num, g.Timestamp) {
			// EIP-4788: The parentBeaconBlockRoot of the genesis block is always
			// the zero hash. This is because the genesis block does not have a parent
			// by definition.
			head.ParentBeaconRoot = new(common.Hash)
			// EIP-4844 fields
			head.ExcessBlobGas = g.ExcessBlobGas
			head.BlobGasUsed = g.BlobGasUsed
			if head.ExcessBlobGas == nil {
				head.ExcessBlobGas = new(uint64)
			}
			if head.BlobGasUsed == nil {
				head.BlobGasUsed = new(uint64)
			}
		}
		// Granite: set TimeMilliseconds
		if confExtra.IsGranite(g.Timestamp) {
			headerExtra.TimeMilliseconds = new(uint64)
			*headerExtra.TimeMilliseconds = g.Timestamp * 1000

			headerExtra.MinDelayExcess = new(acp226.DelayExcess)
			*headerExtra.MinDelayExcess = acp226.InitialDelayExcess
		}
	}

	// Create the genesis block to use the block hash
	block := types.NewBlock(head, nil, nil, nil, trie.NewStackTrie(nil))
	triedbOpt := stateconf.WithTrieDBUpdatePayload(common.Hash{}, block.Hash())

	if _, err := statedb.Commit(0, false, stateconf.WithTrieDBUpdateOpts(triedbOpt)); err != nil {
		panic(fmt.Sprintf("unable to commit genesis block to statedb: %v", err))
	}
	// Commit newly generated states into disk if it's not empty.
	if root != types.EmptyRootHash {
		if err := triedb.Commit(root, true); err != nil {
			panic(fmt.Sprintf("unable to commit genesis block: %v", err))
		}
	}
	return block
}

// Commit writes the block and state of a genesis specification to the database.
// The block is committed as the canonical head block.
func (g *Genesis) Commit(db ethdb.Database, triedb *triedb.Database) (*types.Block, error) {
	block := g.toBlock(db, triedb)
	if block.Number().Sign() != 0 {
		return nil, errors.New("can't commit genesis block with number > 0")
	}
	config := g.Config
	if config == nil {
		return nil, errGenesisNoConfig
	}
	if err := config.CheckConfigForkOrder(); err != nil {
		return nil, err
	}
	rawdb.WriteBlock(db, block)
	rawdb.WriteReceipts(db, block.Hash(), block.NumberU64(), nil)
	rawdb.WriteCanonicalHash(db, block.Hash(), block.NumberU64())
	rawdb.WriteHeadBlockHash(db, block.Hash())
	rawdb.WriteHeadHeaderHash(db, block.Hash())
	rawdb.WriteChainConfig(db, block.Hash(), config)
	return block, nil
}

// MustCommit writes the genesis block and state to db, panicking on error.
// The block is committed as the canonical head block.
func (g *Genesis) MustCommit(db ethdb.Database, triedb *triedb.Database) *types.Block {
	block, err := g.Commit(db, triedb)
	if err != nil {
		panic(err)
	}
	return block
}

// GenesisBlockForTesting creates and writes a block in which addr has the given wei balance.
func GenesisBlockForTesting(db ethdb.Database, addr common.Address, balance *big.Int) *types.Block {
	g := Genesis{
		Config:  params.TestChainConfig,
		Alloc:   types.GenesisAlloc{addr: {Balance: balance}},
		BaseFee: big.NewInt(ap3.InitialBaseFee),
	}
	return g.MustCommit(db, triedb.NewDatabase(db, triedb.HashDefaults))
}

// ReadBlockByHash reads the block with the given hash from the database.
func ReadBlockByHash(db ethdb.Reader, hash common.Hash) *types.Block {
	blockNumber := rawdb.ReadHeaderNumber(db, hash)
	if blockNumber == nil {
		return nil
	}
	return rawdb.ReadBlock(db, hash, *blockNumber)
}
