Fantom-foundation/go-lachesis

// Copyright 2015 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 evmcore

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

    "github.com/ethereum/go-ethereum/common"
    "github.com/ethereum/go-ethereum/core/state"
    "github.com/ethereum/go-ethereum/core/types"
    "github.com/ethereum/go-ethereum/core/vm"
    "github.com/ethereum/go-ethereum/ethdb"
    "github.com/ethereum/go-ethereum/params"

    "github.com/Fantom-foundation/go-lachesis/inter"
)

// BlockGen creates blocks for testing.
// See GenerateChain for a detailed explanation.
type BlockGen struct {
    i       int
    parent  *EvmBlock
    chain   []*EvmBlock
    header  *EvmHeader
    statedb *state.StateDB

    gasPool  *GasPool
    txs      []*types.Transaction
    receipts []*types.Receipt

    config *params.ChainConfig
}

type TestChain struct {
    headers map[common.Hash]*EvmHeader
}

func (tc *TestChain) GetHeader(hash common.Hash, number uint64) *EvmHeader {
    return tc.headers[hash]
}

// SetCoinbase sets the coinbase of the generated block.
// It can be called at most once.
func (b *BlockGen) SetCoinbase(addr common.Address) {
    if b.gasPool != nil {
        if len(b.txs) > 0 {
            panic("coinbase must be set before adding transactions")
        }
        panic("coinbase can only be set once")
    }
    b.header.Coinbase = addr
    b.gasPool = new(GasPool).AddGas(b.header.GasLimit)
}

// AddTx adds a transaction to the generated block. If no coinbase has
// been set, the block's coinbase is set to the zero address.
//
// AddTx panics if the transaction cannot be executed. In addition to
// the protocol-imposed limitations (gas limit, etc.), there are some
// further limitations on the content of transactions that can be
// added. Notably, contract code relying on the BLOCKHASH instruction
// will panic during execution.
func (b *BlockGen) AddTx(tx *types.Transaction) {
    b.AddTxWithChain(nil, tx)
}

// AddTxWithChain adds a transaction to the generated block. If no coinbase has
// been set, the block's coinbase is set to the zero address.
//
// AddTxWithChain panics if the transaction cannot be executed. In addition to
// the protocol-imposed limitations (gas limit, etc.), there are some
// further limitations on the content of transactions that can be
// added. If contract code relies on the BLOCKHASH instruction,
// the block in chain will be returned.
func (b *BlockGen) AddTxWithChain(bc DummyChain, tx *types.Transaction) {
    if b.gasPool == nil {
        b.SetCoinbase(common.Address{})
    }
    b.statedb.Prepare(tx.Hash(), common.Hash{}, len(b.txs))
    receipt, _, _, _, err := ApplyTransaction(b.config, bc, &b.header.Coinbase, b.gasPool, b.statedb, b.header, tx, &b.header.GasUsed, vm.Config{}, false)
    if err != nil {
        panic(err)
    }
    b.txs = append(b.txs, tx)
    b.receipts = append(b.receipts, receipt)
}

// AddUncheckedTx forcefully adds a transaction to the block without any
// validation.
//
// AddUncheckedTx will cause consensus failures when used during real
// chain processing. This is best used in conjunction with raw block insertion.
func (b *BlockGen) AddUncheckedTx(tx *types.Transaction) {
    b.txs = append(b.txs, tx)
}

// Number returns the block number of the block being generated.
func (b *BlockGen) Number() *big.Int {
    return new(big.Int).Set(b.header.Number)
}

// AddUncheckedReceipt forcefully adds a receipts to the block without a
// backing transaction.
//
// AddUncheckedReceipt will cause consensus failures when used during real
// chain processing. This is best used in conjunction with raw block insertion.
func (b *BlockGen) AddUncheckedReceipt(receipt *types.Receipt) {
    b.receipts = append(b.receipts, receipt)
}

// TxNonce returns the next valid transaction nonce for the
// account at addr. It panics if the account does not exist.
func (b *BlockGen) TxNonce(addr common.Address) uint64 {
    if !b.statedb.Exist(addr) {
        panic("account does not exist")
    }
    return b.statedb.GetNonce(addr)
}

// PrevBlock returns a previously generated block by number. It panics if
// num is greater or equal to the number of the block being generated.
// For index -1, PrevBlock returns the parent block given to GenerateChain.
func (b *BlockGen) PrevBlock(index int) *EvmBlock {
    if index >= b.i {
        panic(fmt.Errorf("block index %d out of range (%d,%d)", index, -1, b.i))
    }
    if index == -1 {
        return b.parent
    }
    return b.chain[index]
}

// OffsetTime modifies the time instance of a block, implicitly changing its
// associated difficulty. It's useful to test scenarios where forking is not
// tied to chain length directly.
func (b *BlockGen) OffsetTime(seconds int64) {
    b.header.Time += inter.Timestamp(seconds)
    if b.header.Time <= b.parent.Header().Time {
        panic("block time out of range")
    }
}

// GenerateChain creates a chain of n blocks. The first block's
// parent will be the provided parent. db is used to store
// intermediate states and should contain the parent's state trie.
//
// The generator function is called with a new block generator for
// every block. Any transactions and uncles added to the generator
// become part of the block. If gen is nil, the blocks will be empty
// and their coinbase will be the zero address.
//
// Blocks created by GenerateChain do not contain valid proof of work
// values. Inserting them into BlockChain requires use of FakePow or
// a similar non-validating proof of work implementation.
func GenerateChain(config *params.ChainConfig, parent *EvmBlock, db ethdb.Database, n int, gen func(int, *BlockGen)) ([]*EvmBlock, []types.Receipts, DummyChain) {
    if config == nil {
        config = params.AllEthashProtocolChanges
    }

    chain := &TestChain{
        headers: map[common.Hash]*EvmHeader{},
    }

    blocks, receipts := make([]*EvmBlock, n), make([]types.Receipts, n)
    genblock := func(i int, parent *EvmBlock, statedb *state.StateDB) (*EvmBlock, types.Receipts) {
        b := &BlockGen{i: i, chain: blocks, parent: parent, statedb: statedb, config: config}
        b.header = makeHeader(parent, statedb)

        // Execute any user modifications to the block
        if gen != nil {
            gen(i, b)
        }
        // Finalize and seal the block
        block := &EvmBlock{
            EvmHeader: *b.header,
        }

        // Write state changes to db
        root, err := statedb.Commit(config.IsEIP158(b.header.Number))
        if err != nil {
            panic(fmt.Sprintf("state write error: %v", err))
        }
        if err := statedb.Database().TrieDB().Commit(root, false, nil); err != nil {
            panic(fmt.Sprintf("trie write error: %v", err))
        }
        b.header = block.Header()
        block.Root = root

        return block, b.receipts
    }
    for i := 0; i < n; i++ {
        statedb, err := state.New(parent.Root, state.NewDatabase(db), nil)
        if err != nil {
            panic(err)
        }
        block, receipt := genblock(i, parent, statedb)
        blocks[i] = block
        receipts[i] = receipt
        parent = block

        chain.headers[block.Hash] = block.Header()
    }
    return blocks, receipts, chain
}

func makeHeader(parent *EvmBlock, state *state.StateDB) *EvmHeader {
    var t inter.Timestamp
    if parent.Time == 0 {
        t = 10
    } else {
        t = parent.Time + inter.Timestamp(10*time.Second) // block time is fixed at 10 seconds
    }

    return &EvmHeader{
        ParentHash: parent.Hash,
        Coinbase:   parent.Coinbase,
        GasLimit:   parent.GasLimit,
        Number:     new(big.Int).Add(parent.Number, common.Big1),
        Time:       t,
    }
}

// makeHeaderChain creates a deterministic chain of headers rooted at parent.
func makeHeaderChain(parent *EvmHeader, n int, db ethdb.Database, seed int) []*EvmHeader {
    block := &EvmBlock{}
    block.EvmHeader = *parent

    blocks := makeBlockChain(block, n, db, seed)
    headers := make([]*EvmHeader, len(blocks))
    for i, block := range blocks {
        headers[i] = block.Header()
    }
    return headers
}

// makeBlockChain creates a deterministic chain of blocks rooted at parent.
func makeBlockChain(parent *EvmBlock, n int, db ethdb.Database, seed int) []*EvmBlock {
    blocks, _, _ := GenerateChain(params.TestChainConfig, parent, db, n, func(i int, b *BlockGen) {
        b.SetCoinbase(common.Address{0: byte(seed), 19: byte(i)})
    })
    return blocks
}

type fakeChainReader struct {
    config  *params.ChainConfig
    genesis *EvmBlock
}

// Config returns the chain configuration.
func (cr *fakeChainReader) Config() *params.ChainConfig {
    return cr.config
}

func (cr *fakeChainReader) CurrentHeader() *EvmHeader                            { return nil }
func (cr *fakeChainReader) GetHeaderByNumber(number uint64) *EvmHeader           { return nil }
func (cr *fakeChainReader) GetHeaderByHash(hash common.Hash) *EvmHeader          { return nil }
func (cr *fakeChainReader) GetHeader(hash common.Hash, number uint64) *EvmHeader { return nil }
func (cr *fakeChainReader) GetBlock(hash common.Hash, number uint64) *EvmBlock   { return nil }