// 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 eth

import (
	"crypto/ecdsa"
	"math/big"
	"sort"
	"sync"
	"testing"

	"github.com/ethereum/go-ethereum/consensus/misc/eip4844"
	"github.com/ethereum/go-ethereum/core/state"
	"github.com/ethereum/go-ethereum/crypto/kzg4844"
	"github.com/ethereum/go-ethereum/trie"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/consensus"
	"github.com/ethereum/go-ethereum/consensus/ethash"
	"github.com/ethereum/go-ethereum/core"
	"github.com/ethereum/go-ethereum/core/rawdb"
	"github.com/ethereum/go-ethereum/core/txpool"
	"github.com/ethereum/go-ethereum/core/types"
	"github.com/ethereum/go-ethereum/core/vm"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/eth/downloader"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/params"
	"github.com/holiman/uint256"
)

var (
	// testKey is a private key to use for funding a tester account.
	testKey, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")

	// testAddr is the Ethereum address of the tester account.
	testAddr = crypto.PubkeyToAddress(testKey.PublicKey)
)

// testTxPool is a mock transaction pool that blindly accepts all transactions.
// Its goal is to get around setting up a valid statedb for the balance and nonce
// checks.
type testTxPool struct {
	pool map[common.Hash]*types.Transaction // Hash map of collected transactions

	txFeed       event.Feed   // Notification feed to allow waiting for inclusion
	reannoTxFeed event.Feed   // Notification feed to trigger reannouce
	lock         sync.RWMutex // Protects the transaction pool
}

// newTestTxPool creates a mock transaction pool.
func newTestTxPool() *testTxPool {
	return &testTxPool{
		pool: make(map[common.Hash]*types.Transaction),
	}
}

// Has returns an indicator whether txpool has a transaction
// cached with the given hash.
func (p *testTxPool) Has(hash common.Hash) bool {
	p.lock.Lock()
	defer p.lock.Unlock()

	return p.pool[hash] != nil
}

// Get retrieves the transaction from local txpool with given
// tx hash.
func (p *testTxPool) Get(hash common.Hash) *types.Transaction {
	p.lock.Lock()
	defer p.lock.Unlock()
	return p.pool[hash]
}

// Add appends a batch of transactions to the pool, and notifies any
// listeners if the addition channel is non nil
func (p *testTxPool) Add(txs []*types.Transaction, local bool, sync bool) []error {
	p.lock.Lock()
	defer p.lock.Unlock()

	for _, tx := range txs {
		p.pool[tx.Hash()] = tx
	}
	p.txFeed.Send(core.NewTxsEvent{Txs: txs})
	return make([]error, len(txs))
}

// ReannouceTransactions announce the transactions to some peers.
func (p *testTxPool) ReannouceTransactions(txs []*types.Transaction) []error {
	p.lock.Lock()
	defer p.lock.Unlock()

	for _, tx := range txs {
		p.pool[tx.Hash()] = tx
	}
	p.reannoTxFeed.Send(core.ReannoTxsEvent{Txs: txs})
	return make([]error, len(txs))
}

// Pending returns all the transactions known to the pool
func (p *testTxPool) Pending(filter txpool.PendingFilter) map[common.Address][]*txpool.LazyTransaction {
	p.lock.RLock()
	defer p.lock.RUnlock()

	batches := make(map[common.Address][]*types.Transaction)
	for _, tx := range p.pool {
		from, _ := types.Sender(types.HomesteadSigner{}, tx)
		batches[from] = append(batches[from], tx)
	}
	for _, batch := range batches {
		sort.Sort(types.TxByNonce(batch))
	}
	pending := make(map[common.Address][]*txpool.LazyTransaction)
	for addr, batch := range batches {
		for _, tx := range batch {
			pending[addr] = append(pending[addr], &txpool.LazyTransaction{
				Hash:      tx.Hash(),
				Tx:        tx,
				Time:      tx.Time(),
				GasFeeCap: uint256.MustFromBig(tx.GasFeeCap()),
				GasTipCap: uint256.MustFromBig(tx.GasTipCap()),
				Gas:       tx.Gas(),
				BlobGas:   tx.BlobGas(),
			})
		}
	}
	return pending
}

// SubscribeTransactions should return an event subscription of NewTxsEvent and
// send events to the given channel.
func (p *testTxPool) SubscribeTransactions(ch chan<- core.NewTxsEvent, reorgs bool) event.Subscription {
	return p.txFeed.Subscribe(ch)
}

// SubscribeReannoTxsEvent should return an event subscription of ReannoTxsEvent and
// send events to the given channel.
func (p *testTxPool) SubscribeReannoTxsEvent(ch chan<- core.ReannoTxsEvent) event.Subscription {
	return p.reannoTxFeed.Subscribe(ch)
}

// testHandler is a live implementation of the Ethereum protocol handler, just
// preinitialized with some sane testing defaults and the transaction pool mocked
// out.
type testHandler struct {
	db       ethdb.Database
	chain    *core.BlockChain
	txpool   *testTxPool
	votepool *testVotePool
	handler  *handler
}

// newTestHandler creates a new handler for testing purposes with no blocks.
func newTestHandler() *testHandler {
	return newTestHandlerWithBlocks(0)
}

// newTestHandlerWithBlocks creates a new handler for testing purposes, with a
// given number of initial blocks.
func newTestHandlerWithBlocks(blocks int) *testHandler {
	// Create a database pre-initialize with a genesis block
	db := rawdb.NewMemoryDatabase()
	gspec := &core.Genesis{
		Config: params.TestChainConfig,
		Alloc:  types.GenesisAlloc{testAddr: {Balance: big.NewInt(1000000)}},
	}
	chain, _ := core.NewBlockChain(db, nil, gspec, nil, ethash.NewFaker(), vm.Config{}, nil, nil)

	_, bs, _ := core.GenerateChainWithGenesis(gspec, ethash.NewFaker(), blocks, nil)
	if _, err := chain.InsertChain(bs); err != nil {
		panic(err)
	}
	txpool := newTestTxPool()
	votepool := newTestVotePool()

	handler, _ := newHandler(&handlerConfig{
		Database:   db,
		Chain:      chain,
		TxPool:     txpool,
		Merger:     consensus.NewMerger(rawdb.NewMemoryDatabase()),
		VotePool:   votepool,
		Network:    1,
		Sync:       downloader.SnapSync,
		BloomCache: 1,
	})
	handler.Start(1000, 3)

	return &testHandler{
		db:       db,
		chain:    chain,
		txpool:   txpool,
		votepool: votepool,
		handler:  handler,
	}
}

type mockParlia struct {
	consensus.Engine
}

func (c *mockParlia) Author(header *types.Header) (common.Address, error) {
	return header.Coinbase, nil
}

func (c *mockParlia) VerifyUncles(chain consensus.ChainReader, block *types.Block) error {
	return nil
}

func (c *mockParlia) VerifyHeader(chain consensus.ChainHeaderReader, header *types.Header) error {
	return nil
}

func (c *mockParlia) VerifyHeaders(chain consensus.ChainHeaderReader, headers []*types.Header) (chan<- struct{}, <-chan error) {
	abort := make(chan<- struct{})
	results := make(chan error, len(headers))
	for i := 0; i < len(headers); i++ {
		results <- nil
	}
	return abort, results
}

func (c *mockParlia) Finalize(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, _ *[]*types.Transaction, uncles []*types.Header, withdrawals []*types.Withdrawal,
	_ *[]*types.Receipt, _ *[]*types.Transaction, _ *uint64) (err error) {
	return
}

func (c *mockParlia) FinalizeAndAssemble(chain consensus.ChainHeaderReader, header *types.Header, state *state.StateDB, txs []*types.Transaction,
	uncles []*types.Header, receipts []*types.Receipt, withdrawals []*types.Withdrawal) (*types.Block, []*types.Receipt, error) {
	// Finalize block
	c.Finalize(chain, header, state, &txs, uncles, nil, nil, nil, nil)

	// Assign the final state root to header.
	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))

	// Header seems complete, assemble into a block and return
	return types.NewBlock(header, txs, uncles, receipts, trie.NewStackTrie(nil)), receipts, nil
}

func (c *mockParlia) CalcDifficulty(chain consensus.ChainHeaderReader, time uint64, parent *types.Header) *big.Int {
	return big.NewInt(1)
}

func newTestParliaHandlerAfterCancun(t *testing.T, config *params.ChainConfig, mode downloader.SyncMode, preCancunBlks, postCancunBlks uint64) *testHandler {
	// Have N headers in the freezer
	frdir := t.TempDir()
	db, err := rawdb.NewDatabaseWithFreezer(rawdb.NewMemoryDatabase(), frdir, "", false, false, false, false, false)
	if err != nil {
		t.Fatalf("failed to create database with ancient backend")
	}
	gspec := &core.Genesis{
		Config: config,
		Alloc:  types.GenesisAlloc{testAddr: {Balance: new(big.Int).SetUint64(10 * params.Ether)}},
	}
	engine := &mockParlia{}
	chain, _ := core.NewBlockChain(db, nil, gspec, nil, engine, vm.Config{}, nil, nil)
	signer := types.LatestSigner(config)

	_, bs, _ := core.GenerateChainWithGenesis(gspec, engine, int(preCancunBlks+postCancunBlks), func(i int, gen *core.BlockGen) {
		if !config.IsCancun(gen.Number(), gen.Timestamp()) {
			tx, _ := makeMockTx(config, signer, testKey, gen.TxNonce(testAddr), gen.BaseFee().Uint64(), eip4844.CalcBlobFee(gen.ExcessBlobGas()).Uint64(), false)
			gen.AddTxWithChain(chain, tx)
			return
		}
		tx, sidecar := makeMockTx(config, signer, testKey, gen.TxNonce(testAddr), gen.BaseFee().Uint64(), eip4844.CalcBlobFee(gen.ExcessBlobGas()).Uint64(), true)
		gen.AddTxWithChain(chain, tx)
		gen.AddBlobSidecar(&types.BlobSidecar{
			BlobTxSidecar: *sidecar,
			TxIndex:       0,
			TxHash:        tx.Hash(),
		})
	})
	if _, err := chain.InsertChain(bs); err != nil {
		panic(err)
	}
	txpool := newTestTxPool()
	votepool := newTestVotePool()

	handler, _ := newHandler(&handlerConfig{
		Database:   db,
		Chain:      chain,
		TxPool:     txpool,
		Merger:     consensus.NewMerger(rawdb.NewMemoryDatabase()),
		VotePool:   votepool,
		Network:    1,
		Sync:       mode,
		BloomCache: 1,
	})
	handler.Start(1000, 3)

	return &testHandler{
		db:       db,
		chain:    chain,
		txpool:   txpool,
		votepool: votepool,
		handler:  handler,
	}
}

// close tears down the handler and all its internal constructs.
func (b *testHandler) close() {
	b.handler.Stop()
	b.chain.Stop()
}

// newTestVotePool creates a mock vote pool.
type testVotePool struct {
	pool map[common.Hash]*types.VoteEnvelope // Hash map of collected votes

	voteFeed event.Feed   // Notification feed to allow waiting for inclusion
	lock     sync.RWMutex // Protects the vote pool
}

// newTestVotePool creates a mock vote pool.
func newTestVotePool() *testVotePool {
	return &testVotePool{
		pool: make(map[common.Hash]*types.VoteEnvelope),
	}
}

func (t *testVotePool) PutVote(vote *types.VoteEnvelope) {
	t.lock.Lock()
	defer t.lock.Unlock()

	t.pool[vote.Hash()] = vote
	t.voteFeed.Send(core.NewVoteEvent{Vote: vote})
}

func (t *testVotePool) FetchVoteByBlockHash(blockHash common.Hash) []*types.VoteEnvelope {
	panic("implement me")
}

func (t *testVotePool) GetVotes() []*types.VoteEnvelope {
	t.lock.RLock()
	defer t.lock.RUnlock()

	votes := make([]*types.VoteEnvelope, 0, len(t.pool))
	for _, vote := range t.pool {
		votes = append(votes, vote)
	}
	return votes
}

func (t *testVotePool) SubscribeNewVoteEvent(ch chan<- core.NewVoteEvent) event.Subscription {
	return t.voteFeed.Subscribe(ch)
}

var (
	emptyBlob          = kzg4844.Blob{}
	emptyBlobCommit, _ = kzg4844.BlobToCommitment(emptyBlob)
	emptyBlobProof, _  = kzg4844.ComputeBlobProof(emptyBlob, emptyBlobCommit)
)

func makeMockTx(config *params.ChainConfig, signer types.Signer, key *ecdsa.PrivateKey, nonce uint64, baseFee uint64, blobBaseFee uint64, isBlobTx bool) (*types.Transaction, *types.BlobTxSidecar) {
	if !isBlobTx {
		raw := &types.DynamicFeeTx{
			ChainID:   config.ChainID,
			Nonce:     nonce,
			GasTipCap: big.NewInt(10),
			GasFeeCap: new(big.Int).SetUint64(baseFee + 10),
			Gas:       params.TxGas,
			To:        &common.Address{0x00},
			Value:     big.NewInt(0),
		}
		tx, _ := types.SignTx(types.NewTx(raw), signer, key)
		return tx, nil
	}
	sidecar := &types.BlobTxSidecar{
		Blobs:       []kzg4844.Blob{emptyBlob, emptyBlob},
		Commitments: []kzg4844.Commitment{emptyBlobCommit, emptyBlobCommit},
		Proofs:      []kzg4844.Proof{emptyBlobProof, emptyBlobProof},
	}
	raw := &types.BlobTx{
		ChainID:    uint256.MustFromBig(config.ChainID),
		Nonce:      nonce,
		GasTipCap:  uint256.NewInt(10),
		GasFeeCap:  uint256.NewInt(baseFee + 10),
		Gas:        params.TxGas,
		To:         common.Address{0x00},
		Value:      uint256.NewInt(0),
		BlobFeeCap: uint256.NewInt(blobBaseFee),
		BlobHashes: sidecar.BlobHashes(),
	}
	tx, _ := types.SignTx(types.NewTx(raw), signer, key)
	return tx, sidecar
}