// 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 (
	"fmt"
	"math/big"
	"math/rand"
	"os"
	"path/filepath"
	"runtime"
	"strconv"
	"testing"

	"github.com/ethereum/ethash"
	"github.com/ethereum/go-ethereum/common"
	"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/ethdb"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/params"
	"github.com/ethereum/go-ethereum/pow"
	"github.com/ethereum/go-ethereum/rlp"
	"github.com/hashicorp/golang-lru"
)

func init() {
	runtime.GOMAXPROCS(runtime.NumCPU())
}

func thePow() pow.PoW {
	pow, _ := ethash.NewForTesting()
	return pow
}

func theBlockChain(db ethdb.Database, t *testing.T) *BlockChain {
	var eventMux event.TypeMux
	WriteTestNetGenesisBlock(db, 0)
	blockchain, err := NewBlockChain(db, thePow(), &eventMux)
	if err != nil {
		t.Error("failed creating chainmanager:", err)
		t.FailNow()
		return nil
	}
	blockMan := NewBlockProcessor(db, nil, blockchain, &eventMux)
	blockchain.SetProcessor(blockMan)

	return blockchain
}

// Test fork of length N starting from block i
func testFork(t *testing.T, bman *BlockProcessor, i, N int, f func(td1, td2 *big.Int)) {
	// switch databases to process the new chain
	db, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	// copy old chain up to i into new db with deterministic canonical
	bman2, err := newCanonical(i, db)
	if err != nil {
		t.Fatal("could not make new canonical in testFork", err)
	}
	// assert the bmans have the same block at i
	bi1 := bman.bc.GetBlockByNumber(uint64(i)).Hash()
	bi2 := bman2.bc.GetBlockByNumber(uint64(i)).Hash()
	if bi1 != bi2 {
		fmt.Printf("%+v\n%+v\n\n", bi1, bi2)
		t.Fatal("chains do not have the same hash at height", i)
	}
	bman2.bc.SetProcessor(bman2)

	// extend the fork
	parent := bman2.bc.CurrentBlock()
	chainB := makeChain(parent, N, db, forkSeed)
	_, err = bman2.bc.InsertChain(chainB)
	if err != nil {
		t.Fatal("Insert chain error for fork:", err)
	}

	tdpre := bman.bc.Td()
	// Test the fork's blocks on the original chain
	td, err := testChain(chainB, bman)
	if err != nil {
		t.Fatal("expected chainB not to give errors:", err)
	}
	// Compare difficulties
	f(tdpre, td)

	// Loop over parents making sure reconstruction is done properly
}

func printChain(bc *BlockChain) {
	for i := bc.CurrentBlock().Number().Uint64(); i > 0; i-- {
		b := bc.GetBlockByNumber(uint64(i))
		fmt.Printf("\t%x %v\n", b.Hash(), b.Difficulty())
	}
}

// process blocks against a chain
func testChain(chainB types.Blocks, bman *BlockProcessor) (*big.Int, error) {
	for _, block := range chainB {
		_, _, err := bman.bc.processor.Process(block)
		if err != nil {
			if IsKnownBlockErr(err) {
				continue
			}
			return nil, err
		}
		bman.bc.mu.Lock()
		WriteTd(bman.bc.chainDb, block.Hash(), new(big.Int).Add(block.Difficulty(), bman.bc.GetTd(block.ParentHash())))
		WriteBlock(bman.bc.chainDb, block)
		bman.bc.mu.Unlock()
	}
	return bman.bc.GetTd(chainB[len(chainB)-1].Hash()), nil
}

func loadChain(fn string, t *testing.T) (types.Blocks, error) {
	fh, err := os.OpenFile(filepath.Join("..", "_data", fn), os.O_RDONLY, os.ModePerm)
	if err != nil {
		return nil, err
	}
	defer fh.Close()

	var chain types.Blocks
	if err := rlp.Decode(fh, &chain); err != nil {
		return nil, err
	}

	return chain, nil
}

func insertChain(done chan bool, blockchain *BlockChain, chain types.Blocks, t *testing.T) {
	_, err := blockchain.InsertChain(chain)
	if err != nil {
		fmt.Println(err)
		t.FailNow()
	}
	done <- true
}

func TestLastBlock(t *testing.T) {
	db, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	bchain := theBlockChain(db, t)
	block := makeChain(bchain.CurrentBlock(), 1, db, 0)[0]
	bchain.insert(block)
	if block.Hash() != GetHeadBlockHash(db) {
		t.Errorf("Write/Get HeadBlockHash failed")
	}
}

func TestExtendCanonical(t *testing.T) {
	CanonicalLength := 5
	db, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	// make first chain starting from genesis
	bman, err := newCanonical(CanonicalLength, db)
	if err != nil {
		t.Fatal("Could not make new canonical chain:", err)
	}
	f := func(td1, td2 *big.Int) {
		if td2.Cmp(td1) <= 0 {
			t.Error("expected chainB to have higher difficulty. Got", td2, "expected more than", td1)
		}
	}
	// Start fork from current height (CanonicalLength)
	testFork(t, bman, CanonicalLength, 1, f)
	testFork(t, bman, CanonicalLength, 2, f)
	testFork(t, bman, CanonicalLength, 5, f)
	testFork(t, bman, CanonicalLength, 10, f)
}

func TestShorterFork(t *testing.T) {
	db, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	// make first chain starting from genesis
	bman, err := newCanonical(10, db)
	if err != nil {
		t.Fatal("Could not make new canonical chain:", err)
	}
	f := func(td1, td2 *big.Int) {
		if td2.Cmp(td1) >= 0 {
			t.Error("expected chainB to have lower difficulty. Got", td2, "expected less than", td1)
		}
	}
	// Sum of numbers must be less than 10
	// for this to be a shorter fork
	testFork(t, bman, 0, 3, f)
	testFork(t, bman, 0, 7, f)
	testFork(t, bman, 1, 1, f)
	testFork(t, bman, 1, 7, f)
	testFork(t, bman, 5, 3, f)
	testFork(t, bman, 5, 4, f)
}

func TestLongerFork(t *testing.T) {
	db, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	// make first chain starting from genesis
	bman, err := newCanonical(10, db)
	if err != nil {
		t.Fatal("Could not make new canonical chain:", err)
	}
	f := func(td1, td2 *big.Int) {
		if td2.Cmp(td1) <= 0 {
			t.Error("expected chainB to have higher difficulty. Got", td2, "expected more than", td1)
		}
	}
	// Sum of numbers must be greater than 10
	// for this to be a longer fork
	testFork(t, bman, 0, 11, f)
	testFork(t, bman, 0, 15, f)
	testFork(t, bman, 1, 10, f)
	testFork(t, bman, 1, 12, f)
	testFork(t, bman, 5, 6, f)
	testFork(t, bman, 5, 8, f)
}

func TestEqualFork(t *testing.T) {
	db, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	bman, err := newCanonical(10, db)
	if err != nil {
		t.Fatal("Could not make new canonical chain:", err)
	}
	f := func(td1, td2 *big.Int) {
		if td2.Cmp(td1) != 0 {
			t.Error("expected chainB to have equal difficulty. Got", td2, "expected ", td1)
		}
	}
	// Sum of numbers must be equal to 10
	// for this to be an equal fork
	testFork(t, bman, 0, 10, f)
	testFork(t, bman, 1, 9, f)
	testFork(t, bman, 2, 8, f)
	testFork(t, bman, 5, 5, f)
	testFork(t, bman, 6, 4, f)
	testFork(t, bman, 9, 1, f)
}

func TestBrokenChain(t *testing.T) {
	db, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	bman, err := newCanonical(10, db)
	if err != nil {
		t.Fatal("Could not make new canonical chain:", err)
	}
	db2, err := ethdb.NewMemDatabase()
	if err != nil {
		t.Fatal("Failed to create db:", err)
	}
	bman2, err := newCanonical(10, db2)
	if err != nil {
		t.Fatal("Could not make new canonical chain:", err)
	}
	bman2.bc.SetProcessor(bman2)
	parent := bman2.bc.CurrentBlock()
	chainB := makeChain(parent, 5, db2, forkSeed)
	chainB = chainB[1:]
	_, err = testChain(chainB, bman)
	if err == nil {
		t.Error("expected broken chain to return error")
	}
}

func TestChainInsertions(t *testing.T) {
	t.Skip("Skipped: outdated test files")

	db, _ := ethdb.NewMemDatabase()

	chain1, err := loadChain("valid1", t)
	if err != nil {
		fmt.Println(err)
		t.FailNow()
	}

	chain2, err := loadChain("valid2", t)
	if err != nil {
		fmt.Println(err)
		t.FailNow()
	}

	blockchain := theBlockChain(db, t)

	const max = 2
	done := make(chan bool, max)

	go insertChain(done, blockchain, chain1, t)
	go insertChain(done, blockchain, chain2, t)

	for i := 0; i < max; i++ {
		<-done
	}

	if chain2[len(chain2)-1].Hash() != blockchain.CurrentBlock().Hash() {
		t.Error("chain2 is canonical and shouldn't be")
	}

	if chain1[len(chain1)-1].Hash() != blockchain.CurrentBlock().Hash() {
		t.Error("chain1 isn't canonical and should be")
	}
}

func TestChainMultipleInsertions(t *testing.T) {
	t.Skip("Skipped: outdated test files")

	db, _ := ethdb.NewMemDatabase()

	const max = 4
	chains := make([]types.Blocks, max)
	var longest int
	for i := 0; i < max; i++ {
		var err error
		name := "valid" + strconv.Itoa(i+1)
		chains[i], err = loadChain(name, t)
		if len(chains[i]) >= len(chains[longest]) {
			longest = i
		}
		fmt.Println("loaded", name, "with a length of", len(chains[i]))
		if err != nil {
			fmt.Println(err)
			t.FailNow()
		}
	}

	blockchain := theBlockChain(db, t)

	done := make(chan bool, max)
	for i, chain := range chains {
		// XXX the go routine would otherwise reference the same (chain[3]) variable and fail
		i := i
		chain := chain
		go func() {
			insertChain(done, blockchain, chain, t)
			fmt.Println(i, "done")
		}()
	}

	for i := 0; i < max; i++ {
		<-done
	}

	if chains[longest][len(chains[longest])-1].Hash() != blockchain.CurrentBlock().Hash() {
		t.Error("Invalid canonical chain")
	}
}

type bproc struct{}

func (bproc) Process(*types.Block) (vm.Logs, types.Receipts, error) { return nil, nil, nil }

func makeChainWithDiff(genesis *types.Block, d []int, seed byte) []*types.Block {
	var chain []*types.Block
	for i, difficulty := range d {
		header := &types.Header{
			Coinbase:   common.Address{seed},
			Number:     big.NewInt(int64(i + 1)),
			Difficulty: big.NewInt(int64(difficulty)),
		}
		if i == 0 {
			header.ParentHash = genesis.Hash()
		} else {
			header.ParentHash = chain[i-1].Hash()
		}
		block := types.NewBlockWithHeader(header)
		chain = append(chain, block)
	}
	return chain
}

func chm(genesis *types.Block, db ethdb.Database) *BlockChain {
	var eventMux event.TypeMux
	bc := &BlockChain{chainDb: db, genesisBlock: genesis, eventMux: &eventMux, pow: FakePow{}}
	bc.headerCache, _ = lru.New(100)
	bc.bodyCache, _ = lru.New(100)
	bc.bodyRLPCache, _ = lru.New(100)
	bc.tdCache, _ = lru.New(100)
	bc.blockCache, _ = lru.New(100)
	bc.futureBlocks, _ = lru.New(100)
	bc.processor = bproc{}
	bc.ResetWithGenesisBlock(genesis)

	return bc
}

func TestReorgLongest(t *testing.T) {
	db, _ := ethdb.NewMemDatabase()

	genesis, err := WriteTestNetGenesisBlock(db, 0)
	if err != nil {
		t.Error(err)
		t.FailNow()
	}
	bc := chm(genesis, db)

	chain1 := makeChainWithDiff(genesis, []int{1, 2, 4}, 10)
	chain2 := makeChainWithDiff(genesis, []int{1, 2, 3, 4}, 11)

	bc.InsertChain(chain1)
	bc.InsertChain(chain2)

	prev := bc.CurrentBlock()
	for block := bc.GetBlockByNumber(bc.CurrentBlock().NumberU64() - 1); block.NumberU64() != 0; prev, block = block, bc.GetBlockByNumber(block.NumberU64()-1) {
		if prev.ParentHash() != block.Hash() {
			t.Errorf("parent hash mismatch %x - %x", prev.ParentHash(), block.Hash())
		}
	}
}

func TestBadHashes(t *testing.T) {
	db, _ := ethdb.NewMemDatabase()
	genesis, err := WriteTestNetGenesisBlock(db, 0)
	if err != nil {
		t.Error(err)
		t.FailNow()
	}
	bc := chm(genesis, db)

	chain := makeChainWithDiff(genesis, []int{1, 2, 4}, 10)
	BadHashes[chain[2].Header().Hash()] = true

	_, err = bc.InsertChain(chain)
	if !IsBadHashError(err) {
		t.Errorf("error mismatch: want: BadHashError, have: %v", err)
	}
}

func TestReorgBadHashes(t *testing.T) {
	db, _ := ethdb.NewMemDatabase()
	genesis, err := WriteTestNetGenesisBlock(db, 0)
	if err != nil {
		t.Error(err)
		t.FailNow()
	}
	bc := chm(genesis, db)

	chain := makeChainWithDiff(genesis, []int{1, 2, 3, 4}, 11)
	bc.InsertChain(chain)

	if chain[3].Header().Hash() != bc.LastBlockHash() {
		t.Errorf("last block hash mismatch: want: %x, have: %x", chain[3].Header().Hash(), bc.LastBlockHash())
	}

	// NewChainManager should check BadHashes when loading it db
	BadHashes[chain[3].Header().Hash()] = true

	var eventMux event.TypeMux
	ncm, err := NewBlockChain(db, FakePow{}, &eventMux)
	if err != nil {
		t.Errorf("NewChainManager err: %s", err)
	}

	// check it set head to (valid) parent of bad hash block
	if chain[2].Header().Hash() != ncm.LastBlockHash() {
		t.Errorf("last block hash mismatch: want: %x, have: %x", chain[2].Header().Hash(), ncm.LastBlockHash())
	}

	if chain[2].Header().GasLimit.Cmp(ncm.GasLimit()) != 0 {
		t.Errorf("current block gasLimit mismatch: want: %x, have: %x", chain[2].Header().GasLimit, ncm.GasLimit())
	}
}

func TestReorgShortest(t *testing.T) {
	db, _ := ethdb.NewMemDatabase()
	genesis, err := WriteTestNetGenesisBlock(db, 0)
	if err != nil {
		t.Error(err)
		t.FailNow()
	}
	bc := chm(genesis, db)

	chain1 := makeChainWithDiff(genesis, []int{1, 2, 3, 4}, 10)
	chain2 := makeChainWithDiff(genesis, []int{1, 10}, 11)

	bc.InsertChain(chain1)
	bc.InsertChain(chain2)

	prev := bc.CurrentBlock()
	for block := bc.GetBlockByNumber(bc.CurrentBlock().NumberU64() - 1); block.NumberU64() != 0; prev, block = block, bc.GetBlockByNumber(block.NumberU64()-1) {
		if prev.ParentHash() != block.Hash() {
			t.Errorf("parent hash mismatch %x - %x", prev.ParentHash(), block.Hash())
		}
	}
}

func TestInsertNonceError(t *testing.T) {
	for i := 1; i < 25 && !t.Failed(); i++ {
		db, _ := ethdb.NewMemDatabase()
		genesis, err := WriteTestNetGenesisBlock(db, 0)
		if err != nil {
			t.Error(err)
			t.FailNow()
		}
		bc := chm(genesis, db)
		bc.processor = NewBlockProcessor(db, bc.pow, bc, bc.eventMux)
		blocks := makeChain(bc.currentBlock, i, db, 0)

		fail := rand.Int() % len(blocks)
		failblock := blocks[fail]
		bc.pow = failPow{failblock.NumberU64()}
		n, err := bc.InsertChain(blocks)

		// Check that the returned error indicates the nonce failure.
		if n != fail {
			t.Errorf("(i=%d) wrong failed block index: got %d, want %d", i, n, fail)
		}
		if !IsBlockNonceErr(err) {
			t.Fatalf("(i=%d) got %q, want a nonce error", i, err)
		}
		nerr := err.(*BlockNonceErr)
		if nerr.Number.Cmp(failblock.Number()) != 0 {
			t.Errorf("(i=%d) wrong block number in error, got %v, want %v", i, nerr.Number, failblock.Number())
		}
		if nerr.Hash != failblock.Hash() {
			t.Errorf("(i=%d) wrong block hash in error, got %v, want %v", i, nerr.Hash, failblock.Hash())
		}

		// Check that all no blocks after the failing block have been inserted.
		for _, block := range blocks[fail:] {
			if bc.HasBlock(block.Hash()) {
				t.Errorf("(i=%d) invalid block %d present in chain", i, block.NumberU64())
			}
		}
	}
}

// Tests that chain reorganizations handle transaction removals and reinsertions.
func TestChainTxReorgs(t *testing.T) {
	params.MinGasLimit = big.NewInt(125000)      // Minimum the gas limit may ever be.
	params.GenesisGasLimit = big.NewInt(3141592) // Gas limit of the Genesis block.

	var (
		key1, _ = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
		key2, _ = crypto.HexToECDSA("8a1f9a8f95be41cd7ccb6168179afb4504aefe388d1e14474d32c45c72ce7b7a")
		key3, _ = crypto.HexToECDSA("49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee")
		addr1   = crypto.PubkeyToAddress(key1.PublicKey)
		addr2   = crypto.PubkeyToAddress(key2.PublicKey)
		addr3   = crypto.PubkeyToAddress(key3.PublicKey)
		db, _   = ethdb.NewMemDatabase()
	)
	genesis := WriteGenesisBlockForTesting(db,
		GenesisAccount{addr1, big.NewInt(1000000)},
		GenesisAccount{addr2, big.NewInt(1000000)},
		GenesisAccount{addr3, big.NewInt(1000000)},
	)
	// Create two transactions shared between the chains:
	//  - postponed: transaction included at a later block in the forked chain
	//  - swapped: transaction included at the same block number in the forked chain
	postponed, _ := types.NewTransaction(0, addr1, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key1)
	swapped, _ := types.NewTransaction(1, addr1, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key1)

	// Create two transactions that will be dropped by the forked chain:
	//  - pastDrop: transaction dropped retroactively from a past block
	//  - freshDrop: transaction dropped exactly at the block where the reorg is detected
	var pastDrop, freshDrop *types.Transaction

	// Create three transactions that will be added in the forked chain:
	//  - pastAdd:   transaction added before the reorganiztion is detected
	//  - freshAdd:  transaction added at the exact block the reorg is detected
	//  - futureAdd: transaction added after the reorg has already finished
	var pastAdd, freshAdd, futureAdd *types.Transaction

	chain := GenerateChain(genesis, db, 3, func(i int, gen *BlockGen) {
		switch i {
		case 0:
			pastDrop, _ = types.NewTransaction(gen.TxNonce(addr2), addr2, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key2)

			gen.AddTx(pastDrop)  // This transaction will be dropped in the fork from below the split point
			gen.AddTx(postponed) // This transaction will be postponed till block #3 in the fork

		case 2:
			freshDrop, _ = types.NewTransaction(gen.TxNonce(addr2), addr2, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key2)

			gen.AddTx(freshDrop) // This transaction will be dropped in the fork from exactly at the split point
			gen.AddTx(swapped)   // This transaction will be swapped out at the exact height

			gen.OffsetTime(9) // Lower the block difficulty to simulate a weaker chain
		}
	})
	// Import the chain. This runs all block validation rules.
	evmux := &event.TypeMux{}
	chainman, _ := NewBlockChain(db, FakePow{}, evmux)
	chainman.SetProcessor(NewBlockProcessor(db, FakePow{}, chainman, evmux))
	if i, err := chainman.InsertChain(chain); err != nil {
		t.Fatalf("failed to insert original chain[%d]: %v", i, err)
	}

	// overwrite the old chain
	chain = GenerateChain(genesis, db, 5, func(i int, gen *BlockGen) {
		switch i {
		case 0:
			pastAdd, _ = types.NewTransaction(gen.TxNonce(addr3), addr3, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key3)
			gen.AddTx(pastAdd) // This transaction needs to be injected during reorg

		case 2:
			gen.AddTx(postponed) // This transaction was postponed from block #1 in the original chain
			gen.AddTx(swapped)   // This transaction was swapped from the exact current spot in the original chain

			freshAdd, _ = types.NewTransaction(gen.TxNonce(addr3), addr3, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key3)
			gen.AddTx(freshAdd) // This transaction will be added exactly at reorg time

		case 3:
			futureAdd, _ = types.NewTransaction(gen.TxNonce(addr3), addr3, big.NewInt(1000), params.TxGas, nil, nil).SignECDSA(key3)
			gen.AddTx(futureAdd) // This transaction will be added after a full reorg
		}
	})
	if _, err := chainman.InsertChain(chain); err != nil {
		t.Fatalf("failed to insert forked chain: %v", err)
	}

	// removed tx
	for i, tx := range (types.Transactions{pastDrop, freshDrop}) {
		if GetTransaction(db, tx.Hash()) != nil {
			t.Errorf("drop %d: tx found while shouldn't have been", i)
		}
		if GetReceipt(db, tx.Hash()) != nil {
			t.Errorf("drop %d: receipt found while shouldn't have been", i)
		}
	}
	// added tx
	for i, tx := range (types.Transactions{pastAdd, freshAdd, futureAdd}) {
		if GetTransaction(db, tx.Hash()) == nil {
			t.Errorf("add %d: expected tx to be found", i)
		}
		if GetReceipt(db, tx.Hash()) == nil {
			t.Errorf("add %d: expected receipt to be found", i)
		}
	}
	// shared tx
	for i, tx := range (types.Transactions{postponed, swapped}) {
		if GetTransaction(db, tx.Hash()) == nil {
			t.Errorf("share %d: expected tx to be found", i)
		}
		if GetReceipt(db, tx.Hash()) == nil {
			t.Errorf("share %d: expected receipt to be found", i)
		}
	}
}