// 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 (
	"bytes"
	"context"
	"math/big"
	"sort"
	"sync"

	"github.com/ledgerwatch/turbo-geth/common"
	"github.com/ledgerwatch/turbo-geth/consensus"
	"github.com/ledgerwatch/turbo-geth/consensus/ethash"
	"github.com/ledgerwatch/turbo-geth/core"
	"github.com/ledgerwatch/turbo-geth/core/types"
	"github.com/ledgerwatch/turbo-geth/core/vm"
	"github.com/ledgerwatch/turbo-geth/crypto"
	"github.com/ledgerwatch/turbo-geth/eth/stagedsync"
	"github.com/ledgerwatch/turbo-geth/ethdb"
	"github.com/ledgerwatch/turbo-geth/event"
	"github.com/ledgerwatch/turbo-geth/params"
	"github.com/ledgerwatch/turbo-geth/rlp"
)

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
	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]
}

func (p *testTxPool) GetSerializedTransactions(ctx context.Context, hashes common.Hashes) ([]rlp.RawValue, error) {
	reply := []rlp.RawValue{}
	var size uint64
	buf := bytes.NewBuffer(nil)

	for i := range hashes {
		txn := p.Get(hashes[i])
		if txn == nil {
			reply = append(reply, nil)
			continue
		}
		buf.Reset()
		if err := txn.EncodeRLP(buf); err != nil {
			return nil, err
		}
		reply = append(reply, common.CopyBytes(buf.Bytes()))
		size += uint64(buf.Len())
	}

	return reply, nil
}

// AddRemotes appends a batch of transactions to the pool, and notifies any
// listeners if the addition channel is non nil
func (p *testTxPool) AddRemotes(txs []*types.Transaction) []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))
}

// Pending returns all the transactions known to the pool
func (p *testTxPool) Pending() (types.TransactionsGroupedBySender, error) {
	p.lock.RLock()
	defer p.lock.RUnlock()

	batches := make(map[common.Address]types.Transactions)
	for _, tx := range p.pool {
		from, _ := types.Sender(types.HomesteadSigner{}, tx)
		batches[from] = append(batches[from], tx)
	}
	groups := types.TransactionsGroupedBySender{}
	for _, batch := range batches {
		sort.Sort(types.TxByNonce(batch))
		groups = append(groups, batch)
	}
	return groups, nil
}

// SubscribeNewTxsEvent should return an event subscription of NewTxsEvent and
// send events to the given channel.
func (p *testTxPool) SubscribeNewTxsEvent(ch chan<- core.NewTxsEvent) event.Subscription {
	return p.txFeed.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
	ChainConfig *params.ChainConfig
	vmConfig    *vm.Config
	genesis     *types.Block
	engine      consensus.Engine
	txpool      *testTxPool
	handler     *handler
	headBlock   *types.Block
}

// 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 := ethdb.NewMemoryDatabase()
	genesis := (&core.Genesis{
		Config: params.TestChainConfig,
		Alloc:  core.GenesisAlloc{testAddr: {Balance: big.NewInt(1000000)}},
	}).MustCommit(db)

	headBlock := genesis
	if blocks > 0 {
		bs, _, _ := core.GenerateChain(params.TestChainConfig, genesis, ethash.NewFaker(), db, blocks, nil, false)
		if _, err := stagedsync.InsertBlocksInStages(db, ethdb.DefaultStorageMode, params.TestChainConfig, &vm.Config{}, ethash.NewFaker(), bs, true /* checkRoot */); err != nil {
			panic(err)
		}
		headBlock = bs[len(bs)-1]
	}
	txpool := newTestTxPool()

	handler, _ := newHandler(&handlerConfig{
		Database:    db,
		ChainConfig: params.TestChainConfig,
		genesis:     genesis,
		vmConfig:    &vm.Config{},
		engine:      ethash.NewFaker(),
		TxPool:      txpool,
		Network:     1,
		BloomCache:  1,
	})
	handler.Start(1000)

	return &testHandler{
		db:          db,
		ChainConfig: params.TestChainConfig,
		genesis:     genesis,
		vmConfig:    &vm.Config{},
		engine:      ethash.NewFaker(),
		txpool:      txpool,
		handler:     handler,
		headBlock:   headBlock,
	}
}

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