// Copyright 2016 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 state

import (
	"math/big"
	"testing"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/crypto"
	"github.com/ethereum/go-ethereum/ethdb"
	"github.com/harmony-one/harmony/core/rawdb"
)

// testAccount is the data associated with an account used by the state tests.
type testAccount struct {
	address common.Address
	balance *big.Int
	nonce   uint64
	code    []byte
}

// makeTestState create a sample test state to test node-wise reconstruction.
func makeTestState() (ethdb.Database, Database, common.Hash, []*testAccount) {
	// Create an empty state
	db := rawdb.NewMemoryDatabase()
	sdb := NewDatabase(db)
	state, _ := New(common.Hash{}, sdb, nil)

	// Fill it with some arbitrary data
	var accounts []*testAccount
	for i := byte(0); i < 96; i++ {
		obj := state.GetOrNewStateObject(common.BytesToAddress([]byte{i}))
		acc := &testAccount{address: common.BytesToAddress([]byte{i})}

		obj.AddBalance(big.NewInt(int64(11 * i)))
		acc.balance = big.NewInt(int64(11 * i))

		obj.SetNonce(uint64(42 * i))
		acc.nonce = uint64(42 * i)

		if i%3 == 0 {
			obj.SetCode(crypto.Keccak256Hash([]byte{i, i, i, i, i}), []byte{i, i, i, i, i}, false)
			acc.code = []byte{i, i, i, i, i}
		}
		if i%5 == 0 {
			for j := byte(0); j < 5; j++ {
				hash := crypto.Keccak256Hash([]byte{i, i, i, i, i, j, j})
				obj.SetState(sdb, hash, hash)
			}
		}
		state.updateStateObject(obj)
		accounts = append(accounts, acc)
	}
	root, _ := state.Commit(false)

	// Return the generated state
	return db, sdb, root, accounts
}

// Tests that the node iterator indeed walks over the entire database contents.
func TestNodeIteratorCoverage(t *testing.T) {
	// Create some arbitrary test state to iterate
	db, sdb, root, _ := makeTestState()
	sdb.TrieDB().Commit(root, false)

	state, err := New(root, sdb, nil)
	if err != nil {
		t.Fatalf("failed to create state trie at %x: %v", root, err)
	}
	// Gather all the node hashes found by the iterator
	hashes := make(map[common.Hash]struct{})
	for it := NewNodeIterator(state); it.Next(); {
		if it.Hash != (common.Hash{}) {
			hashes[it.Hash] = struct{}{}
		}
	}
	// Check in-disk nodes
	var (
		seenNodes = make(map[common.Hash]struct{})
		seenCodes = make(map[common.Hash]struct{})
	)
	it := db.NewIterator(nil, nil)
	for it.Next() {
		ok, hash := isTrieNode(sdb.TrieDB().Scheme(), it.Key(), it.Value())
		if !ok {
			continue
		}
		seenNodes[hash] = struct{}{}
	}
	it.Release()

	// Check in-disk codes
	it = db.NewIterator(nil, nil)
	for it.Next() {
		ok, hash := rawdb.IsCodeKey(it.Key())
		if !ok {
			continue
		}
		if _, ok := hashes[common.BytesToHash(hash)]; !ok {
			t.Errorf("state entry not reported %x", it.Key())
		}
		seenCodes[common.BytesToHash(hash)] = struct{}{}
	}
	it.Release()

	// Cross check the iterated hashes and the database/nodepool content
	for hash := range hashes {
		_, ok := seenNodes[hash]
		if !ok {
			_, ok = seenCodes[hash]
		}
		if !ok {
			t.Errorf("failed to retrieve reported node %x", hash)
		}
	}
}

// isTrieNode is a helper function which reports if the provided
// database entry belongs to a trie node or not.
func isTrieNode(scheme string, key, val []byte) (bool, common.Hash) {
	if scheme == rawdb.HashScheme {
		if len(key) == common.HashLength {
			return true, common.BytesToHash(key)
		}
	}
	return false, common.Hash{}
}