// VulcanizeDB
// Copyright © 2019 Vulcanize

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program 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 Affero General Public License for more details.

// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package cold_import

import (
	"errors"
	"strings"

	"github.com/ethereum/go-ethereum/common"
	"github.com/vulcanize/vulcanizedb/pkg/eth/core"
	"github.com/vulcanize/vulcanizedb/pkg/eth/crypto"
	"github.com/vulcanize/vulcanizedb/pkg/fs"
)

const (
	ColdImportClientName         = "LevelDbColdImport"
	ColdImportNetworkID  float64 = 1
)

var (
	NoChainDataErr = errors.New("Level DB path does not include chaindata extension.")
	NoGethRootErr  = errors.New("Level DB path does not include root path to geth.")
)

type ColdImportNodeBuilder struct {
	reader fs.Reader
	parser crypto.PublicKeyParser
}

func NewColdImportNodeBuilder(reader fs.Reader, parser crypto.PublicKeyParser) ColdImportNodeBuilder {
	return ColdImportNodeBuilder{reader: reader, parser: parser}
}

func (cinb ColdImportNodeBuilder) GetNode(genesisBlock []byte, levelPath string) (core.Node, error) {
	var coldNode core.Node
	nodeKeyPath, err := getNodeKeyPath(levelPath)
	if err != nil {
		return coldNode, err
	}
	nodeKey, err := cinb.reader.Read(nodeKeyPath)
	if err != nil {
		return coldNode, err
	}
	nodeID, err := cinb.parser.ParsePublicKey(string(nodeKey))
	if err != nil {
		return coldNode, err
	}
	genesisBlockHash := common.BytesToHash(genesisBlock).String()
	coldNode = core.Node{
		GenesisBlock: genesisBlockHash,
		NetworkID:    ColdImportNetworkID,
		ID:           nodeID,
		ClientName:   ColdImportClientName,
	}
	return coldNode, nil
}

func getNodeKeyPath(levelPath string) (string, error) {
	chaindataExtension := "chaindata"
	if !strings.Contains(levelPath, chaindataExtension) {
		return "", NoChainDataErr
	}
	chaindataExtensionLength := len(chaindataExtension)
	gethRootPathLength := len(levelPath) - chaindataExtensionLength
	if gethRootPathLength <= chaindataExtensionLength {
		return "", NoGethRootErr
	}
	gethRootPath := levelPath[:gethRootPathLength]
	nodeKeyPath := gethRootPath + "nodekey"
	return nodeKeyPath, nil
}