// 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 btc

import (
	"errors"
	"fmt"
	"strconv"

	"github.com/btcsuite/btcd/wire"
	"github.com/btcsuite/btcutil"

	"github.com/vulcanize/vulcanizedb/pkg/ipfs"
	"github.com/vulcanize/vulcanizedb/pkg/ipfs/dag_putters"
	"github.com/vulcanize/vulcanizedb/pkg/super_node/shared"
)

// IPLDPublisher satisfies the IPLDPublisher for ethereum
type IPLDPublisher struct {
	HeaderPutter      shared.DagPutter
	TransactionPutter shared.DagPutter
}

// NewIPLDPublisher creates a pointer to a new Publisher which satisfies the IPLDPublisher interface
func NewIPLDPublisher(ipfsPath string) (*IPLDPublisher, error) {
	node, err := ipfs.InitIPFSNode(ipfsPath)
	if err != nil {
		return nil, err
	}
	return &IPLDPublisher{
		HeaderPutter:      dag_putters.NewBtcHeaderDagPutter(node),
		TransactionPutter: dag_putters.NewBtcTxDagPutter(node),
	}, nil
}

// Publish publishes an IPLDPayload to IPFS and returns the corresponding CIDPayload
func (pub *IPLDPublisher) Publish(payload shared.StreamedIPLDs) (shared.CIDsForIndexing, error) {
	ipldPayload, ok := payload.(IPLDPayload)
	if !ok {
		return nil, fmt.Errorf("eth publisher expected payload type %T got %T", &IPLDPayload{}, payload)
	}
	// Process and publish headers
	headerCid, err := pub.publishHeader(ipldPayload.Header)
	if err != nil {
		return nil, err
	}
	header := HeaderModel{
		CID:         headerCid,
		ParentHash:  ipldPayload.Header.PrevBlock.String(),
		BlockNumber: strconv.Itoa(int(ipldPayload.Height)),
		BlockHash:   ipldPayload.Header.BlockHash().String(),
		Version:     ipldPayload.Header.Version,
		Timestamp:   ipldPayload.Header.Timestamp.UnixNano(),
		Bits:        ipldPayload.Header.Bits,
	}
	// Process and publish transactions
	transactionCids, err := pub.publishTransactions(ipldPayload.Txs, ipldPayload.TxMetaData)
	if err != nil {
		return nil, err
	}
	// Package CIDs and their metadata into a single struct
	return &CIDPayload{
		HeaderCID:       header,
		TransactionCIDs: transactionCids,
	}, nil
}

func (pub *IPLDPublisher) publishHeader(header *wire.BlockHeader) (string, error) {
	cids, err := pub.HeaderPutter.DagPut(header)
	if err != nil {
		return "", err
	}
	return cids[0], nil
}

func (pub *IPLDPublisher) publishTransactions(transactions []*btcutil.Tx, trxMeta []TxModelWithInsAndOuts) ([]TxModelWithInsAndOuts, error) {
	transactionCids, err := pub.TransactionPutter.DagPut(transactions)
	if err != nil {
		return nil, err
	}
	if len(transactionCids) != len(trxMeta) {
		return nil, errors.New("expected one CID for each transaction")
	}
	mappedTrxCids := make([]TxModelWithInsAndOuts, len(transactionCids))
	for i, cid := range transactionCids {
		mappedTrxCids[i] = TxModelWithInsAndOuts{
			CID:         cid,
			Index:       trxMeta[i].Index,
			TxHash:      trxMeta[i].TxHash,
			SegWit:      trxMeta[i].SegWit,
			WitnessHash: trxMeta[i].WitnessHash,
			TxInputs:    trxMeta[i].TxInputs,
			TxOutputs:   trxMeta[i].TxOutputs,
		}
	}
	return mappedTrxCids, nil
}