package order

import (
	"bytes"
	"crypto/rand"
	"encoding/hex"
	"errors"
	"fmt"
	"net"

	"github.com/btcsuite/btcd/btcec"
	"github.com/btcsuite/btcd/wire"
	"github.com/btcsuite/btcutil"
	"github.com/lightninglabs/pool/poolrpc"
	"github.com/lightninglabs/pool/terms"
	"github.com/lightningnetwork/lnd/lntypes"
	"github.com/lightningnetwork/lnd/lnwallet/chainfee"
	"github.com/lightningnetwork/lnd/tor"
)

// ParseRPCOrder parses the incoming raw RPC order into the go native data
// types used in the order struct.
func ParseRPCOrder(version, leaseDuration uint32,
	details *poolrpc.Order) (*Kit, error) {

	var nonce Nonce
	copy(nonce[:], details.OrderNonce)
	kit := NewKit(nonce)

	// If the user didn't provide a nonce, we generate one.
	if nonce == ZeroNonce {
		preimageBytes, err := randomPreimage()
		if err != nil {
			return nil, fmt.Errorf("cannot generate nonce: %v", err)
		}
		var preimage lntypes.Preimage
		copy(preimage[:], preimageBytes)
		kit = NewKitWithPreimage(preimage)
	}

	copy(kit.AcctKey[:], details.TraderKey)
	kit.Version = Version(version)
	kit.FixedRate = details.RateFixed
	kit.Amt = btcutil.Amount(details.Amt)
	kit.MaxBatchFeeRate = chainfee.SatPerKWeight(
		details.MaxBatchFeeRateSatPerKw,
	)
	kit.Units = NewSupplyFromSats(kit.Amt)
	kit.UnitsUnfulfilled = kit.Units
	kit.LeaseDuration = leaseDuration

	switch {
	// If a min units match constraint was not provided, return an error.
	case details.MinUnitsMatch == 0:
		return nil, errors.New("min units match must be greater than 0")

	// The min units match must not exceed the total order units.
	case details.MinUnitsMatch > uint32(kit.Units):
		return nil, errors.New("min units match must not exceed " +
			"total order units")
	}
	kit.MinUnitsMatch = SupplyUnit(details.MinUnitsMatch)

	return kit, nil
}

// parseNodeAddrs parses the set of address in strong format as returned over
// the RPC layer into a proper interface we can use.
func parseNodeAddrs(rpcAddrs []*poolrpc.NodeAddress, orderIsAsk bool) ([]net.Addr, error) {

	if len(rpcAddrs) == 0 && orderIsAsk {
		return nil, fmt.Errorf("ask order doesn't include any node " +
			"addrs")
	}

	nodeAddrs := make([]net.Addr, 0, len(rpcAddrs))
	for _, rpcAddr := range rpcAddrs {
		var (
			addr net.Addr
			err  error
		)

		// Obtain the host to determine if this is a Tor address.
		host, _, err := net.SplitHostPort(rpcAddr.Addr)
		if err != nil {
			host = rpcAddr.Addr
		}

		switch {
		case tor.IsOnionHost(host):
			addr, err = parseOnionAddr(rpcAddr.Addr)

		default:
			addr, err = net.ResolveTCPAddr(
				rpcAddr.Network, rpcAddr.Addr,
			)
		}

		if err != nil {
			return nil, fmt.Errorf("unable to parse node "+
				"addr: %v", err)
		}

		nodeAddrs = append(nodeAddrs, addr)
	}

	return nodeAddrs, nil
}

// ParseRPCServerOrder parses the incoming raw RPC server order into the go
// native data types used in the order struct.
func ParseRPCServerOrder(version uint32, details *poolrpc.ServerOrder,
	orderIsAsk bool, leaseDuration uint32) (*Kit, [33]byte, []net.Addr, [33]byte, error) {

	var (
		nonce       Nonce
		nodeKey     [33]byte
		multiSigKey [33]byte
	)

	copy(nonce[:], details.OrderNonce)
	kit := NewKit(nonce)
	kit.Version = Version(version)
	kit.FixedRate = details.RateFixed
	kit.Amt = btcutil.Amount(details.Amt)
	kit.Units = NewSupplyFromSats(kit.Amt)
	kit.UnitsUnfulfilled = kit.Units
	kit.MaxBatchFeeRate = chainfee.SatPerKWeight(
		details.MaxBatchFeeRateSatPerKw,
	)
	kit.LeaseDuration = leaseDuration

	// If the user didn't provide a nonce, we generate one.
	if nonce == ZeroNonce {
		preimageBytes, err := randomPreimage()
		if err != nil {
			return nil, nodeKey, nil, multiSigKey,
				fmt.Errorf("cannot generate nonce: %v", err)
		}
		var preimage lntypes.Preimage
		copy(preimage[:], preimageBytes)
		kit = NewKitWithPreimage(preimage)
	}

	copy(kit.AcctKey[:], details.TraderKey)

	nodePubKey, err := btcec.ParsePubKey(details.NodePub, btcec.S256())
	if err != nil {
		return nil, nodeKey, nil, multiSigKey,
			fmt.Errorf("unable to parse node pub key: %v",
				err)
	}
	copy(nodeKey[:], nodePubKey.SerializeCompressed())

	nodeAddrs, err := parseNodeAddrs(details.NodeAddr, orderIsAsk)
	if err != nil {
		return nil, nodeKey, nil, multiSigKey, err
	}

	multiSigPubkey, err := btcec.ParsePubKey(
		details.MultiSigKey, btcec.S256(),
	)
	if err != nil {
		return nil, nodeKey, nodeAddrs, multiSigKey,
			fmt.Errorf("unable to parse multi sig pub key: %v", err)
	}
	copy(multiSigKey[:], multiSigPubkey.SerializeCompressed())

	return kit, nodeKey, nodeAddrs, multiSigKey, nil
}

// ParseRPCServerAsk parses the incoming raw RPC server ask into the go
// native data types used in the order struct.
func ParseRPCServerAsk(details *poolrpc.ServerAsk) (*MatchedOrder, error) {
	var (
		o   = &MatchedOrder{}
		kit *Kit
		err error
	)
	kit, o.NodeKey, o.NodeAddrs, o.MultiSigKey, err = ParseRPCServerOrder(
		details.Version, details.Details, true,
		details.LeaseDurationBlocks,
	)
	if err != nil {
		return nil, err
	}

	kit.LeaseDuration = details.LeaseDurationBlocks

	o.Order = &Ask{
		Kit: *kit,
	}

	return o, nil
}

// ParseRPCServerBid parses the incoming raw RPC server bid into the go
// native data types used in the order struct.
func ParseRPCServerBid(details *poolrpc.ServerBid) (*MatchedOrder, error) {
	var (
		o   = &MatchedOrder{}
		kit *Kit
		err error
	)
	kit, o.NodeKey, o.NodeAddrs, o.MultiSigKey, err = ParseRPCServerOrder(
		details.Version, details.Details, false,
		details.LeaseDurationBlocks,
	)
	if err != nil {
		return nil, err
	}

	o.Order = &Bid{
		Kit: *kit,
	}

	return o, nil
}

// ParseRPCBatch parses the incoming raw RPC batch into the go native data types
// used by the order manager.
func ParseRPCBatch(prepareMsg *poolrpc.OrderMatchPrepare) (*Batch,
	error) {

	b := &Batch{
		Version:       BatchVersion(prepareMsg.BatchVersion),
		MatchedOrders: make(map[Nonce][]*MatchedOrder),
		BatchTX:       &wire.MsgTx{},
	}

	// Parse matched orders.
	for ourOrderHex, rpcMatchedOrders := range prepareMsg.MatchedOrders {
		var ourOrder Nonce
		ourOrderBytes, err := hex.DecodeString(ourOrderHex)
		if err != nil {
			return nil, fmt.Errorf("error parsing nonce: %v", err)
		}
		copy(ourOrder[:], ourOrderBytes)
		b.MatchedOrders[ourOrder], err = ParseRPCMatchedOrders(
			rpcMatchedOrders,
		)
		if err != nil {
			return nil, fmt.Errorf("error parsing matched order: "+
				"%v", err)
		}
	}

	// Parse account diff.
	for _, diff := range prepareMsg.ChargedAccounts {
		var acctKeyRaw [33]byte
		acctKey, err := btcec.ParsePubKey(diff.TraderKey, btcec.S256())
		if err != nil {
			return nil, fmt.Errorf("error parsing account key: %v",
				err)
		}
		copy(acctKeyRaw[:], acctKey.SerializeCompressed())
		b.AccountDiffs = append(
			b.AccountDiffs, &AccountDiff{
				AccountKeyRaw: acctKeyRaw,
				AccountKey:    acctKey,
				EndingState:   diff.EndingState,
				EndingBalance: btcutil.Amount(diff.EndingBalance),
				OutpointIndex: diff.OutpointIndex,
			},
		)
	}

	// Parse batch transaction.
	err := b.BatchTX.Deserialize(bytes.NewReader(
		prepareMsg.BatchTransaction,
	))
	if err != nil {
		return nil, fmt.Errorf("error parsing batch TX: %v", err)
	}

	// Convert clearing price, fee rate and rebate.
	b.ClearingPrice = FixedRatePremium(prepareMsg.ClearingPriceRate)
	b.BatchTxFeeRate = chainfee.SatPerKWeight(prepareMsg.FeeRateSatPerKw)
	b.FeeRebate = btcutil.Amount(prepareMsg.FeeRebateSat)

	// Parse the execution fee.
	if prepareMsg.ExecutionFee == nil {
		return nil, fmt.Errorf("execution fee missing")
	}
	b.ExecutionFee = terms.NewLinearFeeSchedule(
		btcutil.Amount(prepareMsg.ExecutionFee.BaseFee),
		btcutil.Amount(prepareMsg.ExecutionFee.FeeRate),
	)

	// Parse the batch ID as public key just to make sure it's valid.
	_, err = btcec.ParsePubKey(prepareMsg.BatchId, btcec.S256())
	if err != nil {
		return nil, fmt.Errorf("error parsing batch ID: %v", err)
	}
	copy(b.ID[:], prepareMsg.BatchId)

	return b, nil
}

// ParseRPCMatchedOrders parses the incoming raw RPC matched orders into the go
// native structs used by the order manager.
func ParseRPCMatchedOrders(orders *poolrpc.MatchedOrder) ([]*MatchedOrder,
	error) {

	var result []*MatchedOrder
	// The only thing we can check in this step is that not both matched
	// bids and matched asks are set at the same time as that wouldn't make
	// sense. Everything else is checked at a later stage when we know more
	// about our order that was matched against.
	switch {
	case len(orders.MatchedAsks) > 0 && len(orders.MatchedBids) > 0:
		return nil, fmt.Errorf("order cannot match both asks and bids")

	case len(orders.MatchedAsks) > 0:
		for _, ask := range orders.MatchedAsks {
			matchedAsk, err := ParseRPCServerAsk(ask.Ask)
			if err != nil {
				return nil, fmt.Errorf("error parsing server "+
					"ask: %v", err)
			}
			matchedAsk.UnitsFilled = SupplyUnit(ask.UnitsFilled)

			result = append(result, matchedAsk)
		}

	case len(orders.MatchedBids) > 0:
		for _, bid := range orders.MatchedBids {
			matchedBid, err := ParseRPCServerBid(bid.Bid)
			if err != nil {
				return nil, fmt.Errorf("error parsing server "+
					"bid: %v", err)
			}
			matchedBid.UnitsFilled = SupplyUnit(bid.UnitsFilled)

			result = append(result, matchedBid)
		}
	}

	return result, nil
}

// randomPreimage creates a new preimage from a random number generator.
func randomPreimage() ([]byte, error) {
	var nonce Nonce
	_, err := rand.Read(nonce[:])
	if err != nil {
		return nil, err
	}
	return nonce[:], nil
}