package paychmgr

import (
	"context"
	"errors"
	"sync"

	"github.com/ipfs/go-cid"
	"github.com/ipfs/go-datastore"
	logging "github.com/ipfs/go-log/v2"
	xerrors "golang.org/x/xerrors"

	"github.com/filecoin-project/go-address"
	"github.com/filecoin-project/go-state-types/abi"
	"github.com/filecoin-project/go-state-types/crypto"
	"github.com/filecoin-project/go-state-types/network"

	"github.com/filecoin-project/lotus/api"
	"github.com/filecoin-project/lotus/chain/actors/builtin/paych"
	"github.com/filecoin-project/lotus/chain/stmgr"
	"github.com/filecoin-project/lotus/chain/types"
)

var log = logging.Logger("paych")

var errProofNotSupported = errors.New("payment channel proof parameter is not supported")

// stateManagerAPI defines the methods needed from StateManager
type stateManagerAPI interface {
	ResolveToKeyAddress(ctx context.Context, addr address.Address, ts *types.TipSet) (address.Address, error)
	GetPaychState(ctx context.Context, addr address.Address, ts *types.TipSet) (*types.Actor, paych.State, error)
	Call(ctx context.Context, msg *types.Message, ts *types.TipSet) (*api.InvocResult, error)
}

// paychAPI defines the API methods needed by the payment channel manager
type PaychAPI interface {
	StateAccountKey(context.Context, address.Address, types.TipSetKey) (address.Address, error)
	StateWaitMsg(ctx context.Context, cid cid.Cid, confidence uint64, limit abi.ChainEpoch, allowReplaced bool) (*api.MsgLookup, error)
	MpoolPushMessage(ctx context.Context, msg *types.Message, maxFee *api.MessageSendSpec) (*types.SignedMessage, error)
	WalletHas(ctx context.Context, addr address.Address) (bool, error)
	WalletSign(ctx context.Context, k address.Address, msg []byte) (*crypto.Signature, error)
	StateNetworkVersion(context.Context, types.TipSetKey) (network.Version, error)
}

// managerAPI defines all methods needed by the manager
type managerAPI interface {
	stateManagerAPI
	PaychAPI
}

// managerAPIImpl is used to create a composite that implements managerAPI
type managerAPIImpl struct {
	stmgr.StateManagerAPI
	PaychAPI
}

type Manager struct {
	// The Manager context is used to terminate wait operations on shutdown
	ctx      context.Context
	shutdown context.CancelFunc

	store  *Store
	sa     *stateAccessor
	pchapi managerAPI

	lk       sync.RWMutex
	channels map[string]*channelAccessor
}

func NewManager(ctx context.Context, shutdown func(), sm stmgr.StateManagerAPI, pchstore *Store, api PaychAPI) *Manager {
	impl := &managerAPIImpl{StateManagerAPI: sm, PaychAPI: api}
	return &Manager{
		ctx:      ctx,
		shutdown: shutdown,
		store:    pchstore,
		sa:       &stateAccessor{sm: impl},
		channels: make(map[string]*channelAccessor),
		pchapi:   impl,
	}
}

// newManager is used by the tests to supply mocks
func newManager(pchstore *Store, pchapi managerAPI) (*Manager, error) {
	pm := &Manager{
		store:    pchstore,
		sa:       &stateAccessor{sm: pchapi},
		channels: make(map[string]*channelAccessor),
		pchapi:   pchapi,
	}
	pm.ctx, pm.shutdown = context.WithCancel(context.Background())
	return pm, pm.Start()
}

// Start restarts tracking of any messages that were sent to chain.
func (pm *Manager) Start() error {
	return pm.restartPending(pm.ctx)
}

// Stop shuts down any processes used by the manager
func (pm *Manager) Stop() error {
	pm.shutdown()
	return nil
}

type GetOpts struct {
	Reserve  bool
	OffChain bool
}

func (pm *Manager) GetPaych(ctx context.Context, from, to address.Address, amt types.BigInt, opts GetOpts) (address.Address, cid.Cid, error) {
	if !opts.Reserve && opts.OffChain {
		return address.Undef, cid.Undef, xerrors.Errorf("can't fund payment channels without on-chain operations")
	}

	chanAccessor, err := pm.accessorByFromTo(from, to)
	if err != nil {
		return address.Undef, cid.Undef, err
	}

	return chanAccessor.getPaych(ctx, amt, opts)
}

func (pm *Manager) AvailableFunds(ctx context.Context, ch address.Address) (*api.ChannelAvailableFunds, error) {
	ca, err := pm.accessorByAddress(ctx, ch)
	if err != nil {
		return nil, err
	}

	ci, err := ca.getChannelInfo(ctx, ch)
	if err != nil {
		return nil, err
	}

	return ca.availableFunds(ctx, ci.ChannelID)
}

func (pm *Manager) AvailableFundsByFromTo(ctx context.Context, from address.Address, to address.Address) (*api.ChannelAvailableFunds, error) {
	ca, err := pm.accessorByFromTo(from, to)
	if err != nil {
		return nil, err
	}

	ci, err := ca.outboundActiveByFromTo(ctx, from, to)
	if err == ErrChannelNotTracked {
		// If there is no active channel between from / to we still want to
		// return an empty ChannelAvailableFunds, so that clients can check
		// for the existence of a channel between from / to without getting
		// an error.
		return &api.ChannelAvailableFunds{
			Channel:             nil,
			From:                from,
			To:                  to,
			ConfirmedAmt:        types.NewInt(0),
			PendingAmt:          types.NewInt(0),
			NonReservedAmt:      types.NewInt(0),
			PendingAvailableAmt: types.NewInt(0),
			PendingWaitSentinel: nil,
			QueuedAmt:           types.NewInt(0),
			VoucherReedeemedAmt: types.NewInt(0),
		}, nil
	}
	if err != nil {
		return nil, err
	}

	return ca.availableFunds(ctx, ci.ChannelID)
}

// GetPaychWaitReady waits until the create channel / add funds message with the
// given message CID arrives.
// The returned channel address can safely be used against the Manager methods.
func (pm *Manager) GetPaychWaitReady(ctx context.Context, mcid cid.Cid) (address.Address, error) {
	// Find the channel associated with the message CID
	pm.lk.Lock()
	ci, err := pm.store.ByMessageCid(ctx, mcid)
	pm.lk.Unlock()

	if err != nil {
		if err == datastore.ErrNotFound {
			return address.Undef, xerrors.Errorf("Could not find wait msg cid %s", mcid)
		}
		return address.Undef, err
	}

	chanAccessor, err := pm.accessorByFromTo(ci.Control, ci.Target)
	if err != nil {
		return address.Undef, err
	}

	return chanAccessor.getPaychWaitReady(ctx, mcid)
}

func (pm *Manager) ListChannels(ctx context.Context) ([]address.Address, error) {
	// Need to take an exclusive lock here so that channel operations can't run
	// in parallel (see channelLock)
	pm.lk.Lock()
	defer pm.lk.Unlock()

	return pm.store.ListChannels(ctx)
}

func (pm *Manager) GetChannelInfo(ctx context.Context, addr address.Address) (*ChannelInfo, error) {
	ca, err := pm.accessorByAddress(ctx, addr)
	if err != nil {
		return nil, err
	}
	return ca.getChannelInfo(ctx, addr)
}

func (pm *Manager) CreateVoucher(ctx context.Context, ch address.Address, voucher paych.SignedVoucher) (*api.VoucherCreateResult, error) {
	ca, err := pm.accessorByAddress(ctx, ch)
	if err != nil {
		return nil, err
	}

	return ca.createVoucher(ctx, ch, voucher)
}

// CheckVoucherValid checks if the given voucher is valid (is or could become spendable at some point).
// If the channel is not in the store, fetches the channel from state (and checks that
// the channel To address is owned by the wallet).
func (pm *Manager) CheckVoucherValid(ctx context.Context, ch address.Address, sv *paych.SignedVoucher) error {
	// Get an accessor for the channel, creating it from state if necessary
	ca, err := pm.inboundChannelAccessor(ctx, ch)
	if err != nil {
		return err
	}

	_, err = ca.checkVoucherValid(ctx, ch, sv)
	return err
}

// CheckVoucherSpendable checks if the given voucher is currently spendable
func (pm *Manager) CheckVoucherSpendable(ctx context.Context, ch address.Address, sv *paych.SignedVoucher, secret []byte, proof []byte) (bool, error) {
	if len(proof) > 0 {
		return false, errProofNotSupported
	}
	ca, err := pm.accessorByAddress(ctx, ch)
	if err != nil {
		return false, err
	}

	return ca.checkVoucherSpendable(ctx, ch, sv, secret)
}

// AddVoucherOutbound adds a voucher for an outbound channel.
// Returns an error if the channel is not already in the store.
func (pm *Manager) AddVoucherOutbound(ctx context.Context, ch address.Address, sv *paych.SignedVoucher, proof []byte, minDelta types.BigInt) (types.BigInt, error) {
	if len(proof) > 0 {
		return types.NewInt(0), errProofNotSupported
	}
	ca, err := pm.accessorByAddress(ctx, ch)
	if err != nil {
		return types.NewInt(0), err
	}
	return ca.addVoucher(ctx, ch, sv, minDelta)
}

// AddVoucherInbound adds a voucher for an inbound channel.
// If the channel is not in the store, fetches the channel from state (and checks that
// the channel To address is owned by the wallet).
func (pm *Manager) AddVoucherInbound(ctx context.Context, ch address.Address, sv *paych.SignedVoucher, proof []byte, minDelta types.BigInt) (types.BigInt, error) {
	if len(proof) > 0 {
		return types.NewInt(0), errProofNotSupported
	}
	// Get an accessor for the channel, creating it from state if necessary
	ca, err := pm.inboundChannelAccessor(ctx, ch)
	if err != nil {
		return types.BigInt{}, err
	}
	return ca.addVoucher(ctx, ch, sv, minDelta)
}

// inboundChannelAccessor gets an accessor for the given channel. The channel
// must either exist in the store, or be an inbound channel that can be created
// from state.
func (pm *Manager) inboundChannelAccessor(ctx context.Context, ch address.Address) (*channelAccessor, error) {
	// Make sure channel is in store, or can be fetched from state, and that
	// the channel To address is owned by the wallet
	ci, err := pm.trackInboundChannel(ctx, ch)
	if err != nil {
		return nil, err
	}

	// This is an inbound channel, so To is the Control address (this node)
	from := ci.Target
	to := ci.Control
	return pm.accessorByFromTo(from, to)
}

func (pm *Manager) trackInboundChannel(ctx context.Context, ch address.Address) (*ChannelInfo, error) {
	// Need to take an exclusive lock here so that channel operations can't run
	// in parallel (see channelLock)
	pm.lk.Lock()
	defer pm.lk.Unlock()

	// Check if channel is in store
	ci, err := pm.store.ByAddress(ctx, ch)
	if err == nil {
		// Channel is in store, so it's already being tracked
		return ci, nil
	}

	// If there's an error (besides channel not in store) return err
	if err != ErrChannelNotTracked {
		return nil, err
	}

	// Channel is not in store, so get channel from state
	stateCi, err := pm.sa.loadStateChannelInfo(ctx, ch, DirInbound)
	if err != nil {
		return nil, err
	}

	// Check that channel To address is in wallet
	to := stateCi.Control // Inbound channel so To addr is Control (this node)
	toKey, err := pm.pchapi.StateAccountKey(ctx, to, types.EmptyTSK)
	if err != nil {
		return nil, err
	}
	has, err := pm.pchapi.WalletHas(ctx, toKey)
	if err != nil {
		return nil, err
	}
	if !has {
		msg := "cannot add voucher for channel %s: wallet does not have key for address %s"
		return nil, xerrors.Errorf(msg, ch, to)
	}

	// Save channel to store
	return pm.store.TrackChannel(ctx, stateCi)
}

// TODO: secret vs proof doesn't make sense, there is only one, not two
func (pm *Manager) SubmitVoucher(ctx context.Context, ch address.Address, sv *paych.SignedVoucher, secret []byte, proof []byte) (cid.Cid, error) {
	if len(proof) > 0 {
		return cid.Undef, errProofNotSupported
	}
	ca, err := pm.accessorByAddress(ctx, ch)
	if err != nil {
		return cid.Undef, err
	}
	return ca.submitVoucher(ctx, ch, sv, secret)
}

func (pm *Manager) AllocateLane(ctx context.Context, ch address.Address) (uint64, error) {
	ca, err := pm.accessorByAddress(ctx, ch)
	if err != nil {
		return 0, err
	}
	return ca.allocateLane(ctx, ch)
}

func (pm *Manager) ListVouchers(ctx context.Context, ch address.Address) ([]*VoucherInfo, error) {
	ca, err := pm.accessorByAddress(ctx, ch)
	if err != nil {
		return nil, err
	}
	return ca.listVouchers(ctx, ch)
}

func (pm *Manager) Settle(ctx context.Context, addr address.Address) (cid.Cid, error) {
	ca, err := pm.accessorByAddress(ctx, addr)
	if err != nil {
		return cid.Undef, err
	}
	return ca.settle(ctx, addr)
}

func (pm *Manager) Collect(ctx context.Context, addr address.Address) (cid.Cid, error) {
	ca, err := pm.accessorByAddress(ctx, addr)
	if err != nil {
		return cid.Undef, err
	}
	return ca.collect(ctx, addr)
}