// +build rpctest

package itest

import (
	"context"
	"fmt"
	"time"

	"github.com/btcsuite/btcutil"
	"github.com/davecgh/go-spew/spew"
	"github.com/lightningnetwork/lnd/lnrpc"
	"github.com/lightningnetwork/lnd/lnrpc/routerrpc"
	"github.com/lightningnetwork/lnd/lntest"
	"github.com/lightningnetwork/lnd/lntest/wait"
)

// testMultiHopRemoteForceCloseOnChainHtlcTimeout tests that if we extend a
// multi-hop HTLC, and the final destination of the HTLC force closes the
// channel, then we properly timeout the HTLC directly on *their* commitment
// transaction once the timeout has expired. Once we sweep the transaction, we
// should also cancel back the initial HTLC.
func testMultiHopRemoteForceCloseOnChainHtlcTimeout(net *lntest.NetworkHarness,
	t *harnessTest, alice, bob *lntest.HarnessNode, c commitType) {

	ctxb := context.Background()

	// First, we'll create a three hop network: Alice -> Bob -> Carol, with
	// Carol refusing to actually settle or directly cancel any HTLC's
	// self.
	aliceChanPoint, bobChanPoint, carol := createThreeHopNetwork(
		t, net, alice, bob, true, c,
	)

	// Clean up carol's node when the test finishes.
	defer shutdownAndAssert(net, t, carol)

	// With our channels set up, we'll then send a single HTLC from Alice
	// to Carol. As Carol is in hodl mode, she won't settle this HTLC which
	// opens up the base for out tests.
	const (
		finalCltvDelta = 40
		htlcAmt        = btcutil.Amount(30000)
	)

	ctx, cancel := context.WithCancel(ctxb)
	defer cancel()

	// We'll now send a single HTLC across our multi-hop network.
	carolPubKey := carol.PubKey[:]
	payHash := makeFakePayHash(t)
	_, err := alice.RouterClient.SendPaymentV2(
		ctx,
		&routerrpc.SendPaymentRequest{
			Dest:           carolPubKey,
			Amt:            int64(htlcAmt),
			PaymentHash:    payHash,
			FinalCltvDelta: finalCltvDelta,
			TimeoutSeconds: 60,
			FeeLimitMsat:   noFeeLimitMsat,
		},
	)
	if err != nil {
		t.Fatalf("unable to send alice htlc: %v", err)
	}

	// Once the HTLC has cleared, all the nodes in our mini network should
	// show that the HTLC has been locked in.
	var predErr error
	nodes := []*lntest.HarnessNode{alice, bob, carol}
	err = wait.Predicate(func() bool {
		predErr = assertActiveHtlcs(nodes, payHash)
		if predErr != nil {
			return false
		}

		return true
	}, time.Second*15)
	if err != nil {
		t.Fatalf("htlc mismatch: %v", predErr)
	}

	// At this point, we'll now instruct Carol to force close the
	// transaction. This will let us exercise that Bob is able to sweep the
	// expired HTLC on Carol's version of the commitment transaction. If
	// Carol has an anchor, it will be swept too.
	ctxt, _ := context.WithTimeout(ctxb, channelCloseTimeout)
	closeChannelAndAssertType(
		ctxt, t, net, carol, bobChanPoint, c == commitTypeAnchors,
		true,
	)

	// At this point, Bob should have a pending force close channel as
	// Carol has gone directly to chain.
	pendingChansRequest := &lnrpc.PendingChannelsRequest{}
	err = wait.Predicate(func() bool {
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		pendingChanResp, err := bob.PendingChannels(
			ctxt, pendingChansRequest,
		)
		if err != nil {
			predErr = fmt.Errorf("unable to query for "+
				"pending channels: %v", err)
			return false
		}
		if len(pendingChanResp.PendingForceClosingChannels) == 0 {
			predErr = fmt.Errorf("bob should have pending " +
				"force close channels but doesn't")
			return false
		}

		return true
	}, time.Second*15)
	if err != nil {
		t.Fatalf(predErr.Error())
	}

	// Bob can sweep his output immediately. If there is an anchor, Bob will
	// sweep that as well.
	expectedTxes := 1
	if c == commitTypeAnchors {
		expectedTxes = 2
	}

	_, err = waitForNTxsInMempool(
		net.Miner.Node, expectedTxes, minerMempoolTimeout,
	)
	if err != nil {
		t.Fatalf("failed to find txes in miner mempool: %v", err)
	}

	// Next, we'll mine enough blocks for the HTLC to expire. At this
	// point, Bob should hand off the output to his internal utxo nursery,
	// which will broadcast a sweep transaction.
	numBlocks := padCLTV(finalCltvDelta - 1)
	if _, err := net.Miner.Node.Generate(numBlocks); err != nil {
		t.Fatalf("unable to generate blocks: %v", err)
	}

	// If we check Bob's pending channel report, it should show that he has
	// a single HTLC that's now in the second stage, as skip the initial
	// first stage since this is a direct HTLC.
	err = wait.Predicate(func() bool {
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		pendingChanResp, err := bob.PendingChannels(
			ctxt, pendingChansRequest,
		)
		if err != nil {
			predErr = fmt.Errorf("unable to query for pending "+
				"channels: %v", err)
			return false
		}

		if len(pendingChanResp.PendingForceClosingChannels) == 0 {
			predErr = fmt.Errorf("bob should have pending for " +
				"close chan but doesn't")
			return false
		}

		forceCloseChan := pendingChanResp.PendingForceClosingChannels[0]
		if len(forceCloseChan.PendingHtlcs) != 1 {
			predErr = fmt.Errorf("bob should have pending htlc " +
				"but doesn't")
			return false
		}
		if forceCloseChan.PendingHtlcs[0].Stage != 2 {
			predErr = fmt.Errorf("bob's htlc should have "+
				"advanced to the second stage: %v", err)
			return false
		}

		return true
	}, time.Second*15)
	if err != nil {
		t.Fatalf("bob didn't hand off time-locked HTLC: %v", predErr)
	}

	// Bob's sweeping transaction should now be found in the mempool at
	// this point.
	sweepTx, err := waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
	if err != nil {
		// If Bob's transaction isn't yet in the mempool, then due to
		// internal message passing and the low period between blocks
		// being mined, it may have been detected as a late
		// registration. As a result, we'll mine another block and
		// repeat the check. If it doesn't go through this time, then
		// we'll fail.
		// TODO(halseth): can we use waitForChannelPendingForceClose to
		// avoid this hack?
		if _, err := net.Miner.Node.Generate(1); err != nil {
			t.Fatalf("unable to generate block: %v", err)
		}
		sweepTx, err = waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
		if err != nil {
			t.Fatalf("unable to find bob's sweeping transaction: "+
				"%v", err)
		}
	}

	// If we mine an additional block, then this should confirm Bob's
	// transaction which sweeps the direct HTLC output.
	block := mineBlocks(t, net, 1, 1)[0]
	assertTxInBlock(t, block, sweepTx)

	// Now that the sweeping transaction has been confirmed, Bob should
	// cancel back that HTLC. As a result, Alice should not know of any
	// active HTLC's.
	nodes = []*lntest.HarnessNode{alice}
	err = wait.Predicate(func() bool {
		predErr = assertNumActiveHtlcs(nodes, 0)
		if predErr != nil {
			return false
		}
		return true
	}, time.Second*15)
	if err != nil {
		t.Fatalf("alice's channel still has active htlc's: %v", predErr)
	}

	// Now we'll check Bob's pending channel report. Since this was Carol's
	// commitment, he doesn't have to wait for any CSV delays. As a result,
	// he should show no additional pending transactions.
	err = wait.Predicate(func() bool {
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		pendingChanResp, err := bob.PendingChannels(
			ctxt, pendingChansRequest,
		)
		if err != nil {
			predErr = fmt.Errorf("unable to query for pending "+
				"channels: %v", err)
			return false
		}
		if len(pendingChanResp.PendingForceClosingChannels) != 0 {
			predErr = fmt.Errorf("bob still has pending channels "+
				"but shouldn't: %v", spew.Sdump(pendingChanResp))
			return false
		}

		return true
	}, time.Second*15)
	if err != nil {
		t.Fatalf(predErr.Error())
	}

	// We'll close out the test by closing the channel from Alice to Bob,
	// and then shutting down the new node we created as its no longer
	// needed. Coop close, no anchors.
	ctxt, _ = context.WithTimeout(ctxb, channelCloseTimeout)
	closeChannelAndAssertType(
		ctxt, t, net, alice, aliceChanPoint, false,
		false,
	)
}