package itest

import (
	"bytes"
	"context"
	"fmt"

	"github.com/btcsuite/btcd/txscript"
	"github.com/btcsuite/btcutil"
	"github.com/lightningnetwork/lnd/lnrpc"
	"github.com/lightningnetwork/lnd/lnrpc/walletrpc"
	"github.com/lightningnetwork/lnd/lntest"
	"github.com/lightningnetwork/lnd/lntest/wait"
	"github.com/lightningnetwork/lnd/sweep"
)

// testCPFP ensures that the daemon can bump an unconfirmed  transaction's fee
// rate by broadcasting a Child-Pays-For-Parent (CPFP) transaction.
//
// TODO(wilmer): Add RBF case once btcd supports it.
func testCPFP(net *lntest.NetworkHarness, t *harnessTest) {
	// Skip this test for neutrino, as it's not aware of mempool
	// transactions.
	if net.BackendCfg.Name() == "neutrino" {
		t.Skipf("skipping reorg test for neutrino backend")
	}

	// We'll start the test by sending Alice some coins, which she'll use to
	// send to Bob.
	ctxb := context.Background()
	ctxt, _ := context.WithTimeout(ctxb, defaultTimeout)
	err := net.SendCoins(ctxt, btcutil.SatoshiPerBitcoin, net.Alice)
	if err != nil {
		t.Fatalf("unable to send coins to alice: %v", err)
	}

	// Create an address for Bob to send the coins to.
	addrReq := &lnrpc.NewAddressRequest{
		Type: lnrpc.AddressType_WITNESS_PUBKEY_HASH,
	}
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	resp, err := net.Bob.NewAddress(ctxt, addrReq)
	if err != nil {
		t.Fatalf("unable to get new address for bob: %v", err)
	}

	// Send the coins from Alice to Bob. We should expect a transaction to
	// be broadcast and seen in the mempool.
	sendReq := &lnrpc.SendCoinsRequest{
		Addr:   resp.Address,
		Amount: btcutil.SatoshiPerBitcoin,
	}
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	if _, err = net.Alice.SendCoins(ctxt, sendReq); err != nil {
		t.Fatalf("unable to send coins to bob: %v", err)
	}

	txid, err := waitForTxInMempool(net.Miner.Node, minerMempoolTimeout)
	if err != nil {
		t.Fatalf("expected one mempool transaction: %v", err)
	}

	// We'll then extract the raw transaction from the mempool in order to
	// determine the index of Bob's output.
	tx, err := net.Miner.Node.GetRawTransaction(txid)
	if err != nil {
		t.Fatalf("unable to extract raw transaction from mempool: %v",
			err)
	}
	bobOutputIdx := -1
	for i, txOut := range tx.MsgTx().TxOut {
		_, addrs, _, err := txscript.ExtractPkScriptAddrs(
			txOut.PkScript, net.Miner.ActiveNet,
		)
		if err != nil {
			t.Fatalf("unable to extract address from pkScript=%x: "+
				"%v", txOut.PkScript, err)
		}
		if addrs[0].String() == resp.Address {
			bobOutputIdx = i
		}
	}
	if bobOutputIdx == -1 {
		t.Fatalf("bob's output was not found within the transaction")
	}

	// Wait until bob has seen the tx and considers it as owned.
	op := &lnrpc.OutPoint{
		TxidBytes:   txid[:],
		OutputIndex: uint32(bobOutputIdx),
	}
	assertWalletUnspent(t, net.Bob, op)

	// We'll attempt to bump the fee of this transaction by performing a
	// CPFP from Alice's point of view.
	bumpFeeReq := &walletrpc.BumpFeeRequest{
		Outpoint:   op,
		SatPerByte: uint32(sweep.DefaultMaxFeeRate.FeePerKVByte() / 2000),
	}
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	_, err = net.Bob.WalletKitClient.BumpFee(ctxt, bumpFeeReq)
	if err != nil {
		t.Fatalf("unable to bump fee: %v", err)
	}

	// We should now expect to see two transactions within the mempool, a
	// parent and its child.
	_, err = waitForNTxsInMempool(net.Miner.Node, 2, minerMempoolTimeout)
	if err != nil {
		t.Fatalf("expected two mempool transactions: %v", err)
	}

	// We should also expect to see the output being swept by the
	// UtxoSweeper. We'll ensure it's using the fee rate specified.
	pendingSweepsReq := &walletrpc.PendingSweepsRequest{}
	ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
	pendingSweepsResp, err := net.Bob.WalletKitClient.PendingSweeps(
		ctxt, pendingSweepsReq,
	)
	if err != nil {
		t.Fatalf("unable to retrieve pending sweeps: %v", err)
	}
	if len(pendingSweepsResp.PendingSweeps) != 1 {
		t.Fatalf("expected to find %v pending sweep(s), found %v", 1,
			len(pendingSweepsResp.PendingSweeps))
	}
	pendingSweep := pendingSweepsResp.PendingSweeps[0]
	if !bytes.Equal(pendingSweep.Outpoint.TxidBytes, op.TxidBytes) {
		t.Fatalf("expected output txid %x, got %x", op.TxidBytes,
			pendingSweep.Outpoint.TxidBytes)
	}
	if pendingSweep.Outpoint.OutputIndex != op.OutputIndex {
		t.Fatalf("expected output index %v, got %v", op.OutputIndex,
			pendingSweep.Outpoint.OutputIndex)
	}
	if pendingSweep.SatPerByte != bumpFeeReq.SatPerByte {
		t.Fatalf("expected sweep sat per byte %v, got %v",
			bumpFeeReq.SatPerByte, pendingSweep.SatPerByte)
	}

	// Mine a block to clean up the unconfirmed transactions.
	mineBlocks(t, net, 1, 2)

	// The input used to CPFP should no longer be pending.
	err = wait.NoError(func() error {
		req := &walletrpc.PendingSweepsRequest{}
		ctxt, _ = context.WithTimeout(ctxb, defaultTimeout)
		resp, err := net.Bob.WalletKitClient.PendingSweeps(ctxt, req)
		if err != nil {
			return fmt.Errorf("unable to retrieve bob's pending "+
				"sweeps: %v", err)
		}
		if len(resp.PendingSweeps) != 0 {
			return fmt.Errorf("expected 0 pending sweeps, found %d",
				len(resp.PendingSweeps))
		}
		return nil
	}, defaultTimeout)
	if err != nil {
		t.Fatalf(err.Error())
	}
}