nip60: fixes, actual Cashu stuff and a wallet.Receive() method.

nip60/swap.go

@@ -0,0 +1,134 @@
+package nip60
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/elnosh/gonuts/cashu"
+	"github.com/elnosh/gonuts/cashu/nuts/nut02"
+	"github.com/elnosh/gonuts/cashu/nuts/nut04"
+	"github.com/elnosh/gonuts/cashu/nuts/nut05"
+	"github.com/nbd-wtf/go-nostr/nip60/client"
+)
+
+// lightningMeltMint does the lightning dance of moving funds between mints
+func lightningMeltMint(
+	ctx context.Context,
+	proofs cashu.Proofs,
+	from string,
+	fromKeysets []nut02.Keyset,
+	to string,
+) (newProofs cashu.Proofs, err error, canTryWithAnotherTargetMint bool, manualActionRequired bool) {
+	// get active keyset of target mint
+	keyset, err := client.GetActiveKeyset(ctx, to)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get keyset keys for %s: %w", to, err), true, false
+	}
+
+	// unblind the signatures from the promises and build the proofs
+	keysetKeys, err := parseKeysetKeys(keyset.Keys)
+	if err != nil {
+		return nil, fmt.Errorf("target mint %s sent us an invalid keyset: %w", to, err), true, false
+	}
+
+	// now we start the melt-mint process in multiple attempts
+	invoicePct := 0.99
+	proofsAmount := proofs.Amount()
+	amount := float64(proofsAmount) * invoicePct
+	fee := uint64(calculateFee(proofs, fromKeysets))
+	var meltQuote string
+	var mintQuote string
+	for range 10 {
+		// request _mint_ quote to the 'to' mint -- this will generate an invoice
+		mintResp, err := client.PostMintQuoteBolt11(ctx, to, nut04.PostMintQuoteBolt11Request{
+			Amount: uint64(amount) - fee,
+			Unit:   cashu.Sat.String(),
+		})
+		if err != nil {
+			return nil, fmt.Errorf("error requesting mint quote from %s: %w", to, err), true, false
+		}
+
+		// request _melt_ quote from the 'from' mint
+		// this melt will pay the invoice generated from the previous mint quote request
+		meltResp, err := client.PostMeltQuoteBolt11(ctx, from, nut05.PostMeltQuoteBolt11Request{
+			Request: mintResp.Request,
+			Unit:    cashu.Sat.String(),
+		})
+		if err != nil {
+			return nil, fmt.Errorf("error requesting melt quote from %s: %w", from, err), false, false
+		}
+
+		// if amount in proofs is less than amount asked from mint in melt request,
+		// lower the amount for mint request (because of lighting fees?)
+		if meltResp.Amount+meltResp.FeeReserve+fee > proofsAmount {
+			invoicePct -= 0.01
+			amount *= invoicePct
+		} else {
+			meltQuote = meltResp.Quote
+			mintQuote = mintResp.Quote
+			goto meltworked
+		}
+	}
+
+	return nil, fmt.Errorf("stop trying to do the melt because the mint part is too expensive"), true, false
+
+meltworked:
+	// request from mint to pay invoice from the mint quote request
+	_, err = client.PostMeltBolt11(ctx, from, nut05.PostMeltBolt11Request{
+		Quote:  meltQuote,
+		Inputs: proofs,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("error melting token: %v", err), false, true
+	}
+
+	sleepTime := time.Millisecond * 200
+	failures := 0
+	for range 12 {
+		sleepTime *= 2
+		time.Sleep(sleepTime)
+
+		// check if the _mint_ invoice was paid
+		mintQuoteStatusResp, err := client.GetMintQuoteState(ctx, to, mintQuote)
+		if err != nil {
+			failures++
+			if failures > 10 {
+				return nil, fmt.Errorf(
+					"target mint %s failed to answer to our mint quote checks (%s): %w; a manual fix is needed",
+					to, meltQuote, err,
+				), false, true
+			}
+		}
+
+		// if it wasn't paid try again
+		if mintQuoteStatusResp.State != nut04.Paid {
+			continue
+		}
+
+		// if it got paid make proceed to get proofs
+		split := []uint64{1, 2, 3, 4}
+		blindedMessages, secrets, rs, err := createBlindedMessages(split, keyset.Id)
+		if err != nil {
+			return nil, fmt.Errorf("error creating blinded messages: %v", err), false, true
+		}
+
+		// request mint to sign the blinded messages
+		mintResponse, err := client.PostMintBolt11(ctx, to, nut04.PostMintBolt11Request{
+			Quote:   mintQuote,
+			Outputs: blindedMessages,
+		})
+		if err != nil {
+			return nil, fmt.Errorf("mint request to %s failed (%s): %w", to, mintQuote, err), false, true
+		}
+
+		proofs, err := constructProofs(mintResponse.Signatures, blindedMessages, secrets, rs, keysetKeys)
+		if err != nil {
+			return nil, fmt.Errorf("error constructing proofs: %w", err), false, true
+		}
+
+		return proofs, nil, false, false
+	}
+
+	return nil, fmt.Errorf("we gave up waiting for the invoice at %s to be paid: %s", to, meltQuote), false, true
+}