cmd/loop: add command for quote

Author: Roasbeef

cmd/loop/main.go

@@ -7,6 +7,8 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/golang/protobuf/jsonpb"
+	"github.com/golang/protobuf/proto"
 	"github.com/lightninglabs/loop/looprpc"
 	"github.com/lightninglabs/loop/swap"
 
@@ -25,6 +27,21 @@ var (
 	maxRoutingFeeRate = int64(50000)
 )
 
+func printRespJSON(resp proto.Message) {
+	jsonMarshaler := &jsonpb.Marshaler{
+		EmitDefaults: true,
+		Indent:       "    ",
+	}
+
+	jsonStr, err := jsonMarshaler.MarshalToString(resp)
+	if err != nil {
+		fmt.Println("unable to decode response: ", err)
+		return
+	}
+
+	fmt.Println(jsonStr)
+}
+
 func fatal(err error) {
 	fmt.Fprintf(os.Stderr, "[loop] %v\n", err)
 	os.Exit(1)
@@ -44,7 +61,7 @@ func main() {
 		},
 	}
 	app.Commands = []cli.Command{
-		loopOutCommand, termsCommand, monitorCommand,
+		loopOutCommand, termsCommand, monitorCommand, quoteCommand,
 	}
 
 	err := app.Run(os.Args)

cmd/loop/quote.go

@@ -0,0 +1,47 @@
+package main
+
+import (
+	"context"
+
+	"github.com/lightninglabs/loop/looprpc"
+	"github.com/urfave/cli"
+)
+
+var quoteCommand = cli.Command{
+	Name:        "quote",
+	Usage:       "get a quote for the cost of a swap",
+	ArgsUsage:   "amt",
+	Description: "Allows to determine the cost of a swap up front",
+	Action:      quote,
+}
+
+func quote(ctx *cli.Context) error {
+	// Show command help if no arguments and flags were provided.
+	if ctx.NArg() < 1 {
+		cli.ShowCommandHelp(ctx, "quote")
+		return nil
+	}
+
+	args := ctx.Args()
+	amt, err := parseAmt(args[0])
+	if err != nil {
+		return err
+	}
+
+	client, cleanup, err := getClient(ctx)
+	if err != nil {
+		return err
+	}
+	defer cleanup()
+
+	ctxb := context.Background()
+	resp, err := client.LoopOutQuote(ctxb, &looprpc.QuoteRequest{
+		Amt: int64(amt),
+	})
+	if err != nil {
+		return err
+	}
+
+	printRespJSON(resp)
+	return nil
+}