implement LUD-15 balanceNotify.

Author: fiatjaf

account_functions.go

@@ -89,3 +89,7 @@ func getAccountIdFromLNURLWithdraw(r *http.Request) (string, error) {
 	log.Error().Err(err).Msg("lnurl-withdraw with no reference to any account")
 	return "", errors.New("Unexpected incomplete lnurl-withdraw.")
 }
+
+func balanceWithReserve(balance int64) int64 {
+	return int64(float64(balance) * 0.992)
+}

account_handlers.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"net/url"
 	"strconv"
 	"time"
 
@@ -162,7 +163,7 @@ func lnurlWithdraw(w http.ResponseWriter, r *http.Request) {
 	// get balance
 	balance := balanceWithReserve(data.GetAccountBalance(accountId))
 
-	if balance < 10000 {
+	if balance < MIN_WITHDRAWABLE {
 		json.NewEncoder(w).Encode(lnurl.ErrorResponse("the minimum withdrawal is 10 sat, your balance is " + strconv.FormatInt(balance, 10) + " msat."))
 		return
 	}
@@ -174,7 +175,7 @@ func lnurlWithdraw(w http.ResponseWriter, r *http.Request) {
 			s.ServiceURL, r.URL.RawQuery),
 		K1:                 hex.EncodeToString(make([]byte, 32)), // we don't care
 		MaxWithdrawable:    balance,
-		MinWithdrawable:    100000,
+		MinWithdrawable:    MIN_WITHDRAWABLE,
 		DefaultDescription: fmt.Sprintf("etleneum.com %s balance withdraw", accountId),
 		BalanceCheck:       getStaticLNURLWithdraw(accountId),
 	})
@@ -187,8 +188,15 @@ func lnurlWithdrawCallback(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	bolt11 := r.URL.Query().Get("pr")
+	// LUD-15, save URL to notify the user later
+	balanceNotify, _ := url.Parse(r.URL.Query().Get("balanceNotify"))
+	if balanceNotify != nil && balanceNotify.Host != "" {
+		data.UpdateAccountMetadata(accountId, func(am *data.AccountMetadata) {
+			am.BalanceNotify = balanceNotify.String()
+		})
+	}
 
+	bolt11 := r.URL.Query().Get("pr")
 	if s.FreeMode {
 		json.NewEncoder(w).Encode(lnurl.OkResponse())
 		return

call_functions.go

@@ -11,6 +11,13 @@ import (
 	"github.com/fiatjaf/etleneum/runlua"
 )
 
+var balanceNotifyClient = http.Client{
+	Timeout: time.Second * 2,
+	CheckRedirect: func(r *http.Request, via []*http.Request) error {
+		return fmt.Errorf("target '%s' has returned a redirect", r.URL)
+	},
+}
+
 type CallContext struct {
 	VisitedContracts map[string]bool
 	Transfers        []data.Transfer
@@ -104,6 +111,28 @@ func runCallGlobal(call *data.Call, useBalance bool) (err error) {
 		return err
 	}
 
+	// at this point the call has succeeded, we can then notify all accounts
+	// that have a balanceNotify URL set on their metadata
+	go func() {
+		time.Sleep(2 * time.Second) // give some time for the call to be finished
+		for key, balance := range callContext.AccountBalances {
+			if balanceWithReserve(balance) >= MIN_WITHDRAWABLE {
+				metadata := data.GetAccountMetadata(key)
+				if metadata.BalanceNotify != "" {
+					log := log.With().Str("account", key).Str("url", metadata.BalanceNotify).Int64("balance", balance).Logger()
+					resp, err := balanceNotifyClient.Post(metadata.BalanceNotify, "", nil)
+					if err != nil {
+						log.Warn().Err(err).Msg("balanceNotify call failed")
+					} else if resp.StatusCode >= 300 {
+						log.Warn().Int("status", resp.StatusCode).Msg("balanceNotify call returned bad status code")
+					} else {
+						log.Info().Msg("balanceNotify call succeeded")
+					}
+				}
+			}
+		}
+	}()
+
 	return nil
 }
 

constants.go

@@ -0,0 +1,3 @@
+package main
+
+const MIN_WITHDRAWABLE = 25000

data/account.go

@@ -7,6 +7,10 @@ import (
 	"path/filepath"
 )
 
+type AccountMetadata struct {
+	BalanceNotify string `json:"balanceNotify"`
+}
+
 func GetAccountBalance(key string) (msatoshi int64) {
 	if err := readJSON(
 		filepath.Join(DatabasePath, "accounts", key, "balance.json"),
@@ -104,3 +108,31 @@ func CancelWithdraw(key string, amount int64, hash string) error {
 	Finish(fmt.Sprintf("withdraw %s has failed.", hash))
 	return nil
 }
+
+func GetAccountMetadata(key string) (am AccountMetadata) {
+	readJSON(
+		filepath.Join(DatabasePath, "accounts", key, "metadata.json"),
+		&am,
+	)
+	return am
+}
+
+func UpdateAccountMetadata(key string, mod func(am *AccountMetadata)) error {
+	Start()
+
+	am := GetAccountMetadata(key)
+
+	mod(&am)
+
+	err := writeJSON(
+		filepath.Join(DatabasePath, "accounts", key, "metadata.json"),
+		am,
+	)
+	if err != nil {
+		Abort()
+		return err
+	}
+
+	Finish(fmt.Sprintf("account %s metadata was updated.", key))
+	return nil
+}

data/git.go

@@ -10,7 +10,7 @@ import (
 	"time"
 )
 
-func execute(name string, args ...string) error {
+func execute(name string, args ...string) (string, error) {
 	stdout := &bytes.Buffer{}
 	stderr := &bytes.Buffer{}
 
@@ -20,49 +20,54 @@ func execute(name string, args ...string) error {
 	cmd.Stderr = stderr
 
 	err := cmd.Run()
+	out := stdout.String() + stderr.String()
 	if err != nil {
 		stdout.WriteTo(os.Stderr)
 		stderr.WriteTo(os.Stderr)
-		return err
+		return out, err
 	}
 
-	return nil
+	return out, nil
 }
 
 func gitAdd(path string) error {
-	if err := execute("git", "add", "."); err != nil {
+	if _, err := execute("git", "add", "."); err != nil {
 		return err
 	}
 
 	return nil
 }
 
 func gitCommit(message string) error {
-	if err := execute("git", "commit", "-m", message, "--no-edit"); err != nil {
+	if out, err := execute("git", "commit", "-m", message, "--no-edit"); err != nil {
+		if strings.Contains(out, "nothing to commit, working tree clean") {
+			return nil
+		}
+
 		return err
 	}
 
 	return nil
 }
 
 func gitReset() error {
-	if err := execute("git", "reset", "--hard", "HEAD"); err != nil {
+	if _, err := execute("git", "reset", "--hard", "HEAD"); err != nil {
 		return err
 	}
 
 	return nil
 }
 
 func gitPull() error {
-	if err := execute("git", "pull", "origin", "master", "--rebase"); err != nil {
+	if _, err := execute("git", "pull", "origin", "master", "--rebase"); err != nil {
 		return err
 	}
 
 	return nil
 }
 
 func gitPush() error {
-	if err := execute("git", "push", "origin", "master"); err != nil {
+	if _, err := execute("git", "push", "origin", "master"); err != nil {
 		return err
 	}
 

data/helpers.go

@@ -1,6 +1,7 @@
 package data
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io/ioutil"
@@ -32,9 +33,14 @@ func writeFile(path string, contents []byte) error {
 }
 
 func writeJSON(path string, contents interface{}) error {
-	if payloadJSON, err := json.MarshalIndent(contents, "", "  "); err != nil {
+	res := &bytes.Buffer{}
+	enc := json.NewEncoder(res)
+	enc.SetIndent("", "  ")
+	enc.SetEscapeHTML(false)
+
+	if err := enc.Encode(contents); err != nil {
 		return err
-	} else if err := writeFile(path, payloadJSON); err != nil {
+	} else if err := writeFile(path, res.Bytes()); err != nil {
 		return err
 	}
 

helpers.go

@@ -42,10 +42,6 @@ func jsonError(w http.ResponseWriter, message string, code int) {
 	})
 }
 
-func balanceWithReserve(balance int64) int64 {
-	return int64(float64(balance) * 0.992)
-}
-
 func diffDeltaOneliner(prefix string, idelta gojsondiff.Delta) (lines []string) {
 	key := prefix
 	if key != "" {

main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"context"
 	"embed"
+	"fmt"
 	"io"
 	"net/http"
 	"net/url"
@@ -54,13 +55,19 @@ var contractstreams = cmap.New()
 var static embed.FS
 
 func main() {
-	http.DefaultClient = &http.Client{Transport: &http.Transport{
-		MaxIdleConns:        10,
-		MaxConnsPerHost:     10,
-		MaxIdleConnsPerHost: 2,
-		IdleConnTimeout:     10 * time.Second,
-		DisableCompression:  true,
-	}}
+	http.DefaultClient = &http.Client{
+		Timeout: time.Second * 5,
+		Transport: &http.Transport{
+			MaxIdleConns:        10,
+			MaxConnsPerHost:     10,
+			MaxIdleConnsPerHost: 2,
+			IdleConnTimeout:     10 * time.Second,
+			DisableCompression:  true,
+		},
+		CheckRedirect: func(r *http.Request, via []*http.Request) error {
+			return fmt.Errorf("target '%s' has returned a redirect", r.URL)
+		},
+	}
 
 	if isRunningAsPlugin() {
 		p := plugin.Plugin{