From a096a22e16c73239cf93ec1bbbc5e1214f79b801 Mon Sep 17 00:00:00 2001
From: Linden <70739041+linden@users.noreply.github.com>
Date: Sun, 18 Feb 2024 15:38:11 -0800
Subject: [PATCH 1/2] feat(`btcutil`): use an empty data directory on `js`

---
 btcutil/appdata.go | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/btcutil/appdata.go b/btcutil/appdata.go
index b6c63b9a29..11d556f31a 100644
--- a/btcutil/appdata.go
+++ b/btcutil/appdata.go
@@ -23,6 +23,11 @@ func appDataDir(goos, appName string, roaming bool) string {
 		return "."
 	}
 
+	// Fallback to an empty string on js since we do not have a file system.
+	if goos == "js" {
+		return ""
+	}
+
 	// The caller really shouldn't prepend the appName with a period, but
 	// if they do, handle it gracefully by trimming it.
 	appName = strings.TrimPrefix(appName, ".")

From 36e494c006bb791eafac6072d99413aabbc7913f Mon Sep 17 00:00:00 2001
From: Linden <70739041+linden@users.noreply.github.com>
Date: Sun, 18 Feb 2024 15:39:28 -0800
Subject: [PATCH 2/2] feat(`addrmgr`): use `localStorage` instead of
 file-system on `js`

---
 addrmgr/addrmanager.go  | 45 ++++++++++++---------
 addrmgr/addrstore.go    | 43 ++++++++++++++++++++
 addrmgr/addrstore_js.go | 87 +++++++++++++++++++++++++++++++++++++++++
 go.mod                  |  3 +-
 go.sum                  |  4 ++
 5 files changed, 162 insertions(+), 20 deletions(-)
 create mode 100644 addrmgr/addrstore.go
 create mode 100644 addrmgr/addrstore_js.go

diff --git a/addrmgr/addrmanager.go b/addrmgr/addrmanager.go
index bdfe9094ce..4e71416656 100644
--- a/addrmgr/addrmanager.go
+++ b/addrmgr/addrmanager.go
@@ -11,11 +11,11 @@ import (
 	"encoding/base32"
 	"encoding/binary"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"math/rand"
 	"net"
-	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
@@ -27,11 +27,21 @@ import (
 	"github.com/btcsuite/btcd/wire"
 )
 
+var ErrNotExist = errors.New("store does not exist")
+
+// store is a basic storage interface. Either using the file system or localStorage in the browser.
+type store interface {
+	Reader() (io.ReadCloser, error)
+	Writer() (io.WriteCloser, error)
+	Remove() error
+	String() string
+}
+
 // AddrManager provides a concurrency safe address manager for caching potential
 // peers on the bitcoin network.
 type AddrManager struct {
 	mtx            sync.RWMutex
-	peersFile      string
+	store          store
 	lookupFunc     func(string) ([]net.IP, error)
 	rand           *rand.Rand
 	key            [32]byte
@@ -407,15 +417,15 @@ func (a *AddrManager) savePeers() {
 		}
 	}
 
-	w, err := os.Create(a.peersFile)
+	w, err := a.store.Writer()
 	if err != nil {
-		log.Errorf("Error opening file %s: %v", a.peersFile, err)
+		log.Errorf("Error opening store %s: %v", a.store, err)
 		return
 	}
 	enc := json.NewEncoder(w)
 	defer w.Close()
 	if err := enc.Encode(&sam); err != nil {
-		log.Errorf("Failed to encode file %s: %v", a.peersFile, err)
+		log.Errorf("Failed to encode peers %s: %v", a.store, err)
 		return
 	}
 }
@@ -426,30 +436,27 @@ func (a *AddrManager) loadPeers() {
 	a.mtx.Lock()
 	defer a.mtx.Unlock()
 
-	err := a.deserializePeers(a.peersFile)
+	err := a.deserializePeers()
 	if err != nil {
-		log.Errorf("Failed to parse file %s: %v", a.peersFile, err)
+		log.Errorf("Failed to parse store %s: %v", a.store, err)
 		// if it is invalid we nuke the old one unconditionally.
-		err = os.Remove(a.peersFile)
+		err = a.store.Remove()
 		if err != nil {
-			log.Warnf("Failed to remove corrupt peers file %s: %v",
-				a.peersFile, err)
+			log.Warnf("Failed to remove corrupt peers %s: %v", a.store, err)
 		}
 		a.reset()
 		return
 	}
-	log.Infof("Loaded %d addresses from file '%s'", a.numAddresses(), a.peersFile)
+	log.Infof("Loaded %d addresses from store '%s'", a.numAddresses(), a.store)
 }
 
-func (a *AddrManager) deserializePeers(filePath string) error {
-
-	_, err := os.Stat(filePath)
-	if os.IsNotExist(err) {
+func (a *AddrManager) deserializePeers() error {
+	r, err := a.store.Reader()
+	if errors.Is(err, ErrNotExist) {
 		return nil
 	}
-	r, err := os.Open(filePath)
 	if err != nil {
-		return fmt.Errorf("%s error opening file: %v", filePath, err)
+		return fmt.Errorf("error opening store: %v", err)
 	}
 	defer r.Close()
 
@@ -457,7 +464,7 @@ func (a *AddrManager) deserializePeers(filePath string) error {
 	dec := json.NewDecoder(r)
 	err = dec.Decode(&sam)
 	if err != nil {
-		return fmt.Errorf("error reading %s: %v", filePath, err)
+		return fmt.Errorf("error reading %s: %v", a.store, err)
 	}
 
 	// Since decoding JSON is backwards compatible (i.e., only decodes
@@ -1206,7 +1213,7 @@ func (a *AddrManager) GetBestLocalAddress(remoteAddr *wire.NetAddressV2) *wire.N
 // Use Start to begin processing asynchronous address updates.
 func New(dataDir string, lookupFunc func(string) ([]net.IP, error)) *AddrManager {
 	am := AddrManager{
-		peersFile:      filepath.Join(dataDir, "peers.json"),
+		store:          NewStore(filepath.Join(dataDir, "peers.json")),
 		lookupFunc:     lookupFunc,
 		rand:           rand.New(rand.NewSource(time.Now().UnixNano())),
 		quit:           make(chan struct{}),
diff --git a/addrmgr/addrstore.go b/addrmgr/addrstore.go
new file mode 100644
index 0000000000..4317a7324d
--- /dev/null
+++ b/addrmgr/addrstore.go
@@ -0,0 +1,43 @@
+//go:build !js && !wasm
+
+package addrmgr
+
+import (
+	"io"
+	"os"
+)
+
+type Store struct {
+	path string
+}
+
+func (s *Store) Reader() (io.ReadCloser, error) {
+	// Open the file.
+	r, err := os.Open(s.path)
+
+	// Convert into a generic error.
+	if os.IsNotExist(err) {
+		return nil, ErrNotExist
+	}
+
+	return r, err
+}
+
+func (s *Store) Writer() (io.WriteCloser, error) {
+	// Create or open the file.
+	return os.Create(s.path)
+}
+
+func (s *Store) Remove() error {
+	return os.Remove(s.path)
+}
+
+func (s *Store) String() string {
+	return s.path
+}
+
+func NewStore(path string) *Store {
+	return &Store{
+		path: path,
+	}
+}
diff --git a/addrmgr/addrstore_js.go b/addrmgr/addrstore_js.go
new file mode 100644
index 0000000000..2b3b725fb0
--- /dev/null
+++ b/addrmgr/addrstore_js.go
@@ -0,0 +1,87 @@
+//go:build js && wasm
+
+package addrmgr
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"strings"
+
+	"github.com/linden/localstorage"
+)
+
+type Store struct {
+	path string
+}
+
+func (s *Store) Reader() (io.ReadCloser, error) {
+	// Get the value from localStorage.
+	val := localstorage.Get(s.path)
+
+	// Convert into a generic error.
+	if val == "" {
+		return nil, ErrNotExist
+	}
+
+	// Create a new buffer storing our value.
+	buf := bytes.NewBufferString(val)
+
+	// Create a NOP closer, we have nothing to do upon close.
+	return io.NopCloser(buf), nil
+}
+
+func (s *Store) Writer() (io.WriteCloser, error) {
+	// Create a new writer.
+	return newWriter(s.path), nil
+}
+
+func (s *Store) Remove() error {
+	// Remove the key/value from localStorage.
+	localstorage.Remove(s.path)
+
+	return nil
+}
+
+func (s *Store) String() string {
+	return s.path
+}
+
+func NewStore(path string) *Store {
+	return &Store{
+		path: path,
+	}
+}
+
+// writer updates the localStorage on write.
+type writer struct {
+	path    string
+	closed  bool
+	builder strings.Builder
+}
+
+func (w *writer) Write(p []byte) (int, error) {
+	if w.closed {
+		return 0, errors.New("writer already closed")
+	}
+
+	// Write the bytes to our string builder.
+	n, _ := w.builder.Write(p)
+
+	// Update the localStorage value.
+	localstorage.Set(w.path, w.builder.String())
+
+	// Return the length written,
+	return n, nil
+}
+
+func (w *writer) Close() error {
+	w.closed = true
+	return nil
+}
+
+func newWriter(path string) *writer {
+	return &writer{
+		path: path,
+	}
+}
diff --git a/go.mod b/go.mod
index 6eea83508e..9f814d4db0 100644
--- a/go.mod
+++ b/go.mod
@@ -14,6 +14,7 @@ require (
 	github.com/gorilla/websocket v1.5.0
 	github.com/jessevdk/go-flags v1.4.0
 	github.com/jrick/logrotate v1.0.0
+	github.com/linden/localstorage v0.0.0-20231117043609-5d94f0a86609
 	github.com/stretchr/testify v1.8.4
 	github.com/syndtr/goleveldb v1.0.1-0.20210819022825-2ae1ddf74ef7
 	golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9
@@ -62,4 +63,4 @@ retract (
 	v0.13.0-beta
 )
 
-go 1.17
+go 1.21.2
diff --git a/go.sum b/go.sum
index ddd7e1ebd0..2127631adf 100644
--- a/go.sum
+++ b/go.sum
@@ -62,6 +62,10 @@ github.com/jrick/logrotate v1.0.0 h1:lQ1bL/n9mBNeIXoTUoYRlK4dHuNJVofX9oWqBtPnSzI
 github.com/jrick/logrotate v1.0.0/go.mod h1:LNinyqDIJnpAur+b8yyulnQw/wDuN1+BYKlTRt3OuAQ=
 github.com/kkdai/bstream v0.0.0-20161212061736-f391b8402d23 h1:FOOIBWrEkLgmlgGfMuZT83xIwfPDxEI2OHu6xUmJMFE=
 github.com/kkdai/bstream v0.0.0-20161212061736-f391b8402d23/go.mod h1:J+Gs4SYgM6CZQHDETBtE9HaSEkGmuNXF86RwHhHUvq4=
+github.com/linden/localstorage v0.0.0-20231116131807-4984ea9234ae h1:aShKD5W7/reF6oTj+JsQP/Yf/7B3sYiqx6K9tIp6KFI=
+github.com/linden/localstorage v0.0.0-20231116131807-4984ea9234ae/go.mod h1:uQBC250C4YSyzxNly4CR02PT2VKoO3H9zlJXbUXVLl8=
+github.com/linden/localstorage v0.0.0-20231117043609-5d94f0a86609 h1:oRjHnrgw7Jo+B0MokX+2L7ugroptSEhvJpc3RenpZL8=
+github.com/linden/localstorage v0.0.0-20231117043609-5d94f0a86609/go.mod h1:uQBC250C4YSyzxNly4CR02PT2VKoO3H9zlJXbUXVLl8=
 github.com/nxadm/tail v1.4.4 h1:DQuhQpB1tVlglWS2hLQ5OV6B5r8aGxSrPc5Qo6uTN78=
 github.com/nxadm/tail v1.4.4/go.mod h1:kenIhsEOeOJmVchQTgglprH7qJGnHDVpk1VPCcaMI8A=
 github.com/onsi/ginkgo v1.6.0/go.mod h1:lLunBs/Ym6LB5Z9jYTR76FiuTmxDTDusOGeTQH+WWjE=