Products: chat command filter, request signing, saved state

Co-Authored-By: Claude Opus 5.5 <[email protected]>

internal/products/state.go

@@ -0,0 +1,119 @@
+package products
+
+import (
+	"encoding/json"
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"sort"
+	"sync"
+)
+
+// FirstLocalID is where the client's numbers for community products start. IMVU's product IDs are far below
+// (about 72 million in 2026), and the client's XML-RPC can't carry numbers past 2^31-1.
+const FirstLocalID = 2_000_000_000
+
+// state is what the proxy remembers between runs, in <data dir>/products.json: the local ID of every product it
+// has served (so outfits keep naming the same product), and the community products each IMVU account wears (IMVU
+// never sees them, so it can't remember them).
+type state struct {
+	mu   sync.Mutex
+	path string
+	data stateData
+}
+
+type stateData struct {
+	IDs  map[string]int64    `json:"ids"`  // product ID -> local ID
+	Worn map[string][]string `json:"worn"` // IMVU user ID -> product IDs
+}
+
+func loadState(path string) (*state, error) {
+	s := &state{path: path, data: stateData{IDs: map[string]int64{}, Worn: map[string][]string{}}}
+	b, err := os.ReadFile(path)
+	if errors.Is(err, fs.ErrNotExist) {
+		return s, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	if err := json.Unmarshal(b, &s.data); err != nil {
+		return nil, err
+	}
+	if s.data.IDs == nil {
+		s.data.IDs = map[string]int64{}
+	}
+	if s.data.Worn == nil {
+		s.data.Worn = map[string][]string{}
+	}
+	return s, nil
+}
+
+// localID is the product's local ID, given one if it has none yet.
+func (s *state) localID(product string) (int64, error) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if id, ok := s.data.IDs[product]; ok {
+		return id, nil
+	}
+	next := int64(FirstLocalID)
+	for _, id := range s.data.IDs {
+		next = max(next, id+1)
+	}
+	if next > 2_147_483_647 {
+		return 0, errors.New("products: out of local IDs")
+	}
+	s.data.IDs[product] = next
+	return next, s.saveLocked()
+}
+
+// worn is the community products the user wears.
+func (s *state) worn(user string) []string {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return append([]string(nil), s.data.Worn[user]...)
+}
+
+// setWorn records the community products the user wears.
+func (s *state) setWorn(user string, products []string) error {
+	products = append([]string(nil), products...)
+	sort.Strings(products)
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if equal(s.data.Worn[user], products) {
+		return nil
+	}
+	if len(products) == 0 {
+		delete(s.data.Worn, user)
+	} else {
+		s.data.Worn[user] = products
+	}
+	return s.saveLocked()
+}
+
+func equal(a, b []string) bool {
+	if len(a) != len(b) {
+		return false
+	}
+	for i := range a {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}
+
+func (s *state) saveLocked() error {
+	b, err := json.MarshalIndent(s.data, "", "  ")
+	if err != nil {
+		return err
+	}
+	if err := os.MkdirAll(filepath.Dir(s.path), 0o700); err != nil {
+		return err
+	}
+	tmp := s.path + ".tmp"
+	if err := os.WriteFile(tmp, b, 0o600); err != nil {
+		return err
+	}
+	return os.Rename(tmp, s.path)
+}