Initial open-source release (MIT): image2api AI gateway

Full Go backend + Vue 3 frontend, OpenAI-compatible API, multi-provider
account pools, billing/admin, Docker one-command deploy with auto HTTPS.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/internal/service/rate_limit.go

@@ -0,0 +1,79 @@
+package service
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/redis/go-redis/v9"
+)
+
+var ErrRateLimited = errors.New("rate limited")
+
+type RateLimitService struct {
+	redis  *redis.Client
+	prefix string
+}
+
+type RateLimitResult struct {
+	Allowed    bool
+	Count      int64
+	Limit      int64
+	RetryAfter time.Duration
+}
+
+func NewRateLimitService(redis *redis.Client) *RateLimitService {
+	return &RateLimitService{
+		redis:  redis,
+		prefix: "rl:",
+	}
+}
+
+func (s *RateLimitService) Allow(ctx context.Context, bucket string, limit int64, window time.Duration) (*RateLimitResult, error) {
+	if limit <= 0 || window <= 0 {
+		return &RateLimitResult{Allowed: true, Limit: limit}, nil
+	}
+
+	key := s.prefix + strings.TrimSpace(bucket)
+	count, err := s.redis.Incr(ctx, key).Result()
+	if err != nil {
+		return nil, err
+	}
+	if count == 1 {
+		if err := s.redis.Expire(ctx, key, window).Err(); err != nil {
+			return nil, err
+		}
+	}
+
+	ttl, err := s.redis.TTL(ctx, key).Result()
+	if err != nil {
+		return nil, err
+	}
+	if ttl < 0 {
+		ttl = window
+	}
+
+	return &RateLimitResult{
+		Allowed:    count <= limit,
+		Count:      count,
+		Limit:      limit,
+		RetryAfter: ttl,
+	}, nil
+}
+
+func (s *RateLimitService) Enforce(ctx context.Context, bucket string, limit int64, window time.Duration) error {
+	result, err := s.Allow(ctx, bucket, limit, window)
+	if err != nil {
+		return err
+	}
+	if result.Allowed {
+		return nil
+	}
+	retry := int(result.RetryAfter.Seconds())
+	if retry < 1 {
+		retry = 1
+	}
+	return fmt.Errorf("%w: 请稍后再试（%d 秒后）", ErrRateLimited, retry)
+}