add domain whois/dns support, refactor codebase

internal/common/cache.go

@@ -0,0 +1,48 @@
+package common
+
+import (
+	"sync"
+	"time"
+)
+
+// cachedItem represents a generic item in the cache.
+type cachedItem struct {
+	data any
+	time time.Time
+}
+
+// Cache provides a thread-safe, generic caching mechanism with a TTL.
+type Cache struct {
+	store sync.Map
+	ttl   time.Duration
+}
+
+// NewCache creates a new generic cache with the specified TTL.
+func NewCache(ttl time.Duration) *Cache {
+	return &Cache{
+		ttl: ttl,
+	}
+}
+
+// Set adds a new entry to the cache.
+func (c *Cache) Set(key any, data any) {
+	c.store.Store(key, cachedItem{
+		data: data,
+		time: time.Now(),
+	})
+}
+
+// Get retrieves an entry from the cache.
+func (c *Cache) Get(key any) (any, bool) {
+	if item, ok := c.store.Load(key); ok {
+		cached := item.(cachedItem)
+		if time.Since(cached.time) < c.ttl {
+			return cached.data, true
+		}
+		c.store.Delete(key)
+	}
+	return nil, false
+}
+
+// Global cache with a 10-minute TTL.
+var cache = NewCache(10 * time.Minute)