Refactor to consolidate APIs into contract package and introduce NFT interface for better modularity and maintainability.

contract/nft/rule.go

@@ -0,0 +1,31 @@
+package nft
+
+import "git.kor-elf.net/kor-elf-shield/go-nftables-client/family"
+
+// Rule is the interface for rule manipulation.
+type Rule interface {
+	// Add adds a new rule.
+	//
+	// This command is equivalent to:
+	// 		nft add rule (ip|ip6|inet|arp|bridge) {table_name} {chain_name} '{ expr }'
+	Add(family family.Type, tableName string, chainName string, expr ...string) error
+
+	// Insert inserts a new rule.
+	// Inserted rules are placed at the beginning of the chain, by default.
+	//
+	// This command is equivalent to:
+	// 		nft insert rule (ip|ip6|inet|arp|bridge) {table_name} {chain_name} '{ expr }'
+	Insert(family family.Type, tableName string, chainName string, expr ...string) error
+
+	// Replace replaces a rule.
+	//
+	// This command is equivalent to:
+	// 		nft replace rule (ip|ip6|inet|arp|bridge) {table_name} {chain_name} {handle} '{ expr }'
+	Replace(family family.Type, tableName string, chainName string, handle uint64, expr ...string) error
+
+	// Delete deletes a rule.
+	//
+	// This command is equivalent to:
+	// 		nft delete rule (ip|ip6|inet|arp|bridge) {table_name} {chain_name} {handle}
+	Delete(family family.Type, tableName string, chainName string, handle uint64) error
+}