[#13] interface: Add methods to CachedChainStorage interface

* Introduce GetOverride, RemoveOverride, ListOverrides
* Implement them in inmemory struct

Signed-off-by: aarifullin <aarifullin@yadro.com>

inmemory.go

@@ -1,12 +1,9 @@
 package policyengine
 
-import "sync/atomic"
-
 type inmemory struct {
-	chainCounter atomic.Uint32
-	namespace    map[Name][]chain
-	resource     map[Name][]chain
-	local        map[Name][]*Chain
+	namespace map[Name][]chain
+	resource  map[Name][]chain
+	local     map[Name][]*Chain
 }
 
 type chain struct {
@@ -77,3 +74,34 @@ func (s *inmemory) AddNameSpaceChain(name Name, namespace string, c *Chain) {
 func (s *inmemory) AddOverride(name Name, c *Chain) {
 	s.local[name] = append(s.local[name], c)
 }
+
+func (s *inmemory) GetOverride(name Name, chainID ChainID) (chain *Chain, found bool) {
+	chains := s.local[name]
+
+	for _, chain = range chains {
+		if chain.ID == chainID {
+			found = true
+			return
+		}
+	}
+
+	return
+}
+
+func (s *inmemory) RemoveOverride(name Name, chainID ChainID) (found bool) {
+	chains := s.local[name]
+
+	for i, chain := range chains {
+		if chain.ID == chainID {
+			s.local[name] = append(chains[:i], chains[i+1:]...)
+			found = true
+			return
+		}
+	}
+
+	return
+}
+
+func (s *inmemory) ListOverrides(name Name) []*Chain {
+	return s.local[name]
+}

interface.go

@@ -9,4 +9,10 @@ type CachedChainStorage interface {
 	AddNameSpaceChain(name Name, namespace string, c *Chain)
 	// Adds a local policy chain used for all operations with this service.
 	AddOverride(name Name, c *Chain)
+	// Gets the local override with given chain id.
+	GetOverride(name Name, chainID ChainID) (chain *Chain, found bool)
+	// Remove the local override with given chain id.
+	RemoveOverride(name Name, chainID ChainID) (removed bool)
+	// ListOverrides returns the list of local overrides.
+	ListOverrides(name Name) []*Chain
 }