fix: enable CEL iterators

Signed-off-by: Jason Cameron <jason.cameron@stanwith.me>

lib/policy/checker/celutils.go

@@ -0,0 +1,61 @@
+package checker
+
+import (
+	"errors"
+	"maps"
+	"reflect"
+	"slices"
+
+	"github.com/google/cel-go/common/types"
+	"github.com/google/cel-go/common/types/ref"
+	"github.com/google/cel-go/common/types/traits"
+)
+
+var ErrNotImplemented = errors.New("cel: functionality not implemented")
+
+type stringSliceIterator struct {
+	keys []string
+	idx  int
+}
+
+func (s *stringSliceIterator) Value() any {
+	return s
+}
+
+func (s *stringSliceIterator) ConvertToNative(typeDesc reflect.Type) (any, error) {
+	return nil, ErrNotImplemented
+}
+
+func (s *stringSliceIterator) ConvertToType(typeValue ref.Type) ref.Val {
+	return types.NewErr("can't convert from %q to %q", types.IteratorType, typeValue)
+}
+
+func (s *stringSliceIterator) Equal(other ref.Val) ref.Val {
+	return types.NewErr("can't compare %q to %q", types.IteratorType, other.Type())
+
+}
+
+func (s *stringSliceIterator) Type() ref.Type {
+	return types.IteratorType
+}
+
+func (s *stringSliceIterator) HasNext() ref.Val {
+	return types.Bool(s.idx < len(s.keys))
+}
+
+func (s *stringSliceIterator) Next() ref.Val {
+	if s.HasNext() != types.True {
+		return nil
+	}
+
+	val := s.keys[s.idx]
+	s.idx++
+	return types.String(val)
+}
+
+func NewMapIterator(m map[string][]string) traits.Iterator {
+	return &stringSliceIterator{
+		keys: slices.Collect(maps.Keys(m)),
+		idx:  0,
+	}
+}

lib/policy/expressions/http_headers.go

@@ -5,6 +5,7 @@ import (
 	"reflect"
 	"strings"
 
+	"github.com/TecharoHQ/anubis/lib/policy/checker"
 	"github.com/google/cel-go/common/types"
 	"github.com/google/cel-go/common/types/ref"
 	"github.com/google/cel-go/common/types/traits"
@@ -66,7 +67,9 @@ func (h HTTPHeaders) Get(key ref.Val) ref.Val {
 	return result
 }
 
-func (h HTTPHeaders) Iterator() traits.Iterator { panic("TODO(Xe): implement me") }
+func (h HTTPHeaders) Iterator() traits.Iterator {
+	return checker.NewMapIterator(h.Header)
+}
 
 func (h HTTPHeaders) IsZeroValue() bool {
 	return len(h.Header) == 0

lib/policy/expressions/url_values.go

@@ -6,6 +6,7 @@ import (
 	"reflect"
 	"strings"
 
+	"github.com/TecharoHQ/anubis/lib/policy/checker"
 	"github.com/google/cel-go/common/types"
 	"github.com/google/cel-go/common/types/ref"
 	"github.com/google/cel-go/common/types/traits"
@@ -69,7 +70,9 @@ func (u URLValues) Get(key ref.Val) ref.Val {
 	return result
 }
 
-func (u URLValues) Iterator() traits.Iterator { panic("TODO(Xe): implement me") }
+func (u URLValues) Iterator() traits.Iterator {
+	return checker.NewMapIterator(u.Values)
+}
 
 func (u URLValues) IsZeroValue() bool {
 	return len(u.Values) == 0