Add generic filter build for filter.Filter

pkg/filter/filter.go

@@ -1,6 +1,17 @@
 package filter
 
 type (
+	filterOpt func(*filter)
+
+	filter struct {
+		constaints      map[string][]any
+		stateConditions map[string]State
+		expression      string
+		orderBy         SortExprSet
+		limit           uint
+		cursor          *PagingCursor
+	}
+
 	Filter interface {
 		// Constraints returns map of attribute idents and values
 		// used for structured filtering ({a1: [v1], a2: [v2, v3]} => "a1 = v1 AND a2 = (v2,v4)")
@@ -23,3 +34,84 @@ type (
 		Cursor() *PagingCursor
 	}
 )
+
+func Generic(oo ...filterOpt) Filter {
+	f := &filter{}
+
+	for _, o := range oo {
+		o(f)
+	}
+
+	return f
+}
+
+// WithConstraint sets single constraint to filter
+func WithConstraint(k string, v any) filterOpt {
+	return func(f *filter) {
+		if f.constaints == nil {
+			f.constaints = make(map[string][]any)
+		}
+
+		f.constaints[k] = append(f.constaints[k], v)
+	}
+}
+
+// WithConstraints set multiple constraints to filter
+func WithConstraints(c map[string][]any) filterOpt {
+	return func(f *filter) {
+		f.constaints = c
+	}
+}
+
+// WithStateConstraint sets single state constraint to filter
+func WithStateConstraint(k string, s State) filterOpt {
+	return func(f *filter) {
+		if f.stateConditions == nil {
+			f.stateConditions = make(map[string]State)
+		}
+
+		f.stateConditions[k] = s
+	}
+}
+
+// WithStateConstraints sets multiple state constraints to filter
+func WithStateConstraints(sc map[string]State) filterOpt {
+	return func(f *filter) {
+		f.stateConditions = sc
+	}
+}
+
+// WithExpression sets expression to filter
+func WithExpression(e string) filterOpt {
+	return func(f *filter) {
+		f.expression = e
+	}
+}
+
+// WithOrderBy sets order by expression
+func WithOrderBy(o SortExprSet) filterOpt {
+	return func(f *filter) {
+		f.orderBy = o
+	}
+}
+
+// WithLimit sets limit to filter
+func WithLimit(l uint) filterOpt {
+	return func(f *filter) {
+		f.limit = l
+	}
+}
+
+// WithCursor sets cursor to filter
+func WithCursor(p *PagingCursor) filterOpt {
+	return func(f *filter) {
+		f.cursor = p
+	}
+}
+
+func (f *filter) Constraints() map[string][]any      { return f.constaints }
+func (f *filter) StateConstraints() map[string]State { return f.stateConditions }
+func (f *filter) Expression() string                 { return f.expression }
+func (f *filter) OrderBy() SortExprSet               { return f.orderBy }
+func (f *filter) Limit() uint                        { return f.limit }
+func (f *filter) Cursor() *PagingCursor              { return f.cursor }