1 files changed, 69 insertions, 0 deletions
diff --git a/filters.go b/filters.go
new file mode 100644
index 0000000..bb57599
--- /dev/null
+++ b/filters.go
@@ -0,0 +1,69 @@
+package main
+
+import (
+	"math/rand"
+	"reflect"
+	"time"
+)
+
+// firstN returns the first n items of a slice.
+func firstN(n int, items interface{}) interface{} {
+	v := reflect.ValueOf(items)
+	if v.Kind() != reflect.Slice {
+		panic("firstN: not a slice")
+	}
+	if v.Len() < n {
+		return items
+	}
+	return v.Slice(0, n).Interface()
+}
+
+// lastN returns the last n items of any slice.
+func lastN(n int, items interface{}) interface{} {
+	v := reflect.ValueOf(items)
+	if v.Kind() != reflect.Slice {
+		panic("lastN: not a slice")
+	}
+	l := v.Len()
+	if l < n {
+		return items
+	}
+	return v.Slice(l-n, l).Interface()
+}
+
+// randomN returns n random items of any slice.
+func randomN(n int, items interface{}) interface{} {
+	v := reflect.ValueOf(items)
+	if v.Kind() != reflect.Slice {
+		panic("randomN: not a slice")
+	}
+	l := v.Len()
+	if l < n {
+		return items
+	}
+	rand.Seed(time.Now().UnixNano())
+	indices := rand.Perm(l)[:n]
+	result := reflect.MakeSlice(v.Type(), n, n)
+	for i, idx := range indices {
+		result.Index(i).Set(v.Index(idx))
+	}
+	return result.Interface()
+}
+
+// filterByType filters pages by their type.
+func filterByType(pageType string, pages interface{}) interface{} {
+	v := reflect.ValueOf(pages)
+	if v.Kind() != reflect.Slice {
+		panic("filterByType: not a slice")
+	}
+
+	var filtered []interface{}
+	for i := 0; i < v.Len(); i++ {
+		page := v.Index(i).Interface().(Page)
+		if page.Type == pageType {
+			filtered = append(filtered, page)
+		}
+	}
+	return filtered
+}
+