Second checkpoint

internal/transport/http/pagination.go

@@ -0,0 +1,29 @@
+package http
+
+// Paginated is the generic list response envelope.
+type Paginated[T any] struct {
+	Data       []T `json:"data"`
+	Page       int `json:"page"`
+	PageSize   int `json:"page_size"`
+	Total      int `json:"total"`
+	TotalPages int `json:"total_pages"`
+}
+
+// newPaginated builds a Paginated envelope, computing total pages and
+// normalizing a nil slice to an empty array.
+func newPaginated[T any](items []T, page, pageSize, total int) Paginated[T] {
+	totalPages := 0
+	if pageSize > 0 {
+		totalPages = (total + pageSize - 1) / pageSize
+	}
+	if items == nil {
+		items = []T{}
+	}
+	return Paginated[T]{
+		Data:       items,
+		Page:       page,
+		PageSize:   pageSize,
+		Total:      total,
+		TotalPages: totalPages,
+	}
+}