Returning pagination metadata.

internal/data/filters.go

@@ -50,3 +50,27 @@ func (f Filters) sortDirection() string {
 	}
 	return "ASC"
 }
+
+// Metadata struct for holding the pagination metadata
+type Metadata struct {
+	CurrentPage  int `json:"current_page,omitempty"`
+	PageSize     int `json:"page_size,omitempty"`
+	FirstPage    int `json:"first_page,omitempty"`
+	LastPage     int `json:"last_page,omitempty"`
+	TotalRecords int `json:"total_records,omitempty"`
+}
+
+// calculateMetadata : calculates the appropriate pagination metadata values given the total number of records, current page, and page size values. Note that when the last page value is calculated, we are dividing two int values, and when dividing integer types in Go the result will also be an integer type, with the modulus (or reminder) dropped. So, for instance, if there were 12 records in total and a page of 5, the last page value would be (12+5-1)/5 = 3.2, which is then truncated to 3 by Go.
+func calculateMetadata(totalRecords, page, pageSize int) Metadata {
+	if totalRecords == 0 {
+		return Metadata{}
+	}
+
+	return Metadata{
+		CurrentPage:  page,
+		PageSize:     pageSize,
+		FirstPage:    1,
+		LastPage:     (totalRecords + pageSize - 1) / pageSize,
+		TotalRecords: totalRecords,
+	}
+}