cache: combine sorting and filtering into a query with its micro-DSL

1 files changed, 128 insertions, 0 deletions

diff --git a/cache/query.go b/cache/query.go
new file mode 100644
index 00000000..d8df00fe
--- /dev/null
+++ b/cache/query.go
@@ -0,0 +1,128 @@
+package cache
+
+import (
+	"fmt"
+	"strings"
+)
+
+type Query struct {
+	Filters
+	OrderBy
+	OrderDirection
+}
+
+// ParseQuery parse a query DSL
+//
+// Ex: "status:open author:descartes sort:edit-asc"
+//
+// Supported filter fields are:
+// - status:
+// - author:
+// - label:
+// - no:
+//
+// Sorting is done with:
+// - sort:
+//
+// Todo: write a complete doc
+func ParseQuery(query string) (*Query, error) {
+	fields := strings.Fields(query)
+
+	result := &Query{
+		OrderBy:        OrderByCreation,
+		OrderDirection: OrderDescending,
+	}
+
+	sortingDone := false
+
+	for _, field := range fields {
+		split := strings.Split(field, ":")
+		if len(split) != 2 {
+			return nil, fmt.Errorf("can't parse \"%s\"", field)
+		}
+
+		switch split[0] {
+		case "status":
+			f, err := StatusFilter(split[1])
+			if err != nil {
+				return nil, err
+			}
+			result.Status = append(result.Status, f)
+
+		case "author":
+			f := AuthorFilter(split[1])
+			result.Author = append(result.Author, f)
+
+		case "label":
+			f := LabelFilter(split[1])
+			result.Label = append(result.Label, f)
+
+		case "no":
+			err := result.parseNoFilter(split[1])
+			if err != nil {
+				return nil, err
+			}
+
+		case "sort":
+			if sortingDone {
+				return nil, fmt.Errorf("multiple sorting")
+			}
+
+			err := result.parseSorting(split[1])
+			if err != nil {
+				return nil, err
+			}
+
+			sortingDone = true
+
+		default:
+			return nil, fmt.Errorf("unknow query field %s", split[0])
+		}
+	}
+
+	return result, nil
+}
+
+func (q *Query) parseNoFilter(query string) error {
+	switch query {
+	case "label":
+		q.NoFilters = append(q.NoFilters, NoLabelFilter())
+	default:
+		return fmt.Errorf("unknown \"no\" filter")
+	}
+
+	return nil
+}
+
+func (q *Query) parseSorting(query string) error {
+	switch query {
+	// default ASC
+	case "id-desc":
+		q.OrderBy = OrderById
+		q.OrderDirection = OrderDescending
+	case "id", "id-asc":
+		q.OrderBy = OrderById
+		q.OrderDirection = OrderAscending
+
+	// default DESC
+	case "creation", "creation-desc":
+		q.OrderBy = OrderByCreation
+		q.OrderDirection = OrderDescending
+	case "creation-asc":
+		q.OrderBy = OrderByCreation
+		q.OrderDirection = OrderAscending
+
+	// default DESC
+	case "edit", "edit-desc":
+		q.OrderBy = OrderByEdit
+		q.OrderDirection = OrderDescending
+	case "edit-asc":
+		q.OrderBy = OrderByEdit
+		q.OrderDirection = OrderAscending
+
+	default:
+		return fmt.Errorf("unknow sorting %s", query)
+	}
+
+	return nil
+}