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-rw-r--r--entity/id.go65
1 files changed, 65 insertions, 0 deletions
diff --git a/entity/id.go b/entity/id.go
new file mode 100644
index 00000000..7fa1785a
--- /dev/null
+++ b/entity/id.go
@@ -0,0 +1,65 @@
+package entity
+
+import (
+ "fmt"
+ "io"
+ "strings"
+
+ "github.com/pkg/errors"
+)
+
+const IdLengthSHA1 = 40
+const IdLengthSHA256 = 64
+const humanIdLength = 7
+
+const UnsetId = Id("unset")
+
+// Id is an identifier for an entity or part of an entity
+type Id string
+
+func (i Id) String() string {
+ return string(i)
+}
+
+func (i Id) Human() string {
+ format := fmt.Sprintf("%%.%ds", humanIdLength)
+ return fmt.Sprintf(format, i)
+}
+
+func (i Id) HasPrefix(prefix string) bool {
+ return strings.HasPrefix(string(i), prefix)
+}
+
+// UnmarshalGQL implement the Unmarshaler interface for gqlgen
+func (i *Id) UnmarshalGQL(v interface{}) error {
+ _, ok := v.(string)
+ if !ok {
+ return fmt.Errorf("IDs must be strings")
+ }
+
+ *i = v.(Id)
+
+ if err := i.Validate(); err != nil {
+ return errors.Wrap(err, "invalid ID")
+ }
+
+ return nil
+}
+
+// MarshalGQL implement the Marshaler interface for gqlgen
+func (i Id) MarshalGQL(w io.Writer) {
+ _, _ = w.Write([]byte(`"` + i.String() + `"`))
+}
+
+// IsValid tell if the Id is valid
+func (i Id) Validate() error {
+ if len(i) != IdLengthSHA1 && len(i) != IdLengthSHA256 {
+ return fmt.Errorf("invalid length")
+ }
+ for _, r := range i {
+ if (r < 'a' || r > 'z') && (r < '0' || r > '9') {
+ return fmt.Errorf("invalid character")
+ }
+ }
+ return nil
+}