package entity import ( "crypto/sha256" "fmt" "io" "strings" "github.com/pkg/errors" ) // sha-256 const idLength = 64 const humanIdLength = 7 const UnsetId = Id("unset") // Id is an identifier for an entity or part of an entity type Id string // DeriveId generate an Id from the serialization of the object or part of the object. func DeriveId(data []byte) Id { // My understanding is that sha256 is enough to prevent collision (git use that, so ...?) // If you read this code, I'd be happy to be schooled. sum := sha256.Sum256(data) return Id(fmt.Sprintf("%x", sum)) } // String return the identifier as a string func (i Id) String() string { return string(i) } // Human return the identifier, shortened for human consumption 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+ i.String() + `"`)) } // Validate tell if the Id is valid func (i Id) Validate() error { // Special case to detect outdated repo if len(i) == 40 { return fmt.Errorf("outdated repository format, please use https://github.com/MichaelMure/git-bug-migration to upgrade") } if len(i) != idLength { return fmt.Errorf("invalid length") } for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 }