package feed

//go:generate stringer -linecomment -type=DataVersion

import (
  "encoding/json"
  "fmt"
)

// Data version for NVD feeds and feed items.
type DataVersion byte

const (
  V40 DataVersion = iota // 4.0
)

// Unmarshal data version from JSON.
func (me *DataVersion) UnmarshalJSON(b []byte) error {
  // decode string, check for error
  var s string
  if err := json.Unmarshal(b, &s); err != nil {
    return err
  }

  // check value
  switch s {
  case "4.0":
    *me = V40
  default:
    // return error
    return fmt.Errorf("unknown data version: %s", s)
  }

  // return success
  return nil
}