omissis/go-jsonschema

package schemas

import (
    "errors"
    "fmt"
    "net/url"
)

var (
    ErrEmptyReference       = errors.New("reference is empty")
    ErrUnsupportedRefFormat = errors.New("unsupported $ref format")
    ErrCannotParseRef       = errors.New("cannot parse $ref")
    ErrUnsupportedRefSchema = errors.New("unsupported $ref schema")
    ErrGetRefType           = errors.New("cannot get $ref type")
)

type RefType string

const (
    RefTypeFile    RefType = "file"
    RefTypeHTTP    RefType = "http"
    RefTypeHTTPS   RefType = "https"
    RefTypeUnknown RefType = "unknown"
)

func GetRefType(ref string) (RefType, error) {
    urlRef, err := url.Parse(ref)
    if err != nil {
        return RefTypeUnknown, fmt.Errorf("%w: %w", ErrGetRefType, err)
    }

    switch urlRef.Scheme {
    case "http":
        return RefTypeHTTP, nil

    case "https":
        return RefTypeHTTPS, nil

    case "file", "":
        return RefTypeFile, nil

    default:
        return RefTypeUnknown, fmt.Errorf("%w: %w", ErrGetRefType, ErrUnsupportedRefSchema)
    }
}