package main import ( "bytes" "crypto/rand" "fmt" "regexp" "strconv" "strings" "github.com/lib/pq" ) var ( // This replaces all special characters tagRegexp = regexp.MustCompile(`[^a-z0-9\-\s]`) tagRegexpSpaces = regexp.MustCompile(`[\s]+`) ) // validateMIME is a helper function to validate uploaded file's MIME type // against the slice of MIME types is given. func validateMIME(typ string, mimes []string) (ok bool) { if len(mimes) > 0 { var ( ok = false ) for _, m := range mimes { if typ == m { ok = true break } } if !ok { return false } } return true } // generateFileName appends the incoming file's name with a small random hash. func generateFileName(fName string) string { name := strings.TrimSpace(fName) if name == "" { name, _ = generateRandomString(10) } return name } // Given an error, pqErrMsg will try to return pq error details // if it's a pq error. func pqErrMsg(err error) string { if err, ok := err.(*pq.Error); ok { if err.Detail != "" { return fmt.Sprintf("%s. %s", err, err.Detail) } } return err.Error() } // normalizeTags takes a list of string tags and normalizes them by // lowercasing and removing all special characters except for dashes. func normalizeTags(tags []string) []string { var ( out []string space = []byte(" ") dash = []byte("-") ) for _, t := range tags { rep := bytes.TrimSpace(tagRegexp.ReplaceAll(bytes.ToLower([]byte(t)), space)) rep = tagRegexpSpaces.ReplaceAll(rep, dash) if len(rep) > 0 { out = append(out, string(rep)) } } return out } // makeMsgTpl takes a page title, heading, and message and returns // a msgTpl that can be rendered as a HTML view. This is used for // rendering arbitrary HTML views with error and success messages. func makeMsgTpl(pageTitle, heading, msg string) msgTpl { if heading == "" { heading = pageTitle } err := msgTpl{} err.Title = pageTitle err.MessageTitle = heading err.Message = msg return err } // parseStringIDs takes a slice of numeric string IDs and // parses each number into an int64 and returns a slice of the // resultant values. func parseStringIDs(s []string) ([]int64, error) { vals := make([]int64, 0, len(s)) for _, v := range s { i, err := strconv.ParseInt(v, 10, 64) if err != nil { return nil, err } if i < 1 { return nil, fmt.Errorf("%d is not a valid ID", i) } vals = append(vals, i) } return vals, nil } // generateRandomString generates a cryptographically random, alphanumeric string of length n. func generateRandomString(n int) (string, error) { const dictionary = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" var bytes = make([]byte, n) if _, err := rand.Read(bytes); err != nil { return "", err } for k, v := range bytes { bytes[k] = dictionary[v%byte(len(dictionary))] } return string(bytes), nil } // strHasLen checks if the given string has a length within min-max. func strHasLen(str string, min, max int) bool { return len(str) >= min && len(str) <= max }