Initial commit

Assisted-by: GLM 5.3

internal/identifiers/identifiers.go

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+// Copyright (c) 2026 Petr Balvín <opensource@petrbalvin.org> (https://petrbalvin.org)
+// SPDX-License-Identifier: PolyForm-Noncommercial-1.0.0
+
+// Package identifiers validates the scholarly identifiers a post or an
+// account can carry: a DOI names the work, an ORCID names an author. It
+// is a leaf so the configuration, the domain object, the payload
+// builders and the admin share one rule without importing one another.
+//
+// The rules are syntactic on purpose. A DOI resolves through doi.org and
+// an ORCID through orcid.org, and both publish registries; asking those
+// services here would tie a save to the network, leak who is writing to
+// a third party, and make the offline binary wait on someone else's
+// uptime. Syntax plus the ORCID check digit catches every realistic
+// typo; resolution stays the consumer's job.
+package identifiers
+
+import (
+	"regexp"
+	"strings"
+)
+
+var doiRe = regexp.MustCompile(`\A10\.[0-9]{4,9}/\S+\z`)
+
+// orcidRe is the display form: four groups of four digits, the last
+// character a digit or the uppercase X that stands for a checksum of 10.
+var orcidRe = regexp.MustCompile(`\A[0-9]{4}-[0-9]{4}-[0-9]{4}-[0-9]{3}[0-9X]\z`)
+
+// NormalizeDOI accepts the bare form, a doi: scheme and a doi.org URL,
+// and returns the bare identifier; an empty result means the input
+// carries no DOI at all.
+func NormalizeDOI(text string) string {
+	text = strings.TrimSpace(text)
+	for _, prefix := range []string{
+		"https://doi.org/", "http://doi.org/", "doi.org/", "doi:",
+	} {
+		if len(text) > len(prefix) && strings.EqualFold(text[:len(prefix)], prefix) {
+			text = strings.TrimSpace(text[len(prefix):])
+			break
+		}
+	}
+	return text
+}
+
+// ValidDOI reports whether text is a syntactically valid bare DOI: the
+// 10. prefix, a registrant needle of four to nine digits, a slash, and
+// a non-empty suffix without spaces.
+func ValidDOI(text string) bool {
+	return doiRe.MatchString(NormalizeDOI(text))
+}
+
+// NormalizeORCID trims and lower-cases to upper; it fixes no body.
+func NormalizeORCID(text string) string {
+	return strings.ToUpper(strings.TrimSpace(text))
+}
+
+// ValidORCID reports whether text is an ORCID iD in display form with a
+// correct ISO 7064 (MOD 11-2) check digit.
+func ValidORCID(text string) bool {
+	id := NormalizeORCID(text)
+	if !orcidRe.MatchString(id) {
+		return false
+	}
+	digits := strings.ReplaceAll(id, "-", "")
+	total := 0
+	for _, r := range digits[:15] {
+		total = (total + int(r-'0')) * 2
+	}
+	remainder := (12 - total%11) % 11
+	want := byte('0' + remainder)
+	if remainder == 10 {
+		want = 'X'
+	}
+	return digits[15] == want
+}
+
+// DOIURL names the resolver for a bare or already-prefixed DOI; an
+// invalid input yields "".
+func DOIURL(text string) string {
+	doi := NormalizeDOI(text)
+	if !doiRe.MatchString(doi) {
+		return ""
+	}
+	return "https://doi.org/" + doi
+}
+
+// ORCIDURL names the public record for a valid iD; an invalid input
+// yields "".
+func ORCIDURL(text string) string {
+	id := NormalizeORCID(text)
+	if !ValidORCID(id) {
+		return ""
+	}
+	return "https://orcid.org/" + id
+}