Files
notarius/internal/modules/dnd/items/identity/identity.go

138 lines
4.5 KiB
Go

// Package identity owns the stable identity policy for D&D item types.
package identity
import (
"crypto/sha256"
"encoding/hex"
"encoding/json"
"fmt"
"strings"
"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd"
"gitea.maximumdirect.net/eric/notarius/internal/modules/dnd/shared"
)
const (
// Policy identifies the complete item comparison and ID derivation policy.
// A future semantic change must use a new value.
Policy = "dnd.item_registry.identity.v1"
// IdentityPolicy is an explicit alias for callers recording policy
// fingerprints.
IdentityPolicy = Policy
)
const idPrefix = "item:sha256:"
// IssueCode identifies one deterministic registry identity problem.
type IssueCode string
const (
IssueEmptyCanonicalName IssueCode = "empty_canonical_name"
IssueInvalidID IssueCode = "invalid_id"
IssueIDMismatch IssueCode = "id_mismatch"
IssueDuplicateCanonical IssueCode = "duplicate_canonical_identity"
IssueDuplicateID IssueCode = "duplicate_id"
)
// Issue is an inspectable identity validation problem.
type Issue struct {
Code IssueCode
RecordIndex int
Value string
}
// NormalizeDisplay trims and collapses Unicode whitespace while retaining all
// other observed spelling and punctuation.
func NormalizeDisplay(value string) string {
return strings.Join(strings.Fields(value), " ")
}
// ComparisonKey returns the stable key used for item-type identity comparisons.
func ComparisonKey(value string) string {
return shared.ComparisonKey(value)
}
// DeriveID returns the deterministic ID for an item type. Empty identity keys
// intentionally produce an empty ID so shape validation can report the missing
// identity instead of manufacturing one.
func DeriveID(name string) string {
key := ComparisonKey(name)
if key == "" {
return ""
}
identity, err := json.Marshal([]string{Policy, key})
if err != nil {
return ""
}
digest := sha256.Sum256(identity)
return idPrefix + hex.EncodeToString(digest[:])
}
// IDFor is a concise alias for DeriveID for callers that work with IDs as
// values rather than derivation operations.
func IDFor(name string) string { return DeriveID(name) }
// IsValidID reports whether value has the exact durable item ID syntax.
func IsValidID(value string) bool {
if len(value) != len(idPrefix)+sha256.Size*2 || !strings.HasPrefix(value, idPrefix) {
return false
}
for _, r := range value[len(idPrefix):] {
if !(r >= '0' && r <= '9') && !(r >= 'a' && r <= 'f') {
return false
}
}
return true
}
// ValidID is an alias for IsValidID.
func ValidID(value string) bool { return IsValidID(value) }
// ValidateRegistry checks item-type identity invariants without changing the
// input. Items with the same comparison name describe the same item type and
// are rejected as duplicate registry records.
func ValidateRegistry(items []dnd.Item) []Issue {
issues := make([]Issue, 0)
canonicalOwners := make(map[string][]int)
idOwners := make(map[string][]int)
for recordIndex, item := range items {
canonical := ComparisonKey(item.Name)
if canonical == "" {
issues = append(issues, Issue{Code: IssueEmptyCanonicalName, RecordIndex: recordIndex, Value: item.Name})
} else {
canonicalOwners[canonical] = append(canonicalOwners[canonical], recordIndex)
}
if !IsValidID(item.ID) {
issues = append(issues, Issue{Code: IssueInvalidID, RecordIndex: recordIndex, Value: item.ID})
} else if expected := DeriveID(item.Name); item.ID != expected {
issues = append(issues, Issue{Code: IssueIDMismatch, RecordIndex: recordIndex, Value: item.ID})
}
if item.ID != "" {
idOwners[item.ID] = append(idOwners[item.ID], recordIndex)
}
}
for recordIndex, item := range items {
canonical := ComparisonKey(item.Name)
if canonical != "" && len(canonicalOwners[canonical]) > 1 && canonicalOwners[canonical][0] != recordIndex {
issues = append(issues, Issue{Code: IssueDuplicateCanonical, RecordIndex: recordIndex, Value: item.Name})
}
if item.ID != "" && len(idOwners[item.ID]) > 1 && idOwners[item.ID][0] != recordIndex {
issues = append(issues, Issue{Code: IssueDuplicateID, RecordIndex: recordIndex, Value: item.ID})
}
}
return issues
}
// ValidateList validates the identity members of list.
func ValidateList(list dnd.ItemRegistry) []Issue { return ValidateRegistry(list.Items) }
// Error makes an issue useful in simple callers while preserving its
// structured fields for aggregate diagnostics.
func (i Issue) Error() string {
return fmt.Sprintf("%s at record %d", i.Code, i.RecordIndex)
}