gno.land/p/nt/grc721/metadata/v0⧉

1package metadata23import (4	"chain"56	"gno.land/p/nt/grc721/v0"7)89const Kind = "metadata"1011// NewMetadata attaches a metadata extension and registers it as a core Extension.12// Attach it before the first mint so every token is indexed.13func NewMetadata(coreLedger *grc721.PrivateLedger) (*Metadata, *Ledger) {14	if coreLedger == nil {15		panic("metadata: nil core ledger")16	}1718	st := &storage{}19	core := coreLedger.ReadToken()20	led := &Ledger{core: core, st: st}21	coreLedger.RegisterExtension(led)2223	return &Metadata{core: core, st: st}, led24}2526func (m *Metadata) ExtensionKind() string { return Kind }2728func (m *Metadata) TokenID() string { return m.core.ID() }2930func (m *Metadata) TokenURI(tid grc721.TokenID) (string, error) {31	v := m.st.uris.Get(tid.String())32	if v == nil {33		return "", ErrNoTokenURI34	}3536	return v.(string), nil37}3839func (m *Metadata) TokenMetadata(tid grc721.TokenID) (Data, error) {40	v := m.st.data.Get(tid.String())41	if v == nil {42		return Data{}, ErrNoMetadata43	}4445	return v.(Data), nil46}4748func (m *Metadata) HasTokenURI(tid grc721.TokenID) bool {49	return m.st.uris.Has(tid.String())50}5152func (m *Metadata) HasMetadata(tid grc721.TokenID) bool {53	return m.st.data.Has(tid.String())54}5556// SetTokenURI sets the EIP-721 tokenURI of tid; issuer-only so a holder cannot57// rewrite the URI after acquisition.58func (led *Ledger) SetTokenURI(tid grc721.TokenID, uri string) error {59	if _, err := led.core.OwnerOf(tid); err != nil {60		return ErrTokenNotMinted61	}6263	led.st.uris.Set(tid.String(), uri)6465	chain.Emit(66		TokenURIUpdateEvent,67		"token", led.core.ID(),68		"tokenId", tid.String(),69		"uri", uri,70	)7172	return nil73}7475// SetTokenMetadata sets the OpenSea on-chain metadata of tid; issuer-only.76func (led *Ledger) SetTokenMetadata(tid grc721.TokenID, data Data) error {77	if _, err := led.core.OwnerOf(tid); err != nil {78		return ErrTokenNotMinted79	}8081	led.st.data.Set(tid.String(), data)8283	chain.Emit(84		MetadataUpdateEvent,85		"token", led.core.ID(),86		"tokenId", tid.String(),87	)8889	return nil90}9192func (led *Ledger) ExtensionKind() string { return Kind }9394func (led *Ledger) OnMint(to address, tid grc721.TokenID)           {}95func (led *Ledger) OnTransfer(from, to address, tid grc721.TokenID) {}9697// OnBurn clears per-token state so it cannot resurface on re-mint.98func (led *Ledger) OnBurn(tid grc721.TokenID) {99	tidStr := tid.String()100	led.st.uris.Remove(tidStr)101	led.st.data.Remove(tidStr)102}103