From 6f5737a763eabdf8e58159d945ccb9bc63ffd48c Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Thu, 13 Feb 2025 23:05:39 -0300
Subject: [PATCH] pointers from tags helpers.

---
 pointers.go | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/pointers.go b/pointers.go
index 6436cb3..93d605a 100644
--- a/pointers.go
+++ b/pointers.go
@@ -2,6 +2,8 @@ package nostr
 
 import (
 	"fmt"
+	"strconv"
+	"strings"
 )
 
 type Pointer interface {
@@ -15,6 +17,23 @@ type ProfilePointer struct {
 	Relays    []string `json:"relays,omitempty"`
 }
 
+func ProfilePointerFromTag(refTag Tag) (ProfilePointer, error) {
+	pk := (refTag)[1]
+	if !IsValidPublicKey(pk) {
+		return ProfilePointer{}, fmt.Errorf("invalid pubkey '%s'", pk)
+	}
+
+	pointer := ProfilePointer{
+		PublicKey: pk,
+	}
+	if len(refTag) > 2 {
+		if relay := (refTag)[2]; IsValidRelayURL(relay) {
+			pointer.Relays = []string{relay}
+		}
+	}
+	return pointer, nil
+}
+
 func (ep ProfilePointer) MatchesEvent(_ Event) bool { return false }
 func (ep ProfilePointer) AsTagReference() string    { return ep.PublicKey }
 
@@ -32,6 +51,26 @@ type EventPointer struct {
 	Kind   int      `json:"kind,omitempty"`
 }
 
+func EventPointerFromTag(refTag Tag) (EventPointer, error) {
+	id := (refTag)[1]
+	if !IsValid32ByteHex(id) {
+		return EventPointer{}, fmt.Errorf("invalid id '%s'", id)
+	}
+
+	pointer := EventPointer{
+		ID: id,
+	}
+	if len(refTag) > 2 {
+		if relay := (refTag)[2]; IsValidRelayURL(relay) {
+			pointer.Relays = []string{relay}
+		}
+		if len(refTag) > 3 && IsValidPublicKey((refTag)[3]) {
+			pointer.Author = (refTag)[3]
+		}
+	}
+	return pointer, nil
+}
+
 func (ep EventPointer) MatchesEvent(evt Event) bool { return evt.ID == ep.ID }
 func (ep EventPointer) AsTagReference() string      { return ep.ID }
 
@@ -53,6 +92,34 @@ type EntityPointer struct {
 	Relays     []string `json:"relays,omitempty"`
 }
 
+func EntityPointerFromTag(refTag Tag) (EntityPointer, error) {
+	spl := strings.SplitN(refTag[1], ":", 3)
+	if len(spl) != 3 {
+		return EntityPointer{}, fmt.Errorf("invalid addr ref '%s'", refTag[1])
+	}
+	if !IsValidPublicKey(spl[1]) {
+		return EntityPointer{}, fmt.Errorf("invalid addr pubkey '%s'", spl[1])
+	}
+
+	kind, err := strconv.Atoi(spl[0])
+	if err != nil || kind > (1<<16) {
+		return EntityPointer{}, fmt.Errorf("invalid addr kind '%s'", spl[0])
+	}
+
+	pointer := EntityPointer{
+		Kind:       kind,
+		PublicKey:  spl[1],
+		Identifier: spl[2],
+	}
+	if len(refTag) > 2 {
+		if relay := (refTag)[2]; IsValidRelayURL(relay) {
+			pointer.Relays = []string{relay}
+		}
+	}
+
+	return pointer, nil
+}
+
 func (ep EntityPointer) MatchesEvent(evt Event) bool {
 	return ep.PublicKey == evt.PubKey &&
 		ep.Kind == evt.Kind &&