Lightning Zaps
Added initial lightning zaps/tipping integration Changelog-Added: Receive Lightning Zaps
This commit is contained in:
William Casarin
322
damus/Util/Zap.swift
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322
damus/Util/Zap.swift
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//
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// Zap.swift
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// damus
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//
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// Created by William Casarin on 2023-01-15.
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//
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import Foundation
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enum ZapSource {
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case author(String)
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// TODO: anonymous
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//case anonymous
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}
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public struct NoteZapTarget: Equatable {
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public let note_id: String
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public let author: String
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}
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public enum ZapTarget: Equatable {
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case profile(String)
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case note(NoteZapTarget)
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public static func note(id: String, author: String) -> ZapTarget {
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return .note(NoteZapTarget(note_id: id, author: author))
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}
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var pubkey: String {
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switch self {
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case .profile(let pk):
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return pk
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case .note(let note_target):
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return note_target.author
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}
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}
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var id: String {
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switch self {
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case .note(let note_target):
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return note_target.note_id
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case .profile(let pk):
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return pk
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}
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}
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}
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struct ZapRequest {
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let ev: NostrEvent
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}
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struct Zap {
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public let event: NostrEvent
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public let invoice: ZapInvoice
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public let zapper: String /// zap authorizer
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public let target: ZapTarget
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public let request: ZapRequest
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public static func from_zap_event(zap_ev: NostrEvent, zapper: String) -> Zap? {
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/// Make sure that we only create a zap event if it is authorized by the profile or event
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guard zapper == zap_ev.pubkey else {
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return nil
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}
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guard let bolt11_str = event_tag(zap_ev, name: "bolt11") else {
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return nil
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}
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guard let bolt11 = decode_bolt11(bolt11_str) else {
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return nil
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}
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/// Any amount invoices are not allowed
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guard let zap_invoice = invoice_to_zap_invoice(bolt11) else {
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return nil
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}
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// Some endpoints don't have this, let's skip the check for now. We're mostly trusting the zapper anyways
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/*
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guard let preimage = event_tag(zap_ev, name: "preimage") else {
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return nil
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}
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guard preimage_matches_invoice(preimage, inv: zap_invoice) else {
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return nil
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}
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*/
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guard let desc = get_zap_description(zap_ev, inv_desc: zap_invoice.description) else {
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return nil
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}
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guard let zap_req = decode_nostr_event_json(desc) else {
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return nil
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}
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guard let target = determine_zap_target(zap_req) else {
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return nil
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}
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return Zap(event: zap_ev, invoice: zap_invoice, zapper: zapper, target: target, request: ZapRequest(ev: zap_req))
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}
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}
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/// Fetches the description from either the invoice, or tags, depending on the type of invoice
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func get_zap_description(_ ev: NostrEvent, inv_desc: InvoiceDescription) -> String? {
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switch inv_desc {
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case .description(let string):
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return string
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case .description_hash(let deschash):
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guard let desc = event_tag(ev, name: "description") else {
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return nil
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}
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guard let data = desc.data(using: .utf8) else {
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return nil
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}
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guard sha256(data) == deschash else {
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return nil
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}
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return desc
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}
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}
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func invoice_to_zap_invoice(_ invoice: Invoice) -> ZapInvoice? {
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guard case .specific(let amt) = invoice.amount else {
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return nil
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}
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return ZapInvoice(description: invoice.description, amount: amt, string: invoice.string, expiry: invoice.expiry, payment_hash: invoice.payment_hash, created_at: invoice.created_at)
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}
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func preimage_matches_invoice<T>(_ preimage: String, inv: LightningInvoice<T>) -> Bool {
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guard let raw_preimage = hex_decode(preimage) else {
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return false
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}
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let hashed = sha256(Data(raw_preimage))
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return inv.payment_hash == hashed
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}
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func determine_zap_target(_ ev: NostrEvent) -> ZapTarget? {
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guard let ptag = event_tag(ev, name: "p") else {
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return nil
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}
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if let etag = event_tag(ev, name: "e") {
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return ZapTarget.note(id: etag, author: ptag)
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}
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return .profile(ptag)
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}
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func decode_bolt11(_ s: String) -> Invoice? {
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var bs = blocks()
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bs.num_blocks = 0
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blocks_init(&bs)
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let bytes = s.utf8CString
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let _ = bytes.withUnsafeBufferPointer { p in
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damus_parse_content(&bs, p.baseAddress)
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}
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guard bs.num_blocks == 1 else {
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blocks_free(&bs)
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return nil
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}
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let block = bs.blocks[0]
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guard let converted = convert_block(block, tags: []) else {
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blocks_free(&bs)
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return nil
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}
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guard case .invoice(let invoice) = converted else {
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blocks_free(&bs)
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return nil
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}
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blocks_free(&bs)
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return invoice
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}
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func event_tag(_ ev: NostrEvent, name: String) -> String? {
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for tag in ev.tags {
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if tag.count >= 2 && tag[0] == name {
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return tag[1]
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}
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}
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return nil
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}
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func decode_nostr_event_json(_ desc: String) -> NostrEvent? {
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let decoder = JSONDecoder()
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guard let dat = desc.data(using: .utf8) else {
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return nil
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}
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guard let ev = try? decoder.decode(NostrEvent.self, from: dat) else {
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return nil
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}
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return ev
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}
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func decode_zap_request(_ desc: String) -> ZapRequest? {
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let decoder = JSONDecoder()
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guard let jsonData = desc.data(using: .utf8) else {
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return nil
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}
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guard let jsonArray = try? JSONSerialization.jsonObject(with: jsonData) as? [[Any]] else {
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return nil
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}
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for array in jsonArray {
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guard array.count == 2 else {
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continue
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}
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let mkey = array.first.flatMap { $0 as? String }
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if let key = mkey, key == "application/nostr" {
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guard let dat = try? JSONSerialization.data(withJSONObject: array[1], options: []) else {
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return nil
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}
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guard let zap_req = try? decoder.decode(NostrEvent.self, from: dat) else {
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return nil
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}
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guard zap_req.kind == 9734 else {
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return nil
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}
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/// Ensure the signature on the zap request is correct
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guard case .ok = validate_event(ev: zap_req) else {
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return nil
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}
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return ZapRequest(ev: zap_req)
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}
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}
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return nil
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}
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func fetch_zapper_from_lnurl(_ lnurl: String) async -> String? {
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guard let endpoint = await fetch_static_payreq(lnurl) else {
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return nil
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}
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guard let allows = endpoint.allowsNostr, allows else {
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return nil
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}
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guard let key = endpoint.nostrPubkey, key.count == 64 else {
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return nil
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}
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return endpoint.nostrPubkey
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}
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func decode_lnurl(_ lnurl: String) -> URL? {
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guard let decoded = try? bech32_decode(lnurl) else {
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return nil
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}
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guard decoded.hrp == "lnurl" else {
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return nil
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}
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guard let url = URL(string: String(decoding: decoded.data, as: UTF8.self)) else {
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return nil
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}
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return url
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}
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func fetch_static_payreq(_ lnurl: String) async -> LNUrlPayRequest? {
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guard let url = decode_lnurl(lnurl) else {
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return nil
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}
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guard let ret = try? await URLSession.shared.data(from: url) else {
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return nil
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}
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let json_str = String(decoding: ret.0, as: UTF8.self)
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guard let endpoint: LNUrlPayRequest = decode_json(json_str) else {
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return nil
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}
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return endpoint
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}
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func fetch_zap_invoice(_ payreq: LNUrlPayRequest, zapreq: NostrEvent, amount: Int64) async -> String? {
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guard var base_url = payreq.callback.flatMap({ URLComponents(string: $0) }) else {
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return nil
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}
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let zappable = payreq.allowsNostr ?? false
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var query = [URLQueryItem(name: "amount", value: "\(amount)")]
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if zappable {
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if let json = encode_json(zapreq) {
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query.append(URLQueryItem(name: "nostr", value: json))
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}
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}
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base_url.queryItems = query
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guard let url = base_url.url else {
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return nil
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}
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print("url \(url)")
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guard let ret = try? await URLSession.shared.data(from: url) else {
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return nil
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}
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let json_str = String(decoding: ret.0, as: UTF8.self)
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guard let result: LNUrlPayResponse = decode_json(json_str) else {
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print("fetch_zap_invoice error: \(json_str)")
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return nil
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}
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return result.pr
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}
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