nostr: add nip17::extract_relay_list and `nip17::extract_owned_rela…

…y_list`

Signed-off-by: Yuki Kishimoto <yukikishimoto@protonmail.com>

CHANGELOG.md

@@ -85,6 +85,7 @@
 * nostr: add `NostrSigner::backend` ([Yuki Kishimoto])
 * nostr: add `EventBuilder::private_msg` ([Yuki Kishimoto])
 * nostr: add `EventBuilder::tag` and `EventBuilder::tags` ([Yuki Kishimoto])
+* nostr: add `nip17::extract_relay_list` and `nip17::extract_owned_relay_list` ([Yuki Kishimoto])
 * database: add `NostrEventsDatabase` trait ([Yuki Kishimoto])
 * pool: add relay reconnection and disconnection unit tests ([Yuki Kishimoto])
 * sdk: allow to specify relay pool notification channel size in `Options` ([Yuki Kishimoto])

crates/nostr/src/nips/mod.rs

@@ -20,6 +20,7 @@ pub mod nip10;
 pub mod nip11;
 pub mod nip13;
 pub mod nip15;
+pub mod nip17;
 pub mod nip19;
 pub mod nip21;
 pub mod nip26;

crates/nostr/src/nips/nip17.rs

@@ -0,0 +1,43 @@
+// Copyright (c) 2022-2023 Yuki Kishimoto
+// Copyright (c) 2023-2024 Rust Nostr Developers
+// Distributed under the MIT software license
+
+//! NIP17: Private Direct Message
+//!
+//! <https://github.com/nostr-protocol/nips/blob/master/17.md>
+
+use alloc::boxed::Box;
+use core::iter;
+
+use crate::types::Url;
+use crate::{Event, Kind, TagStandard};
+
+/// Extracts the relay list
+pub fn extract_relay_list<'a>(event: &'a Event) -> Box<dyn Iterator<Item = &'a Url> + 'a> {
+    if event.kind != Kind::InboxRelays {
+        return Box::new(iter::empty());
+    }
+
+    Box::new(event.tags.iter().filter_map(|tag| {
+        if let Some(TagStandard::Relay(url)) = tag.as_standardized() {
+            Some(url)
+        } else {
+            None
+        }
+    }))
+}
+
+/// Extracts the relay list
+pub fn extract_owned_relay_list(event: Event) -> Box<dyn Iterator<Item = Url>> {
+    if event.kind != Kind::InboxRelays {
+        return Box::new(iter::empty());
+    }
+
+    Box::new(event.tags.into_iter().filter_map(|tag| {
+        if let Some(TagStandard::Relay(url)) = tag.to_standardized() {
+            Some(url)
+        } else {
+            None
+        }
+    }))
+}

crates/nostr/src/prelude.rs

@@ -4,6 +4,7 @@
 
 //! Prelude
 
+#![allow(unused_imports)]
 #![allow(unknown_lints)]
 #![allow(ambiguous_glob_reexports)]
 #![doc(hidden)]
@@ -40,6 +41,7 @@ pub use crate::nips::nip10::{self, *};
 pub use crate::nips::nip11::{self, *};
 pub use crate::nips::nip13::{self, *};
 pub use crate::nips::nip15::{self, *};
+pub use crate::nips::nip17::{self, *};
 pub use crate::nips::nip19::{self, *};
 pub use crate::nips::nip21::{self, *};
 pub use crate::nips::nip26::{self, *};