nostr 0.44.3

Rust implementation of the Nostr protocol.
Documentation 
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// Copyright (c) 2022-2023 Yuki Kishimoto
// Copyright (c) 2023-2025 Rust Nostr Developers
// Distributed under the MIT software license

//! NIP65: Relay List Metadata
//!
//! <https://github.com/nostr-protocol/nips/blob/master/65.md>

use core::fmt;
use core::str::FromStr;

use crate::{Event, RelayUrl, TagStandard};

/// NIP56 error
#[derive(Debug, PartialEq, Eq)]
pub enum Error {
    /// Invalid Relay Metadata
    InvalidRelayMetadata,
}

#[cfg(feature = "std")]
impl std::error::Error for Error {}

impl fmt::Display for Error {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::InvalidRelayMetadata => f.write_str("Invalid relay metadata"),
        }
    }
}

/// Relay Metadata
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum RelayMetadata {
    /// Read
    Read,
    /// Write
    Write,
}

impl RelayMetadata {
    /// Get as `&str`.
    pub fn as_str(&self) -> &str {
        match self {
            Self::Read => "read",
            Self::Write => "write",
        }
    }
}

impl fmt::Display for RelayMetadata {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        f.write_str(self.as_str())
    }
}

impl FromStr for RelayMetadata {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        match s {
            "read" => Ok(Self::Read),
            "write" => Ok(Self::Write),
            _ => Err(Error::InvalidRelayMetadata),
        }
    }
}

/// Extracts the relay info (url, optional read/write flag) from the event
#[inline]
pub fn extract_relay_list(
    event: &Event,
) -> impl Iterator<Item = (&RelayUrl, &Option<RelayMetadata>)> {
    event.tags.iter().filter_map(|tag| {
        if let Some(TagStandard::RelayMetadata {
            relay_url,
            metadata,
        }) = tag.as_standardized()
        {
            Some((relay_url, metadata))
        } else {
            None
        }
    })
}

/// Extracts the relay info (url, optional read/write flag) from the event
#[inline]
pub fn extract_owned_relay_list(
    event: Event,
) -> impl Iterator<Item = (RelayUrl, Option<RelayMetadata>)> {
    event.tags.into_iter().filter_map(|tag| {
        if let Some(TagStandard::RelayMetadata {
            relay_url,
            metadata,
        }) = tag.to_standardized()
        {
            Some((relay_url, metadata))
        } else {
            None
        }
    })
}