r402-protocol 0.20.0

Wire types, CAIP-2, scheme markers, and money for the x402 payment protocol.
Documentation 
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//! Facilitator `/supported` response.

use std::collections::HashMap;

use compact_str::CompactString;
use serde::{Deserialize, Serialize};
use serde_with::{VecSkipError, serde_as};

use crate::network::ChainId;

/// A single payment kind advertised by a facilitator.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase", deny_unknown_fields)]
#[non_exhaustive]
pub struct SupportedPaymentKind {
    /// x402 protocol version (`2`).
    pub x402_version: u8,
    /// Scheme name (`"exact"`, `"upto"`, …).
    pub scheme: CompactString,
    /// CAIP-2 network identifier.
    pub network: CompactString,
    /// Optional scheme-specific extras (fee payer, memo, …).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub extra: Option<serde_json::Value>,
}

impl SupportedPaymentKind {
    /// Constructs a kind from the three required fields.
    #[must_use]
    pub fn new(
        x402_version: u8,
        scheme: impl Into<CompactString>,
        network: impl Into<CompactString>,
    ) -> Self {
        Self {
            x402_version,
            scheme: scheme.into(),
            network: network.into(),
            extra: None,
        }
    }

    /// Attaches an `extra` JSON blob.
    #[must_use]
    pub fn with_extra(mut self, extra: serde_json::Value) -> Self {
        self.extra = Some(extra);
        self
    }

    /// Attaches an optional `extra` blob.
    #[must_use]
    pub fn with_optional_extra(mut self, extra: Option<serde_json::Value>) -> Self {
        self.extra = extra;
        self
    }
}

/// Response body of a facilitator's `/supported` endpoint.
///
/// `extensions` is a JSON array of extension identifiers.
#[serde_as]
#[derive(Clone, Default, Debug, PartialEq, Eq, Serialize, Deserialize)]
#[serde(rename_all = "camelCase", deny_unknown_fields)]
#[non_exhaustive]
pub struct SupportedResponse {
    /// Supported payment kinds. Invalid entries are silently skipped.
    #[serde_as(as = "VecSkipError<_>")]
    pub kinds: Vec<SupportedPaymentKind>,
    /// Supported extension identifiers.
    #[serde(default)]
    pub extensions: Vec<CompactString>,
    /// Signer addresses indexed by CAIP-2 pattern (`"eip155:8453"`, `"solana:*"`).
    #[serde(default)]
    pub signers: HashMap<CompactString, Vec<CompactString>>,
}

impl SupportedResponse {
    /// Empty response.
    #[must_use]
    pub fn new() -> Self {
        Self::default()
    }

    /// Replaces the `kinds` list.
    #[must_use]
    pub fn with_kinds(mut self, kinds: Vec<SupportedPaymentKind>) -> Self {
        self.kinds = kinds;
        self
    }

    /// Replaces the `extensions` identifier list.
    #[must_use]
    pub fn with_extensions(mut self, extensions: Vec<CompactString>) -> Self {
        self.extensions = extensions;
        self
    }

    /// Replaces the per-pattern signer map.
    #[must_use]
    #[allow(
        clippy::implicit_hasher,
        reason = "wire map is a JSON object with no hasher contract"
    )]
    pub fn with_signers(mut self, signers: HashMap<CompactString, Vec<CompactString>>) -> Self {
        self.signers = signers;
        self
    }

    /// Signer addresses matching the given chain (exact and `namespace:*`).
    #[must_use]
    pub fn signers_for_chain(&self, chain_id: &ChainId) -> Vec<&str> {
        let exact = CompactString::from(chain_id.to_string());
        let wildcard = CompactString::from(format!("{}:*", chain_id.namespace()));
        let mut out = Vec::new();
        if let Some(list) = self.signers.get(&exact) {
            out.extend(list.iter().map(CompactString::as_str));
        }
        if let Some(list) = self.signers.get(&wildcard) {
            out.extend(list.iter().map(CompactString::as_str));
        }
        out
    }
}