openvtc-core 0.3.1

//! Verified Relationship Credentials (VRC).
//!
//! VRCs are credentials issued between parties in an established relationship.
//! This module provides storage (`Vrcs`), request/reject message builders
//! (`VrcRequest`, `VRCRequestReject`), and a trait for wrapping credentials
//! into DIDComm messages (`DtgCredentialMessage`).

use crate::{MessageType, errors::OpenVTCError};
use affinidi_tdk::didcomm::Message;
use dtg_credentials::DTGCredential;
use serde::{Deserialize, Serialize};
use std::{
    collections::{
        HashMap,
        hash_map::{Keys, Values},
    },
    sync::Arc,
    time::SystemTime,
};
use tracing::{debug, warn};
use uuid::Uuid;

/// Collection of VRCs, keyed by the remote party's persona DID and then by VRC ID.
///
/// Typically two instances are maintained: one for issued VRCs and one for received VRCs.
///
/// # Stored VRCs are held to the current specification on load
///
/// A VRC stored by an earlier build carries the retired pre-v1 DTG context and no
/// `issuerScope`, and `dtg-credentials` refuses it. Deserializing the map
/// strictly would make one such credential fail the whole protected config — a
/// crash at unlock. Instead each stored VRC is parsed on its own: a
/// non-conformant one is **dropped with a logged reason** and counted in
/// [`Vrcs::retired`], which the relationships view shows so the member knows to
/// ask the peer for a fresh one. Nothing non-conformant is kept, and nothing is
/// dropped silently.
#[derive(Serialize, Debug, Clone, Default)]
pub struct Vrcs {
    /// Hashmap of VRCs
    /// key = the remote party's persona DID
    /// secondary key is the VRC-ID
    vrcs: HashMap<Arc<String>, HashMap<Arc<String>, Arc<DTGCredential>>>,
    /// How many stored VRCs were set aside on load as non-conformant (pre-v1).
    /// Persisted, so the notice survives the save that drops them.
    #[serde(default, skip_serializing_if = "is_zero")]
    retired: usize,
}

fn is_zero(n: &usize) -> bool {
    *n == 0
}

impl<'de> Deserialize<'de> for Vrcs {
    fn deserialize<D: serde::Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> {
        #[derive(Deserialize)]
        struct Raw {
            #[serde(default)]
            vrcs: HashMap<Arc<String>, HashMap<Arc<String>, serde_json::Value>>,
            #[serde(default)]
            retired: usize,
        }
        let raw = Raw::deserialize(deserializer)?;
        let mut vrcs: HashMap<Arc<String>, HashMap<Arc<String>, Arc<DTGCredential>>> =
            HashMap::new();
        let mut retired = raw.retired;
        for (remote, by_id) in raw.vrcs {
            for (vrc_id, value) in by_id {
                match serde_json::from_value::<DTGCredential>(value) {
                    Ok(vrc) => {
                        vrcs.entry(remote.clone())
                            .or_default()
                            .insert(vrc_id, Arc::new(vrc));
                    }
                    Err(e) => {
                        retired += 1;
                        warn!(
                            remote = %remote,
                            reason = %e,
                            "dropping a stored VRC that does not conform to DTG Credentials v1 — ask the peer to issue a fresh one"
                        );
                    }
                }
            }
        }
        Ok(Vrcs { vrcs, retired })
    }
}

impl Vrcs {
    /// How many stored VRCs were set aside on load because they pre-date DTG
    /// Credentials v1. See the type's docs.
    #[must_use]
    pub fn retired(&self) -> usize {
        self.retired
    }

    /// Forget the retired count, once the member has been told.
    pub fn clear_retired(&mut self) {
        self.retired = 0;
    }

    /// Returns an iterator over all per-relationship VRC maps.
    pub fn values(&self) -> Values<'_, Arc<String>, HashMap<Arc<String>, Arc<DTGCredential>>> {
        self.vrcs.values()
    }

    /// Returns an iterator over all remote P-DID keys that have associated VRCs.
    pub fn keys(&self) -> Keys<'_, Arc<String>, HashMap<Arc<String>, Arc<DTGCredential>>> {
        self.vrcs.keys()
    }

    /// Returns all VRCs for the given remote P-DID, or `None` if no VRCs exist.
    pub fn get(&self, id: &Arc<String>) -> Option<&HashMap<Arc<String>, Arc<DTGCredential>>> {
        self.vrcs.get(id)
    }

    /// Insert a new VRC for the given remote P-DID.
    ///
    /// # Errors
    ///
    /// Returns `OpenVTCError::InvalidMessage` if the VRC has no proof value.
    pub fn insert(
        &mut self,
        remote_p_did: &Arc<String>,
        vrc: Arc<DTGCredential>,
    ) -> Result<(), OpenVTCError> {
        let hash = Arc::new(
            vrc.proof_value()
                .ok_or_else(|| OpenVTCError::InvalidMessage("VRC has no proof value".to_string()))?
                .to_string(),
        );

        self.vrcs
            .entry(remote_p_did.clone())
            .and_modify(|hm| {
                hm.insert(hash.clone(), vrc.clone());
            })
            .or_insert({
                let mut hm = HashMap::new();
                hm.insert(hash, vrc);
                hm
            });

        Ok(())
    }

    /// Removes a VRC by its ID from all relationships.
    pub fn remove_vrc(&mut self, vrc_id: &Arc<String>) {
        debug!("removing VRC {}", vrc_id);
        for r in self.vrcs.values_mut() {
            r.retain(|vrc_id_key, _| vrc_id_key != vrc_id);
        }
    }

    /// Removes all VRCs for the given remote P-DID.
    ///
    /// Returns `true` if any VRCs were removed.
    pub fn remove_relationship(&mut self, remote_p_did: &Arc<String>) -> bool {
        let removed = self.vrcs.remove(remote_p_did).is_some();
        if removed {
            debug!("removing VRCs for relationship {}", remote_p_did);
        }
        removed
    }
}

/// Extension trait for wrapping a `DTGCredential` into a DIDComm message.
pub trait DtgCredentialMessage {
    /// Builds a DIDComm message containing this credential as the body.
    ///
    /// The message type is set to `VRCIssued`. An optional `thid` (thread ID)
    /// links the message to a prior VRC request conversation.
    ///
    /// # Errors
    ///
    /// Returns an error if the system clock is unavailable or the credential
    /// cannot be serialized to JSON.
    fn message(&self, from: &str, to: &str, thid: Option<&str>) -> Result<Message, OpenVTCError>;
}

impl DtgCredentialMessage for DTGCredential {
    fn message(&self, from: &str, to: &str, thid: Option<&str>) -> Result<Message, OpenVTCError> {
        let now = SystemTime::now()
            .duration_since(SystemTime::UNIX_EPOCH)
            .map_err(|e| OpenVTCError::Config(format!("System clock error: {e}")))?
            .as_secs();
        let mut builder = Message::build(
            Uuid::new_v4().to_string(),
            String::from(MessageType::VRCIssued),
            serde_json::to_value(self)?,
        )
        .from(from.to_string())
        .to(to.to_string())
        .created_time(now)
        .expires_time(now + 60 * 60 * 48); // 48 hours

        if let Some(thid_value) = thid {
            builder = builder.thid(thid_value.to_string());
        }

        Ok(builder.finalize())
    }
}

// ****************************************************************************
// VRC Request Structure
// ****************************************************************************

/// A request asking a remote party to issue a VRC.
///
/// Contains optional hints to help the issuer create the VRC, but does not
/// guarantee the issuer will honor the requested details.
#[derive(Default, Serialize, Deserialize, Debug, Clone)]
#[serde(rename_all = "camelCase")]
pub struct VrcRequest {
    /// Optional reason for the VRC request.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reason: Option<String>,
}

impl VrcRequest {
    /// Creates a DIDComm message for this VRC request.
    ///
    /// # Errors
    ///
    /// Returns an error if the system clock is unavailable or the request
    /// cannot be serialized to JSON.
    pub fn create_message(
        &self,
        to: &Arc<String>,
        from: &Arc<String>,
    ) -> Result<Message, OpenVTCError> {
        let now = SystemTime::now()
            .duration_since(SystemTime::UNIX_EPOCH)
            .map_err(|e| OpenVTCError::Config(format!("System clock error: {e}")))?
            .as_secs();
        Ok(Message::build(
            Uuid::new_v4().to_string(),
            crate::protocol_urls::VRC_REQUEST.to_string(),
            serde_json::to_value(self)?,
        )
        .from(from.to_string())
        .to(to.to_string())
        .created_time(now)
        .expires_time(now + 60 * 60 * 48) // 48 hours
        .finalize())
    }
}

// ****************************************************************************
// VRC Request Reject Structure
// ****************************************************************************

/// DIDComm message body for rejecting a VRC request.
#[derive(Default, Serialize, Deserialize, Debug, Clone)]
#[serde(rename_all = "camelCase")]
pub struct VRCRequestReject {
    /// Optional reason for the rejection.
    #[serde(skip_serializing_if = "Option::is_none")]
    pub reason: Option<String>,
}

impl VRCRequestReject {
    /// Creates a DIDComm rejection message for a VRC request.
    ///
    /// # Errors
    ///
    /// Returns an error if the system clock is unavailable or the body
    /// cannot be serialized to JSON.
    pub fn create_message(
        to: &Arc<String>,
        from: &Arc<String>,
        thid: &Arc<String>,
        reason: Option<String>,
    ) -> Result<Message, OpenVTCError> {
        let now = SystemTime::now()
            .duration_since(SystemTime::UNIX_EPOCH)
            .map_err(|e| OpenVTCError::Config(format!("System clock error: {e}")))?
            .as_secs();
        Ok(Message::build(
            Uuid::new_v4().to_string(),
            crate::protocol_urls::VRC_REJECTED.to_string(),
            serde_json::to_value(VRCRequestReject { reason })?,
        )
        .from(from.to_string())
        .to(to.to_string())
        .thid(thid.to_string())
        .created_time(now)
        .expires_time(now + 60 * 60 * 48) // 48 hours
        .finalize())
    }
}

/// Build an unsigned VRC that carries its own identifier.
///
/// `DTGCredential::new_vrc` leaves `id` unset, and a credential with no
/// identifier cannot be stored under one — so a peer that keys relationship
/// credentials by `id` cannot make a re-issue idempotent, tell a renewal from a
/// duplicate, or reference this VRC from a `witnessed/1` statement (`object.digestMultibase`).
///
/// Nothing rejects a VRC for a missing `id` *today*. That is exactly what the
/// reciprocal membership credential looked like, right up until a community
/// started keying on it and every delivery began failing silently — so this is
/// a gap being closed before it bites rather than after.
///
/// The id is set here, before signing, because it has to be: a Data Integrity
/// proof covers every member but `proof`, so one spliced in afterwards leaves a
/// document whose proof no longer verifies. Building and identifying in one
/// call is what stops the two being separated later.
///
/// `issuer_scope` is the scope declared for `issuer` — pass
/// [`crate::dtg::relationship_issuer_scope`] for the identifier the relationship
/// uses: `pairwise` for a relationship DID, `directed` for a persona DID.
pub fn new_identified_vrc(
    issuer: &str,
    issuer_scope: dtg_credentials::IssuerScope,
    subject: &str,
    valid_from: chrono::DateTime<chrono::Utc>,
    valid_until: Option<chrono::DateTime<chrono::Utc>>,
) -> DTGCredential {
    DTGCredential::new_vrc(
        issuer.to_string(),
        issuer_scope,
        subject.to_string(),
        valid_from,
        valid_until,
    )
    .with_id(format!("urn:uuid:{}", uuid::Uuid::new_v4()))
}

#[cfg(test)]
mod tests {
    use super::*;

    /// A VRC must carry a top-level `id`, distinct from
    /// `credentialSubject.id` (which names the *subject*).
    #[test]
    fn an_issued_vrc_carries_its_own_identifier() {
        let vrc = new_identified_vrc(
            "did:key:zIssuerR",
            dtg_credentials::IssuerScope::Pairwise,
            "did:key:zSubjectR",
            chrono::Utc::now(),
            None,
        );
        let value = serde_json::to_value(&vrc).expect("serialise");
        assert_eq!(value["issuerScope"], "pairwise");
        assert_eq!(value["@context"][1], dtg_credentials::DTG_CONTEXT_V1);

        let id = value["id"].as_str().expect("a top-level id");
        assert!(id.starts_with("urn:uuid:"), "got {id}");
        assert_eq!(value["credentialSubject"]["id"], "did:key:zSubjectR");
        assert_eq!(value["issuer"], "did:key:zIssuerR");
    }

    /// Two issuances must not collide, or a peer keying by `id` would read
    /// every re-issue as a repeat of the first.
    #[test]
    fn each_issued_vrc_gets_a_fresh_identifier() {
        let now = chrono::Utc::now();
        let scope = dtg_credentials::IssuerScope::Pairwise;
        let a = new_identified_vrc("did:key:zI", scope, "did:key:zS", now, None);
        let b = new_identified_vrc("did:key:zI", scope, "did:key:zS", now, None);
        assert_ne!(a.id(), b.id());
        assert!(a.id().is_some());
    }

    /// A VRC stored before DTG Credentials v1 must not stop the config loading:
    /// it is dropped, counted, and the conformant ones beside it survive.
    #[test]
    fn a_pre_v1_stored_vrc_is_set_aside_on_load() {
        let current = serde_json::to_value(new_identified_vrc(
            "did:key:zI",
            dtg_credentials::IssuerScope::Pairwise,
            "did:key:zS",
            chrono::Utc::now(),
            None,
        ))
        .unwrap();
        let mut old = current.clone();
        old["@context"][1] = serde_json::json!(crate::dtg::fixtures::RETIRED_CONTEXT);
        old.as_object_mut().unwrap().remove("issuerScope");
        let stored = serde_json::json!({
            "vrcs": { "did:key:zRemote": { "zOld": old, "zNew": current } }
        });

        let vrcs: Vrcs = serde_json::from_value(stored).expect("loads despite the old VRC");
        assert_eq!(vrcs.retired(), 1);
        let remote = Arc::new("did:key:zRemote".to_string());
        let kept = vrcs.get(&remote).expect("the conformant VRC is kept");
        assert_eq!(kept.len(), 1);
        assert!(kept.contains_key(&Arc::new("zNew".to_string())));

        // The count survives a save, so the notice outlives the drop.
        let again: Vrcs = serde_json::from_value(serde_json::to_value(&vrcs).unwrap()).unwrap();
        assert_eq!(again.retired(), 1);
    }

    #[test]
    fn test_vrcs_default_empty() {
        let vrcs = Vrcs::default();
        assert_eq!(
            vrcs.keys().count(),
            0,
            "Default Vrcs should have no entries"
        );
        assert_eq!(vrcs.values().count(), 0);
    }

    #[test]
    fn test_vrcs_remove_relationship() {
        let mut vrcs = Vrcs::default();
        let key = Arc::new("did:remote:1".to_string());
        // remove on empty should return false
        assert!(!vrcs.remove_relationship(&key));
    }

    #[test]
    fn test_vrcs_get_missing_key() {
        let vrcs = Vrcs::default();
        let key = Arc::new("did:nonexistent".to_string());
        assert!(
            vrcs.get(&key).is_none(),
            "get on missing key should return None"
        );
    }

    #[test]
    fn test_vrc_request_default() {
        let req = VrcRequest::default();
        assert!(req.reason.is_none());
    }

    #[test]
    fn test_vrc_request_serde_roundtrip() {
        let req = VrcRequest {
            reason: Some("testing".to_string()),
        };
        let json = serde_json::to_string(&req).expect("serialize");
        let restored: VrcRequest = serde_json::from_str(&json).expect("deserialize");
        assert_eq!(restored.reason.as_deref(), Some("testing"));
    }

    #[test]
    fn test_vrc_request_reject_serde_roundtrip() {
        let reject = VRCRequestReject {
            reason: Some("not trusted".to_string()),
        };
        let json = serde_json::to_string(&reject).expect("serialize");
        let restored: VRCRequestReject = serde_json::from_str(&json).expect("deserialize");
        assert_eq!(restored.reason.as_deref(), Some("not trusted"));
    }
}