qcomm-core 0.1.0

//! Nostr Transport with NIP-17 and PQC Extensions
//!
//! Implements Nostr protocol for relay-based messaging with
//! encrypted DMs (NIP-17) and post-quantum cryptography extensions.

use super::{Transport, TransportCapability, TransportMessage, MessageMetadata};
use crate::{Error, Result};
use async_trait::async_trait;
use base64::{Engine as _, engine::general_purpose::STANDARD as BASE64};
use serde::{Deserialize, Serialize};
use sha2::{Sha256, Digest};
use std::collections::VecDeque;
use std::sync::Arc;
use tokio::sync::Mutex;

/// Nostr event kinds
pub mod kind {
    /// NIP-17 sealed DM (encrypted)
    pub const SEALED_DM: u16 = 1059;
    /// NIP-17 gift wrap
    pub const GIFT_WRAP: u16 = 1060;
    /// Our custom PQC extension
    pub const PQC_MESSAGE: u16 = 30078;
    /// PQC key announcement
    pub const PQC_KEY_ANNOUNCE: u16 = 30079;
}

/// Nostr event structure
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct NostrEvent {
    /// Event ID (32-byte hex)
    pub id: String,
    /// Public key of creator (32-byte hex)
    pub pubkey: String,
    /// Unix timestamp
    pub created_at: u64,
    /// Event kind
    pub kind: u16,
    /// Tags
    pub tags: Vec<Vec<String>>,
    /// Content (may be encrypted)
    pub content: String,
    /// Signature (64-byte hex)
    pub sig: String,
}

impl NostrEvent {
    /// Compute event ID
    pub fn compute_id(&self) -> String {
        let serialized = serde_json::json!([
            0,
            &self.pubkey,
            self.created_at,
            self.kind,
            &self.tags,
            &self.content
        ]);

        let hash = Sha256::digest(serialized.to_string().as_bytes());
        hex::encode(hash)
    }

    /// Create a gift-wrapped DM (NIP-17)
    pub fn gift_wrap(
        sender_pubkey: &str,
        recipient_pubkey: &str,
        content: &str,
        _timestamp: u64,
    ) -> Self {
        // In production, this would:
        // 1. Create a rumor (unsigned event)
        // 2. Seal it with NIP-44 encryption
        // 3. Gift wrap with ephemeral key

        let now = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_secs();

        Self {
            id: String::new(), // Will be computed
            pubkey: sender_pubkey.to_string(),
            created_at: now,
            kind: kind::GIFT_WRAP,
            tags: vec![vec!["p".to_string(), recipient_pubkey.to_string()]],
            content: content.to_string(), // Would be encrypted
            sig: String::new(), // Will be signed
        }
    }

    /// Create a PQC message event
    pub fn pqc_message(
        sender_pubkey: &str,
        recipient_pubkey: &str,
        encrypted_content: &[u8],
        kem_ciphertext: &[u8],
    ) -> Self {
        let now = std::time::SystemTime::now()
            .duration_since(std::time::UNIX_EPOCH)
            .unwrap()
            .as_secs();

        Self {
            id: String::new(),
            pubkey: sender_pubkey.to_string(),
            created_at: now,
            kind: kind::PQC_MESSAGE,
            tags: vec![
                vec!["p".to_string(), recipient_pubkey.to_string()],
                vec!["pqc".to_string(), "ml-kem-1024".to_string()],
                vec!["kem".to_string(), BASE64.encode(kem_ciphertext)],
            ],
            content: BASE64.encode(encrypted_content),
            sig: String::new(),
        }
    }
}

/// WebSocket message for relay communication
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(untagged)]
pub enum RelayMessage {
    /// Event message ["EVENT", <subscription_id>, <event>]
    Event(String, String, NostrEvent),
    /// Request message ["REQ", <subscription_id>, <filter>...]
    Request(String, String, serde_json::Value),
    /// Close subscription ["CLOSE", <subscription_id>]
    Close(String, String),
    /// OK response ["OK", <event_id>, <success>, <message>]
    Ok(String, String, bool, String),
    /// EOSE (end of stored events)
    Eose(String, String),
}

/// Nostr relay connection
pub struct RelayConnection {
    /// Relay URL
    pub url: String,
    /// Connection status
    pub connected: bool,
    /// Subscription IDs
    pub subscriptions: Vec<String>,
}

/// Nostr transport
pub struct NostrTransport {
    /// Relay connections
    relays: Vec<RelayConnection>,
    /// Our public key (hex)
    pubkey: String,
    /// Incoming message queue
    incoming: Arc<Mutex<VecDeque<TransportMessage>>>,
    /// Event cache (for deduplication)
    seen_events: Arc<Mutex<std::collections::HashSet<String>>>,
}

impl NostrTransport {
    /// Create a new Nostr transport
    pub fn new(pubkey: String, relay_urls: Vec<String>) -> Self {
        let relays = relay_urls
            .into_iter()
            .map(|url| RelayConnection {
                url,
                connected: false,
                subscriptions: Vec::new(),
            })
            .collect();

        Self {
            relays,
            pubkey,
            incoming: Arc::new(Mutex::new(VecDeque::new())),
            seen_events: Arc::new(Mutex::new(std::collections::HashSet::new())),
        }
    }

    /// Add a relay
    pub fn add_relay(&mut self, url: String) {
        self.relays.push(RelayConnection {
            url,
            connected: false,
            subscriptions: Vec::new(),
        });
    }

    /// Get connected relays
    pub fn connected_relays(&self) -> Vec<&str> {
        self.relays
            .iter()
            .filter(|r| r.connected)
            .map(|r| r.url.as_str())
            .collect()
    }

    /// Subscribe to events for our pubkey
    async fn subscribe(&mut self, relay_idx: usize) -> Result<String> {
        let sub_id = format!("qcomm_{}", rand::random::<u64>());

        let filter = serde_json::json!({
            "#p": [&self.pubkey],
            "kinds": [kind::GIFT_WRAP, kind::PQC_MESSAGE],
            "since": std::time::SystemTime::now()
                .duration_since(std::time::UNIX_EPOCH)
                .unwrap()
                .as_secs() - 86400, // Last 24 hours
        });

        // In production, would send via WebSocket:
        // ["REQ", sub_id, filter]

        if let Some(relay) = self.relays.get_mut(relay_idx) {
            relay.subscriptions.push(sub_id.clone());
        }

        Ok(sub_id)
    }

    /// Publish an event to relays
    async fn publish(&self, event: NostrEvent) -> Result<()> {
        // In production, would send to all connected relays via WebSocket
        let _message = serde_json::json!(["EVENT", event]);

        for relay in &self.relays {
            if relay.connected {
                tracing::debug!("Publishing to relay: {}", relay.url);
                // ws.send(message).await?
            }
        }

        Ok(())
    }

    /// Process incoming event
    async fn process_event(&self, event: NostrEvent) -> Result<Option<TransportMessage>> {
        // Check if we've seen this event
        let mut seen = self.seen_events.lock().await;
        if seen.contains(&event.id) {
            return Ok(None);
        }
        seen.insert(event.id.clone());
        drop(seen);

        // Determine event type
        match event.kind {
            kind::GIFT_WRAP | kind::SEALED_DM => {
                // Decrypt NIP-17 message
                // In production, would:
                // 1. Unwrap gift
                // 2. Unseal with our key
                // 3. Extract plaintext

                Ok(Some(TransportMessage {
                    id: event.id.clone(),
                    from: event.pubkey.clone(),
                    to: self.pubkey.clone(),
                    payload: event.content.as_bytes().to_vec(),
                    timestamp: event.created_at * 1000,
                    metadata: MessageMetadata::Nostr {
                        event_id: event.id,
                        relay: String::new(), // Would be actual relay
                    },
                }))
            }
            kind::PQC_MESSAGE => {
                // PQC encrypted message
                // Extract KEM ciphertext and decrypt

                let payload = BASE64.decode(&event.content)
                    .map_err(|e| Error::InvalidMessage(e.to_string()))?;

                Ok(Some(TransportMessage {
                    id: event.id.clone(),
                    from: event.pubkey.clone(),
                    to: self.pubkey.clone(),
                    payload,
                    timestamp: event.created_at * 1000,
                    metadata: MessageMetadata::Nostr {
                        event_id: event.id,
                        relay: String::new(),
                    },
                }))
            }
            _ => Ok(None),
        }
    }
}

#[async_trait]
impl Transport for NostrTransport {
    fn name(&self) -> &str {
        "Nostr"
    }

    fn capabilities(&self) -> Vec<TransportCapability> {
        vec![
            TransportCapability::Send,
            TransportCapability::Receive,
            TransportCapability::OfflineDelivery,
            TransportCapability::GroupChannel,
            TransportCapability::PostQuantum,
        ]
    }

    async fn is_connected(&self) -> bool {
        self.relays.iter().any(|r| r.connected)
    }

    async fn connect(&mut self) -> Result<()> {
        // In production, would establish WebSocket connections to all relays
        // using tokio-tungstenite

        for relay in &mut self.relays {
            tracing::info!("Connecting to relay: {}", relay.url);

            // Simulate connection for now
            relay.connected = true;
        }

        // Subscribe to our messages on all relays
        for i in 0..self.relays.len() {
            if self.relays[i].connected {
                self.subscribe(i).await?;
            }
        }

        Ok(())
    }

    async fn disconnect(&mut self) -> Result<()> {
        for relay in &mut self.relays {
            relay.connected = false;
            relay.subscriptions.clear();
        }
        Ok(())
    }

    async fn send(&self, message: TransportMessage) -> Result<()> {
        // Create Nostr event from message
        let event = NostrEvent::pqc_message(
            &self.pubkey,
            &message.to,
            &message.payload,
            &[], // KEM ciphertext would go here
        );

        self.publish(event).await
    }

    async fn receive(&mut self) -> Result<TransportMessage> {
        loop {
            if let Some(msg) = self.incoming.lock().await.pop_front() {
                return Ok(msg);
            }

            // In production, would process incoming WebSocket messages
            tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;

            if !self.is_connected().await {
                return Err(Error::Nostr("Disconnected".into()));
            }
        }
    }

    async fn poll(&mut self) -> Result<Option<TransportMessage>> {
        Ok(self.incoming.lock().await.pop_front())
    }
}

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

    #[test]
    fn test_event_id_computation() {
        let event = NostrEvent {
            id: String::new(),
            pubkey: "a".repeat(64),
            created_at: 1234567890,
            kind: 1,
            tags: vec![],
            content: "Hello".to_string(),
            sig: String::new(),
        };

        let id = event.compute_id();
        assert_eq!(id.len(), 64); // 32 bytes as hex
    }

    #[tokio::test]
    async fn test_nostr_transport() {
        let transport = NostrTransport::new(
            "a".repeat(64),
            vec!["wss://relay.example.com".into()],
        );

        assert!(!transport.is_connected().await);
        assert_eq!(transport.name(), "Nostr");
    }
}