//! PQxdh handshake implementation
//!
//! Implements X25519Kyber768 hybrid key exchange for post-quantum security.

const std = @import("std");
const Session = @import("session.zig").Session;
const SessionConfig = @import("config.zig").SessionConfig;

/// Handshake state machine
pub const Handshake = struct {
    /// Initiate handshake as client
    pub fn initiate(
        peer_did: []const u8,
        config: SessionConfig,
        ctx: anytype,
    ) !Session {
        // TODO: Implement PQxdh initiation
        _ = peer_did;
        _ = config;
        _ = ctx;
        
        var session = Session.new(peer_did, config);
        session.state = .handshake_initiated;
        return session;
    }
    
    /// Resume existing session
    pub fn resume(
        peer_did: []const u8,
        stored: StoredSession,
        ctx: anytype,
    ) !Session {
        // TODO: Implement fast resumption
        _ = peer_did;
        _ = stored;
        _ = ctx;
        
        return Session.new(peer_did, .{});
    }
    
    /// Respond to handshake as server
    pub fn respond(
        request: HandshakeRequest,
        config: SessionConfig,
        ctx: anytype,
    ) !Session {
        // TODO: Implement PQxdh response
        _ = request;
        _ = config;
        _ = ctx;
        
        return Session.new("", config);
    }
};

/// Incoming handshake request
pub const HandshakeRequest = struct {
    peer_did: []const u8,
    ephemeral_pubkey: []const u8,
    prekey_id: u64,
    signature: [64]u8,
};

/// Stored session for resumption
const StoredSession = @import("session.zig").StoredSession;