# Swarm peering: the peer-hive declarations and the optional
# WireGuard inter-hive mesh. The peers are serialised into hive-c0re's
# environment (HYPERHIVE_PEERS / HIVE_PEER_CA_PATHS — see ./hive-c0re)
# and consumed by identity.rs + the dashboard's P33RS tab; the mesh
# config below is host-level networking.
{
  lib,
  config,
  ...
}:
{
  # Peer hives in the same swarm. Each entry declares a remote hive
  # reachable from this host.
  options.services.hyperhive.swarm.peers = lib.mkOption {
    type = lib.types.attrsOf (
      lib.types.submodule {
        options = {
          certFingerprint = lib.mkOption {
            type = lib.types.nullOr lib.types.str;
            default = null;
            example = "sha256:b1946ac92492d2347c6235b4d2611184a3f5b6cae6c19d6e3c2f0a8e7d4c9f12";
            description = ''
              Expected TLS certificate fingerprint for this peer's HTTPS
              endpoint. Null = trust the system CA bundle (for Let's
              Encrypt peers). Set to pin a self-signed cert.

              Format: the literal `sha256:` followed by exactly 64
              hex digits (case-insensitive, no colon separators) — the
              SHA-256 digest of the peer's DER-encoded leaf certificate.
              Generate with `openssl x509 -noout -fingerprint -sha256`,
              then strip the colons and prepend `sha256:`. A malformed
              value is ignored with a warning rather than weakening
              trust. See docs/swarm.md for the full recipe.

              Scopes only to hive-c0re's own peer HTTPS checks — it does
              NOT help Matrix federation (tuwunel validates against its
              container trust bundle). For a self-signed peer whose root
              CA you want trusted hive-wide (every agent + Matrix
              federation), set `caCert` below.
            '';
          };

          caCert = lib.mkOption {
            type = lib.types.nullOr lib.types.path;
            default = null;
            example = "./peers/edge-ca.pem";
            description = ''
              Path to this peer hive's root CA certificate (PEM). When
              set, the CA is embedded (at build time, into the nix store
              — no runtime file on the host) and trusted **everywhere the
              hive's own internal CA is**: it rides alongside `hive-ca.pem`
              in each agent's `security.pki.certificateFiles` (via the
              meta-flake renderer), and is added to the Matrix homeserver
              container's trust bundle so tuwunel validates *federation*
              TLS from a self-signed peer hive whose cert chains to it.
              This is the CA-trust path that `certFingerprint`
              (leaf-pinning, c0re-only) can't cover, and is what unblocks
              Matrix federation with a self-signed peer hive. Trust stays
              inside the hive (agents + the Matrix container), never the
              host system trust store. Mutually complementary with
              `certFingerprint`; set `caCert` for the federation case. See
              docs/swarm.md.
            '';
          };

          wireguardPublicKey = lib.mkOption {
            type = lib.types.nullOr lib.types.str;
            default = null;
            example = "base64pubkey=";
            description = ''
              WireGuard public key for this peer host. Required when
              `services.hyperhive.swarm.wireguard.enable = true` and
              you want this peer reachable over the mesh. Null = TLS-
              only peering (public internet, no mesh tunnel).
            '';
          };

          wireguardEndpoint = lib.mkOption {
            type = lib.types.nullOr lib.types.str;
            default = null;
            example = "203.0.113.1:51820";
            description = ''
              WireGuard endpoint for this peer in `host:port` form.
              Required when the peer host is behind a firewall and
              this host needs to initiate the tunnel. Null = this host
              waits for the peer to connect (peer-initiates; peer must
              have an endpoint pointing back at this host).
            '';
          };

          wireguardAddress = lib.mkOption {
            type = lib.types.nullOr lib.types.str;
            default = null;
            example = "10.100.0.2/32";
            description = ''
              IP address (with prefix) of the peer host on the
              WireGuard mesh. Used as the `allowedIPs` for the peer's
              WireGuard config entry and injected into `HYPERHIVE_PEERS`
              so hive-c0re can route intra-swarm traffic to the mesh
              address rather than the public domain. Required to include
              the peer in the WireGuard mesh (peers missing this field
              are silently excluded from `wg-hive`).
            '';
          };
        };
      }
    );
    default = { };
    example = {
      "lab.example.com" = {
        certFingerprint = "sha256:b1946ac92492d2347c6235b4d2611184a3f5b6cae6c19d6e3c2f0a8e7d4c9f12";
      };
      "edge.corp" = { };
    };
    description = ''
      Peer hives in the same swarm. The attrset key is the peer's DNS
      domain — used for dashboard links and Matrix federation discovery.
      Null `certFingerprint` trusts the system CA bundle; set it to pin
      a self-signed TLS cert. Add `wireguardPublicKey` + `wireguardAddress`
      (and optionally `wireguardEndpoint`) to include the peer in the
      WireGuard mesh when `swarm.wireguard.enable = true`.
    '';
  };

  # WireGuard mesh config for the local host.
  # When enabled, a `wg-hive` interface connects to all peers that have
  # `wireguardPublicKey` declared. Peers reachable over the mesh are
  # preferred for inter-hive traffic (no public TLS round-trip needed);
  # peers without a public key still work via normal HTTPS.
  options.services.hyperhive.swarm.wireguard = {
    enable = lib.mkOption {
      type = lib.types.bool;
      default = false;
      description = ''
        Enable the WireGuard inter-hive mesh. When true, a `wg-hive`
        interface is brought up connecting to all swarm peers that
        declare a `wireguardPublicKey`. Requires
        `privateKeyFile` to be set.
      '';
    };

    privateKeyFile = lib.mkOption {
      type = lib.types.nullOr lib.types.path;
      default = null;
      example = "/etc/wireguard/hive.key";
      description = ''
        Path to the host's WireGuard private key file. The file must
        be readable by root and should have mode 0400. Generate with
        `wg genkey > /etc/wireguard/hive.key`. Required when
        `swarm.wireguard.enable = true`.
      '';
    };

    address = lib.mkOption {
      type = lib.types.str;
      default = "";
      example = "10.100.0.1/24";
      description = ''
        IP address (with prefix) of this host on the WireGuard mesh.
        Use a /24 (or broader) prefix so the routing table covers all
        peer /32 routes. Example: `"10.100.0.1/24"` for a 256-host mesh.
      '';
    };

    listenPort = lib.mkOption {
      type = lib.types.port;
      default = 51820;
      description = ''
        UDP port the local WireGuard interface listens on. Must be
        reachable from peer hosts when they initiate the tunnel.
        Default: 51820 (standard WireGuard port).
      '';
    };

    persistentKeepalive = lib.mkOption {
      type = lib.types.nullOr lib.types.int;
      default = 25;
      example = 25;
      description = ''
        Seconds between keepalive packets sent to each peer. Useful
        when this host (or a peer) is behind NAT — keeps the UDP hole
        open. Set to null to disable. Default: 25 seconds.
      '';
    };
  };

  # Gated on the c0re daemon being enabled (the historical shape — the
  # mesh is part of the coordinator host's networking).
  config = lib.mkIf config.services.hyperhive.c0re.enable {
    assertions = lib.optionals config.services.hyperhive.swarm.wireguard.enable [
      {
        assertion = config.services.hyperhive.swarm.wireguard.privateKeyFile != null;
        message = ''
          services.hyperhive.swarm.wireguard.enable requires
          services.hyperhive.swarm.wireguard.privateKeyFile to be set.
          Generate a key: wg genkey > /etc/wireguard/hive.key
        '';
      }
      {
        assertion = config.services.hyperhive.swarm.wireguard.address != "";
        message = ''
          services.hyperhive.swarm.wireguard.enable requires
          services.hyperhive.swarm.wireguard.address to be set
          (e.g. "10.100.0.1/24").
        '';
      }
    ];

    # WireGuard inter-hive mesh. Brings up a `wg-hive` interface and
    # connects to each peer that has `wireguardPublicKey` set.
    networking.wireguard.interfaces = lib.mkIf config.services.hyperhive.swarm.wireguard.enable (
      let
        wgCfg = config.services.hyperhive.swarm.wireguard;
        meshPeers = lib.filterAttrs (
          _: p: p.wireguardPublicKey != null && p.wireguardAddress != null
        ) config.services.hyperhive.swarm.peers;
      in
      {
        wg-hive = {
          ips = [ wgCfg.address ];
          listenPort = wgCfg.listenPort;
          privateKeyFile = wgCfg.privateKeyFile;
          peers = lib.mapAttrsToList (
            _domain: p:
            {
              publicKey = p.wireguardPublicKey;
              allowedIPs = [ p.wireguardAddress ];
            }
            // lib.optionalAttrs (p.wireguardEndpoint != null) {
              endpoint = p.wireguardEndpoint;
            }
            // lib.optionalAttrs (wgCfg.persistentKeepalive != null) {
              persistentKeepalive = wgCfg.persistentKeepalive;
            }
          ) meshPeers;
        };
      }
    );

    # Open the WireGuard UDP port on the host firewall when the mesh is
    # on (host-level networking — not inside containers).
    networking.firewall.allowedUDPPorts = lib.mkIf config.services.hyperhive.swarm.wireguard.enable [
      config.services.hyperhive.swarm.wireguard.listenPort
    ];
  };
}