# The swarm's directory: one entry per hive, **including this one**,
# identical on every host in the swarm. `services.hyperhive.hiveName`
# says which entry is us, and `peerHives` below derives the rest.
#
# Why a directory rather than a per-host peer list: every field here is
# intrinsic to the hive it describes — none of them says anything about
# the *pair*. A list where every field is intrinsic is a directory each
# host was keeping its own copy of, which is O(n²) duplication that
# deduplicates without loss. It is also a correctness gain: two hosts
# could hold different endpoints for the same third hive and nothing
# detected it. One entry per hive makes that unrepresentable.
#
# Consumed by hive-c0re's environment (HYPERHIVE_PEERS — see
# ./hive-c0re), identity.rs + the dashboard's P33RS tab, and the mesh in
# ./swarm-wireguard.nix. The mesh lives there rather than here because
# bringing up an interface is host networking rather than swarm
# bookkeeping, and a host that runs no hive still needs it.
{
  lib,
  config,
  ...
}:
let
  cfg = config.services.hyperhive;
  swarmCfg = cfg.swarm;
in
{
  options.services.hyperhive.swarm.hives = lib.mkOption {
    type = lib.types.attrsOf (
      lib.types.submodule {
        options = {
          domain = lib.mkOption {
            type = lib.types.str;
            example = "lab.example.com";
            description = ''
              Public DNS domain this hive occupies — used for dashboard
              links, peer HTTPS checks and Matrix federation discovery.

              Deliberately has no default. It is conventionally
              `<name>.<swarm.domain>`, but defaulting to that would let
              a typo'd swarm domain produce a name that resolves
              somewhere real; an eval failure naming the hive is the
              better outcome.
            '';
          };

          certFingerprint = lib.mkOption {
            type = lib.types.nullOr lib.types.str;
            default = null;
            example = "sha256:b1946ac92492d2347c6235b4d2611184a3f5b6cae6c19d6e3c2f0a8e7d4c9f12";
            description = ''
              Expected TLS certificate fingerprint for this hive's HTTPS
              endpoint. Null = trust the CA bundle — which for a hive
              inside the swarm CA hierarchy is the normal case, since
              every hive under the swarm root already chains to it.
              Set it to pin a leaf that no CA in the bundle vouches for.

              Format: the literal `sha256:` followed by exactly 64
              hex digits (case-insensitive, no colon separators) — the
              SHA-256 digest of the 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/README.md for the full recipe.

              Scopes only to hive-c0re's own peer HTTPS checks — it does
              NOT help Matrix federation, which validates against the
              container's trust bundle. There is no per-hive CA field to
              cover that case any more: the swarm root is the trust path
              (see ./swarm-ca.nix).
            '';
          };

          wireguardPublicKey = lib.mkOption {
            type = lib.types.nullOr lib.types.str;
            default = null;
            example = "base64pubkey=";
            description = ''
              WireGuard public key for this hive's host. Required when
              `services.hyperhive.swarm.wireguard.enable = true` and
              you want this hive 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 hive in `host:port` form.
              Null = this hive has no reachable endpoint, so the tunnel
              is initiated from the other side.

              Reads like a fact about the relationship and is not: it
              says whether *this* hive can be dialled, which every other
              hive in the swarm needs the same answer to.
            '';
          };

          wireguardAddress = lib.mkOption {
            type = lib.types.nullOr lib.types.str;
            default = null;
            example = "10.100.0.2/32";
            description = ''
              IP address (with prefix) of this hive's host on the
              WireGuard mesh. Used as the `allowedIPs` for its
              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
              a hive in the mesh (entries missing this field are
              silently excluded from `wg-hive`).
            '';
          };
        };
      }
    );
    default = { };
    example = {
      pr1ma = {
        domain = "pr1ma.example.com";
        wireguardAddress = "10.100.0.1/32";
        wireguardEndpoint = "203.0.113.1:51820";
      };
      edge = {
        domain = "edge.example.com";
        wireguardAddress = "10.100.0.2/32";
      };
    };
    description = ''
      Every hive in this swarm, keyed by `hiveName` — **including this
      host's own hive**. The same attrset is meant to be identical on
      every host in the swarm, so it can be written once and shared;
      `services.hyperhive.hiveName` is what makes a given host read it
      as "me and four others" rather than "five peers".

      Empty (the default) means this host is not part of a swarm. Once
      non-empty it must contain an entry for `hiveName`, which is
      asserted — a hive that lists everyone but itself would otherwise
      derive its own peer set as *everything* and peer with itself.
    '';
  };

  options.services.hyperhive.swarm.peerHives = lib.mkOption {
    type = lib.types.attrsOf (lib.types.attrsOf lib.types.unspecified);
    readOnly = true;
    internal = true;
    description = ''
      Read-only: `hives` minus this host's own entry. Derived once here
      rather than in each consumer, because "everything that isn't me"
      is a filter four different modules were re-implementing and only
      one of them has to be wrong for a hive to peer with itself.
    '';
  };

  config = {
    services.hyperhive.swarm.peerHives = lib.filterAttrs (name: _: name != cfg.hiveName) swarmCfg.hives;

    assertions = [
      {
        # Guarded on `hiveName != null` so the required-hiveName
        # assertion in ./hyperhive.nix is what fires for that case —
        # two assertions naming the same missing value is noise.
        assertion = swarmCfg.hives == { } || cfg.hiveName == null || swarmCfg.hives ? ${cfg.hiveName};
        message = ''
          services.hyperhive.swarm.hives has no entry for this hive
          (services.hyperhive.hiveName = "${toString cfg.hiveName}").

          `hives` describes every hive in the swarm including this one,
          so that every host can share one identical attrset. Add:

            services.hyperhive.swarm.hives."${toString cfg.hiveName}" = {
              domain = "${toString cfg.domain}";
            };

          Declared hives: ${lib.concatStringsSep ", " (lib.attrNames swarmCfg.hives)}
        '';
      }
    ];
  };

  # `enableRequiredServices` is declared in ./swarm-required-services.nix
  # together with the per-service `enable`s it asserts — it is a
  # deployment-shape switch rather than swarm bookkeeping, so it lives
  # with its consequences instead of here.

  options.services.hyperhive.swarm.snapshotStore = {
    address = lib.mkOption {
      type = lib.types.nullOr lib.types.str;
      default = null;
      example = "10.100.0.1";
      description = ''
        Mesh address of the swarm's snapshot store — the single
        `btrfs receive` endpoint every hive in this swarm pushes agent
        snapshots to. Bare IP, no prefix.

        There is exactly **one** store per swarm, not one per peer: the
        receiver keys destinations by *agent*, so an agent that migrates
        between hives keeps a single unbroken incremental chain. Per-hive
        stores would split that chain in two, which is the case the store
        exists to serve.

        Null means this swarm has no store configured, and pushing fails
        saying so rather than guessing an address. Set it on every hive
        that pushes; the receiving host separately sets
        `services.hyperhive.snapshotStore.enable`.
      '';
    };

    port = lib.mkOption {
      type = lib.types.port;
      default = 51821;
      description = ''
        TCP port the swarm's snapshot store listens on. Must match the
        receiving host's `services.hyperhive.snapshotStore.port`.

        Defaulted (unlike `address`) because it is a shared convention
        both sides read from the same option docs — whereas an address
        is deployment-specific and cannot be guessed.
      '';
    };
  };

}