# Standalone cluster-config.json generator
# Usage: nix-build cluster-config-generator.nix --argstr hostname node01 --argstr clusterName plasmacloud
{ pkgs ? import <nixpkgs> {}
, hostname ? "node01"
, clusterName ? "plasmacloud"
, topologyFile ? ./example-topology.nix
}:

let
  # Import topology module
  lib = pkgs.lib;

  # Evaluate the topology file
  topologyEval = import topologyFile { inherit lib; };

  # Get the cluster configuration
  cluster = topologyEval.nix-nos.clusters.${clusterName} or (throw "Cluster ${clusterName} not found");
  node = cluster.nodes.${hostname} or (throw "Node ${hostname} not found in cluster ${clusterName}");

  # Determine bootstrap node
  controlPlaneNodes = lib.filter (n: cluster.nodes.${n}.role == "control-plane") (lib.attrNames cluster.nodes);
  bootstrapNodeName =
    if cluster.bootstrapNode != null
    then cluster.bootstrapNode
    else lib.head controlPlaneNodes;

  isBootstrap = hostname == bootstrapNodeName;

  # Leader URL (bootstrap node's API endpoint)
  bootstrapNode = cluster.nodes.${bootstrapNodeName};
  leaderUrl = "https://${bootstrapNode.ip}:${toString bootstrapNode.apiPort}";

  # Initial peers for Raft cluster
  initialPeers = map (nodeName: {
    id = nodeName;
    addr = "${cluster.nodes.${nodeName}.ip}:${toString cluster.nodes.${nodeName}.raftPort}";
  }) controlPlaneNodes;

  # FlareDB peers (all control-plane nodes)
  flaredbPeers = map (nodeName:
    "${cluster.nodes.${nodeName}.ip}:${toString (cluster.nodes.${nodeName}.apiPort + 100)}"
  ) controlPlaneNodes;

  # Generate cluster config
  clusterConfig = {
    node_id = hostname;
    node_role = node.role;
    bootstrap = isBootstrap;
    cluster_name = cluster.name;
    leader_url = leaderUrl;
    raft_addr = "${node.ip}:${toString node.raftPort}";
    initial_peers = initialPeers;
    flaredb_peers = flaredbPeers;
    services = node.services;
    metadata = node.metadata;
  };

  # Convert to JSON
  configJson = builtins.toJSON clusterConfig;

in pkgs.writeTextFile {
  name = "cluster-config-${hostname}.json";
  text = configJson;
  destination = "/cluster-config.json";
}