{ config, lib, pkgs, ... }:

with lib;
let
  cfg = config.modules.services.atticd;
in
{
  options.modules.services.atticd = {
    enable = mkEnableOption "Whether to enable atticd, a Multi-tenant Nix Binary Cache";

    hosts = mkOption { type = types.listOf types.str; description = "List of FQDNs where attic is reachable at"; };
    baseURL = mkOption { type = types.str; description = "URL to use as a API Endpoint"; };

    storagePath = mkOption { type = types.path; description = "Path to the directory to store all files under"; };

    watchStore = mkEnableOption "Whether to watch the Nix store for new paths";

    secrets = {
      attic-credentials = mkOption { type = types.path; description = "Path to the acme environment file"; };
    };
  };

  config = mkIf cfg.enable {
    services.atticd = {
      enable = true;
      credentialsFile = cfg.secrets.attic-credentials;

      settings = {
        listen = "[::]:4005";
        allowed-hosts = cfg.hosts;
        api-endpoint = cfg.baseURL;

        database.url = "postgres://atticd?host=/run/postgresql";

        require-proof-of-possession = false;

        # Data chunking
        #
        # Warning: If you change any of the values here, it will be
        # difficult to reuse existing chunks for newly-uploaded NARs
        # since the cutpoints will be different. As a result, the
        # deduplication ratio will suffer for a while after the change.
        chunking = {
          # The minimum NAR size to trigger chunking
          #
          # IUUU, chunking is disabled entirely for newly-uploaded NARs.
          # If 1, all NARs are chunked.
          nar-size-threshold = 64 * 1024; # 64 KiB

          # The preferred minimum size of a chunk, in bytes
          min-size = 16 * 1024; # 16 KiB

          # The preferred average size of a chunk, in bytes
          avg-size = 64 * 1024; # 64 KiB

          # The preferred maximum size of a chunk, in bytes
          max-size = 256 * 1024; # 256 KiB
        };
        storage = {
          type = "local";
          path = cfg.storagePath;
        };
        compression = {
          type = "zstd";
          level = 9;
        };
        garbage-collection = {
          interval = "12 hours";
          default-retention-period = "4 weeks";
        };
      };
    };

    services.postgresql.ensureDatabases = [ "atticd" ];
    services.postgresql.ensureUsers = [
      {
        name = "atticd";
        ensureDBOwnership = true;
      }
    ];

    systemd.services.atticd-watch-store = mkIf cfg.watchStore {
      wantedBy = [ "multi-user.target" ];
      wants = [ "network-online.target" ];
      serviceConfig = {
        ExecStart = "${pkgs.attic}/bin/attic watch-store hydra";
        Restart = "on-failure";
        RestartSec = "5s";
        ProtectKernelLogs = true;
        ProtectKernelModules = true;
        ProtectKernelTunables = true;
        ProtectProc = "invisible";
        ProtectSystem = "strict";
        RestrictAddressFamilies = [ "AF_INET" "AF_INET6" "AF_UNIX" ];
        RestrictNamespaces = true;
        RestrictSUIDSGID = true;
      };
    };
  };
}