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

with lib;

let
  cfg = config.gortium.clamav;
  clamavPkg = pkgs.clamav;

  clamdConfig = pkgs.writeText "clamd.conf" ''
    LogFile /var/log/clamav/clamd.log
    LogTime yes
    LogVerbose yes
    LogSyslog yes
    LocalSocket /run/clamav/clamd.sock
    TCPSocket 3310
    TCPAddr 127.0.0.1
    User clamav
    AllowSupplementaryGroups yes
    ${cfg.clamdExtraConfig}
  '';

  freshclamConfig = pkgs.writeText "freshclam.conf" ''
    DatabaseDirectory /var/lib/clamav
    LogFile /var/log/clamav/freshclam.log
    LogTime yes
    LogVerbose yes
    LogSyslog yes
    User clamav
    AllowSupplementaryGroups yes
    ${cfg.freshclamExtraConfig}
  '';

  # Daily scan — logging only, no auto-quarantine/delete
  scanScript = pkgs.writeShellScript "clamav-daily-scan" ''
    set -e
    PATHS="${concatStringsSep " " cfg.scanPaths}"
    if [ -z "$PATHS" ]; then
      echo "No paths configured for daily scan"
      exit 0
    fi
    echo "=== ClamAV daily scan started: $(date) ==="
    ${clamavPkg}/bin/clamdscan --fdpass --log=/var/log/clamav/daily-scan.log --no-summary $PATHS
    echo "=== ClamAV daily scan finished: $(date) ==="
  '';
in
{
  ##### Options #####
  options.gortium.clamav = {
    enable = mkEnableOption "ClamAV antivirus — installs clamav CLI tools";

    enableDaemon = mkOption {
      type = types.bool;
      default = true;
      description = ''
        Run clamd daemon + freshclam updater + daily scheduled scan.
        Set to false on machines where you only want the CLI tools
        (clamscan, clamdscan) for manual on-demand scanning.
      '';
    };

    onAccessScanning = mkOption {
      type = types.bool;
      default = false;
      description = ''
        Enable on-access scanning via clamonacc (fanotify-based).
        Resource-heavy; server use only. Requires enableDaemon = true.
      '';
    };

    scanPaths = mkOption {
      type = types.listOf types.str;
      default = [
        "/home"
        "/nix/store"
        "/var/lib"
        "/etc"
        "/tmp"
        "/var/tmp"
      ];
      description = "Paths for the daily scheduled scan.";
    };

    dailyScanTime = mkOption {
      type = types.str;
      default = "daily";
      description = ''
        When to run the daily scan. systemd calendar expression
        or shortcuts like "daily", "weekly", "04:00".
      '';
    };

    clamdExtraConfig = mkOption {
      type = types.lines;
      default = "";
      description = "Extra lines appended to clamd.conf";
    };

    freshclamExtraConfig = mkOption {
      type = types.lines;
      default = "";
      description = "Extra lines appended to freshclam.conf";
    };
  };

  ##### Implementation #####
  config = mkIf cfg.enable {
    # 1. Package — always installed when enable = true
    environment.systemPackages = [ clamavPkg ];

    # Everything below uses mkIf cfg.enableDaemon — conditionalized per attribute

    # 2. Users/groups (only if daemon runs)
    users.users.clamav = mkIf cfg.enableDaemon {
      isSystemUser = true;
      group = "clamav";
      home = "/var/lib/clamav";
      createHome = true;
      description = "ClamAV daemon user";
    };
    users.groups.clamav = mkIf cfg.enableDaemon {};

    # 3. Directories (only if daemon runs)
    systemd.tmpfiles.rules = mkIf cfg.enableDaemon [
      "d /var/lib/clamav 0750 clamav clamav -"
      "d /var/log/clamav 0750 clamav clamav -"
      "d /run/clamav 0755 clamav clamav -"
    ];

    # 4. ClamAV daemon (clamd)
    systemd.services.clamav-daemon = mkIf cfg.enableDaemon {
      description = "ClamAV Anti-Virus Daemon";
      after = [ "network.target" ];
      wantedBy = [ "multi-user.target" ];
      path = [ clamavPkg ];

      preStart = ''
        mkdir -p /var/lib/clamav /var/log/clamav /run/clamav
        chown clamav:clamav /var/lib/clamav /var/log/clamav /run/clamav
      '';

      serviceConfig = {
        Type = "simple";
        ExecStart = "${clamavPkg}/bin/clamd --config-file=${clamdConfig}";
        ExecReload = "${pkgs.coreutils}/bin/kill -HUP $MAINPID";
        Restart = "on-failure";
        RestartSec = "10s";
        User = "clamav";
        Group = "clamav";
        RuntimeDirectory = "clamav";
        RuntimeDirectoryMode = "0755";
        StateDirectory = "clamav";
        StateDirectoryMode = "0750";
        LogsDirectory = "clamav";
        LogsDirectoryMode = "0750";
        PrivateTmp = true;
        ProtectSystem = "strict";
        ProtectHome = true;
        ReadWritePaths = [
          "/var/lib/clamav"
          "/var/log/clamav"
          "/run/clamav"
        ];
        NoNewPrivileges = true;
      };
    };

    # 5. freshclam (database updater) — hourly via timer
    systemd.services.clamav-freshclam = mkIf cfg.enableDaemon {
      description = "ClamAV Virus Database Updater";
      after = [ "network.target" ];
      wantedBy = [ "multi-user.target" ];
      path = [ clamavPkg pkgs.curl ];

      serviceConfig = {
        Type = "oneshot";
        ExecStart = "${clamavPkg}/bin/freshclam --config-file=${freshclamConfig} --daemon-notify=${clamdConfig}";
        User = "clamav";
        Group = "clamav";
        PrivateTmp = true;
        ProtectSystem = "full";
        NoNewPrivileges = true;
      };
    };
    systemd.timers.clamav-freshclam = mkIf cfg.enableDaemon {
      description = "ClamAV database update timer";
      wantedBy = [ "timers.target" ];
      timerConfig = {
        OnCalendar = "hourly";
        Persistent = true;
        RandomizedDelaySec = "1800";
      };
    };

    # 6. Daily scan — logging only, no auto-quarantine
    systemd.services.clamav-daily-scan = mkIf cfg.enableDaemon {
      description = "ClamAV Daily Scheduled Scan";
      after = [ "clamav-daemon.service" ];
      requires = [ "clamav-daemon.service" ];
      path = [ clamavPkg ];

      serviceConfig = {
        Type = "oneshot";
        ExecStart = "${scanScript}";
        User = "clamav";
        Group = "clamav";
        PrivateTmp = true;
        ProtectSystem = "strict";
        ReadWritePaths = [ "/var/log/clamav" ];
      };
    };
    systemd.timers.clamav-daily-scan = mkIf cfg.enableDaemon {
      description = "ClamAV daily scan timer";
      wantedBy = [ "timers.target" ];
      timerConfig = {
        OnCalendar = cfg.dailyScanTime;
        Persistent = true;
      };
    };

    # 7. On-access scanning (clamonacc) — needs enableDaemon
    systemd.services.clamav-onaccess = mkIf (cfg.enableDaemon && cfg.onAccessScanning) {
      description = "ClamAV On-Access Scanner (clamonacc)";
      after = [ "clamav-daemon.service" ];
      requires = [ "clamav-daemon.service" ];
      wantedBy = [ "multi-user.target" ];
      path = [ clamavPkg ];

      serviceConfig = {
        Type = "simple";
        ExecStart = "${clamavPkg}/bin/clamonacc --config-file=${clamdConfig} --fdpass --log=/var/log/clamav/clamonacc.log";
        Restart = "on-failure";
        RestartSec = "10s";
        User = "root";  # clamonacc needs root for fanotify
        Group = "root";
        PrivateTmp = true;
        NoNewPrivileges = true;
      };
    };
  };
}