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

let
  syncthingDevices = {
    #mobile devices
    blechkasten.id    = "HGPWBVY-RD4JKBQ-X3V53IB-KRVDXEQ-4YLN5F2-WPPSMYR-SOXGTY6-IDFOAAC";
    coladose.id       = "BNCAOEB-CYTYIBA-ZKFJKRB-DX4C3MT-SDH7IWQ-5EI35PJ-YUIJSYH-COCGUAW";
    seifenkiste.id    = "6YZT5PZ-EKXZBMV-C2MJL75-OCQ36LC-L3QIRPW-VJ5EU3C-2ICZDDO-IZ7IGAO";

    iphone.id         = "3SM3LJV-XMHYW2D-MU5WQ3T-KGYUJOI-LXOL6YI-BSVZ2B5-QJ6GVXN-MPWMKQ7";

    #servers
    hector.name       = "hector.ctu.cx";
    hector.id         = "MVGBPSX-YSZNBDO-E7HZFGJ-WULYWQ5-XDHVMJO-BKA4R37-GPPRLLS-Z5DQMQJ";
    wanderduene.name  = "wanderduene.ctu.cx";
    wanderduene.id    = "WEFYARN-GY3WZXB-TIXBI56-ZZ77AHS-GFH5SH2-Q35NTBI-VPT3OEM-EQNAMQH";
    briefkasten.name  = "briefkasten.home.ctu.cx";
    briefkasten.id    = "QI2EPUE-4VMZ3XV-LXX3GXP-RHCWTRY-AACLSGL-YG7MIYV-THST74N-KJGIBQ6";
  };

  enabledShares = {
    briefkasten = [
      "ctucx-music-orig"
      "ctucx-media"
    ];
  };

  defaultVersioning = {
    type   = "trashcan";
    params = {
      cleanoutDays = "3";
    };
  };


  isCurrentHost     = key: value: key != config.networking.hostName;

  deviceNames = (
    syncthingDevices
    |> lib.filterAttrs isCurrentHost
    |> builtins.attrNames
  );

  shareDeviceNames = share: (
    enabledShares
    |> lib.filterAttrs isCurrentHost
    |> lib.filterAttrs (key: value: builtins.elem share value)
    |> builtins.attrNames
  );

  isShareEnabled = share: (
    if builtins.hasAttr config.networking.hostName enabledShares then
      (if builtins.elem share enabledShares.${config.networking.hostName} then true else false)
    else
      false
  );


in rec {

  dataDir = config.services.syncthing.dataDir;
  devices = lib.mkMerge [ (lib.filterAttrs isCurrentHost syncthingDevices) ];

  folders = {
    "${dataDir}/Audiobooks" = {
      enable     = lib.mkDefault true;
      id         = "ctucx-audiobooks";
      label      = "Audiobooks";
      devices    = deviceNames;
      versioning = lib.mkDefault defaultVersioning;
    };

    "${dataDir}/Documents" = {
      enable     = lib.mkDefault true;
      id         = "ctucx-documents";
      label      = "Documents";
      devices    = deviceNames;
      versioning = lib.mkDefault defaultVersioning;
    };

    "${dataDir}/Music" = {
      enable     = lib.mkDefault true;
      id         = "ctucx-music";
      label      = "Music";
      devices    = deviceNames;
      versioning = lib.mkDefault defaultVersioning;
    };

    "${dataDir}/Pictures" = {
      enable     = lib.mkDefault true;
      id         = "ctucx-pictures";
      label      = "Pictures";
      devices    = deviceNames;
      versioning = lib.mkDefault defaultVersioning;
    };

    "${dataDir}/Videos" = {
      enable     = lib.mkDefault true;
      id         = "ctucx-videos";
      label      = "Videos";
      devices    = deviceNames;
      versioning = lib.mkDefault defaultVersioning;
    };

    "${dataDir}/Bahn-Richtlinien" = {
      enable     = lib.mkDefault true;
      id         = "Bahn-Richtlinien";
      label      = "Bahn-Richtlinien";
      devices    = deviceNames;
      versioning = lib.mkDefault defaultVersioning;
    };

    "${dataDir}/Music (Originals)" = rec {
      enable     = lib.mkDefault (isShareEnabled "${id}");
      id         = "ctucx-music-orig";
      label      = "Music (Originals)";
      devices    = shareDeviceNames "${id}";
      versioning = lib.mkDefault defaultVersioning;
    };

    "${dataDir}/Media (legacy)" = rec {
      enable     = lib.mkDefault (isShareEnabled "${id}");
      id         = "ctucx-media";
      label      = "Media (legacy)";
      devices    = shareDeviceNames "${id}";
      versioning = lib.mkDefault defaultVersioning;
    };
  };

}