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

let
  serviceValidation = import ../validation/service/kiwix.nix;
  service_data = import ../config/services.nix;
  kiwix = serviceValidation.getKiwix service_data;

  rootDir = kiwix.root_dir;

  zimUrls = kiwix.urls;

  updater = pkgs.writeShellScriptBin "kiwix-updater" ''
    set -e

    URLS=(
      ${builtins.concatStringsSep " " zimUrls}
    )

    download() {
      local url=''$1
      local filename=''$(basename "''$url")
      local filepath="${rootDir}"/''$filename

      if [ -f "''$filepath" ]; then
        echo "''$filepath exists!"
        return 0
      fi
      cd ${rootDir}
      ${pkgs.wget}/bin/wget --continue --quiet "''$url" -O "''$filename.tmp"
      mv ''$filename.tmp ''$filename
    }

    build_lib() {
      {
        echo '<?xml version="1.0" encoding="UTF-8"?>'
        echo '<library>'
        for zim in "${rootDir}"/*.zim; do
          if [ -f "''$zim" ]; then
            filename=''$(basename "''$zim")
            size=''$(stat -c%s "''$zim")
            case "''$filename" in
              *_en_*)
                title="English Wikipedia (Text Only)"
                lang="eng"
                ;;
              *_de_*)
                title="German Wikipedia (Text Only)"
                lang="deu"
                ;;
              *)
                title="''$filename"
                lang="unknown"
                ;;
            esac
            cat << EOF
  <book id="''$filename" path="/data/''$filename" title="''$title" language="''$lang">
    <title>''$title</title>
    <language>''$lang</language>
    <path>/data/''$filename</path>
    <size>''$size</size>
  </book>
EOF
          fi
        done
        echo '</library>' 
      } > "${rootDir}/library.xml.tmp"
      mv "${rootDir}/library.xml.tmp" "${rootDir}/library.xml"
    }

    for url in "''${URLS[@]}"; do
      download "''$url"
    done
  
    build_lib

    ${pkgs.systemd}/bin/systemctl restart podman-kiwix-serve.service
  '';
in {

  environment.systemPackages = with pkgs; [
    wget
    curl
  ];

  services.cron = {
    enable = true;
    systemCronJobs = [
      "0 3 * * * root ${updater}/bin/kiwix-updater >/dev/null 2>&1"
    ];
  };
}