{ hostRegistry, nixpkgs, config, pkgs, ... }:
let
  webroot = "/var/www";
  deployCommand = "${pkgs.systemd}/bin/systemctl start deploy-c3d2-web.service";
in
{
  boot.tmpOnTmpfs = true;
  # Network setup
  networking.hostName = "c3d2-web";
  networking.useNetworkd = true;
  networking.interfaces.eth0.ipv4.addresses = [{
    address = hostRegistry.hosts.${config.networking.hostName}.ip4;
    prefixLength = 26;
  }];
  networking.defaultGateway = "172.20.73.1";
  networking.firewall.allowedTCPPorts = [ 80 443 ];

  # Web server
  services.nginx = {
    enable = true;
    virtualHosts = {
      "www.c3d2.de" = {
        default = true;
        serverAliases = [
          "c3d2.de"
          "c3dd.de" "www.c3dd.de"
          "cccdd.de" "www.cccdd.de"
          "dresden.ccc.de" "www.dresden.ccc.de"
        ];
        # TODO:
        # enableACME = true;
        # forceSSL = true;
        root = "${webroot}/c3d2";
        extraConfig = ''
          index portal.html;
        '';
        locations = {
          # SpaceAPI
          "/status.png".proxyPass = "http://[${hostRegistry.hosts.spaceapi.ip6}]:3000/status.png";
          "/spaceapi.json".proxyPass = "http://[${hostRegistry.hosts.spaceapi.ip6}]:3000/spaceapi.json";
          # Jabber
          # TODO: does this work?
          "/http-bind".proxyPass = "http://jabber.c3d2.de:5280/http-bind";
          # TODO: websockets too?
        };
      };

      "datenspuren.de" = {
        serverAliases = [
          "www.datenspuren.de"
        ];
        # TODO:
        # enableACME = true;
        # forceSSL = true;
        root = "${webroot}/c3d2/datenspuren";
        extraConfig = ''
          index index.html;
          rewrite ^/$ /2021/ redirect;
        '';
      };

      "c3d2-web.serv.zentralwerk.org" = {
        enableACME = true;
        forceSSL = true;
        root = webroot;
        locations."/hooks/".proxyPass = "http://localhost:9000/hooks/";
      };
    };
  };

  # Build user
  users.groups.c3d2-web = {};
  users.users.c3d2-web = {
    isSystemUser = true;
    group = "c3d2-web";
    home = "/var/lib/c3d2-web";
  };

  systemd.tmpfiles.rules = [
    "d ${webroot}/c3d2 0755 c3d2-web ${config.users.users.c3d2-web.group} -"
    "d ${webroot}/log 0755 c3d2-web ${config.users.users.c3d2-web.group} -"
    "d ${config.users.users.c3d2-web.home} 0700 c3d2-web ${config.users.users.c3d2-web.group} -"
  ];

  # Build script
  systemd.services.deploy-c3d2-web = {
    wantedBy = [ "multi-user.target" ];
    path = with pkgs; [ git nix curl ];
    script = ''
      # Build at least once
      touch ${config.users.users.c3d2-web.home}/deploy-pending

      TEMP=$(mktemp -d)
      cd $TEMP

      git clone --depth=1 https://gitea.c3d2.de/c3d2/c3d2-web.git
      cd c3d2-web

      # Loop in case the webhook was called while we were building
      while [ -e ${config.users.users.c3d2-web.home}/deploy-pending ]; do
        rm ${config.users.users.c3d2-web.home}/deploy-pending
        git pull
        REV=$(git rev-parse HEAD)

        set +e
        curl -X POST \
          "https://gitea.c3d2.de/api/v1/repos/c3d2/c3d2-web/statuses/$REV?token=${pkgs.c3d2-web.giteaToken}" \
          -H "accept: application/json" \
          -H "Content-Type: application/json" \
          -d "{ \"context\": \"c3d2-web\", \"description\": \"building...\", \"state\": \"pending\", \"target_url\": \"https://c3d2-web.serv.zentralwerk.org/log/build-$REV.txt\"}"

        nix-shell shell.nix \
          -I nixpkgs=${nixpkgs} \
          --run "make -j$(nproc) export DESTDIR=${webroot}/c3d2" \
          2>&1 \
          >${webroot}/log/build-$REV.txt

        if [ $? = 0 ]; then
          STATUS="{ \"context\": \"c3d2-web\", \"description\": \"deployed\", \"state\": \"success\", \"target_url\": \"https://c3d2-web.serv.zentralwerk.org/log/build-$REV.txt\"}"
        else
          STATUS="{ \"context\": \"c3d2-web\", \"description\": \"build failure\", \"state\": \"failure\", \"target_url\": \"https://c3d2-web.serv.zentralwerk.org/log/build-$REV.txt\"}"
        fi
        curl -X POST \
          "https://gitea.c3d2.de/api/v1/repos/c3d2/c3d2-web/statuses/$REV?token=${pkgs.c3d2-web.giteaToken}" \
          -H "accept: application/json" \
          -H "Content-Type: application/json" \
          -d "$STATUS"

        set -e
      done
    '';
    serviceConfig = {
      User = "c3d2-web";
      Group = config.users.users.c3d2-web.group;
      PrivateTmp = true;
      ProtectSystem = "full";
      ReadWritePaths = webroot;
    };
  };

  systemd.timers.deploy-c3d2-web = {
    partOf = [ "deploy-c3d2-web.service" ];
    wantedBy = [ "timers.target" ];
    timerConfig.OnCalendar = "hourly";
  };

  security.sudo.extraRules = [ {
    users = [ "c3d2-web" ];
    commands = [ {
      command = deployCommand;
      options = [ "NOPASSWD" ];
    } ];
  } ];

  systemd.services.webhook =
    let
      hooksJson = pkgs.writeText "hooks.json" (builtins.toJSON [ {
        id = "deploy-c3d2-web";
        execute-command = pkgs.writeShellScript "deploy-c3d2-web" ''
          # Request (re-)deployment
          touch ${config.users.users.c3d2-web.home}/deploy-pending

          # Start deploy-c3d2-web.service if not already running
          exec /run/wrappers/bin/sudo ${deployCommand}
        '';
      } ]);
    in {
      wantedBy = [ "multi-user.target" ];
      serviceConfig = {
        ExecStart = "${pkgs.webhook}/bin/webhook -hooks ${hooksJson} -verbose -ip 127.0.0.1";
        User = "c3d2-web";
        Group = config.users.users.c3d2-web.group;
        PrivateTmp = true;
        ProtectSystem = "full";
      };
    };
  # TODO: letsencrypt /.well-known before DNS switch
}