#! /usr/bin/env bash

# More info at: https://github.com/elitak/nixos-infect

set -e -o pipefail

makeConf() {
  # Skip everything if main config already present
  [[ -e /etc/nixos/configuration.nix ]] && return 0
  # NB <<"EOF" quotes / $ ` in heredocs, <<EOF does not
  mkdir /etc/nixos
  mkdir -p /etc/nixos/mailserver/system
  mkdir /etc/nixos/mailserver/userdata
  mkdir /etc/nixos/api
  mkdir /etc/nixos/letsencrypt
  mkdir /etc/nixos/backup
  mkdir /etc/nixos/passmgr
  mkdir /etc/nixos/nginx
  mkdir /etc/nixos/git
  mkdir /etc/nixos/nextcloud
  mkdir /etc/nixos/resources
  mkdir /etc/nixos/videomeet
  mkdir /etc/nixos/openconnect

  # Prevent grep for sending error code 1 (and halting execution) when no lines are selected : https://www.unix.com/man-page/posix/1P/grep
  local IFS=$'\n' 
  for trypath in /root/.ssh/authorized_keys $HOME/.ssh/authorized_keys; do 
      [[ -r "$trypath" ]] \
      && keys=$(sed -E 's/^.*((ssh|ecdsa)-[^[:space:]]+)[[:space:]]+([^[:space:]]+)([[:space:]]*.*)$/\1 \3\4/' "$trypath") \
      && break
  done
  local network_import=""

  [[ -n "$doNetConf" ]] && network_import="./networking.nix # generated at runtime by nixos-infect"
  cat > /etc/nixos/configuration.nix << EOF
{ pkgs, lib, ... }: 
{
  imports = [
    ./hardware-configuration.nix
    $network_import
    $NIXOS_IMPORT
    ./files.nix
	./mailserver/system/mailserver.nix
    ./openconnect/shadowsocks.nix
    ./api/api.nix
	./letsencrypt/acme.nix
	./backup/restic.nix
	./passmgr/bitwarden.nix
	./nginx/nginx.nix
	./nextcloud/nextcloud.nix
    ./resources/limits.nix
    ./videomeet/jitsi.nix
	./git/gitea.nix
  ];

  boot.cleanTmpDir = true;
  networking = {
    hostName = "$(hostname)";
    firewall = {
      allowedTCPPorts = lib.mkForce [ 22 443 80 143 587 8388 ];
      allowedUDPPorts = lib.mkForce [ 22 443 80 143 587 8388 ];
    };
  };
  time.timeZone = "Europe/Uzhgorod";
  i18n.defaultLocale = "en_GB.UTF-8";
  users.users.root.openssh.authorizedKeys.keys = [$(while read -r line; do echo -n "
    \"$line\" "; done <<< "$keys")
  ];
  services.openssh = {
    enable = true;
    passwordAuthentication = true;
    permitRootLogin = "yes";
    openFirewall = false;
  };
  programs.ssh = {
    pubkeyAcceptedKeyTypes = [ "ssh-ed25519" ];
    hostKeyAlgorithms = [ "ssh-ed25519" ];
  };
  environment.systemPackages = with pkgs; [
    letsencrypt
    mkpasswd
    git
    wget
    curl
    restic
    pwgen
    tmux
    sudo
    python3
  ] ++ (with python38Packages; [
    pip
    flask
    pandas
  ]);
  environment.variables = {
    DOMAIN = "$DOMAIN";
    AWS_ACCESS_KEY_ID = "$AWS_ACCESS_KEY_ID";
    AWS_SECRET_ACCESS_KEY = "$AWS_SECRET_ACCESS_KEY";
  };
  system.autoUpgrade.enable = true;
  system.autoUpgrade.allowReboot = false;
  system.autoUpgrade.channel = https://nixos.org/channels/nixos-20.09-small;
  nix = {
    optimise.automatic = true;
    gc = {
      automatic = true;
      options = "--delete-older-than 7d";
    };
  };
  boot.kernel.sysctl = {
    "net.ipv4.ip_forward" = 1;
  };
  swapDevices = [
    {
      device = "/swapfile";
      priority = 0;
      size = 2048;
    }
  ];
  security = {
    sudo = {
      enable = true;
      wheelNeedsPassword = true;
    };
  };
}
EOF
  # If you rerun this later, be sure to prune the filesSystems attr
    cat > /etc/nixos/hardware-configuration.nix << EOF
{ ... }:
{
  imports = [ <nixpkgs/nixos/modules/profiles/qemu-guest.nix> ];
  boot.loader.grub.device = "$grubdev";
  fileSystems."/" = { device = "$rootfsdev"; fsType = "ext4"; };
}
EOF

    cat > /etc/nixos/files.nix << EOF
{ pkgs, ... }:
{
  systemd.tmpfiles.rules =
    let
      nextcloudDBPass = builtins.replaceStrings [ "\n" "\"" "\\\" ] [ "\\\n" "\\\\\"" "\\\\\\\\" ] ''
      $PASSWORD
      '';
      nextcloudAdminPass = builtins.replaceStrings [ "\n" "\"" "\\\" ] [ "\\\n" "\\\\\"" "\\\\\\\\" ] ''
      $PASSWORD
      '';
      resticPass = builtins.replaceStrings [ "\n" "\"" "\\\" ] [ "\\\n" "\\\\\"" "\\\\\\\\" ] ''
      $PASSWORD
      '';
      shadowsocksPass = builtins.replaceStrings [ "\n" "\"" "\\\" ] [ "\\\n" "\\\\\"" "\\\\\\\\" ] ''
      $PASSWORD
      '';
      domain = builtins.replaceStrings [ "\n" "\"" "\\\" ] [ "\\\n" "\\\\\"" "\\\\\\\\" ] ''
      $DOMAIN
      '';
    in
      [
        "d /var/restic 0660 restic - - -"
        "d /var/bitwarden 0777 bitwarden_rs bitwarden_rs -"
        "d /var/api 0775 unit unit -"
        "d /var/bitwarden/backup 0777 bitwarden_rs bitwarden_rs -"
        "f /var/domain 0444 selfprivacy-api selfprivacy-api - \${domain}"
        "f /var/restic/restic-repo-password 0660 restic - - \${resticPass}"
        "f /var/nextcloud-db-pass 0440 nextcloud nextcloud - \${nextcloudDBPass}"
        "f /var/nextcloud-admin-pass 0440 nextcloud nextcloud - \${nextcloudAdminPass}"
        "f /var/shadowsocks-password 0440 nobody nobody - \${shadowsocksPass}"
      ];
}
EOF

    cat > /etc/nixos/mailserver/system/mailserver.nix << EOF
{ config, pkgs, lib, ... }:
{
  imports = [
    (builtins.fetchTarball {
      # Pick a commit from the branch you are interested in
      url = "https://gitlab.com/simple-nixos-mailserver/nixos-mailserver/-/archive/99f843de/nixos-mailserver-99f843de.tar.gz";

      # And set its hash
      sha256 = "1af7phs8a2j26ywsm5mfhzvqmy0wdsph7ajs9s65c4r1bfq646fw";
    })
  ];

  services.dovecot2 = {
    enablePAM = lib.mkForce true;
    showPAMFailure = lib.mkForce true;
  };
  mailserver = {
    enable = true;
    fqdn = "$DOMAIM";
    domains = [ "$DOMAIN" ];

    # A list of all login accounts. To create the password hashes, use
    # mkpasswd -m sha-512 "super secret password"
    loginAccounts = {
	"$USER@$DOMAIN" = {
	    hashedPassword = "$HASHED_PASSWORD";

            #aliases = [
            #    "mail@example.com"
            #];

            # Make this user the catchAll address for domains blah.com and
            # example2.com
            catchAll = [
		"$DOMAIN"
            ];
	    sieveScript = ''
	        require ["fileinto", "mailbox"];
		if header :contains "Chat-Version" "1.0"
		{	
    		  fileinto :create "DeltaChat";
		  stop;
		}
	    '';
        };
        
    };

    # Extra virtual aliases. These are email addresses that are forwarded to
    # loginAccounts addresses.
    extraVirtualAliases = {
        # address = forward address;
	 "admin@$DOMAIN" = "$USER@$DOMAIN";
    };

    # Use Let's Encrypt certificates. Note that this needs to set up a stripped
    # down nginx and opens port 80.
    certificateScheme = 3;

    # Enable IMAP and POP3
    enableImap = true;
    enableImapSsl = true;
    enablePop3 = false;
    enablePop3Ssl = false;
    dkimSelector = "selector";

    # Enable the ManageSieve protocol
    enableManageSieve = true;

    virusScanning = false;
  };
}
EOF

    cat > /etc/nixos/letsencrypt/acme.nix << EOF
{ pkgs, ... }:
{
  users.groups.acmerecievers = {
    members = [ "nginx" "dovecot2" "postfix" "virtualMail" "bitwarden_rs" "nextcloud" ];
  };
  security.acme = {
    acceptTerms = true;
    email = "$USER@$DOMAIN";
    certs = {
      "$DOMAIN" = {
        group = "acmerecievers";
      };
      "git.$DOMAIN" = {
        group = "acmerecievers";
      };
      "cloud.$DOMAIN" = {
        group = "acmerecievers";
      };
      "password.$DOMAIN" = {
        group = "acmerecievers";
      };
      "api.$DOMAIN" = {
        group = "acmerecievers";
      };
      "meet.$DOMAIN" = {
        group = "acmerecievers";
      };
    };
  };
}
EOF

    cat > /etc/nixos/backup/restic.nix << EOF
{ pkgs, ... }:
{
  services.restic.backups = {
    options = {
      passwordFile = "/etc/restic/resticPasswd";
      repository = "s3:s3.anazonaws.com/$S3_BUCKET";
      initialize = true;
      paths = [
        "/var/dkim"
        "/var/vmail"
      ];
      timerConfig = {
        OnCalendar = [ "daily" ];
      };
      user = "restic";
      pruneOpts = [
        "--keep-daily 5"
      ];
    };
  };
  users.users.restic = {
    isNormalUser = false;
  };
  environment.etc."restic/resticPasswd".text = ''
$PASSWORD
  '';
  environment.etc."restic/s3Passwd".text = ''
AWS_ACCESS_KEY_ID=$AWS_ACCESS_KEY_ID
AWS_SECRET_ACCESS_KEY=$AWS_SECRET_ACCESS_KEY
  '';
}
EOF
  
    cat > /etc/nixos/passmgr/bitwarden.nix << EOF
{ pkgs, ... }:
{
  services.bitwarden_rs = {
    enable = true;
    dbBackend = "sqlite";
    backupDir = "/var/bitwarden/backup";
    config = {
      domain = "https://password.$DOMAIN/";
      signupsAllowed = true;
      rocketPort = 8222;
      rocketLog = "warning";
    };
  };
}
EOF

    cat > /etc/nixos/nginx/nginx.nix << EOF
{ pkgs, ... }:
{
  services.nginx = {
    enable = true;
    recommendedGzipSettings = true;
    recommendedOptimisation = true;
    recommendedProxySettings = true;
    recommendedTlsSettings = true;

    virtualHosts = {
      "$DOMAIN" = {
        enableACME = true;
        forceSSL = true;
        };
      "git.$DOMAIN" = {
        enableACME = true;
        forceSSL = true;
        locations = {
          "/" = {
            proxyPass = "http://127.0.0.1:3000";
	    extraConfig = ''
proxy_headers_hash_max_size 512;
proxy_headers_hash_bucket_size 128;
            '';
	      };
        };
      };
      "cloud.$DOMAIN" = {
        enableACME = true;
	forceSSL = true;
        locations = {
          "/" = {
            proxyPass = "http://127.0.0.1:80/";
	    extraConfig = ''
proxy_headers_hash_max_size 512;
proxy_headers_hash_bucket_size 128;
	    '';
	      };
	    };
      };
      "password.$DOMAIN" = {
        enableACME = true;
	    forceSSL = true;
        locations = {
          "/" = {
            proxyPass = "http://127.0.0.1:8222";
	    extraConfig = ''
proxy_headers_hash_max_size 512;
proxy_headers_hash_bucket_size 128;
	    '';
	  };
	};
      };
      "api.$DOMAIN" = {
        enableACME = true;
	forceSSL = true;
        locations = {
          "/" = {
            proxyPass = "http://127.0.0.1:5050";
	    extraConfig = ''
proxy_headers_hash_max_size 512;
proxy_headers_hash_bucket_size 128;
            '';
	      };
	    };
      };
    };
  };
}
EOF

    cat > /etc/nixos/nextcloud/nextcloud.nix << EOF
{ pkgs, ... }:
{
  services.nextcloud = {
    enable = true;
    package = pkgs.nextcloud20;
    hostName = "cloud.$DOMAIN";

    # Use HTTPS for links
    https = false;
    
    # Auto-update Nextcloud Apps
    autoUpdateApps.enable = true;
    # Set what time makes sense for you
    autoUpdateApps.startAt = "05:00:00";

    config = {
      # Further forces Nextcloud to use HTTPS
      overwriteProtocol = "http";

      # Nextcloud PostegreSQL database configuration, recommended over using SQLite
      dbtype = "sqlite";
      dbuser = "nextcloud";
      dbhost = "/run/postgresql"; # nextcloud will add /.s.PGSQL.5432 by itself
      dbname = "nextcloud";
      dbpassFile = "/var/nextcloud-db-pass";

      adminpassFile = "/var/nextcloud-admin-pass";
      adminuser = "admin";
    };
  };
}
EOF

    cat > /etc/nixos/git/gitea.nix << EOF
{ pkgs, ... }:
{
  services = {
    gitea = {
      enable = true;
      stateDir = "/var/lib/gitea";
      log = {
        rootPath = "/var/lib/gitea/log";
        level = "Warn";
      };
      user = "gitea";
      database = {
        type = "sqlite3";
        host = "127.0.0.1";
        name = "gitea";
	user = "gitea";
	path = "/var/lib/gitea/data/gitea.db";
	createDatabase = true;
      };
      ssh = {
        enable = true;
        clonePort = 22;
      };
      lfs = {
        enable = true;
        contentDir = "/var/lib/gitea/lfs";
      };
      appName = "SelfPrivacy git Service";
      repositoryRoot = "/var/lib/gitea/repositories";
      domain = "git.$DOMAIN";
      rootUrl = "https://$DOMAIN/";
      httpAddress = "0.0.0.0";
      httpPort = 3000;
      cookieSecure = true;
      settings = {
        mailer = {
          ENABLED = false;
	    };
	    ui = {
          DEFAULT_THEME = "arc-green";
	    };
	    picture = {
          DISABLE_GRAVATAR = true;
	    };
	    admin = {
          ENABLE_KANBAN_BOARD = true;
	    };
	    repository = {
          FORCE_PRIVATE = false;
	    };
      };
    };
  };
}
EOF

    cat > /etc/nixos/resources/limits.nix << EOF
{ pkgs, ... }:
{
  systemd.services = {
    dovecot2 = {
      serviceConfig = {
        cpuAccounting = true;
	    cpuQuota = "20%";
        memoryAccounting = true;
        memoryMax = "256M";
	    startLimitIntervalSec = 500;
	    startLimitBurst = 5;
	    blockIOWeigth = 25;
      };
    };
    postfix = {
      serviceConfig = {
        cpuAccounting = true;
	    cpuQuota = "20%";
	    memoryAccounting = true;
	    memoryMax = "256M";
	    startLimitIntervalSec = 500;
	    startLimitBurst = 5;
	    blockIOWeigth = 25;
      };
    };
    ocserv = {
      serviceConfig = {
        cpuAccounting = true;
	    cpuQuota = "70%";
	    memoryAccounting = true;
	    memoryMax = "512M";
	    startLimitIntervalSec = 500;
	    startLimitBurst = 5;
      };
    };
    nginx = {
      serviceConfig = {
        cpuAccounting = true;
        cpuQuota = "70%";
        memoryAccounting = true;
        memoryMax = "768M";
        startLimitIntervalSec = 500;
        startLimitBurst = 5;
	    blockIOWeigth = 10;
      };	
    };
  };
}
EOF

    cat > /etc/nixos/videomeet/jitsi.nix << EOF
{ pkgs, ... }:
{
  services.jitsi-meet = {
    enable = true;
    hostName = "meet.$DOMAIN";
    nginx.enable = true;
    interfaceConfig = {
      SHOW_JITSI_WATERMARK = false;
      SHOW_WATERMARK_FOR_GUESTS = false;
    };
      
  };
}
EOF

cat > /etc/nixos/api/api.nix << EOF
{ pkgs, ... }:
{
  services.selfprivacy-api = {
    enable = true;
  };

  users.users."selfprivacy-api" = {
    isNormalUser = false;
    extraGroups = [ "opendkim" ];
  };
  users.groups."selfprivacy-api" = {
    members = [ "selfprivacy-api" ];
  };
}
EOF

cat > /etc/nixos/api/api-package.nix << EOF
{ nixpkgs ? import <nixpkgs> {}, pythonPkgs ? nixpkgs.pkgs.python37Packages }:

let
  inherit (nixpkgs) pkgs;
  inherit pythonPkgs;

  selfprivacy-api = { buildPythonPackage, flask, flask-restful, pandas }:
    buildPythonPackage rec {
      pname = "selfprivacy-api";
      version = "1.0";
      src = builtins.fetchGit {
        url = "https://git.selfprivacy.org/ilchub/selfprivacy-rest-api.git";
        rev = "d7a6b3ca12d936165a4fc1c6265a2dfc3fd6229e";
      };
      propagatedBuildInputs = [ flask flask-restful pandas ];
      meta = {
        description = ''
          SelfPrivacy Server Management API
        '';
      };
    };
  drv = pythonPkgs.callPackage selfprivacy-api {};
in
  if pkgs.lib.inNixShell then drv.env else drv
EOF

cat > /etc/nixos/api/api-service.nix << EOF
{ config, lib, pkgs, ... }:

with lib;

let
  selfprivacy-api = pkgs.callPackage ./api-package.nix {};
  cfg = config.services.selfprivacy-api;
  directionArg = if cfg.direction == ""
    then ""
    else "--direction=\${cfg.direction}";
in 
{
  options.services.selfprivacy-api = {
    enable = mkOption {
      default = false;
      type = types.bool;
      description = ''
        Enable SelfPrivacy API service
      '';
    };
  };
  config = lib.mkIf cfg.enable {

    systemd.services.selfprivacy-api = {
      description = "API Server used to control system from the mobile application";
      environment = {
        PYTHONUNBUFFERED = "1";
      };
      path = [ "/var/" "/var/dkim/" ];
      after = [ "network-online.target" ];
      wantedBy = [ "network-online.target" ];
      serviceConfig = {
        User = "root";
        PrivateDevices = "true";
        ProtectKernelTunables = "true";
        ProtectKernelModules = "true";
        LockPersonality = "true";
        RestrictRealtime = "true";
        SystemCallFilter = "@system-service @network-io @signal";
        SystemCallErrorNumber = "EPERM";
        ExecStart = "\${selfprivacy-api}/bin/main.py";
        Restart = "always";
        RestartSec = "5";
      };
    };
  };
}
EOF

cat > /etc/nixos/openconnect/shadowsocks.nix << EOF
{ pkgs, ...}:
{
  services = {
    shadowsocks = {
      enable = true;
      localAddress = [ "[::0]" "0.0.0.0" ];
      port = 8388;
      passwordFile = "/var/shadowsocks-password";
      mode = "tcp_and_udp";
      fastOpen = true;
      encryptionMethod = "chacha20-ietf-poly1305";
    };
  };
}
EOF

  [[ -n "$doNetConf" ]] && makeNetworkingConf
}

makeNetworkingConf() {
  # XXX It'd be better if we used procfs for all this...
  local IFS=$'\n'
  eth0_name=$(ip address show | grep '^2:' | awk -F': ' '{print $2}')
  eth0_ip4s=$(ip address show dev "$eth0_name" | grep 'inet ' | sed -r 's|.*inet ([0-9.]+)/([0-9]+).*|{ address="\1"; prefixLength=\2; }|')
  eth0_ip6s=$(ip address show dev "$eth0_name" | grep 'inet6 ' | sed -r 's|.*inet6 ([0-9a-f:]+)/([0-9]+).*|{ address="\1"; prefixLength=\2; }|' || '')
  gateway=$(ip route show dev "$eth0_name" | grep default | sed -r 's|default via ([0-9.]+).*|\1|')
  gateway6=$(ip -6 route show dev "$eth0_name" | grep default | sed -r 's|default via ([0-9a-f:]+).*|\1|' || true)
  ether0=$(ip address show dev "$eth0_name" | grep link/ether | sed -r 's|.*link/ether ([0-9a-f:]+) .*|\1|')

  eth1_name=$(ip address show | grep '^3:' | awk -F': ' '{print $2}')||true
  if [ -n "$eth1_name" ];then
    eth1_ip4s=$(ip address show dev "$eth1_name" | grep 'inet ' | sed -r 's|.*inet ([0-9.]+)/([0-9]+).*|{ address="\1"; prefixLength=\2; }|')
    eth1_ip6s=$(ip address show dev "$eth1_name" | grep 'inet6 ' | sed -r 's|.*inet6 ([0-9a-f:]+)/([0-9]+).*|{ address="\1"; prefixLength=\2; }|' || '')
    ether1=$(ip address show dev "$eth1_name" | grep link/ether | sed -r 's|.*link/ether ([0-9a-f:]+) .*|\1|')
    interfaces1=<< EOF
      $eth1_name = {
        ipv4.addresses = [$(for a in "${eth1_ip4s[@]}"; do echo -n "
          $a"; done)
        ];
        ipv6.addresses = [$(for a in "${eth1_ip6s[@]}"; do echo -n "
          $a"; done)
        ];
EOF
    extraRules1="ATTR{address}==\"${ether1}\", NAME=\"${eth1_name}\""
  else
    interfaces1=""
    extraRules1=""
  fi

  readarray nameservers < <(grep ^nameserver /etc/resolv.conf | sed -r 's/^nameserver[[:space:]]+([0-9.a-fA-F]+).*/"\1"/')

  if [[ "$eth0_name" = eth* ]]; then
    predictable_inames="usePredictableInterfaceNames = lib.mkForce false;"
  else
    predictable_inames="usePredictableInterfaceNames = lib.mkForce true;"
  fi
  cat > /etc/nixos/networking.nix << EOF
{ lib, ... }: {
  # This file was populated at runtime with the networking
  # details gathered from the active system.
  networking = {
    nameservers = [ ${nameservers[@]} ];
    defaultGateway = "${gateway}";
    defaultGateway6 = "${gateway6}";
    dhcpcd.enable = false;
    $predictable_inames
    interfaces = {
      $eth0_name = {
        ipv4.addresses = [$(for a in "${eth0_ip4s[@]}"; do echo -n "
          $a"; done)
        ];
        ipv6.addresses = [$(for a in "${eth0_ip6s[@]}"; do echo -n "
          $a"; done)
        ];
        ipv4.routes = [ { address = "${gateway}"; prefixLength = 32; } ];
        ipv6.routes = [ { address = "${gateway6}"; prefixLength = 32; } ];
      };
      $interfaces1
    };
  };
  services.udev.extraRules = ''
    ATTR{address}=="${ether0}", NAME="${eth0_name}"
    $extraRules1
  '';
}
EOF
}

makeSwap() {
  # TODO check currently available swapspace first
  swapFile=$(mktemp /tmp/nixos-infect.XXXXX.swp)
  dd if=/dev/zero "of=$swapFile" bs=1M count=$((1*1024))
  chmod 0600 "$swapFile"
  mkswap "$swapFile"
  swapon -v "$swapFile"
}

removeSwap() {
  swapoff -a
  rm -vf /tmp/nixos-infect.*.swp
}

prepareEnv() {
  # $grubdev is used in makeConf()
  for grubdev in /dev/vda /dev/sda; do [[ -e $grubdev ]] && break; done

  # Retrieve root fs block device
  #                   (get root mount)  (get partition or logical volume)
  rootfsdev=$(mount | grep "on / type" | awk '{print $1;}')

  # DigitalOcean doesn't seem to set USER while running user data
  export USER="root"
  export HOME="/root"

  # Nix installer tries to use sudo regardless of whether we're already uid 0
  #which sudo || { sudo() { eval "$@"; }; export -f sudo; }
  # shellcheck disable=SC2174
  mkdir -p -m 0755 /nix
}

fakeCurlUsingWget() {
  # Use adapted wget if curl is missing
  which wget && { \
    curl() {
      eval "wget $(
        (local isStdout=1
        for arg in "$@"; do
          case "$arg" in
            "-o")
              echo "-O";
              isStdout=0
              ;;
            "-O")
              isStdout=0
              ;;
            "-L")
              ;;
            *)
              echo "$arg"
              ;;
          esac
        done;
        [[ $isStdout -eq 1 ]] && echo "-O-"
        )| tr '\n' ' '
      )"
    }; export -f curl; }
}

req() {
  type "$1" > /dev/null 2>&1 || which "$1" > /dev/null 2>&1
}

checkEnv() {
  # Perform some easy fixups before checking
  # TODO prevent multiple calls to apt-get update
  which dnf && dnf install -y perl-Digest-SHA # Fedora 24
  which bzcat || (which yum && yum install -y bzip2) \
              || (which apt-get && apt-get update && apt-get install -y bzip2) \
              || true
  which xzcat || (which yum && yum install -y xz-utils) \
              || (which apt-get && apt-get update && apt-get install -y xz-utils) \
              || true
  which curl  || fakeCurlUsingWget \
              || (which apt-get && apt-get update && apt-get install -y curl) \
              || true

  [[ "$(whoami)" == "root" ]] || { echo "ERROR: Must run as root"; return 1; }

  req curl || req wget || { echo "ERROR: Missing both curl and wget"; return 1; }
  req bzcat            || { echo "ERROR: Missing bzcat";              return 1; }
  req xzcat            || { echo "ERROR: Missing xzcat";              return 1; }
  req groupadd         || { echo "ERROR: Missing groupadd";           return 1; }
  req useradd          || { echo "ERROR: Missing useradd";            return 1; }
  req ip               || { echo "ERROR: Missing ip";                 return 1; }
  req awk              || { echo "ERROR: Missing awk";                return 1; }
  req cut              || { echo "ERROR: Missing cut";                return 1; }
}

infect() {
  # Add nix build users
  # FIXME run only if necessary, rather than defaulting true
  groupadd nixbld -g 30000 || true
  for i in {1..10}; do
    useradd -c "Nix build user $i" -d /var/empty -g nixbld -G nixbld -M -N -r -s "$(which nologin)" "nixbld$i" || true
  done
  # TODO use addgroup and adduser as fallbacks
  #addgroup nixbld -g 30000 || true
  #for i in {1..10}; do adduser -DH -G nixbld nixbld$i || true; done

  curl -L https://nixos.org/nix/install | $SHELL

  # shellcheck disable=SC1090
  source ~/.nix-profile/etc/profile.d/nix.sh

  [[ -z "$NIX_CHANNEL" ]] && NIX_CHANNEL="nixos-19.09"
  nix-channel --remove nixpkgs
  nix-channel --add "https://nixos.org/channels/$NIX_CHANNEL" nixos
  nix-channel --update

  export NIXOS_CONFIG=/etc/nixos/configuration.nix

  nix-env --set \
    -I nixpkgs=$HOME/.nix-defexpr/channels/nixos \
    -f '<nixpkgs/nixos>' \
    -p /nix/var/nix/profiles/system \
    -A system

  # Remove nix installed with curl | bash
  rm -fv /nix/var/nix/profiles/default*
  /nix/var/nix/profiles/system/sw/bin/nix-collect-garbage

  # Reify resolv.conf
  [[ -L /etc/resolv.conf ]] && mv -v /etc/resolv.conf /etc/resolv.conf.lnk && cat /etc/resolv.conf.lnk > /etc/resolv.conf

  # Stage the Nix coup d'état
  touch /etc/NIXOS
  echo etc/nixos                   > /etc/NIXOS_LUSTRATE
  echo etc/resolv.conf            >> /etc/NIXOS_LUSTRATE
  echo root/.nix-defexpr/channels >> /etc/NIXOS_LUSTRATE

  rm -rf /boot.bak
  mv -v /boot /boot.bak
  /nix/var/nix/profiles/system/bin/switch-to-configuration boot
}

[ "$PROVIDER" = "digitalocean" ] && doNetConf=y # digitalocean requires detailed network config to be generated


prepareEnv
makeSwap # smallest (512MB) droplet needs extra memory!
checkEnv
makeConf
infect
removeSwap

if [[ -z "$NO_REBOOT" ]]; then
  reboot
fi