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

let
  cfg = config.nixosWorkstations.workstationSetup;

  passwordHelper = pkgs.writeTextFile {
    name = "nixos-workstations-password-helper";
    executable = true;
    text = ''
      #!${pkgs.expect}/bin/expect -f

      # Les secrets arrivent uniquement par stdin depuis l'application.
      # Ils ne sont jamais passés dans argv et aucun transcript n'est affiché.
      log_user 0
      exp_internal 0
      set timeout 30

      if {[gets stdin current] < 0 || [gets stdin newpass] < 0 || [gets stdin confirm] < 0} {
        puts stderr "INPUT_ERROR"
        exit 20
      }

      if {$newpass ne $confirm} {
        puts stderr "CONFIRM_MISMATCH"
        exit 21
      }

      spawn -noecho ${pkgs.coreutils}/bin/env LC_ALL=C LANG=C /run/wrappers/bin/passwd

      expect {
        -re {(?i)(current.*password|unix password|password.*current).*:} {
          send -- "$current\r"
        }
        eof {
          puts stderr "CURRENT_REJECTED"
          exit 22
        }
        timeout {
          puts stderr "TIMEOUT_CURRENT"
          exit 124
        }
      }

      # Efface la copie du mot de passe actuel dès qu'elle n'est plus utile.
      set current ""

      expect {
        -re {(?i)new.*password.*:} {
          send -- "$newpass\r"
        }
        eof {
          puts stderr "CURRENT_REJECTED"
          exit 23
        }
        timeout {
          puts stderr "TIMEOUT_NEW"
          exit 124
        }
      }

      expect {
        -re {(?i)(retype|repeat|confirm).*password.*:} {
          send -- "$confirm\r"
        }
        -re {(?i)new.*password.*:} {
          puts stderr "NEW_REJECTED"
          exit 24
        }
        eof {
          puts stderr "NEW_REJECTED"
          exit 25
        }
        timeout {
          puts stderr "TIMEOUT_CONFIRM"
          exit 124
        }
      }

      set newpass ""
      set confirm ""

      expect eof
      set waitResult [wait]
      set exitCode [lindex $waitResult 3]

      if {$exitCode == 0} {
        puts "OK"
        exit 0
      }

      puts stderr "PASSWD_FAILED"
      exit $exitCode
    '';
  };

  pinHelper = pkgs.writeTextFile {
    name = "nixos-workstations-pin-helper";
    executable = true;
    text = ''
      #!${pkgs.expect}/bin/expect -f

      # Même principe que pour passwd : aucune valeur secrète dans argv.
      log_user 0
      exp_internal 0
      set timeout 30

      if {[gets stdin current] < 0 || [gets stdin newpin] < 0 || [gets stdin confirm] < 0} {
        puts stderr "INPUT_ERROR"
        exit 30
      }

      if {$newpin ne $confirm} {
        puts stderr "CONFIRM_MISMATCH"
        exit 31
      }

      spawn -noecho ${pkgs.coreutils}/bin/env LC_ALL=C LANG=C ${pkgs.yubikey-manager}/bin/ykman fido access change-pin

      set transcript ""

      expect {
        -re {Enter your current PIN.*:} {
          append transcript $expect_out(buffer)
          send -- "$current\r"
        }
        -re {No YubiKey|Failed to connect|No FIDO} {
          puts stderr "NO_YUBIKEY"
          exit 32
        }
        eof {
          append transcript $expect_out(buffer)
          if {[regexp -nocase {No YubiKey|Failed to connect|No FIDO} $transcript]} {
            puts stderr "NO_YUBIKEY"
          } else {
            puts stderr "PIN_FAILED"
          }
          exit 33
        }
        timeout {
          puts stderr "TIMEOUT_CURRENT_PIN"
          exit 124
        }
      }

      set current ""

      expect {
        -re {Enter your new PIN.*:} {
          append transcript $expect_out(buffer)
          send -- "$newpin\r"
        }
        eof {
          append transcript $expect_out(buffer)
          puts stderr "PIN_FAILED"
          exit 34
        }
        timeout {
          puts stderr "TIMEOUT_NEW_PIN"
          exit 124
        }
      }

      expect {
        -re {(?i)(repeat|confirm).*:} {
          append transcript $expect_out(buffer)
          send -- "$confirm\r"
        }
        eof {
          append transcript $expect_out(buffer)
          puts stderr "PIN_FAILED"
          exit 35
        }
        timeout {
          puts stderr "TIMEOUT_CONFIRM_PIN"
          exit 124
        }
      }

      set newpin ""
      set confirm ""

      expect eof
      append transcript $expect_out(buffer)
      set waitResult [wait]
      set exitCode [lindex $waitResult 3]

      if {$exitCode == 0} {
        puts "OK"
        exit 0
      }

      if {[regexp -nocase {Wrong PIN|PIN_INVALID} $transcript]} {
        puts stderr "WRONG_PIN"
      } elseif {[regexp -nocase {authentication is currently blocked|PIN_AUTH_BLOCKED} $transcript]} {
        puts stderr "PIN_AUTH_BLOCKED"
      } elseif {[regexp -nocase {PIN is blocked|PIN_BLOCKED} $transcript]} {
        puts stderr "PIN_BLOCKED"
      } elseif {[regexp -nocase {No YubiKey|Failed to connect|No FIDO} $transcript]} {
        puts stderr "NO_YUBIKEY"
      } elseif {[regexp -nocase {complexity|policy|at least|at most} $transcript]} {
        puts stderr "PIN_POLICY"
      } else {
        puts stderr "PIN_FAILED"
      }

      exit $exitCode
    '';
  };

  workstationSetup = pkgs.stdenv.mkDerivation {
    pname = "nixos-workstations-setup";
    version = "1.0.0";

    src = ../workstation-setup;

    nativeBuildInputs = [
      pkgs.cmake
      pkgs.ninja
      pkgs.pkg-config
      pkgs.kdePackages.wrapQtAppsHook
    ];

    buildInputs = with pkgs.kdePackages; [
      qtbase
      qtdeclarative
      qtwayland
      kirigami
    ];

    cmakeFlags = [
      "-DPASSWORD_HELPER_PATH=${passwordHelper}"
      "-DPIN_HELPER_PATH=${pinHelper}"
      "-DTARGET_USER=${cfg.user}"
    ];
  };

  launcher = pkgs.writeShellScript "nixos-workstations-setup-launcher" ''
    set -eu

    if [ "$(${pkgs.coreutils}/bin/id -un)" != ${lib.escapeShellArg cfg.user} ]; then
      exit 0
    fi

    state_dir="''${XDG_STATE_HOME:-$HOME/.local/state}/nixos-workstations"
    password_marker="$state_dir/password-initialized"
    pin_marker="$state_dir/yubikey-pin-initialized"

    if [ -e "$password_marker" ] && [ -e "$pin_marker" ]; then
      exit 0
    fi

    # Ne jamais générer de core dump contenant potentiellement un secret.
    ulimit -c 0

    # Laisse Plasma finir son démarrage sans créer de logique de supervision
    # susceptible de tuer ou manipuler la session utilisateur.
    ${pkgs.coreutils}/bin/sleep 3

    exec ${workstationSetup}/bin/nixos-workstations-setup
  '';

in
{
  options.nixosWorkstations.workstationSetup = {
    enable = lib.mkEnableOption "assistant plein écran de finalisation du poste";

    user = lib.mkOption {
      type = lib.types.str;
      default = "alice";
      description = "Utilisateur devant effectuer la personnalisation initiale.";
    };
  };

  config = lib.mkIf cfg.enable {
    environment.systemPackages = [
      workstationSetup
      pkgs.yubikey-manager
    ];

    environment.etc."xdg/autostart/nixos-workstations-setup.desktop".text = ''
      [Desktop Entry]
      Type=Application
      Name=Finalisation du poste
      Comment=Personnalisation sécurisée des moyens d'authentification
      Exec=${launcher}
      OnlyShowIn=KDE;
      NoDisplay=true
      StartupNotify=false
    '';
  };
}