# NixOS and other nix users: the desktop front end (Qt Quick) with the engine
# it embeds, built and installed the nix way.
#
#   nix-build                  # ./result/bin/cst-agent-app, run it in place
#   nix-env -f . -i cst-agent  # into the user profile: PATH, menu entry, icon
#
# The Qt apps hook is what makes the installed binary find Qt's plugins and
# QML modules outside a nix-shell (this is also what keeps them out of
# nix-collect-garbage's reach). Only the window is installed: the CLI has its
# own installer, scripts/bootstrap_linux.sh.
{ pkgs ? import <nixpkgs> { } }:

let
  # The version lives in one place: the header the engine and the APK read.
  vLine = re:
    let
      hit = pkgs.lib.findFirst
        (l: builtins.match "#define ${re} ([0-9]+)" l != null) ""
        (pkgs.lib.splitString "\n" (builtins.readFile ./include/cst_version.h));
    in
    builtins.head (builtins.match "#define ${re} ([0-9]+)" hit);
in
pkgs.stdenv.mkDerivation {
  pname = "cst-agent";
  version =
    "${vLine "CST_VERSION_MAJOR"}.${vLine "CST_VERSION_MINOR"}.${vLine "CST_VERSION_PATCH"}";

  # Not the whole checkout: third_party/ (the static curl/mbedTLS/ncurses
  # sources, the NDK builds), the build directories and the session store are
  # gigabytes this build never reads -- curl, ncurses and Qt come from nixpkgs.
  src = builtins.filterSource
    (path: type:
      !(builtins.elem (baseNameOf path) [
        ".agent"
        ".cursor"
        ".gen"
        ".git"
        "build-android-arm64-v8a"
        "build-apk-android"
        "build-win-tui"
        "dist"
        "result"
        "third_party"
      ]))
    ./.;

  nativeBuildInputs = with pkgs; [ cmake pkg-config qt6.wrapQtAppsHook ];
  # qtwayland so a Wayland session gets a native client, qtsvg for the icon
  # theme: Breeze's icons are SVG, and without the image format plugin the
  # window falls back to text glyphs.
  buildInputs = with pkgs; [
    qt6.qtbase
    qt6.qtdeclarative
    qt6.qtwayland
    qt6.qtsvg
    curl
    curl.dev
    ncurses
    ncurses.dev
  ];

  cmakeFlags = [ "-DCST_BUILD_APP=ON" "-DCMAKE_BUILD_TYPE=Release" ];

  # The "app" component is the window, its launcher entry and the icon;
  # app/CMakeLists.txt is the one place that knows where each goes.
  installPhase = ''
    runHook preInstall
    cmake --install . --component app --prefix "$out"
    runHook postInstall
  '';

  doCheck = true;
  # One test cannot pass here: tests/test_sandbox.c has the engine run a
  # sandboxed command and asserts Landlock *denied* the write outside the
  # workspace, and Landlock does not work inside the nix build sandbox -- the
  # command succeeds and the assertion trips. The other 40 run; the full set
  # is `make check` / `ctest` in the dev tree.
  checkPhase = ''
    runHook preCheck
    ctest --output-on-failure -j"$NIX_BUILD_CORES" -E test_sandbox
    runHook postCheck
  '';
  # The tests write settings, sessions, undo files and a scratch workspace:
  # give them a home of their own.
  preCheck = ''
    export HOME="$TMPDIR/home"
    export XDG_CONFIG_HOME="$HOME/.config" XDG_CACHE_HOME="$HOME/.cache"
    export XDG_DATA_HOME="$HOME/.local/share"
    mkdir -p "$XDG_CONFIG_HOME" "$XDG_CACHE_HOME" "$XDG_DATA_HOME"
  '';

  meta = {
    description =
      "Local coding agent: Qt Quick front end with the engine in-process";
    homepage = "https://git.whcself.xyz/WHC/CST-agent";
    platforms = pkgs.lib.platforms.linux;
    mainProgram = "cst-agent-app";
  };
}