peerspeak/flake.nix

{
  description = "PeerSpeak — decentralized P2P voice chat (Rust/iroh/PipeWire/Opus/iced)";

  # Pinned to the same channel the hosts run (nixos-config tracks nixos-26.05),
  # so the libraries this shell links and dlopens are built against the same
  # release as the PipeWire daemon and Vulkan ICD actually running on the
  # machine. Floating to unstable here would reintroduce precisely the
  # client/server version skew the pin exists to prevent.
  inputs.nixpkgs.url = "github:nixos/nixpkgs/nixos-26.05";

  outputs =
    { nixpkgs, ... }:
    let
      system = "x86_64-linux";
      pkgs = nixpkgs.legacyPackages.${system};

      # Libraries that iced/winit/wgpu open with dlopen at RUNTIME rather than
      # linking at build time. Because nothing links them, they never land in
      # the binary's rpath — under `cargo run` the loader finds them only
      # through LD_LIBRARY_PATH. Leaving them out builds fine and then panics
      # at window creation, which is a genuinely confusing failure, so they are
      # listed explicitly instead of discovered the hard way.
      runtimeLibs = with pkgs; [
        vulkan-loader # wgpu's Vulkan backend (iced's renderer)
        libxkbcommon # winit keyboard handling
        wayland # wayland-sys, dlopen'd on a Wayland session
        libx11 # x11-dl, dlopen'd on the X11 fallback path
        libxcursor
        libxrandr
        libxi
      ];

      # Screen sharing spawns pixelpass as a CHILD PROCESS, and pixelpass in
      # turn drives GStreamer as a subprocess. That makes these tools a
      # dependency of peerspeak's own test suite, not just of pixelpass:
      # `tests/screenshare_host_fault.rs` starts a real pixelpass host, which
      # aborts at its preflight if gst-launch-1.0 is missing.
      #
      # Deliberately duplicated from pixelpass's flake rather than importing it
      # as an input. The two projects are mutually optional by design — neither
      # is a dependency of the other, and the coupling is a runtime subprocess
      # contract. Making one flake consume the other would quietly reintroduce
      # exactly the build-level dependency that rule exists to prevent.
      screenshareTools = with pkgs; [
        gst_all_1.gstreamer
        gst_all_1.gst-plugins-base
        gst_all_1.gst-plugins-good
        gst_all_1.gst-plugins-bad
        gst_all_1.gst-plugins-ugly
        gst_all_1.gst-libav
        pipewire # pipewiresrc (Wayland capture; ships in this pkg)
      ];
    in
    {
      devShells.${system}.default = pkgs.mkShell {
        nativeBuildInputs = with pkgs; [
          rustc
          cargo
          rustfmt
          clippy

          # The supply-chain gates .gitea/workflows/ci.yml runs, so the same
          # checks are reproducible locally before a push. These were `cargo
          # install`ed on the CachyOS side, which does not carry over — those
          # binaries link that distro's glibc and will not run here.
          # cargo-deny reads deny.toml; cargo-audit reads .cargo/audit.toml.
          cargo-audit
          cargo-deny
          # Debian packaging (`cargo deb --no-build`). Note the .deb itself
          # should still be built inside a Debian/Ubuntu distrobox so the
          # binary links that distro's glibc — see the packaging notes in
          # Cargo.toml.
          cargo-deb

          pkg-config

          # pipewire-sys and libspa-sys generate their bindings with bindgen,
          # which needs a real libclang present at build time.
          clang

          # audiopus_sys prefers the system libopus via pkg-config but falls
          # back to a vendored CMake build; cmake keeps that fallback working
          # rather than failing obscurely inside a build script.
          cmake

          # build.rs shells out to `git rev-parse --short=8 HEAD` to stamp
          # PEERSPEAK_GIT_SHORT into the binary (surfaced in Settings).
          git
        ]
        ++ screenshareTools
        ++ [
          pkgs.pulseaudio # `pactl`, used by pixelpass's audio routing
          pkgs.mpv # the screen-share viewer
        ];

        buildInputs =
          with pkgs;
          [
            alsa-lib # alsa-sys, pulled in by rodio/cpal
            libopus # audiopus_sys, linked dynamically
            pipewire # pipewire-sys + libspa-sys: the Linux audio backend
          ]
          ++ runtimeLibs;

        # bindgen finds libclang through this variable specifically — having
        # clang on PATH is not sufficient.
        LIBCLANG_PATH = "${pkgs.llvmPackages.libclang.lib}/lib";

        LD_LIBRARY_PATH = pkgs.lib.makeLibraryPath runtimeLibs;

        # NixOS keeps every GStreamer plugin in its own store path, so the
        # gst-launch-1.0 that pixelpass spawns discovers them ONLY through this
        # search path. Same reasoning as hosts/darp5 and hosts/cazen in
        # nixos-config.
        GST_PLUGIN_SYSTEM_PATH_1_0 =
          pkgs.lib.makeSearchPathOutput "lib" "lib/gstreamer-1.0" screenshareTools;

        # Only greet an interactive shell. shellHook also runs under
        # `nix develop --command …`, where printing this would interleave the
        # banner with the command's own output.
        shellHook = ''
          if [ -t 1 ]; then
            echo "peerspeak — rustc $(rustc --version | cut -d' ' -f2) / cargo $(cargo --version | cut -d' ' -f2)"
            echo "  cargo build --release                       build"
            echo "  cargo test                                  lib tests"
            echo "  cargo clippy --all-targets -- -D warnings    lint"
            echo
            echo "Screen sharing spawns pixelpass as a child process — it must be"
            echo "on PATH. Build it from ../pixelpass and add its target/release."
          fi
        '';
      };
    };
}