{ lib, stdenv, fetchgit, elixir, erlang, rebar3, git, writeShellScript }:

let
  systantBase = stdenv.mkDerivation rec {
    pname = "systant-base";
    version = "0.1.0";

    src = fetchgit {
      url = "https://git.ryanpandya.com/ryan/systant.git";
      rev = "f8173a1afb03623039ff504c587d7322a9876f3d";
      sha256 = "sha256-1cRfSoH+JdO4a7q4hRZSkoDMk2wMCYRIyCIN56FSUgg=";
    };

    nativeBuildInputs = [ elixir erlang rebar3 git ];

    MIX_ENV = "prod";
    
    configurePhase = ''
      export MIX_HOME=$TMPDIR/mix
      export HEX_HOME=$TMPDIR/hex
      export REBAR_CACHE_DIR=$TMPDIR/rebar3
      
      mix local.hex --force
      mix local.rebar --force
    '';

    buildPhase = ''
      mix deps.get || true
      mix deps.compile || true
      mix compile
      mix release
    '';

    installPhase = ''
      mkdir -p $out
      cp -r _build/prod/rel/systant/* $out/
    '';
  };

  systantWrapper = writeShellScript "systant" ''
    #!/bin/bash
    export RELEASE_COOKIE="systant-cookie-change-in-production"
    exec ${systantBase}/bin/systant "$@"
  '';

in stdenv.mkDerivation {
  pname = "systant";
  version = "0.1.0";
  
  buildCommand = ''
    mkdir -p $out/bin
    cp ${systantWrapper} $out/bin/systant
    chmod +x $out/bin/systant
    
    # Copy the rest of the release
    cp -r ${systantBase}/* $out/
    
    echo "Wrapper created - RELEASE_COOKIE will be set by wrapper script"
  '';

  meta = with lib; {
    description = "Systant - System stats MQTT daemon";
    homepage = "https://git.ryanpandya.com/ryan/systant";
    license = licenses.mit;
    platforms = platforms.linux;
  };
}