nixpkgs/pkgs/development/erlang-modules/build-hex.nix

{ stdenv, erlang, rebar3, openssl, libyaml, fetchHex, fetchFromGitHub,
  rebar3-pc, buildEnv }:

{ name, version, sha256
, hexPkg ? name
, buildInputs ? [], erlangDeps ? [], pluginDeps ? []
, postPatch ? ""
, compilePorts ? false
, meta ? {}
, ... }@attrs:

with stdenv.lib;

let
  plugins = pluginDeps ++ (if compilePorts then [rebar3-pc] else []);
  getDeps = drv: [drv] ++ (map getDeps drv.erlangDeps);
  recursiveDeps = unique (flatten (map getDeps erlangDeps));
  recursivePluginsDeps = unique (flatten (map getDeps plugins));

  erlEnv = drv: buildEnv {
    name = "erlang-env-${drv.name}";
    paths = [ drv ] ++ recursiveDeps;
    ignoreCollisions = false;
    meta = drv.meta;
  };

  shell = drv: let
    drvEnv = erlEnv drv;
  in stdenv.mkDerivation {
    name = "interactive-shell-${drv.name}";
    nativeBuildInputs = [ erlang drvEnv ];
    shellHook = ''
      export ERL_LIBS="${drvEnv}";
    '';
  };
  pkg = self: stdenv.mkDerivation (attrs // {
    name = "${name}-${version}";

    buildInputs = buildInputs ++ [ erlang rebar3 openssl libyaml ];

    src = fetchHex {
      pkg = hexPkg;
      inherit version;
      inherit sha256;
    };

    postPatch = ''
      rm -f rebar rebar3
      if [ -e "src/${name}.app.src" ]; then
        sed -i -e 's/{ *vsn *,[^}]*}/{vsn, "${version}"}/' "src/${name}.app.src"
      fi

      ${if compilePorts then ''
        echo "{plugins, [pc]}." >> rebar.config
      '' else ''''}

      ${rebar3.setupRegistry}

      ${postPatch}
    '';

    configurePhase = ''
      runHook preConfigure
      ${concatMapStrings (dep: ''
        header "linking erlang dependency ${dep}"
        ln -s "${dep}/${dep.name}" "_build/default/lib/${dep.name}"
        stopNest
      '') recursiveDeps}
      ${concatMapStrings (dep: ''
        header "linking rebar3 plugins ${dep}"
        ln -s "${dep}/${dep.name}" "_build/default/plugins/${dep.name}"
        stopNest
      '') recursivePluginsDeps}
      runHook postConfigure
    '';

    buildPhase = ''
      runHook preBuild
      HOME=. rebar3 compile
      ${if compilePorts then ''
        HOME=. rebar3 pc compile
      '' else ''''}
      runHook postBuild
    '';

    installPhase = ''
      runHook preInstall
      mkdir -p "$out/${name}"
      for reldir in src ebin priv include; do
        fd="_build/default/lib/${name}/$reldir"
        [ -d "$fd" ] || continue
        cp -Hrt "$out/${name}" "$fd"
        success=1
      done
      runHook postInstall
    '';

    meta = {
      inherit (erlang.meta) platforms;
    } // meta;

    passthru = {
      packageName = name;
      env = shell self;
      inherit erlangDeps;
    };
  });
in
  fix pkg