lv2: use brewed python

Formula/lv2.rb

@@ -1,9 +1,13 @@
 class Lv2 < Formula
+  include Language::Python::Shebang
+  include Language::Python::Virtualenv
+
   desc "Portable plugin standard for audio systems"
   homepage "https://lv2plug.in/"
   url "https://lv2plug.in/spec/lv2-1.18.2.tar.bz2"
   sha256 "4e891fbc744c05855beb5dfa82e822b14917dd66e98f82b8230dbd1c7ab2e05e"
   license "ISC"
+  revision 1
 
   livecheck do
     url "https://lv2plug.in/spec/"
@@ -18,11 +22,69 @@ class Lv2 < Formula
     sha256 cellar: :any_skip_relocation, all:           "6cfa4a566aeb2febb8b912f9c9311a9e4c51b7044694abb425276964016fd099"
   end
 
-  depends_on :macos # Due to Python 2
+  depends_on "[email protected]"
+  depends_on "six"
+
+  # importlib_metadata can be removed after switching this formula to use [email protected] (or newer)
+  resource "importlib_metadata" do
+    url "https://files.pythonhosted.org/packages/73/0f/def168c6162596051dcc6acaffc4984ec742eb0c79ce02e51ddc11772b1c/importlib_metadata-4.11.2.tar.gz"
+    sha256 "b36ffa925fe3139b2f6ff11d6925ffd4fa7bc47870165e3ac260ac7b4f91e6ac"
+  end
+
+  resource "isodate" do
+    url "https://files.pythonhosted.org/packages/db/7a/c0a56c7d56c7fa723988f122fa1f1ccf8c5c4ccc48efad0d214b49e5b1af/isodate-0.6.1.tar.gz"
+    sha256 "48c5881de7e8b0a0d648cb024c8062dc84e7b840ed81e864c7614fd3c127bde9"
+  end
+
+  resource "Markdown" do
+    url "https://files.pythonhosted.org/packages/15/06/d60f21eda994b044cbd496892d4d4c5c708aa597fcaded7d421513cb219b/Markdown-3.3.6.tar.gz"
+    sha256 "76df8ae32294ec39dcf89340382882dfa12975f87f45c3ed1ecdb1e8cefc7006"
+  end
+
+  resource "Pygments" do
+    url "https://files.pythonhosted.org/packages/94/9c/cb656d06950268155f46d4f6ce25d7ffc51a0da47eadf1b164bbf23b718b/Pygments-2.11.2.tar.gz"
+    sha256 "4e426f72023d88d03b2fa258de560726ce890ff3b630f88c21cbb8b2503b8c6a"
+  end
+
+  resource "rdflib" do
+    url "https://files.pythonhosted.org/packages/42/ff/00084798ba8d21f9e79044c4b8e56d0fca4bb7dd428ae693bcbfdbaa4a06/rdflib-6.1.1.tar.gz"
+    sha256 "8dbfa0af2990b98471dacbc936d6494c997ede92fd8ed693fb84ee700ef6f754"
+  end
+
+  # Dependency of importlib_metadata, remove with importlib_metadata
+  resource "zipp" do
+    url "https://files.pythonhosted.org/packages/94/64/3115548d41cb001378099cb4fc6a6889c64ef43ac1b0e68c9e80b55884fa/zipp-3.7.0.tar.gz"
+    sha256 "9f50f446828eb9d45b267433fd3e9da8d801f614129124863f9c51ebceafb87d"
+  end
 
   def install
-    system "./waf", "configure", "--prefix=#{prefix}", "--no-plugins", "--lv2dir=#{lib}"
-    system "./waf", "build"
-    system "./waf", "install"
+    # Python resources and virtualenv are for the lv2specgen.py script that is installed
+    venv = virtualenv_create(libexec, Formula["[email protected]"].opt_bin/"python3")
+    venv.pip_install resources
+    rw_info = python_shebang_rewrite_info("#{libexec}/bin/python3")
+    rewrite_shebang rw_info, *Dir.glob("lv2specgen/*.py")
+
+    system Formula["[email protected]"].opt_bin/"python3", "./waf", "configure",
+           "--prefix=#{prefix}", "--no-plugins", "--lv2dir=#{lib}"
+    system Formula["[email protected]"].opt_bin/"python3", "./waf", "build"
+    system Formula["[email protected]"].opt_bin/"python3", "./waf", "install"
+
+    (pkgshare/"example").install "plugins/eg-amp.lv2/amp.c"
+  end
+
+  test do
+    output = shell_output("#{bin}/lv2specgen.py --help")
+
+    # lv2specgen.py will only display help text if it is able to load required Python modules
+    assert_match "Write HTML documentation for an RDF ontology.", output
+
+    # Pygments support in lv2specgen.py is optional, ensure that there were no errors in loading Pygments
+    refute_match "Error importing pygments, syntax highlighting disabled.", output
+
+    # Try building a simple lv2 plugin
+    dynamic_flag = OS.mac? ? "-dynamiclib" : "-shared"
+    system ENV.cc, pkgshare/"example/amp.c", "-I#{include}",
+           "-DEG_AMP_LV2_VERSION=1.0.0", "-DHAVE_LV2=1", "-fPIC", dynamic_flag,
+           "-o", shared_library("amp")
   end
 end