fontforge: Enable Python extension

Build the Python extension by default and install it to the right location.

Fixes #4689.
Closes #12535.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Library/Formula/fontforge.rb

@@ -27,10 +27,23 @@ def install
             "--enable-double",
             "--without-freetype-bytecode"]
 
-    args << "--without-python" if ARGV.include? "--without-python"
+    if ARGV.include? "--without-python"
+      args << "--without-python"
+    else
+      python_prefix = `python-config --prefix`.strip
+      python_version = `python-config --libs`.match('-lpython(\d+\.\d+)').captures.at(0)
+      args << "--with-python-headers=#{python_prefix}/include/python#{python_version}"
+      args << "--with-python-lib=-lpython#{python_version}"
+      args << "--enable-pyextension"
+    end
 
+    # Fix linking to correct Python library
+    ENV.prepend "LDFLAGS", "-L#{python_prefix}/lib" unless ARGV.include? "--without-python"
     # Fix linker error; see: http://trac.macports.org/ticket/25012
     ENV.append "LDFLAGS", "-lintl"
+    # Reset ARCHFLAGS to match how we build
+    ENV["ARCHFLAGS"] = MacOS.prefer_64_bit? ? "-arch x86_64" : "-arch i386"
+
     system "./configure", *args
 
     # Fix hard-coded install locations that don't respect the target bindir
@@ -39,6 +52,12 @@ def install
       s.gsub! "ln -s /usr/local/bin/fontforge", "ln -s $(bindir)/fontforge"
     end
 
+    # Fix install location of Python extension; see:
+    # http://sourceforge.net/mailarchive/message.php?msg_id=26827938
+    inreplace "Makefile" do |s|
+      s.gsub! "python setup.py install --prefix=$(prefix) --root=$(DESTDIR)", "python setup.py install --prefix=$(prefix)"
+    end
+
     # Fix hard-coded include file paths. Reported usptream:
     # http://sourceforge.net/mailarchive/forum.php?thread_name=C1A32103-A62D-468B-AD8A-A8E0E7126AA5%40smparkes.net&forum_name=fontforge-devel
     # https://trac.macports.org/ticket/33284
@@ -51,13 +70,29 @@ def install
     system "make install"
   end
 
-  def caveats; <<-EOS.undent
-    fontforge is an X11 application.
+  def which_python
+    "python" + `python -c 'import sys;print(sys.version[:3])'`.strip
+  end
 
-    To install the Mac OS X wrapper application run:
+  def caveats
+    general_caveats = <<-EOS.undent
+      fontforge is an X11 application.
+
+      To install the Mac OS X wrapper application run:
         brew linkapps
-    or:
+      or:
         ln -s #{prefix}/FontForge.app /Applications
     EOS
+
+    python_caveats = <<-EOS.undent
+
+      To use the Python extension with non-homebrew Python, you need to amend your
+      PYTHONPATH like so:
+        export PYTHONPATH=#{HOMEBREW_PREFIX}/lib/#{which_python}/site-packages:$PYTHONPATH
+    EOS
+
+    s = general_caveats
+    s += python_caveats unless ARGV.include? "--without-python"
+    return s
   end
 end