nzbget: use resources

Formula/nzbget.rb

@@ -1,17 +1,5 @@
 require 'formula'
 
-class Libpar2 < Formula
-  homepage 'http://parchive.sourceforge.net/'
-  url 'https://downloads.sourceforge.net/project/parchive/libpar2/0.2/libpar2-0.2.tar.gz'
-  sha1 '4b3da928ea6097a8299aadafa703fc6d59bdfb4b'
-
-  # Bugfixes and ability to cancel par2 repair
-  patch do
-    url "https://gist.github.com/raw/4576230/e722f2113195ee9b8ee67c1c424aa3f2085b1066/libpar2-0.2-nzbget.patch"
-    sha1 "0dca03f42c0997fd6b537a7dc539d705afb76157"
-  end
-end
-
 class Nzbget < Formula
   homepage 'http://sourceforge.net/projects/nzbget/'
   url 'https://downloads.sourceforge.net/project/nzbget/nzbget-stable/12.0/nzbget-12.0.tar.gz'
@@ -24,23 +12,38 @@ class Nzbget < Formula
 
   fails_with :clang do
     build 500
-    cause "Clang older than 5.1 requires flexible array members to be trivially destructible"
+    cause <<-EOS.undent
+      Clang older than 5.1 requires flexible array members to be POD types.
+      More recent versions require only that they be trivially destructible.
+      EOS
+  end
+
+  resource "libpar2" do
+    url "https://downloads.sourceforge.net/project/parchive/libpar2/0.2/libpar2-0.2.tar.gz"
+    sha1 "4b3da928ea6097a8299aadafa703fc6d59bdfb4b"
+  end
+
+  # Bugfixes and ability to cancel par2 repair
+  resource "libpar2_patch" do
+    url "https://gist.github.com/raw/4576230/e722f2113195ee9b8ee67c1c424aa3f2085b1066/libpar2-0.2-nzbget.patch"
+    sha1 "0dca03f42c0997fd6b537a7dc539d705afb76157"
   end
 
   def install
-    # Install libpar2 privately
-    libpar2_prefix = libexec/'libpar2'
-    Libpar2.new('libpar2').brew do
+    resource("libpar2").stage do
+      buildpath.install resource("libpar2_patch")
+      system "patch -p1 < #{buildpath}/libpar2-0.2-nzbget.patch"
+
       system "./configure", "--disable-debug", "--disable-dependency-tracking",
-                            "--prefix=#{libpar2_prefix}"
+                            "--prefix=#{libexec}/lp2"
       system "make install"
     end
 
     # Tell configure where libpar2 is, and tell it to use OpenSSL
     system "./configure", "--disable-debug", "--disable-dependency-tracking",
                           "--prefix=#{prefix}",
-                          "--with-libpar2-includes=#{libpar2_prefix}/include",
-                          "--with-libpar2-libraries=#{libpar2_prefix}/lib",
+                          "--with-libpar2-includes=#{libexec}/lp2/include",
+                          "--with-libpar2-libraries=#{libexec}/lp2/lib",
                           "--with-tlslib=OpenSSL"
     system "make"
     ENV.j1