Alternative arrangement for node and iojs

This PR
- takes iojs out of keg-only
- conflicts node and iojs
- patches iojs’s installed npm
- currently leaves in the iojs patch flag from Homebrew#36357

Library/Formula/iojs.rb

@@ -9,29 +9,99 @@ class Iojs < Formula
     sha1 "f62a32113ae476095c7bcdee8dffe6c87f3675a8" => :mountain_lion
   end
 
-  keg_only "iojs conflicts with node (which is currently more established)"
+  conflicts_with "node", :because => "node and iojs both install a binary/link named node"
 
   option "with-debug", "Build with debugger hooks"
+  option "without-npm", "npm will not be installed"
+  option "without-completion", "npm bash completion will not be installed"
 
   depends_on :python => :build
 
+  resource "npm" do
+    url "https://registry.npmjs.org/npm/-/npm-2.3.0.tgz"
+    sha1 "3588ec5c18fb5ac41e5721b0ea8ece3a85ab8b4b"
+  end
+
   def install
     args = %W[--prefix=#{prefix} --without-npm]
     args << "--debug" if build.with? "debug"
 
     system "./configure", *args
     system "make", "install"
+
+  if build.with? "npm"
+      resource("npm").stage npm_buildpath = buildpath/"npm_install"
+      # make sure npm can find node
+      ENV.prepend_path "PATH", bin
+
+      # set log level temporarily for npm's `make install`
+      ENV["NPM_CONFIG_LOGLEVEL"] = "verbose"
+
+      cd npm_buildpath do
+        p = Patch.create(:p1, :DATA)
+        p.path = Pathname.new(__FILE__).expand_path
+        p.apply
+
+        system "./configure", "--prefix=#{libexec}/npm"
+        system "make", "install"
+      end
+
+      if build.with? "completion"
+        bash_completion.install \
+          npm_buildpath/"lib/utils/completion.sh" => "npm"
+      end
+    end
+  end
+
+  def post_install
+    return if build.without? "npm"
+
+    node_modules = HOMEBREW_PREFIX/"lib/node_modules"
+    node_modules.mkpath
+    npm_exec = node_modules/"npm/bin/npm-cli.js"
+    # Kill npm but preserve all other modules across node updates/upgrades.
+    rm_rf node_modules/"npm"
+
+    cp_r libexec/"npm/lib/node_modules/npm", node_modules
+    # This symlink doesn't hop into homebrew_prefix/bin automatically so
+    # remove it and make our own. This is a small consequence of our bottle
+    # npm make install workaround. All other installs **do** symlink to
+    # homebrew_prefix/bin correctly. We ln rather than cp this because doing
+    # so mimics npm's normal install.
+    ln_sf npm_exec, "#{HOMEBREW_PREFIX}/bin/npm"
+
+    # Let's do the manpage dance. It's just a jump to the left.
+    # And then a step to the right, with your hand on rm_f.
+    ["man1", "man3", "man5", "man7"].each do |man|
+      # Dirs must exist first: https://github.com/Homebrew/homebrew/issues/35969
+      mkdir_p HOMEBREW_PREFIX/"share/man/#{man}"
+      rm_f Dir[HOMEBREW_PREFIX/"share/man/#{man}/{npm.,npm-,npmrc.}*"]
+      ln_sf Dir[libexec/"npm/share/man/#{man}/npm*"], HOMEBREW_PREFIX/"share/man/#{man}"
+    end
+
+    npm_root = node_modules/"npm"
+    npmrc = npm_root/"npmrc"
+    npmrc.atomic_write("prefix = #{HOMEBREW_PREFIX}\n")
   end
 
-  def caveats; <<-EOS.undent
-    iojs was installed without npm. To install npm with iojs compatability:
-      brew install node --with-iojs-patch
+  def caveats;
+    s = ""
 
-    To prepend iojs to your PATH add to your ~/.bashrc:
-      export PATH="#{Formula["iojs"].opt_bin}:$PATH"
+    if build.with? "npm"
+      s += <<-EOS.undent
+        If you update npm itself, do NOT use the npm update command.
+        The upstream-recommended way to update npm is:
+          npm install -g npm@latest
+      EOS
+    else
+      s += <<-EOS.undent
+        Homebrew has NOT installed npm. If you later install it, you should supplement
+        your NODE_PATH with the npm module folder:
+          #{HOMEBREW_PREFIX}/lib/node_modules
+      EOS
+    end
 
-    This will also e.g. make npm use iojs's node.
-    EOS
+    s
   end
 
   test do
@@ -41,5 +111,39 @@ def caveats; <<-EOS.undent
     output = `#{bin}/iojs #{path}`.strip
     assert_equal "hello", output
     assert_equal 0, $?.exitstatus
+
+    if build.with? "npm"
+      # make sure npm can find node
+      ENV.prepend_path "PATH", opt_bin
+      assert_equal which("node"), opt_bin/"node"
+      assert (HOMEBREW_PREFIX/"bin/npm").exist?, "npm must exist"
+      assert (HOMEBREW_PREFIX/"bin/npm").executable?, "npm must be executable"
+      system "#{HOMEBREW_PREFIX}/bin/npm", "--verbose", "install", "npm@latest"
+    end
   end
 end
+
+__END__
+diff --git a/node_modules/node-gyp/lib/install.js b/node_modules/node-gyp/lib/install.js
+index 6f72e6a..ebc4e57 100644
+--- a/node_modules/node-gyp/lib/install.js
++++ b/node_modules/node-gyp/lib/install.js
+@@ -39,7 +39,7 @@ function install (gyp, argv, callback) {
+     }
+   }
+
+-  var distUrl = gyp.opts['dist-url'] || gyp.opts.disturl || 'http://nodejs.org/dist'
++  var distUrl = gyp.opts['dist-url'] || gyp.opts.disturl || 'https://iojs.org/dist'
+
+
+   // Determine which node dev files version we are installing
+@@ -185,7 +185,7 @@ function install (gyp, argv, callback) {
+
+       // now download the node tarball
+       var tarPath = gyp.opts['tarball']
+-      var tarballUrl = tarPath ? tarPath : distUrl + '/v' + version + '/node-v' + version + '.tar.gz'
++      var tarballUrl = tarPath ? tarPath : distUrl + '/v' + version + '/iojs-v' + version + '.tar.gz'
+         , badDownload = false
+         , extractCount = 0
+         , gunzip = zlib.createGunzip()
+

Library/Formula/node.rb

@@ -10,6 +10,8 @@ class Node < Formula
     sha1 "b5d7094ed826813b2cc35303bcde8269b1ad9292" => :mountain_lion
   end
 
+  conflicts_with "iojs", :because => "node and iojs both install a binary/link named node"
+
   devel do
     url "https://nodejs.org/dist/v0.11.15/node-v0.11.15.tar.gz"
     sha256 "e613d274baa4c99a0518038192491433f7877493a66d8505af263f6310991d01"