require "fileutils"
require "tmpdir"
require "etc"

# Homebrew extends Ruby's `FileUtils` to make our code more readable.
# @see http://ruby-doc.org/stdlib-1.8.7/libdoc/fileutils/rdoc/FileUtils.html Ruby's FileUtils API
module FileUtils
  # Create a temporary directory then yield. When the block returns,
  # recursively delete the temporary directory. Passing opts[:retain]
  # or calling `do |staging| ... staging.retain!` in the block will skip
  # the deletion and retain the temporary directory's contents.
  def mktemp(prefix = name, opts = {})
    Mktemp.new(prefix, opts).run do |staging|
      yield staging
    end
  end

  module_function :mktemp

  # Performs mktemp's functionality, and tracks the results.
  # Each instance is only intended to be used once.
  class Mktemp
    include FileUtils

    # Path to the tmpdir used in this run, as a Pathname.
    attr_reader :tmpdir

    def initialize(prefix = name, opts = {})
      @prefix = prefix
      @retain = opts[:retain]
      @quiet = false
    end

    # Instructs this Mktemp to retain the staged files
    def retain!
      @retain = true
    end

    # True if the staged temporary files should be retained
    def retain?
      @retain
    end

    # Instructs this Mktemp to not emit messages when retention is triggered
    def quiet!
      @quiet = true
    end

    def to_s
      "[Mktemp: #{tmpdir} retain=#{@retain} quiet=#{@quiet}]"
    end

    def run
      @tmpdir = Pathname.new(Dir.mktmpdir("#{@prefix}-", HOMEBREW_TEMP))

      # Make sure files inside the temporary directory have the same group as the
      # brew instance.
      #
      # Reference from `man 2 open`
      # > When a new file is created, it is given the group of the directory which
      # contains it.
      group_id = if HOMEBREW_BREW_FILE.grpowned?
                   HOMEBREW_BREW_FILE.stat.gid
                 else
                   Process.gid
                 end
      begin
        # group_id.to_s makes OS X 10.6.7 (ruby-1.8.7-p174) and earlier happy.
        chown(nil, group_id.to_s, tmpdir)
      rescue Errno::EPERM
        opoo "Failed setting group \"#{Etc.getgrgid(group_id).name}\" on #{tmpdir}"
      end

      begin
        Dir.chdir(tmpdir) { yield self }
      ensure
        ignore_interrupts { rm_rf(tmpdir) } unless retain?
      end
    ensure
      if retain? && !@tmpdir.nil? && !@quiet
        ohai "Kept temporary files"
        puts "Temporary files retained at #{@tmpdir}"
      end
    end
  end

  # @private
  alias_method :old_mkdir, :mkdir

  # A version of mkdir that also changes to that folder in a block.
  def mkdir(name, &_block)
    old_mkdir(name)
    if block_given?
      chdir name do
        yield
      end
    end
  end
  module_function :mkdir

  # The #copy_metadata method in all current versions of Ruby has a
  # bad bug which causes copying symlinks across filesystems to fail;
  # see #14710.
  # This was resolved in Ruby HEAD after the release of 1.9.3p194, but
  # never backported into the 1.9.3 branch. Fixed in 2.0.0.
  # The monkey-patched method here is copied directly from upstream fix.
  if RUBY_VERSION < "2.0.0"
    # @private
    class Entry_
      alias_method :old_copy_metadata, :copy_metadata
      def copy_metadata(path)
        st = lstat
        unless st.symlink?
          File.utime st.atime, st.mtime, path
        end
        begin
          if st.symlink?
            begin
              File.lchown st.uid, st.gid, path
            rescue NotImplementedError
            end
          else
            File.chown st.uid, st.gid, path
          end
        rescue Errno::EPERM
          # clear setuid/setgid
          if st.symlink?
            begin
              File.lchmod st.mode & 01777, path
            rescue NotImplementedError
            end
          else
            File.chmod st.mode & 01777, path
          end
        else
          if st.symlink?
            begin
              File.lchmod st.mode, path
            rescue NotImplementedError
            end
          else
            File.chmod st.mode, path
          end
        end
      end
    end
  end

  # Run `scons` using a Homebrew-installed version rather than whatever is in the `PATH`.
  def scons(*args)
    system Formulary.factory("scons").opt_bin/"scons", *args
  end

  # Run the `rake` from the `ruby` Homebrew is using rather than whatever is in the `PATH`.
  def rake(*args)
    system RUBY_BIN/"rake", *args
  end

  # Run `make` 3.81 or newer.
  # Uses the system make on Leopard and newer, and the
  # path to the actually-installed make on Tiger or older.
  def make(*args)
    if Utils.popen_read("/usr/bin/make", "--version").match(/Make (\d\.\d+)/)[1] > "3.80"
      system "/usr/bin/make", *args
    else
      make = Formula["make"].opt_bin/"make"
      make_path = make.exist? ? make.to_s : (Formula["make"].opt_bin/"gmake").to_s
      system make_path, *args
    end
  end

  if method_defined?(:ruby)
    # @private
    alias_method :old_ruby, :ruby
  end

  # Run the `ruby` Homebrew is using rather than whatever is in the `PATH`.
  def ruby(*args)
    system RUBY_PATH, *args
  end

  # Run `xcodebuild` without Homebrew's compiler environment variables set.
  def xcodebuild(*args)
    removed = ENV.remove_cc_etc
    system "xcodebuild", *args
  ensure
    ENV.update(removed)
  end
end

# Shim File.write for Ruby 1.8.7, where it's absent
unless File.respond_to?(:write)
  class File
    def self.write(filename, contents)
      File.open(filename, "w") do |file|
        file.write contents
      end
    end
  end
end