# Gets a patch from a GitHub commit or pull request and applies it to Homebrew.
# Optionally, installs it too.

require 'utils'
require 'formula'

module Homebrew
  def tap arg
    match = arg.match(%r[homebrew-(\w+)/])
    match[1].downcase if match
  end

  def pull
    if ARGV.empty?
      onoe 'This command requires at least one argument containing a URL or pull request number'
    end

    if ARGV[0] == '--rebase'
      onoe 'You meant `git pull --rebase`.'
    end

    ARGV.named.each do |arg|
      if arg.to_i > 0
        url = 'https://github.com/Homebrew/homebrew/pull/' + arg
        issue = arg
      else
        url_match = arg.match HOMEBREW_PULL_OR_COMMIT_URL_REGEX
        unless url_match
          ohai 'Ignoring URL:', "Not a GitHub pull request or commit: #{arg}"
          next
        end

        url = url_match[0]
        issue = url_match[3]
      end

      if tap_name = tap(url)
        user = url_match[1].downcase
        tap_dir = HOMEBREW_REPOSITORY/"Library/Taps/#{user}/homebrew-#{tap_name}"
        safe_system "brew", "tap", "#{user}/#{tap_name}" unless tap_dir.exist?
        Dir.chdir tap_dir
      else
        Dir.chdir HOMEBREW_REPOSITORY
      end

      if ARGV.include? '--bottle'
        if issue
          url = "https://github.com/BrewTestBot/homebrew/compare/homebrew:master...pr-#{issue}"
        else
          raise "No pull request detected!"
        end
      end

      # GitHub provides commits'/pull-requests' raw patches using this URL.
      url += '.patch'

      # The cache directory seems like a good place to put patches.
      HOMEBREW_CACHE.mkpath
      patchpath = HOMEBREW_CACHE + File.basename(url)
      curl url, '-o', patchpath

      # Store current revision
      revision = `git rev-parse --short HEAD`.strip

      ohai 'Applying patch'
      patch_args = []
      # Normally we don't want whitespace errors, but squashing them can break
      # patches so an option is provided to skip this step.
      if ARGV.include? '--ignore-whitespace' or ARGV.include? '--clean'
        patch_args << '--whitespace=nowarn'
      else
        patch_args << '--whitespace=fix'
      end

      # Fall back to three-way merge if patch does not apply cleanly
      patch_args << "-3"
      patch_args << patchpath

      begin
        safe_system 'git', 'am', *patch_args
      rescue ErrorDuringExecution
        system 'git', 'am', '--abort'
        odie 'Patch failed to apply: aborted.'
      ensure
        patchpath.unlink
      end

      changed_formulae = []

      if tap_dir
        formula_dir = %w[Formula HomebrewFormula].find { |d| tap_dir.join(d).directory? } || ""
      else
        formula_dir = "Library/Formula"
      end

      Utils.popen_read(
        "git", "diff-tree", "-r", "--name-only",
        "--diff-filter=AM", revision, "HEAD", "--", formula_dir
      ).each_line do |line|
        name = File.basename(line.chomp, ".rb")

        begin
          changed_formulae << Formula[name]
        # Make sure we catch syntax errors.
        rescue Exception => e
          next
        end
      end

      unless ARGV.include?('--bottle')
        changed_formulae.each do |f|
          next unless f.bottle
          opoo "#{f} has a bottle: do you need to update it with --bottle?"
        end
      end

      if issue && !ARGV.include?('--clean')
        ohai "Patch closes issue ##{issue}"
        message = `git log HEAD^.. --format=%B`

        if ARGV.include? '--bump'
          onoe 'Can only bump one changed formula' unless changed_formulae.length == 1
          f = changed_formulae.first
          subject = "#{f.name} #{f.version}"
          ohai "New bump commit subject: #{subject}"
          message = "#{subject}\n\n#{message}"
        end

        # If this is a pull request, append a close message.
        unless message.include? 'Closes #'
          message += "\nCloses ##{issue}."
          safe_system 'git', 'commit', '--amend', '--signoff', '-q', '-m', message
        end
      end

      ohai 'Patch changed:'
      safe_system "git", "diff-tree", "-r", "--stat", revision, "HEAD"

      if ARGV.include? '--install'
        changed_formulae.each do |f|
          ohai "Installing #{f.name}"
          install = f.installed? ? 'upgrade' : 'install'
          safe_system 'brew', install, '--debug', f.name
        end
      end
    end
  end
end