class AbstractDownloadStrategy
  def initialize url, name, version, specs
    @url=url
    case specs when Hash
      @spec = specs.keys.first # only use first spec
      @ref = specs.values.first
    end
  end

  def expand_safe_system_args args
    args.each_with_index do |arg, ii|
      if arg.is_a? Hash
        unless ARGV.verbose?
          args[ii] = arg[:quiet_flag]
        else
          args.delete_at ii
        end
        return args
      end
    end
    # 2 as default because commands are eg. svn up, git pull
    args.insert(2, '-q') unless ARGV.verbose?
    return args
  end

  def quiet_safe_system *args
    safe_system(*expand_safe_system_args(args))
  end
end

class CurlDownloadStrategy < AbstractDownloadStrategy
  attr_reader :tarball_path

  def initialize url, name, version, specs
    super
    @unique_token="#{name}-#{version}" unless name.to_s.empty? or name == '__UNKNOWN__'
    if @unique_token
      @tarball_path=HOMEBREW_CACHE+(@unique_token+ext)
    else
      @tarball_path=HOMEBREW_CACHE+File.basename(@url)
    end
  end

  def cached_location
    @tarball_path
  end

  # Private method, can be overridden if needed.
  def _fetch
    curl @url, '-o', @tarball_path
  end

  def fetch
    ohai "Downloading #{@url}"
    unless @tarball_path.exist?
      begin
        _fetch
      rescue Exception
        ignore_interrupts { @tarball_path.unlink if @tarball_path.exist? }
        raise
      end
    else
      puts "File already downloaded in #{File.dirname(@tarball_path)}"
    end
    return @tarball_path # thus performs checksum verification
  end

  def stage
    if @tarball_path.extname == '.jar'
      magic_bytes = nil
    elsif @tarball_path.extname == '.pkg'
      # Use more than 4 characters to not clash with magicbytes
      magic_bytes = "____pkg"
    else
      # get the first four bytes
      File.open(@tarball_path) { |f| magic_bytes = f.read(4) }
    end

    # magic numbers stolen from /usr/share/file/magic/
    case magic_bytes
    when /^PK\003\004/ # .zip archive
      quiet_safe_system '/usr/bin/unzip', {:quiet_flag => '-qq'}, @tarball_path
      chdir
    when /^\037\213/, /^BZh/, /^\037\235/  # gzip/bz2/compress compressed
      # TODO check if it's really a tar archive
      safe_system '/usr/bin/tar', 'xf', @tarball_path
      chdir
    when '____pkg'
      safe_system '/usr/sbin/pkgutil', '--expand', @tarball_path, File.basename(@url)
      chdir
    when 'Rar!'
      quiet_safe_system 'unrar', 'x', {:quiet_flag => '-inul'}, @tarball_path
    else
      # we are assuming it is not an archive, use original filename
      # this behaviour is due to ScriptFileFormula expectations
      # So I guess we should cp, but we mv, for this historic reason
      # HOWEVER if this breaks some expectation you had we *will* change the
      # behaviour, just open an issue at github
      # We also do this for jar files, as they are in fact zip files, but
      # we don't want to unzip them
      FileUtils.mv @tarball_path, File.basename(@url)
    end
  end

private
  def chdir
    entries=Dir['*']
    case entries.length
      when 0 then raise "Empty archive"
      when 1 then Dir.chdir entries.first rescue nil
    end
  end

  def ext
    # GitHub uses odd URLs for zip files, so check for those
    rx=%r[https?://(www\.)?github\.com/.*/(zip|tar)ball/]
    if rx.match @url
      if $2 == 'zip'
        '.zip'
      else
        '.tgz'
      end
    else
      Pathname.new(@url).extname
    end
  end
end

# Detect and download from Apache Mirror
class CurlApacheMirrorDownloadStrategy < CurlDownloadStrategy
  def _fetch
    # Fetch mirror list site
    require 'open-uri'
    mirror_list = open(@url).read()

    # Parse out suggested mirror
    #   Yep, this is ghetto, grep the first <strong></strong> element content
    mirror_url = mirror_list[/<strong>([^<]+)/, 1]

    raise "Couldn't determine mirror. Try again later." if mirror_url.nil?

    ohai "Best Mirror #{mirror_url}"
    # Start download from that mirror
    curl mirror_url, '-o', @tarball_path
  end
end

# Download via an HTTP POST.
# Query parameters on the URL are converted into POST parameters
class CurlPostDownloadStrategy < CurlDownloadStrategy
  def _fetch
    base_url,data = @url.split('?')
    curl base_url, '-d', data, '-o', @tarball_path
  end
end

# Use this strategy to download but not unzip a file.
# Useful for installing jars.
class NoUnzipCurlDownloadStrategy < CurlDownloadStrategy
  def stage
    FileUtils.cp @tarball_path, File.basename(@url)
  end
end

# Normal strategy tries to untar as well
class GzipOnlyDownloadStrategy < CurlDownloadStrategy
  def stage
    FileUtils.mv @tarball_path, File.basename(@url)
    safe_system '/usr/bin/gunzip', '-f', File.basename(@url)
  end
end

# This Download Strategy is provided for use with sites that
# only provide HTTPS and also have a broken cert.
# Try not to need this, as we probably won't accept the formula.
class CurlUnsafeDownloadStrategy < CurlDownloadStrategy
  def _fetch
    curl @url, '--insecure', '-o', @tarball_path
  end
end

# This strategy extracts our binary packages.
class CurlBottleDownloadStrategy <CurlDownloadStrategy
  def initialize url, name, version, specs
    super
    @tarball_path = HOMEBREW_CACHE/"#{name}-#{version}.bottle#{ext}"
  end
  def stage
    ohai "Pouring #{File.basename(@tarball_path)}"
    super
  end
end

class SubversionDownloadStrategy <AbstractDownloadStrategy
  def initialize url, name, version, specs
    super
    @unique_token="#{name}--svn" unless name.to_s.empty? or name == '__UNKNOWN__'
    @co=HOMEBREW_CACHE+@unique_token
  end

  def cached_location
    @co
  end

  def fetch
    @url.sub!(/^svn\+/, '') if @url =~ %r[^svn\+http://]
    ohai "Checking out #{@url}"
    if @spec == :revision
      fetch_repo @co, @url, @ref
    elsif @spec == :revisions
      # nil is OK for main_revision, as fetch_repo will then get latest
      main_revision = @ref.delete :trunk
      fetch_repo @co, @url, main_revision, true

      get_externals do |external_name, external_url|
        fetch_repo @co+external_name, external_url, @ref[external_name], true
      end
    else
      fetch_repo @co, @url
    end
  end

  def stage
    quiet_safe_system svn, 'export', '--force', @co, Dir.pwd
  end

  def shell_quote str
    # Oh god escaping shell args.
    # See http://notetoself.vrensk.com/2008/08/escaping-single-quotes-in-ruby-harder-than-expected/
    str.gsub(/\\|'/) { |c| "\\#{c}" }
  end

  def get_externals
    `'#{shell_quote(svn)}' propget svn:externals '#{shell_quote(@url)}'`.chomp.each_line do |line|
      name, url = line.split(/\s+/)
      yield name, url
    end
  end

  def _fetch_command svncommand, url, target
    [svn, svncommand, '--force', url, target]
  end

  def fetch_repo target, url, revision=nil, ignore_externals=false
    # Use "svn up" when the repository already exists locally.
    # This saves on bandwidth and will have a similar effect to verifying the
    # cache as it will make any changes to get the right revision.
    svncommand = target.exist? ? 'up' : 'checkout'
    args = _fetch_command svncommand, url, target
    args << '-r' << revision if revision
    args << '--ignore-externals' if ignore_externals
    quiet_safe_system(*args)
  end

  # Try HOMEBREW_SVN, a Homebrew-built svn, and finally the OS X system svn.
  # Not all features are available in the 10.5 system-provided svn.
  def svn
    return ENV['HOMEBREW_SVN'] if ENV['HOMEBREW_SVN']
    return "#{HOMEBREW_PREFIX}/bin/svn" if File.exist? "#{HOMEBREW_PREFIX}/bin/svn"
    return '/usr/bin/svn'
  end
end

# Require a newer version of Subversion than 1.4.x (Leopard-provided version)
class StrictSubversionDownloadStrategy < SubversionDownloadStrategy
  def svn
    exe = super
    `#{exe} --version` =~ /version (\d+\.\d+(\.\d+)*)/
    svn_version = $1
    version_tuple=svn_version.split(".").collect {|v|Integer(v)}

    if version_tuple[0] == 1 and version_tuple[1] <= 4
      onoe "Detected Subversion (#{exe}, version #{svn_version}) is too old."
      puts "Subversion 1.4.x will not export externals correctly for this formula."
      puts "You must either `brew install subversion` or set HOMEBREW_SVN to the path"
      puts "of a newer svn binary."
    end
    return exe
  end
end

class GitDownloadStrategy < AbstractDownloadStrategy
  def initialize url, name, version, specs
    super
    @unique_token="#{name}--git" unless name.to_s.empty? or name == '__UNKNOWN__'
    @clone=HOMEBREW_CACHE+@unique_token
  end

  def cached_location
    @clone
  end

  def support_depth?
    @url =~ %r(git://) or @url =~ %r(https://github.com/)
  end

  def fetch
    raise "You must install Git: brew install git" unless system "/usr/bin/which -s git"

    ohai "Cloning #{@url}"

    if @clone.exist?
      Dir.chdir(@clone) do
        # Check for interupted clone from a previous install
        unless system 'git', 'status', '-s'
          ohai "Removing invalid .git repo from cache"
          FileUtils.rm_rf @clone
        end
      end
    end

    unless @clone.exist?
      # Note: first-time checkouts are always done verbosely
      git_args = %w(git clone)
      git_args << "--depth" << "1" if support_depth?
      git_args << @url << @clone
      safe_system *git_args
    else
      puts "Updating #{@clone}"
      Dir.chdir(@clone) do
        safe_system 'git', 'remote', 'set-url', 'origin', @url
        quiet_safe_system 'git', 'fetch', 'origin'
        # If we're going to checkout a tag, then we need to fetch new tags too.
        quiet_safe_system 'git', 'fetch', '--tags' if @spec == :tag
      end
    end
  end

  def stage
    dst = Dir.getwd
    Dir.chdir @clone do
      if @spec and @ref
        ohai "Checking out #{@spec} #{@ref}"
        case @spec
        when :branch
          nostdout { quiet_safe_system 'git', 'checkout', "origin/#{@ref}" }
        when :tag
          nostdout { quiet_safe_system 'git', 'checkout', @ref }
        end
      end
      # http://stackoverflow.com/questions/160608/how-to-do-a-git-export-like-svn-export
      safe_system 'git', 'checkout-index', '-a', '-f', "--prefix=#{dst}/"
      # check for submodules
      if File.exist?('.gitmodules')
        safe_system 'git', 'submodule', 'init'
        safe_system 'git', 'submodule', 'update'
        sub_cmd = "git checkout-index -a -f \"--prefix=#{dst}/$path/\""
        safe_system 'git', 'submodule', '--quiet', 'foreach', '--recursive', sub_cmd
      end
    end
  end
end

class CVSDownloadStrategy < AbstractDownloadStrategy
  def initialize url, name, version, specs
    super
    @unique_token="#{name}--cvs" unless name.to_s.empty? or name == '__UNKNOWN__'
    @co=HOMEBREW_CACHE+@unique_token
  end

  def cached_location; @co; end

  def fetch
    ohai "Checking out #{@url}"

    # URL of cvs cvs://:pserver:anoncvs@www.gccxml.org:/cvsroot/GCC_XML:gccxml
    # will become:
    # cvs -d :pserver:anoncvs@www.gccxml.org:/cvsroot/GCC_XML login
    # cvs -d :pserver:anoncvs@www.gccxml.org:/cvsroot/GCC_XML co gccxml
    mod, url = split_url(@url)

    unless @co.exist?
      Dir.chdir HOMEBREW_CACHE do
        safe_system '/usr/bin/cvs', '-d', url, 'login'
        safe_system '/usr/bin/cvs', '-d', url, 'checkout', '-d', @unique_token, mod
      end
    else
      puts "Updating #{@co}"
      Dir.chdir(@co) { safe_system '/usr/bin/cvs', 'up' }
    end
  end

  def stage
    FileUtils.cp_r Dir[@co+"*"], Dir.pwd

    require 'find'
    Find.find(Dir.pwd) do |path|
      if FileTest.directory?(path) && File.basename(path) == "CVS"
        Find.prune
        FileUtil.rm_r path, :force => true
      end
    end
  end

private
  def split_url(in_url)
    parts=in_url.sub(%r[^cvs://], '').split(/:/)
    mod=parts.pop
    url=parts.join(':')
    [ mod, url ]
  end
end

class MercurialDownloadStrategy < AbstractDownloadStrategy
  def initialize url, name, version, specs
    super
    @unique_token="#{name}--hg" unless name.to_s.empty? or name == '__UNKNOWN__'
    @clone=HOMEBREW_CACHE+@unique_token
  end

  def cached_location; @clone; end

  def fetch
    raise "You must `easy_install mercurial'" unless system "/usr/bin/which hg"

    ohai "Cloning #{@url}"

    unless @clone.exist?
      url=@url.sub(%r[^hg://], '')
      safe_system 'hg', 'clone', url, @clone
    else
      puts "Updating #{@clone}"
      Dir.chdir(@clone) do
        safe_system 'hg', 'pull'
        safe_system 'hg', 'update'
      end
    end
  end

  def stage
    dst=Dir.getwd
    Dir.chdir @clone do
      if @spec and @ref
        ohai "Checking out #{@spec} #{@ref}"
        Dir.chdir @clone do
          safe_system 'hg', 'archive', '-y', '-r', @ref, '-t', 'files', dst
        end
      else
        safe_system 'hg', 'archive', '-y', '-t', 'files', dst
      end
    end
  end
end

class BazaarDownloadStrategy < AbstractDownloadStrategy
  def initialize url, name, version, specs
    super
    @unique_token="#{name}--bzr" unless name.to_s.empty? or name == '__UNKNOWN__'
    @clone=HOMEBREW_CACHE+@unique_token
  end

  def cached_location; @clone; end

  def fetch
    raise "You must install bazaar first" \
          unless system "/usr/bin/which bzr"

    ohai "Cloning #{@url}"
    unless @clone.exist?
      url=@url.sub(%r[^bzr://], '')
      # 'lightweight' means history-less
      safe_system 'bzr', 'checkout', '--lightweight', url, @clone
    else
      puts "Updating #{@clone}"
      Dir.chdir(@clone) { safe_system 'bzr', 'update' }
    end
  end

  def stage
    dst=Dir.getwd
    Dir.chdir @clone do
      if @spec and @ref
        ohai "Checking out #{@spec} #{@ref}"
        Dir.chdir @clone do
          safe_system 'bzr', 'export', '-r', @ref, dst
        end
      else
        safe_system 'bzr', 'export', dst
      end
    end
  end
end

class FossilDownloadStrategy < AbstractDownloadStrategy
  def initialize url, name, version, specs
    super
    @unique_token="#{name}--fossil" unless name.to_s.empty? or name == '__UNKNOWN__'
    @clone=HOMEBREW_CACHE+@unique_token
  end

  def cached_location; @clone; end

  def fetch
    raise "You must install fossil first" \
          unless system "/usr/bin/which fossil"

    ohai "Cloning #{@url}"
    unless @clone.exist?
      url=@url.sub(%r[^fossil://], '')
      safe_system 'fossil', 'clone', url, @clone
    else
      puts "Updating #{@clone}"
      safe_system 'fossil', 'pull', '-R', @clone
    end
  end

  def stage
    # TODO: The 'open' and 'checkout' commands are very noisy and have no '-q' option.
    safe_system 'fossil', 'open', @clone
    if @spec and @ref
      ohai "Checking out #{@spec} #{@ref}"
      safe_system 'fossil', 'checkout', @ref
    end
  end
end

def detect_download_strategy url
  case url
    # We use a special URL pattern for cvs
  when %r[^cvs://] then CVSDownloadStrategy
    # Standard URLs
  when %r[^bzr://] then BazaarDownloadStrategy
  when %r[^git://] then GitDownloadStrategy
  when %r[^hg://] then MercurialDownloadStrategy
  when %r[^svn://] then SubversionDownloadStrategy
  when %r[^svn\+http://] then SubversionDownloadStrategy
  when %r[^fossil://] then FossilDownloadStrategy
    # Some well-known source hosts
  when %r[^https?://github\.com/.+\.git$] then GitDownloadStrategy
  when %r[^https?://(.+?\.)?googlecode\.com/hg] then MercurialDownloadStrategy
  when %r[^https?://(.+?\.)?googlecode\.com/svn] then SubversionDownloadStrategy
  when %r[^https?://(.+?\.)?sourceforge\.net/svnroot/] then SubversionDownloadStrategy
  when %r[^http://svn.apache.org/repos/] then SubversionDownloadStrategy
  when %r[^http://www.apache.org/dyn/closer.cgi] then CurlApacheMirrorDownloadStrategy
    # Otherwise just try to download
  else CurlDownloadStrategy
  end
end