#--
# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
# All rights reserved.
# See LICENSE.txt for permissions.
#++

require 'rubygems/command'
require 'rubygems/exceptions'
require 'rubygems/package'
require 'rubygems/ext'
require 'rubygems/user_interaction'
require 'fileutils'

##
# The installer installs the files contained in the .gem into the Gem.home.
#
# Gem::Installer does the work of putting files in all the right places on the
# filesystem including unpacking the gem into its gem dir, installing the
# gemspec in the specifications dir, storing the cached gem in the cache dir,
# and installing either wrappers or symlinks for executables.
#
# The installer invokes pre and post install hooks.  Hooks can be added either
# through a rubygems_plugin.rb file in an installed gem or via a
# rubygems/defaults/#{RUBY_ENGINE}.rb or rubygems/defaults/operating_system.rb
# file.  See Gem.pre_install and Gem.post_install for details.

class Gem::Installer

  ##
  # Paths where env(1) might live.  Some systems are broken and have it in
  # /bin

  ENV_PATHS = %w[/usr/bin/env /bin/env]

  ##
  # Deprecated in favor of Gem::Ext::BuildError

  ExtensionBuildError = Gem::Ext::BuildError # :nodoc:

  include Gem::UserInteraction

  ##
  # Filename of the gem being installed.

  attr_reader :gem

  ##
  # The directory a gem's executables will be installed into

  attr_reader :bin_dir

  attr_reader :build_root # :nodoc:

  ##
  # The gem repository the gem will be installed into

  attr_reader :gem_home

  ##
  # The options passed when the Gem::Installer was instantiated.

  attr_reader :options

  ##
  # Sets the specification for .gem-less installs.

  attr_writer :spec

  @path_warning = false

  @install_lock = Mutex.new

  class << self

    ##
    # True if we've warned about PATH not including Gem.bindir

    attr_accessor :path_warning

    ##
    # Certain aspects of the install process are not thread-safe. This lock is
    # used to allow multiple threads to install Gems at the same time.

    attr_reader :install_lock

    ##
    # Overrides the executable format.
    #
    # This is a sprintf format with a "%s" which will be replaced with the
    # executable name.  It is based off the ruby executable name's difference
    # from "ruby".

    attr_writer :exec_format

    # Defaults to use Ruby's program prefix and suffix.
    def exec_format
      @exec_format ||= Gem.default_exec_format
    end

  end

  ##
  # Constructs an Installer instance that will install the gem located at
  # +gem+.  +options+ is a Hash with the following keys:
  #
  # :bin_dir:: Where to put a bin wrapper if needed.
  # :development:: Whether or not development dependencies should be installed.
  # :env_shebang:: Use /usr/bin/env in bin wrappers.
  # :force:: Overrides all version checks and security policy checks, except
  #          for a signed-gems-only policy.
  # :format_executable:: Format the executable the same as the Ruby executable.
  #                      If your Ruby is ruby18, foo_exec will be installed as
  #                      foo_exec18.
  # :ignore_dependencies:: Don't raise if a dependency is missing.
  # :install_dir:: The directory to install the gem into.
  # :security_policy:: Use the specified security policy.  See Gem::Security
  # :user_install:: Indicate that the gem should be unpacked into the users
  #                 personal gem directory.
  # :only_install_dir:: Only validate dependencies against what is in the
  #                     install_dir
  # :wrappers:: Install wrappers if true, symlinks if false.
  # :build_args:: An Array of arguments to pass to the extension builder
  #               process. If not set, then Gem::Command.build_args is used

  def initialize(gem, options={})
    require 'fileutils'

    @gem = gem
    @options = options
    @package = Gem::Package.new @gem

    process_options

    @package.security_policy = @security_policy

    if options[:user_install] and not options[:unpack] then
      @gem_home = Gem.user_dir
      @bin_dir = Gem.bindir gem_home unless options[:bin_dir]
      check_that_user_bin_dir_is_in_path
    end
  end

  ##
  # Checks if +filename+ exists in +@bin_dir+.
  #
  # If +@force+ is set +filename+ is overwritten.
  #
  # If +filename+ exists and is a RubyGems wrapper for different gem the user
  # is consulted.
  #
  # If +filename+ exists and +@bin_dir+ is Gem.default_bindir (/usr/local) the
  # user is consulted.
  #
  # Otherwise +filename+ is overwritten.

  def check_executable_overwrite filename # :nodoc:
    return if @force

    generated_bin = File.join @bin_dir, formatted_program_filename(filename)

    return unless File.exist? generated_bin

    ruby_executable = false
    existing = nil

    open generated_bin, 'rb' do |io|
      next unless io.gets =~ /^#!/ # shebang
      io.gets # blankline

      # TODO detect a specially formatted comment instead of trying
      # to run a regexp against Ruby code.
      next unless io.gets =~ /This file was generated by RubyGems/

      ruby_executable = true
      existing = io.read.slice(/^gem (['"])(.*?)(\1),/, 2)
    end

    return if spec.name == existing

    # somebody has written to RubyGems' directory, overwrite, too bad
    return if Gem.default_bindir != @bin_dir and not ruby_executable

    question = "#{spec.name}'s executable \"#{filename}\" conflicts with "

    if ruby_executable then
      question << existing

      return if ask_yes_no "#{question}\nOverwrite the executable?", false

      conflict = "installed executable from #{existing}"
    else
      question << generated_bin

      return if ask_yes_no "#{question}\nOverwrite the executable?", false

      conflict = generated_bin
    end

    raise Gem::InstallError,
      "\"#{filename}\" from #{spec.name} conflicts with #{conflict}"
  end

  ##
  # Lazy accessor for the spec's gem directory.

  def gem_dir
    @gem_dir ||= File.join(gem_home, "gems", spec.full_name)
  end

  ##
  # Lazy accessor for the installer's spec.

  def spec
    @spec ||= @package.spec
  rescue Gem::Package::Error => e
    raise Gem::InstallError, "invalid gem: #{e.message}"
  end

  ##
  # Installs the gem and returns a loaded Gem::Specification for the installed
  # gem.
  #
  # The gem will be installed with the following structure:
  #
  #   @gem_home/
  #     cache/<gem-version>.gem #=> a cached copy of the installed gem
  #     gems/<gem-version>/... #=> extracted files
  #     specifications/<gem-version>.gemspec #=> the Gem::Specification

  def install
    pre_install_checks

    FileUtils.rm_f File.join gem_home, 'specifications', @spec.spec_name

    run_pre_install_hooks

    # Completely remove any previous gem files
    FileUtils.rm_rf gem_dir

    FileUtils.mkdir_p gem_dir

    spec.loaded_from = spec_file

    if @options[:install_as_default]
      extract_bin
      write_default_spec
    else
      extract_files

      build_extensions
      write_build_info_file
      run_post_build_hooks

      generate_bin
      write_spec
      write_cache_file
    end

    say spec.post_install_message unless spec.post_install_message.nil?

    Gem::Installer.install_lock.synchronize { Gem::Specification.add_spec spec }

    run_post_install_hooks

    spec

  # TODO This rescue is in the wrong place. What is raising this exception?
  # move this rescue to around the code that actually might raise it.
  rescue Zlib::GzipFile::Error
    raise Gem::InstallError, "gzip error installing #{gem}"
  end

  def run_pre_install_hooks # :nodoc:
    Gem.pre_install_hooks.each do |hook|
      if hook.call(self) == false then
        location = " at #{$1}" if hook.inspect =~ /@(.*:\d+)/

        message = "pre-install hook#{location} failed for #{spec.full_name}"
        raise Gem::InstallError, message
      end
    end
  end

  def run_post_build_hooks # :nodoc:
    Gem.post_build_hooks.each do |hook|
      if hook.call(self) == false then
        FileUtils.rm_rf gem_dir

        location = " at #{$1}" if hook.inspect =~ /@(.*:\d+)/

        message = "post-build hook#{location} failed for #{spec.full_name}"
        raise Gem::InstallError, message
      end
    end
  end

  def run_post_install_hooks # :nodoc:
    Gem.post_install_hooks.each do |hook|
      hook.call self
    end
  end

  ##
  #
  # Return an Array of Specifications contained within the gem_home
  # we'll be installing into.

  def installed_specs
    @specs ||= begin
      specs = []

      Dir[File.join(gem_home, "specifications", "*.gemspec")].each do |path|
        spec = Gem::Specification.load path.untaint
        specs << spec if spec
      end

      specs
    end
  end

  ##
  # Ensure that the dependency is satisfied by the current installation of
  # gem.  If it is not an exception is raised.
  #
  # spec       :: Gem::Specification
  # dependency :: Gem::Dependency

  def ensure_dependency(spec, dependency)
    unless installation_satisfies_dependency? dependency then
      raise Gem::InstallError, "#{spec.name} requires #{dependency}"
    end
    true
  end

  ##
  # True if the gems in the system satisfy +dependency+.

  def installation_satisfies_dependency?(dependency)
    return true if @options[:development] and dependency.type == :development
    return true if installed_specs.detect { |s| dependency.matches_spec? s }
    return false if @only_install_dir
    not dependency.matching_specs.empty?
  end

  ##