require 'rubygems'
require 'rubygems/dependency_list'
require 'rubygems/package'
require 'rubygems/installer'
require 'rubygems/spec_fetcher'
require 'rubygems/user_interaction'
require 'rubygems/source_local'
require 'rubygems/source_specific_file'
require 'rubygems/available_set'

##
# Installs a gem along with all its dependencies from local and remote gems.

class Gem::DependencyInstaller

  include Gem::UserInteraction

  attr_reader :gems_to_install
  attr_reader :installed_gems

  ##
  # Documentation types.  For use by the Gem.done_installing hook

  attr_reader :document

  DEFAULT_OPTIONS = {
    :env_shebang         => false,
    :document            => %w[ri],
    :domain              => :both, # HACK dup
    :force               => false,
    :format_executable   => false, # HACK dup
    :ignore_dependencies => false,
    :prerelease          => false,
    :security_policy     => nil, # HACK NoSecurity requires OpenSSL. AlmostNo? Low?
    :wrappers            => true,
    :build_args          => nil,
    :build_docs_in_background => false,
  }.freeze

  ##
  # Creates a new installer instance.
  #
  # Options are:
  # :cache_dir:: Alternate repository path to store .gem files in.
  # :domain:: :local, :remote, or :both.  :local only searches gems in the
  #           current directory.  :remote searches only gems in Gem::sources.
  #           :both searches both.
  # :env_shebang:: See Gem::Installer::new.
  # :force:: See Gem::Installer#install.
  # :format_executable:: See Gem::Installer#initialize.
  # :ignore_dependencies:: Don't install any dependencies.
  # :install_dir:: See Gem::Installer#install.
  # :prerelease:: Allow prerelease versions.  See #install.
  # :security_policy:: See Gem::Installer::new and Gem::Security.
  # :user_install:: See Gem::Installer.new
  # :wrappers:: See Gem::Installer::new
  # :build_args:: See Gem::Installer::new

  def initialize(options = {})
    if options[:install_dir] then
      @gem_home = options[:install_dir]

      # HACK shouldn't change the global settings
      Gem::Specification.dirs = @gem_home
      Gem.ensure_gem_subdirectories @gem_home
      options[:install_dir] = @gem_home # FIX: because we suck and reuse below
    end

    options = DEFAULT_OPTIONS.merge options

    @bin_dir             = options[:bin_dir]
    @dev_shallow         = options[:dev_shallow]
    @development         = options[:development]
    @document            = options[:document]
    @domain              = options[:domain]
    @env_shebang         = options[:env_shebang]
    @force               = options[:force]
    @format_executable   = options[:format_executable]
    @ignore_dependencies = options[:ignore_dependencies]
    @prerelease          = options[:prerelease]
    @security_policy     = options[:security_policy]
    @user_install        = options[:user_install]
    @wrappers            = options[:wrappers]
    @build_args          = options[:build_args]
    @build_docs_in_background = options[:build_docs_in_background]

    # Indicates that we should not try to update any deps unless
    # we absolutely must.
    @minimal_deps        = options[:minimal_deps]

    @installed_gems = []
    @toplevel_specs = nil

    @install_dir = options[:install_dir] || Gem.dir
    @cache_dir = options[:cache_dir] || @install_dir

    # Set with any errors that SpecFetcher finds while search through
    # gemspecs for a dep
    @errors = nil
  end

  attr_reader :errors

  ##
  # Indicated, based on the requested domain, if local
  # gems should be considered.

  def consider_local?
    @domain == :both or @domain == :local
  end

  ##
  # Indicated, based on the requested domain, if remote
  # gems should be considered.

  def consider_remote?
    @domain == :both or @domain == :remote
  end

  ##
  # Returns a list of pairs of gemspecs and source_uris that match
  # Gem::Dependency +dep+ from both local (Dir.pwd) and remote (Gem.sources)
  # sources.  Gems are sorted with newer gems preferred over older gems, and
  # local gems preferred over remote gems.

  def find_gems_with_sources(dep)
    set = Gem::AvailableSet.new

    if consider_local?
      sl = Gem::Source::Local.new

      if spec = sl.find_gem(dep.name)
        if dep.matches_spec? spec
          set.add spec, sl
        end
      end
    end

    if consider_remote?
      begin
        found, errors = Gem::SpecFetcher.fetcher.spec_for_dependency dep

        if @errors
          @errors += errors
        else
          @errors = errors
        end

        set << found

      rescue Gem::RemoteFetcher::FetchError => e
        # FIX if there is a problem talking to the network, we either need to always tell
        # the user (no really_verbose) or fail hard, not silently tell them that we just
        # couldn't find their requested gem.
        if Gem.configuration.really_verbose then
          say "Error fetching remote data:\t\t#{e.message}"
          say "Falling back to local-only install"
        end
        @domain = :local
      end
    end

    set
  end

  ##
  # Gathers all dependencies necessary for the installation from local and
  # remote sources unless the ignore_dependencies was given.

  def gather_dependencies
    specs = @available.all_specs

    # these gems were listed by the user, always install them
    keep_names = specs.map { |spec| spec.full_name }

    if @dev_shallow
      @toplevel_specs = keep_names
    end

    dependency_list = Gem::DependencyList.new @development
    dependency_list.add(*specs)
    to_do = specs.dup
    add_found_dependencies to_do, dependency_list unless @ignore_dependencies

    # REFACTOR maybe abstract away using Gem::Specification.include? so
    # that this isn't dependent only on the currently installed gems
    dependency_list.specs.reject! { |spec|
      not keep_names.include?(spec.full_name) and
      Gem::Specification.include?(spec)
    }

    unless dependency_list.ok? or @ignore_dependencies or @force then
      reason = dependency_list.why_not_ok?.map { |k,v|
        "#{k} requires #{v.join(", ")}"
      }.join("; ")
      raise Gem::DependencyError, "Unable to resolve dependencies: #{reason}"
    end

    @gems_to_install = dependency_list.dependency_order.reverse
  end

  def add_found_dependencies to_do, dependency_list
    seen = {}
    dependencies = Hash.new { |h, name| h[name] = Gem::Dependency.new name }

    until to_do.empty? do
      spec = to_do.shift

      # HACK why is spec nil?
      next if spec.nil? or seen[spec.name]
      seen[spec.name] = true

      deps = spec.runtime_dependencies

      if @development
        if @dev_shallow
          if @toplevel_specs.include? spec.full_name
            deps |= spec.development_dependencies
          end
        else
          deps |= spec.development_dependencies
        end
      end

      deps.each do |dep|
        dependencies[dep.name] = dependencies[dep.name].merge dep

        if @minimal_deps
          next if Gem::Specification.any? do |installed_spec|
                    dep.name == installed_spec.name and
                      dep.requirement.satisfied_by? installed_spec.version
                  end
        end

        results = find_gems_with_sources(dep)

        results.sorted.each do |t|
          to_do.push t.spec
        end

        results.remove_installed! dep

        @available << results
        results.inject_into_list dependency_list
      end
    end

    dependency_list.remove_specs_unsatisfied_by dependencies
  end

  ##
  # Finds a spec and the source_uri it came from for gem +gem_name+ and
  # +version+.  Returns an Array of specs and sources required for
  # installation of the gem.

  def find_spec_by_name_and_version(gem_name,
                                    version = Gem::Requirement.default,
                                    prerelease = false)

    set = Gem::AvailableSet.new

    if consider_local?
      if File.file? gem_name then
        src = Gem::Source::SpecificFile.new(gem_name)
        set.add src.spec, src
      else
        local = Gem::Source::Local.new

        if s = local.find_gem(gem_name, version)
          set.add s, local
        end
      end
    end

    if set.empty?
      dep = Gem::Dependency.new gem_name, version
      # HACK Dependency objects should be immutable
      dep.prerelease = true if prerelease

      set = find_gems_with_sources(dep)
      set.match_platform!
    end

    if set.empty?
      raise Gem::SpecificGemNotFoundException.new(gem_name, version, @errors)
    end

    @available = set
  end

  ##
  # Installs the gem +dep_or_name+ and all its dependencies.  Returns an Array
  # of installed gem specifications.
  #
  # If the +:prerelease+ option is set and there is a prerelease for
  # +dep_or_name+ the prerelease version will be installed.
  #
  # Unless explicitly specified as a prerelease dependency, prerelease gems
  # that +dep_or_name+ depend on will not be installed.
  #
  # If c-1.a depends on b-1 and a-1.a and there is a gem b-1.a available then
  # c-1.a, b-1 and a-1.a will be installed.  b-1.a will need to be installed
  # separately.

  def install dep_or_name, version = Gem::Requirement.default
    if String === dep_or_name then
      find_spec_by_name_and_version dep_or_name, version, @prerelease
    else
      dep = dep_or_name.dup
      dep.prerelease = @prerelease
      @available = find_gems_with_sources(dep).pick_best!
    end

    @installed_gems = []

    gather_dependencies

    # REFACTOR is the last gem always the one that the user requested?
    # This code assumes that but is that actually validated by the code?

    last = @gems_to_install.size - 1
    @gems_to_install.each_with_index do |spec, index|
      # REFACTOR more current spec set hardcoding, should be abstracted?
      next if Gem::Specification.include?(spec) and index != last

      # TODO: make this sorta_verbose so other users can benefit from it
      say "Installing gem #{spec.full_name}" if Gem.configuration.really_verbose

      source = @available.source_for spec

      begin
        # REFACTOR make the fetcher to use configurable
        local_gem_path = source.download spec, @cache_dir
      rescue Gem::RemoteFetcher::FetchError
        # TODO I doubt all fetch errors are recoverable, we should at least
        # report the errors probably.
        next if @force
        raise
      end

      if @development
        if @dev_shallow
          is_dev = @toplevel_specs.include? spec.full_name
        else
          is_dev = true
        end
      end

      inst = Gem::Installer.new local_gem_path,
                                :bin_dir             => @bin_dir,
                                :development         => is_dev,
                                :env_shebang         => @env_shebang,
                                :force               => @force,
                                :format_executable   => @format_executable,
                                :ignore_dependencies => @ignore_dependencies,
                                :install_dir         => @install_dir,
                                :security_policy     => @security_policy,
                                :user_install        => @user_install,
                                :wrappers            => @wrappers,
                                :build_args          => @build_args

      spec = inst.install

      @installed_gems << spec
    end

    # Since this is currently only called for docs, we can be lazy and just say
    # it's documentation. Ideally the hook adder could decide whether to be in
    # the background or not, and what to call it.
    in_background "Installing documentation" do
      start = Time.now
      Gem.done_installing_hooks.each do |hook|
        hook.call self, @installed_gems
      end
      finish = Time.now
      say "Done installing documentation for #{@installed_gems.map(&:name).join(', ')} (#{(finish-start).to_i} sec)."
    end unless Gem.done_installing_hooks.empty?

    @installed_gems
  end

  def in_background what
    fork_happened = false
    if @build_docs_in_background and Process.respond_to?(:fork)
      begin
        Process.fork do
          yield
        end
        fork_happened = true
        say "#{what} in a background process."
      rescue NotImplementedError
      end
    end
    yield unless fork_happened
  end
end