#!/usr/bin/env ruby
#
# Create a chunk morphology to integrate Omnibus software in Baserock
#
# Copyright (C) 2014  Codethink Limited
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; version 2 of the License.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with this program; if not, write to the Free Software Foundation, Inc.,
# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

require 'bundler'
require 'omnibus'

require 'optparse'
require 'rubygems/commands/build_command'
require 'rubygems/commands/install_command'
require 'shellwords'

require_relative 'importer_base'

BANNER = "Usage: omnibus.to_chunk PROJECT_DIR PROJECT_NAME SOURCE_DIR SOFTWARE_NAME"

DESCRIPTION = <<-END
Generate a .morph file for a given Omnibus software component.
END

class Omnibus::Builder
  # It's possible to use `gem install` in build commands, which is a great
  # way of subverting the dependency tracking Omnibus provides. It's done
  # in `omnibus-chef/config/software/chefdk.rb`, for example.
  #
  # To handle this, here we extend the class that executes the build commands
  # to detect when `gem install` is run. It uses the Gem library to turn the
  # commandline back into a Bundler::Dependency object that we can use.
  #
  # We also trap `gem build` so we know when a software component is a RubyGem
  # that should be handled by 'rubygems.to_chunk'.

  class GemBuildCommandParser < Gem::Commands::BuildCommand
    def gemspec_path(args)
      handle_options args
      if options[:args].length != 1
        raise Exception, "Invalid `gem build` commandline: 1 argument " +
                         "expected, got #{options[:args]}."
      end
      options[:args][0]
    end
  end

  class GemInstallCommandParser < Gem::Commands::InstallCommand
    def dependency_list_from_commandline(args)
      handle_options args

      # `gem install foo*` is sometimes used when installing a locally built
      # Gem, to avoid needing to know the exact version number that was built.
      # We only care about remote Gems being installed, so anything with a '*'
      # in its name can be ignored.
      gem_names = options[:args].delete_if { |name| name.include?('*') }

      gem_names.collect do |gem_name|
        Bundler::Dependency.new(gem_name, options[:version])
      end
    end
  end

  def gem(command, options = {})
    # This function re-implements the 'gem' function in the build-commands DSL.
    if command.start_with? 'build'
      parser = GemBuildCommandParser.new
      args = Shellwords.split(command).drop(1)
      if built_gemspec != nil
        raise Exception, "More than one `gem build` command was run as part " +
                         "of the build process. The 'rubygems.to_chunk' " +
                         "program currently supports only one .gemspec " +
                         "build per chunk, so this can't be processed " +
                         "automatically."
      end
      @built_gemspec = parser.gemspec_path(args)
    elsif command.start_with? 'install'
      parser = GemInstallCommandParser.new
      args = Shellwords.split(command).drop(1)
      args_without_build_flags = args.take_while { |item| item != '--' }
      gems = parser.dependency_list_from_commandline(args_without_build_flags)
      manually_installed_rubygems.concat gems
    end
  end

  def built_gemspec
    @built_gemspec
  end

  def manually_installed_rubygems
    @manually_installed_rubygems ||= []
  end
end

class OmnibusChunkMorphologyGenerator < Importer::Base
  def initialize
    local_data = YAML.load_file(local_data_path("omnibus.yaml"))
    @dependency_blacklist = local_data['dependency-blacklist']
  end

  def parse_options(arguments)
    opts = create_option_parser(BANNER, DESCRIPTION)

    parsed_arguments = opts.parse!(arguments)

    if parsed_arguments.length != 4 and parsed_arguments.length != 5
      STDERR.puts "Expected 4 or 5 arguments, got #{parsed_arguments}."
      opts.parse(['-?'])
      exit 255
    end

    project_dir, project_name, source_dir, software_name, expected_version = \
      parsed_arguments
    # Not yet implemented
    #if expected_version != nil
    #  expected_version = Gem::Version.new(expected_version)
    #end
    [project_dir, project_name, source_dir, software_name, expected_version]
  end

  class SubprocessError < RuntimeError
  end

  def run_tool_capture_output(tool_name, *args)
    tool_path = local_data_path(tool_name)

    # FIXME: something breaks when we try to share this FD, it's not
    # ideal that the subprocess doesn't log anything, though.
    env_changes = {'MORPH_LOG_FD' => nil}

    command = [[tool_path, tool_name], *args]
    log.info("Running #{command.join(' ')} in #{scripts_dir}")

    text = IO.popen(
      env_changes, command, :chdir => scripts_dir, :err => [:child, :out]
    ) do |io|
      io.read
    end

    if $? == 0
      text
    else
      raise SubprocessError, text
    end
  end

  def generate_chunk_morph_for_rubygems_software(software, source_dir)
    # This is a better heuristic for getting the name of the Gem
    # than the software name, it seems ...
    gem_name = software.relative_path

    text = run_tool_capture_output('rubygems.to_chunk', source_dir, gem_name)
    log.debug("Text from output: #{text}, result #{$?}")

    morphology = YAML::load(text)
    return morphology
  rescue SubprocessError => e
    error "Tried to import #{software.name} as a RubyGem, got the " \
          "following error from rubygems.to_chunk: #{e.message}"
    exit 1
  end

  def resolve_rubygems_deps(requirements)
    return {} if requirements.empty?

    log.info('Resolving RubyGem requirements with Bundler')

    fake_gemfile = Bundler::Dsl.new
    fake_gemfile.source('https://rubygems.org')

    requirements.each do |dep|
      fake_gemfile.gem(dep.name, dep.requirement)
    end

    definition = fake_gemfile.to_definition('Gemfile.lock', true)
    resolved_specs = definition.resolve_remotely!

    Hash[resolved_specs.collect { |spec| [spec.name, spec.version.to_s]}]
  end

  def generate_chunk_morph_for_software(project, software, source_dir)
    if software.builder.built_gemspec != nil
      morphology = generate_chunk_morph_for_rubygems_software(software,
                                                              source_dir)
    else
      morphology = {
        "name" => software.name,
        "kind" => "chunk",
        "description" => "Automatically generated by omnibus.to_chunk"
      }
    end

    omnibus_deps = {}
    rubygems_deps = {}

    software.dependencies.each do |name|
      software = Omnibus::Software.load(project, name)
      if @dependency_blacklist.member? name
        log.info(
          "Not adding #{name} as a dependency as it is marked to be ignored.")
      elsif software.fetcher.instance_of?(Omnibus::PathFetcher)
        log.info(
          "Not adding #{name} as a dependency: it's installed from " +
          "a path which probably means that it is package configuration, not " +
          "a 3rd-party component to be imported.")
      elsif software.fetcher.instance_of?(Omnibus::NullFetcher)
        if software.builder.built_gemspec
          log.info(
            "Adding #{name} as a RubyGem dependency because it builds " +
            "#{software.builder.built_gemspec}")
          rubygems_deps[name] = software.version
        else
          log.info(
            "Not adding #{name} as a dependency: no sources listed.")
        end
      else
        omnibus_deps[name] = software.version
      end
    end

    gem_requirements = software.builder.manually_installed_rubygems
    rubygems_deps = resolve_rubygems_deps(gem_requirements)

    morphology.update({
      # Possibly this tool should look at software.build and
      # generate suitable configure, build and install-commands.
      # For now: don't bother!

      # FIXME: are these build or runtime dependencies? We'll assume both.
      "x-build-dependencies-omnibus" => omnibus_deps,
      "x-runtime-dependencies-omnibus" => omnibus_deps,

      "x-build-dependencies-rubygems" => {},
      "x-runtime-dependencies-rubygems" => rubygems_deps,
    })

    if software.description
      morphology['description'] = software.description + '\n\n' +
        morphology['description']
    end

    morphology
  end

  def run
    project_dir, project_name, source_dir, software_name = parse_options(ARGV)

    log.info("Creating chunk morph for #{software_name} from project " +
             "#{project_name}, defined in #{project_dir}")

    Dir.chdir(project_dir)

    project = Omnibus::Project.load(project_name)

    software = Omnibus::Software.load(@project, software_name)

    morph = generate_chunk_morph_for_software(project, software, source_dir)

    write_morph(STDOUT, morph)
  end
end

OmnibusChunkMorphologyGenerator.new.run