#!/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/install_command'
require 'shellwords'
require 'yaml'

TARGET_PROJECT = 'chefdk'  # should come from args

TARGET_SOFTWARE = 'chefdk' # should come from args

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.

  class GemInstallCommandParser < Gem::Commands::InstallCommand
    def dependency_list_from_commandline(args)
      handle_options args
      options[:args].collect do |gem_name|
        Bundler::Dependency.new(gem_name, options[:version])
      end
    end
  end

  def gem(command, options = {})
    # This function implements the 'gem' function in the build-commands DSL.
    if command.match /^install/
      parser = GemInstallCommandParser.new
      args = Shellwords.split(command).drop(1)
      gems = parser.dependency_list_from_commandline(args)
      manually_installed_rubygems.concat gems
    end
  end

  def manually_installed_rubygems
    @manually_installed_rubygems ||= []
  end
end

class OmnibusChunkMorphologyGenerator
  def deps_for_software(software)
    deps = Hash.new
    software.dependencies.each do |dep|
      deps[dep] = 0
    end
    software.builder.manually_installed_rubygems.each do |dep|
      deps[dep.name] = dep.requirement.to_s
    end
    deps
  end

  def generate_chunk_morph_for_software(software)
    {
      "name" => software.name,
      "kind" => "chunk",
      # 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" => deps_for_software(software),
      "x-runtime-dependencies-omnibus" => deps_for_software(software),
    }
  end

  def write_morph(file, morph)
    file.write(YAML.dump(morph))
  end

  def run
    project = Omnibus::Project.load(TARGET_PROJECT)

    software = Omnibus::Software.load(project, TARGET_SOFTWARE)

    morph = generate_chunk_morph_for_software(software)

    write_morph(STDOUT, morph)
  end
end

OmnibusChunkMorphologyGenerator.new.run