#!/usr/bin/ruby
# vim: set sw=2 sts=2 et tw=80 :
require 'bundler'
require 'optparse'
require 'optparse/time'
require 'logger'

class BundlerDumpRpmDeps
  def initialize
    @requires_text = "BuildRequires:  "
    parse_options
    process_bundler
  end

  def process_bundler
    #
    # TODO: have a commaldine option to specify those.
    # e.g. in mastodon you also want to skip the no_docker and heroku group
    #
    bad_groups = [:test, :development]
    bd=Bundler::Dsl.evaluate('Gemfile', 'Gemfile.lock', {})
    bd.dependencies.each do |dep|
      next if (dep.groups - bad_groups).empty?
      # this skips local deps
      next if dep.source and not(dep.source.path.nil?)
      dep.requirement.requirements.each do |req|
        req_str = rpmify(dep.name, *req)
        puts "#{@requires_text}%{rubygem #{dep.name}#{req_str}}"
      end
    end
  end

  def parse_options
    opt_parser = OptionParser.new do |opts|
      opts.banner = "Usage: bundlerdumpdeps [options]"

      opts.separator ""
      opts.separator "Specific options:"

      opts.on('-b', "Buildtime Requires (default)") do
        @requires_text = "BuildRequires:  "
      end

      opts.on('-r', "Runtime Requires") do |args|
        @requires_text = "Requires:       "
      end
    end
    opt_parser.parse!(ARGV)
  end

  def expand_pessimistic(version)
    splitted = version.to_s.split('.')
    sub_version = nil
    if splitted.length > 1
      end_index = splitted.length-1
      end_index = 3 if end_index > 3
      sub_version = splitted.slice(0,end_index).join('.')
    else
      sub_version = splitted[0]
    end
    ":#{sub_version} >= #{version}"
  end

  # (python3-prometheus_client >= 0.4.0 with python3-prometheus_client < 0.9.0)
  def rpmify(dep_name, op, version)
    case op
      when '~>'
        return expand_pessimistic(version)
      when '>='
        if version != Gem::Version.new(0)
          return " #{op} #{version}"
        end
      when '!='
        return " > #{version}"
      when '='
        return " #{op} #{version}"
      when '<'
        return " #{op} #{version}"
      when '<='
        return " =< #{version}"
      else
        STDERR.puts "Unknown operator '#{op}' called with version '#{version}'"
        exit 1
    end
  end

end

BundlerDumpRpmDeps.new