#!/usr/bin/env ruby

#
# Annotate your "bundle outdated" with GitHub compare URLs
#

require 'open-uri'
require 'json'

def rubygems_gem_info(gem_name)
  JSON.parse(`curl -s https://rubygems.org/api/v1/gems/#{gem_name}.json`)
end

def github_repo_tags(repo)
  JSON.parse(`curl -s https://api.github.com/repos/#{repo}/tags`)
end

def rubygems_github_repo(gem_name)
  if gem_info = rubygems_gem_info(gem_name)
    %w(source_code_uri project_uri homepage_uri).each do |key|
      if repo_name = gem_info[key].to_s[%r{//github\.com/([^/]+/[^/]+)}, 1]
        return repo_name
      end
    end
  end
  nil
end

def github_compare_url(gem_name, first_version, second_version)
  if github_repo = rubygems_github_repo(gem_name)
    tags = github_repo_tags(github_repo)
    return unless tags.is_a?(Array)
    tags = tags.sort_by { |tag| tag['name'].length }

    first_tag  = tags.detect { |tag| tag['name'].index(first_version) }
    second_tag = tags.detect { |tag| tag['name'].index(second_version) }

    if first_tag && second_tag
      "https://github.com/#{github_repo}/compare/#{first_tag['name']}...#{second_tag['name']}"
    end
  end
end

IO.popen('bundle outdated', 'r') do |io|
  io.each_line do |line|
    line = line.chomp
    if m = line.match(/^\s+\* (\S+) \((\S+) > (\S+)\)/)
      if url = github_compare_url(m[1], m[3], m[2])
        puts "#{line} — #{url}"
      else
        puts line
      end
    else
      puts line
    end
  end
end