require 'thor'
require 'gitx'
require 'gitx/cli/base_command'

module Gitx
  module Cli
    class NukeCommand < BaseCommand
      desc 'nuke', 'nuke the specified aggregate branch and reset it to a known good state'
      method_option :destination, :type => :string, :aliases => '-d', :desc => 'destination branch to reset to'
      def nuke(bad_branch)
        good_branch = options[:destination] || ask("What branch do you want to reset #{bad_branch} to? (default: #{bad_branch})")
        good_branch = bad_branch if good_branch.length == 0

        last_known_good_tag = current_build_tag(good_branch)
        return unless yes?("Reset #{bad_branch} to #{last_known_good_tag}? (y/n)", :green)
        assert_aggregate_branch!(bad_branch)
        return if migrations_need_to_be_reverted?(bad_branch, last_known_good_tag)

        say 'Resetting '
        say "#{bad_branch} ", :green
        say 'branch to '
        say last_known_good_tag, :green

        checkout_branch Gitx::BASE_BRANCH
        run_cmd "git branch -D #{bad_branch}", :allow_failure => true
        run_cmd "git push origin --delete #{bad_branch}", :allow_failure => true
        run_cmd "git checkout -b #{bad_branch} #{last_known_good_tag}"
        run_cmd "git push origin #{bad_branch}"
        run_cmd "git branch --set-upstream-to origin/#{bad_branch}"
        checkout_branch Gitx::BASE_BRANCH
      end

      private

      def migrations_need_to_be_reverted?(bad_branch, last_known_good_tag)
        return false unless File.exist?('db/migrate')
        outdated_migrations = run_cmd("git diff #{last_known_good_tag}...#{bad_branch} --name-only db/migrate").split
        return false if outdated_migrations.empty?

        say "#{bad_branch} contains migrations that may need to be reverted.  Ensure any reversable migrations are reverted on affected databases before nuking.", :red
        say 'Example commands to revert outdated migrations:'
        outdated_migrations.reverse.each do |migration|
          version = File.basename(migration).split('_').first
          say "rake db:migrate:down VERSION=#{version}"
        end
        !yes?("Are you sure you want to nuke #{bad_branch}? (y/n) ", :green)
      end

      def current_build_tag(branch)
        last_build_tag = build_tags_for_branch(branch).last
        raise "No known good tag found for branch: #{branch}.  Verify tag exists via `git tag -l 'build-#{branch}-*'`" unless last_build_tag
        last_build_tag
      end

      def build_tags_for_branch(branch)
        run_cmd 'git fetch --tags'
        build_tags = run_cmd("git tag -l 'build-#{branch}-*'").split
        build_tags.sort
      end
    end
  end
end