#!/usr/bin/env ruby

require 'net/smtp'

def run(command)
  output = `#{command} 2>&1`
  if not $?.success?
    raise Exception, "Command Failed '#{command}': #{output}"
  end
  output
end

def branch_list(command)
  run(command)
    .split("\n")
    .select { |x| (x =~ / -> /).nil? }
    .map { |x| x.strip.split('/', 2).last }
    .select { |x| (x =~ /^master$/).nil? }
end

def send_email(from, from_alias, to, to_alias, subject, message)
    msg = <<END_OF_MESSAGE
From: #{from_alias} <#{from}>
To: #{to_alias} <#{to}>
Subject: #{subject}
    
#{message}
END_OF_MESSAGE
    
    Net::SMTP.start('localhost') do |smtp|
        smtp.send_message msg, from, to
    end
end

# Update repository and remove all stale branches
run "git remote update --prune"

branches = branch_list("git branch -r")
unclean_merges = []

branches.each do |branch|
  begin
    run "git reset --hard HEAD"
    run "git checkout origin/#{branch}"
    begin
      run "git merge --no-ff origin/master"
      #run "git push origin HEAD:refs/heads/#{branch}"
    rescue Exception
      unclean_merges << branch
      raise
    end
    puts "Successfully updated branch '#{branch}'"
  rescue Exception
    puts "Failed to update branch '#{branch}'"
  end
end

run "git reset --hard HEAD"
run "git checkout master"

if not unclean_merges.empty?
  send_email(
    "no-reply@drakerlabs.com", "Jenkins Merger",
    "nowell@strite.org", "Dev Team",
    "Unclean master merges",
    "The following branches were unable to merge master cleanly:\n#{unclean_merges.join("\n")}"
    )
end