desc 'deploy [STAGE]', 'Guided deployment across branches'
long_desc <<-LONGDESC
Example: `geordi deploy production`

Merge, push and deploy with a single command! There are several scenarios where
this command comes in handy:

1) *Production deploy:* From the master branch, run `geordi deploy production`.
   This will merge `master` to `production`, push and deploy to production.

2) *Feature branch deploy:* From the feature branch, run `geordi deploy staging`.
   This will merge the feature branch to `master`, push and deploy to staging.

3) *Simple deploy:* If the source branch matches the target branch, merging will
   be skipped.

Calling the command without arguments will infer the target stage from the
current branch and fall back to master/staging.

When your project does not have a `deploy:migrations` task, this command will
run `cap deploy` instead when called with `-M`: `geordi deploy -M staging`.
LONGDESC

option :no_migrations, :aliases => '-M', :type => :boolean,
  :desc => 'Run cap deploy instead of cap deploy:migrations'

def deploy(target_stage = nil)
  # Set/Infer default values
  branch_stage_map = { 'master' => 'staging', 'production' => 'production'}
  proposed_stage = target_stage || branch_stage_map.fetch(Util.current_branch, 'staging')

  target_stage = prompt 'Deployment capistrano stage:', proposed_stage
  source_branch = prompt 'Source branch:', Util.current_branch
  target_branch = prompt 'Deploy branch:', branch_stage_map.invert.fetch(target_stage, 'master')

  merge_needed = (source_branch != target_branch)

  announce "Checking whether your #{source_branch} branch is ready"
  if `git status -s | wc -l`.strip != '0'
    fail "Your #{source_branch} branch holds uncommitted changes. Fix that first."
  else
    note 'All good.'
  end

  if merge_needed
    announce "Checking what's in your #{target_branch} branch right now"
    Util.system! "git checkout #{target_branch} && git pull"
  end

  announce "You are about to #{'merge & ' if merge_needed}push & deploy"
  note "From branch #{source_branch}"
  note "Merge into branch #{target_branch}" if merge_needed
  note "Deploy to #{target_stage}"
  Util.system! "git --no-pager log origin/#{target_branch}..#{source_branch} --oneline"

  if prompt('Go ahead with the deployment?', 'n', /y|yes/)
    cap3 = file_containing?('Capfile', 'capistrano/setup')
    capistrano_call = "cap #{target_stage} deploy"
    capistrano_call << ':migrations' unless cap3 || options.no_migrations
    capistrano_call = "bundle exec #{capistrano_call}" if file_containing?('Gemfile', /capistrano/)

    puts
    command = "git push && #{capistrano_call}"
    command = "git merge #{source_branch} && " << command if merge_needed
    Util.system! command, :show_cmd => true

    success 'Deployment complete.'
  else
    fail 'Deployment cancelled.'
  end

end