#!/usr/bin/env ruby

require "date"
require "optparse"

def run(command, abort_on_fail: true)
  puts "> #{command}" if $VERBOSE

  system(command, exception: abort_on_fail)
rescue StandardError => e
  raise "#{command.inspect} failed: #{e}"
end

channel = ENV.fetch("FOREM_RELEASE_CHANNEL", "stable")
date = ENV.fetch("FOREM_RELEASE_DATE", Date.today.to_s).delete("-")
hotfix = ENV.fetch("FOREM_RELEASE_HOTFIX", 0)
remote = ENV.fetch("FOREM_RELEASE_REMOTE", "origin")
source = ENV.fetch("FOREM_STAGING_FROM", "#{channel}-next")

OptionParser.new ARGV.dup do |options|
  options.banner = <<~USAGE
    Usage: #{$PROGRAM_NAME} [options]

    Releases are named CHANNEL.DATE.HOTFIX_COUNT. Example: #{channel}.#{date}.#{hotfix}

  USAGE

  options.on "-c", "--channel CHANNEL",
             "Specify the release channel (defaults to #{channel.inspect})" do |release_channel|
    channel = release_channel
  end

  options.on "-d", "--date DATE", "Specify the release date (defaults to today)" do |release_date|
    date = release_date.delete("-")
  end

  options.on "-f", "--from BRANCH/COMMIT/TAG",
             "Specify the source branch for this release (defaults to #{source.inspect})" do |from_branch|
    source = from_branch
  end

  options.on "-h", "--hotfix HOTFIX",
             "Specify the hotfix count for this release branch (defaults to #{hotfix.inspect})" do |hotfix_opt|
    hotfix = hotfix_opt
  end

  options.on "-r", "--remote REMOTE", "Git remote to push to (defaults to #{remote.inspect})" do |git_remote|
    remote = git_remote
  end

  options.on "-v", "--verbose", "Enable verbose mode" do
    $VERBOSE = true
  end
end.parse!

original_branch = `git branch --show-current`.strip

begin
  tag = "#{channel}.#{date}.#{hotfix}"
  puts "Building #{tag}..."

  [source, channel].each do |branch|
    run "git checkout --quiet #{branch}"
    run "git pull --quiet --ff-only #{remote} #{branch}"
    puts "Pulled latest #{branch.inspect}"
  end

  run "git merge --quiet #{source} --no-ff --message 'Merge #{source} into #{channel}'"
  puts "Merged #{source} into #{channel}"

  begin
    File.write ".release-version", tag
    run "git add .release-version"
    run "git commit --message 'Version #{tag}'"
    run "git tag #{tag}"
    puts "Tagged #{tag}"
  rescue StandardError
    # If `git tag` fails, it's because the tag already exists. In this case, git
    # will have already output an error that looks like this:
    #
    #     fatal: tag 'stable.20210512.0' already exists
    #
    warn "Should the hotfix count be set to something other than #{hotfix}?" \
         "Or maybe you need to delete the tag locally (hint: `git tag --delete #{tag}`)"
    exit 1
  end

  run "git push --quiet #{remote} #{channel}"
  puts "Pushed #{channel} to #{remote}"

  run "git push --quiet #{remote} #{tag}"
  puts "Pushed #{tag} to #{remote}"
ensure
  # Go back to the branch we were on before running this script
  run "git checkout --quiet #{original_branch}"
end