Rake task for Git based Rails app semantic versioning.

version.rake

#gem 'colorize'
module Version
  VERSION_FILE   = "#{Rails.root}/config/initializers/version.rb"
  PATTERN        = /(\d+)\.(\d+)\.(\d+)-(.*)/
  PATTERN_NOMETA = /(\d+\.\d+\.\d+)/

  @@major = 0; @@minor = 0; @@patch = 0; @@build = 'a'
  @@version_rb = File.read(VERSION_FILE)

  def self.version_rb
    @@version_rb || ""
  end

  def self.set(major, minor, patch, build)
    @@major, @@minor, @@patch, @@build = major.to_i, minor.to_i, patch.to_i, build.to_s
  end

  def self.increment_major
    @@major += 1
  end

  def self.increment_minor
    @@minor += 1
  end

  def self.increment_patch
    @@patch += 1
  end

  def self.semantic
    "#{@@major}.#{@@minor}.#{@@patch}-#{@@build}"
  end

  def self.semantic_short
    "#{@@major}.#{@@minor}.#{@@patch}"
  end

  def self.valid? version
    self::PATTERN =~ version
  end

  def self.current_version
    self.version_rb.split('=')[1].tr("\'\" ",'').strip
  end
end

module Repo
  class Cmd
    def perform_and_parse cmd
      parse `#{cmd}`
    end

    def parse result
      result[1..-1].strip if result =~ /^\w+/   #Specific logic
    end
  end

  def self.version
    cmd = Cmd.new
    cmd.perform_and_parse( 'git describe --always --tags' )
  end
end

def describe version
  return version if version and Version.valid? version
  Repo.version
end

def check_version
  raise "Please update version file or tag.".red if Version::PATTERN_NOMETA.match(Version.current_version)[1] != Version::PATTERN_NOMETA.match(Repo.version)[1]
end

def version_info
  ver    = describe Version.current_version
  semver = Version::PATTERN.match( ver )
  Version.set(semver[1], semver[2], semver[3], semver[4])
end

def bump args
  check_version
  version_info
  args.to_hash.each { |k,v| Version.class_eval("increment_#{k}") unless v.empty? }
  bumped_version = "0.0.0"
  STDOUT.puts "Updating to version: #{Version.semantic.green}, Is it the correct version? (y/n)"
  input = STDIN.gets.chomp
  if input.downcase == 'y'
    File.open Version::VERSION_FILE, 'w' do |file|
      file.write "VERSION='#{Version.semantic}'"
      bumped_version = Version.semantic
      puts "File #{Version::VERSION_FILE.red} updated!"
    end
  else
    puts "Bye.".green
  end
  bumped_version
end

desc "Prints the current application version"
task :version do
  puts <<HELP
Available commands are:
-----------------------
rake version:bump[major, minor, patch]  # Update patch version, run: rake version:bump[,,patch]
rake version:create_tag[version]        # Create v0.8.1 tag, run: rake version:create_tag[0.8.1]
rake version:tag                        # Get latest git tag version, run: rake version:tag

HELP
  msg = Version.current_version ? "Current version is: #{Version.current_version.green}" : "There is no version set in #{VERSION_FILE}"
  puts msg
end

namespace :version do
  desc "Bump version"
  task :bump, [:major, :minor, :patch] do |task, args|
    bumped_version = bump args
    if ( bumped_version > Repo.version )
      STDOUT.puts 'Good idea to create new git tag too now? (y/n)'
      input = STDIN.gets.chomp
      Rake::Task['version:create_tag'].invoke(Version.semantic_short) if input.downcase == 'y'
    end
  end

  desc "Get the latest tag version"
  task :tag do
    puts "Version from git tag: #{git_describe_tag.green}"
  end

  desc "Create a new git tag"
  task :create_tag, [:version] do |task, args|
    `git tag v#{args[:version]}`
    puts "Tag: " + "v#{args[:version]}".green + " created!"
  end
end