require "open3"


module Buildr

  BUILD_TASKS = {
    :build    =>"Build the project",
    :clean    =>"Clean files generated during a build",
    :package  =>"Create packages",
    :install  =>"Install packages created by the project",
    :uninstall=>"Remove previously installed packages",
    :deploy   =>"Deploy packages created by the project"
  }

  # Handles the build and clean tasks.
  BUILD_TASKS.each { |name, comment| Project.local_task(task(name)).add_comment(comment) }

  Project.on_define do |project|
    BUILD_TASKS.each { |name, comment| project.recursive_task name }
  end

  class Project
    def build(*args, &block)
      task("build").enhance args, &block
    end

    def clean(*args, &block)
      task("clean").enhance args, &block
    end
  end

  Project.on_define do |project|
    # Make sure these tasks are defined in the project.
    project.build
    project.clean
  end


  class Release

    VERSION_NUMBER_PATTERN  = /VERSION_NUMBER\s*=\s*(["'])(.*)\1/
    NEXT_VERSION_PATTERN    = /NEXT_VERSION\s*=\s*(["'])(.*)\1/

    class << self
      def svn_ignores()
        @ignores = (@ignores || []).map { |pat| pat.is_a?(Regexp) ? pat : Regexp.new("^.*\s+#{Regexp.escape pat}$") }
      end
    end

    def initialize(rakefile = nil)
      @rakefile = rakefile || File.read(Rake.application.rakefile)
    end

    attr_reader :rakefile

    def invoke()
      # Make sure we don't have anything uncommitted in SVN.
      check_status
      # Update current version to next version before deploying.
      next_ver = update_version
      # Run the deployment externally using the new version number
      # (from the modified Rakefile).
      sh "rake deploy"
      # Update the next version as well to the next increment and commit.
      update_next_version next_ver
      # Tag the repository for this release.
      tag_repository next_ver
      # Update the next version to end with -SNAPSHOT.
      update_version_to_snapshot next_ver
    end

    def check_status()
      ignores = Release.svn_ignores
      status = svn("status", "--ignore-externals", :verbose=>false).
        reject { |line| line =~ /^X\s/ || ignores.any? { |pat| line =~ pat } }
      fail "Uncommitted SVN files violate the First Principle Of Release!\n#{status}" unless
        status.empty?
    end

    # Change the Rakefile and update the current version number to the
    # next version number (VERSION_NUMBER = NEXT_VERSION). We need this
    # before making a release with the next version. Return the next version.
    def update_version()
      rakefile = read_rakefile
      version = rakefile.scan(VERSION_NUMBER_PATTERN)[0][1] or
        fail "Looking for VERSION_NUMBER = \"...\" in your Rakefile, none found"
      next_ver = rakefile.scan(NEXT_VERSION_PATTERN)[0][1] or
        fail "Looking for NEXT_VERSION = \"...\" in your Rakefile, none found"
      if verbose
        puts "Current version:  #{version}"
        puts "Next version:     #{next_ver}"
      end
      # Switch version numbers.
      write_rakefile rakefile.gsub(VERSION_NUMBER_PATTERN) { |ver| ver.sub(/(["']).*\1/, %Q{"#{next_ver}"}) }
      next_ver
    end

    # Change the Rakefile and update the next version number to one after
    # (NEXT_VERSION = NEXT_VERSION + 1). We do this to automatically increment
    # future version number after each successful release.
    def update_next_version(version)
      # Update to new version number.
      nums = version.split(".")
      nums[-1] = nums[-1].to_i + 1
      next_ver = nums.join(".")
      write_rakefile read_rakefile.gsub(NEXT_VERSION_PATTERN) { |ver| ver.sub(/(["']).*\1/, %Q{"#{next_ver}"}) }
      # Commit new version number.
      svn "commit", "-m", "Changed version number to #{version}", rakefile
    end

    # Create a tag in the SVN repository.
    def tag_repository(version)
      # Copy to tag.
      cur_url = svn("info").scan(/URL: (.*)/)[0][0]
      new_url = cur_url.sub(/trunk$/, "tags/#{version}")
      svn "remove", new_url, "-m", "Removing old copy" rescue nil
      svn "copy", cur_url, new_url, "-m", "Release #{version}"
    end

    def update_version_to_snapshot(version)
      version += "-SNAPSHOT"
      write_rakefile read_rakefile.gsub(VERSION_NUMBER_PATTERN) { |ver| ver.sub(/(["']).*\1/, %Q{"#{version}"}) }
      # Commit new version number.
      svn "commit", "-m", "Changed version number to #{version}", rakefile
    end

  protected

    def read_rakefile()
      File.read(rakefile)
    end

    def write_rakefile(contents)
      File.open(rakefile, "w") { |file| file.write contents }
    end

    def svn(*args)
      if Hash === args.last
        options = args.pop
      else
        options = { :verbose=>verbose }
      end
      puts ["svn", *args].join(" ") if options[:verbose]
      Open3.popen3("svn", *args) do |stdin, stdout, stderr|
        stdin.close
        error = stderr.read
        fail error unless error.empty?
        returning(stdout.read) { |output| puts output if Rake.application.options.trace }
      end
    end

  end


  desc "Make a release"
  task("release").tap do |release|
    class << release
      def release()
        @release ||= Release.new
      end
    end
    release.enhance { release.invoke }
  end
end