require 'fileutils'

module Temp

  # A Copier object provides various methods for creating a project from a
  # template. It can also be given a path to the directory where templates can
  # be found.
  class Copier

    attr_reader :options

    def initialize(options = {})
      @options = options
      @template_dir = File.expand_path(options[:template_dir] || '~/.temp')
    end

    # Creates a new project from a template. If a path is supplied, the
    # project's name will be the last item in the path. Otherwise, it will have
    # the same name as the template and be created in the current working
    # directory.
    def create_project(project = nil, template)
      project = File.expand_path(project || template)
      template_path = File.expand_path(File.join(@template_dir, template))

      raise 'project already exists' if File.exist? project
      raise 'template does not exist' unless File.exist? template_path

      ignore = read_tempignore(template)
      files = find_files(template, ignore)

      if File.file? template_path
        FileUtils.cp(template_path, project)
      else
        FileUtils.mkdir(project)
        files.each do |file|
          p = File.join(project, file)
          t = File.join(template_path, file)

          if File.directory? t
            FileUtils.mkdir(p)
          else
            FileUtils.cp(t, p)
          end
        end
      end
    end

    # Returns an array of all files in a template, optionally ignoring all files
    # in ignore.
    def find_files(template, ignore = [])
      template = File.expand_path(File.join(@template_dir, template))
      Dir.glob(File.join(template, '**/*')).map do |file|
        file.sub(template + '/', '')
      end - ignore
    end

    # Returns an array of files in a template to ignore.
    def read_tempignore(template)
      template = File.expand_path(File.join(@template_dir, template))
      tempignore = File.join(template, '.tempignore')
      files = ['.tempignore']

      if File.exist? tempignore
        files |= File.read(tempignore).split(?\n).map do |line|
          Dir.glob(File.join(template, line)).map do |file|
            file.sub(template + '/', '')
          end
        end.flatten
      end

      files
    end

  end

end