require 'fileutils'

module Temp

  # A Copier object provides various functions 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 with the given path from the given template name.
    def create_project(project, template)
      project = File.expand_path(project)
      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)

      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

    # 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