require 'haml'
require 'csv'
require 'logger'
require "petrify/version"

module Petrify
  @@output_dir = '_site'
  @@working_dir = File.join(Dir.pwd, @@output_dir)
  @@views_dir = 'views'
  @@layout_fn = File.join(@@views_dir, 'layout.haml')
  
  # https://stackoverflow.com/questions/917566/ruby-share-logger-instance-among-module-classes#6768164
  @@log = Logger.new($stdout)
  @@log.level = Logger::INFO

  # Write an HTML page using a specified template and optional data
  def self.page(path_items, template, locals = {})
    dir = create_path(path_items)
    fn = File.join(dir, 'index.html')
    
    # https://stackoverflow.com/questions/6125265/using-layouts-in-haml-files-independently-of-rails
    html = Haml::Engine.new(File.read(@@layout_fn)).render(Object.new, locals) do
      Haml::Engine.new(File.read(File.join(@@views_dir, "#{template}.haml"))).render(Object.new, locals)
    end

    File.write(fn, html)
    @@log.info fn
    # TODO - add page to sitemap.xml or sitemap.txt
    # https://support.google.com/webmasters/answer/183668?hl=en&ref_topic=4581190
  end

  # Write a CSV file from an array of hashes (or an empty array)
  def self.csv(path_items, filename, data)
    dir = create_path(path_items)
    fn = File.join(dir, filename + '.csv')
    
    if data.size > 0
      csv_string = CSV.generate do |csv|
        csv << data.first.keys # header row
        data.each { |row| csv << row.values }
      end
    else
      # There's no data so write an empty file (no header row either)
      csv_string = ''
    end
    
    File.write(fn, csv_string)
    @@log.info fn
  end
  
  # Write an arbitrary file to output (eg a JSON file)
  def self.file(path_items, filename, data)
    dir = create_path(path_items)
    fn = File.join(dir, filename)    
    File.write(fn, data)
    @@log.info fn
  end

  def self.setup
    # Recursively delete working directory to ensure no redundant files are left behind from previous builds.
    # But preserve dot-files (especially .git directory)
    FileUtils.rm_r(Dir.glob(File.join(@@working_dir, '*')))
    Dir.mkdir(@@working_dir) unless File.directory?(@@working_dir)

    # Copy `public` dir to output dir
    FileUtils.copy_entry('public', @@working_dir)
  end

  def self.create_path(path_items)
    dir = File.join(@@output_dir, path_items)
    FileUtils.mkdir_p(dir)
    @@log.debug dir
    dir
  end
end