require 'noumenon/content_repository'
require 'yaml'
require 'fileutils'

# A content repository which uses YAML files within the filesystem for storage.
# 
# @example The structure of a filesystem repository
#   index.yml
#   |- about
#      |- index.yml
#      |- team.yml
#      |- company.yml
#   contact.yml
#
# @example A piece of content
#   template: team_member
#   name: Jon Wood
#   position: Head Honcho of Awesomeness
#   bio: Jon's just awesome, we'll leave it at that.
#
# @api public
class Noumenon::ContentRepository::FileSystem < Noumenon::ContentRepository
  # @param [ Hash ] options A hash of options.
  # @option options [ String ] :path The path to access the repository at.
  # @api public
  def initialize(options = {})
    unless options.key? :path
      raise ArgumentError.new("You must provide a path to the content repository: Noumenon::ContentRepository::FileSystem.new(path: '/tmp')")
    end

    super options
  end
  
  # Loads a piece of content from the repository.
  #
  # @param [ String ] path The path to load from.
  # @param [ Boolean ] check_for_index Whether sub-directories of the same name should be checked for an index.yml file
  # @return [ Hash, #each, nil ] The piece of content, or nil if it could not be found.
  # @api public
  def get(path, check_for_index = true)
    if content = read_file("#{path}.yml")
      YAML.load(content).symbolize_keys
    elsif check_for_index
      return get("#{path}/index", false)
    end
  end
  
  # Saves a piece of content to the repsitory.
  #
  # @see Noumenon::Repository#put
  # @api public
  def put(path, content = {})
    create_tree(path)
     
    path = File.join(path, "index") if File.exist?(repository_path(path))
    write_file "#{path}.yml", content.symbolize_keys.to_yaml
  end
  
  # Return any content items below the path specified.
  #
  # @see Noumenon::Repository#children
  # @api public
  def children(root = "/", depth = 1, include_root = true)
    root.gsub! /\/$/, ''
    
    pattern = File.join(repository_path(root), "*")
    
    items = Dir.glob(pattern).collect { |i|
      i.gsub(repository_path("/"), "/").
        gsub(".yml", "")
    }.reject { |i| i.gsub(root, "").split("/").size > depth + 1 }
    items.delete(File.join(root, "index")) unless include_root
     
    items.collect { |item|
      path = item == "" ? "/" : item.gsub("index", "")
      
      # Loading every item probably isn't scalable, but it'll do for now. We can add caching
      # at a later date if needed.
      page = get(path).merge({ path: path })
      page[:children] = children(page[:path], depth - 1, false) if depth - 1 > 0
      page
    }.sort { |a, b| a[:path] <=> b[:path] }
  end
  
  private
  # Return the on-disk path to a repository item.
  def repository_path(path)
    File.join(options[:path], path)
  end
  
  # Creates any neccesary directories, and moves files that conflict with newly created
  # directories to index.yml
  def create_tree(path)
    path_on_disk = File.dirname(repository_path(path))
    
    unless File.exists?(path_on_disk)
      FileUtils.mkdir_p(path_on_disk)
      create_indexes(path)
    end
  end
  
  def write_file(path, content)
    path_on_disk = repository_path(path)
    directory = File.dirname(path_on_disk)
    FileUtils.mkdir_p(directory) unless File.exist?(directory)

    File.open(path_on_disk, "w") { |f| f.print content }
  end

  def read_file(path)
    begin
      File.read(repository_path(path))
    rescue Errno::ENOENT => e
      nil
    end
  end

  # Moves conflicting YAML files into directory/index.yml
  #
  # For example given
  #
  #   /foo
  #   /foo.yml
  #
  # /foo.yml will be moved to /foo/index.yml
  def create_indexes(path)
    sub_path = options[:path]
    
    path.split("/").each do |directory|
      move_to_index File.join(sub_path, directory)
      sub_path = File.join(sub_path, directory)
    end
  end

  def move_to_index(path)
    path_on_disk = path
    yaml_file = "#{path_on_disk}.yml"
    
    if File.exist? yaml_file
      FileUtils.mv yaml_file, File.join("#{path_on_disk}/index.yml")
    end
  end
end