# encoding: utf-8

module Nanoc3::DataSources

  # = Items
  #
  # The filesystem data source stores its items in nested directories. A item
  # is represented by a single file. The root directory is the 'content'
  # directory.
  #
  # The metadata for a item is embedded into the file itself. It is stored at
  # the top of the file, between '---' (three dashes) separators. For example:
  #
  #   ---
  #   title: "Moo!"
  #   ---
  #   h1. Hello!
  #
  # The identifier of a item is determined as follows. A file with an
  # 'index.*' filename, such as 'index.txt', will have the filesystem path
  # with the 'index.*' part stripped as a identifier. For example,
  # 'foo/bar/index.html' will have '/foo/bar/' as identifier.
  #
  # A file with a filename not starting with 'index.', such as 'foo.html',
  # will have an identifier ending in 'foo/'. For example, 'foo/bar.html' will
  # have '/foo/bar/' as identifier.
  #
  # Note that it is possible for two different, separate files to have the
  # same identifier. It is therefore recommended to avoid such situations.
  #
  # Some more examples:
  #
  #   content/index.html          --> /
  #   content/foo.html            --> /foo/
  #   content/foo/index.html      --> /foo/
  #   content/foo/bar.html        --> /foo/bar/
  #   content/foo/bar/index.html  --> /foo/bar/
  #
  # File extensions are ignored by nanoc. The file extension does not
  # determine the filters to run on it; the metadata in the file defines the
  # list of filters.
  #
  # = Layouts
  #
  # Layouts are stored as files in the 'layouts' directory. Similar to items,
  # each layout consists of a metadata part and a content part, separated by
  # '---' (three dashes).
  #
  # = Code Snippets
  #
  # Code snippets are stored in '.rb' files in the 'lib' directory. Code
  # snippets can reside in sub-directories.
  class FilesystemCombined < Nanoc3::DataSource

    include Nanoc3::DataSources::FilesystemCommon

    ########## VCSes ##########

    attr_accessor :vcs

    def vcs
      @vcs ||= Nanoc3::Extra::VCSes::Dummy.new
    end

    ########## Preparation ##########

    def up
    end

    def down
    end

    def setup
      # Create directories
      %w( content layouts lib ).each do |dir|
        FileUtils.mkdir_p(dir)
        vcs.add(dir)
      end
    end

    ########## Loading data ##########

    def items
      files('content', true).map do |filename|
        # Read and parse data
        meta, content = *parse_file(filename, 'item')

        # Get attributes
        attributes = meta.merge(:file => Nanoc3::Extra::FileProxy.new(filename))

        # Get actual identifier
        if filename =~ /\/index\.[^\/]+$/
          identifier = filename.sub(/^content/, '').sub(/index\.[^\/\.]+$/, '') + '/'
        else
          identifier = filename.sub(/^content/, '').sub(/\.[^\/\.]+$/, '') + '/'
        end

        # Get mtime
        mtime = File.stat(filename).mtime

        # Build item
        Nanoc3::Item.new(content, attributes, identifier, mtime)
      end
    end

    def layouts
      files('layouts', true).map do |filename|
        # Read and parse data
        meta, content = *parse_file(filename, 'layout')

        # Get actual identifier
        if filename =~ /\/index\.[^\/]+$/
          identifier = filename.sub(/^layouts/, '').sub(/index\.[^\/\.]+$/, '') + '/'
        else
          identifier = filename.sub(/^layouts/, '').sub(/\.[^\/\.]+$/, '') + '/'
        end

        # Get mtime
        mtime = File.stat(filename).mtime

        # Build layout
        Nanoc3::Layout.new(content, meta, identifier, mtime)
      end.compact
    end

    ########## Creating data ##########

    # Creates a new item with the given content, attributes and identifier.
    def create_item(content, attributes, identifier)
      # Determine path
      if identifier == '/'
        path = 'content/index.html'
      else
        path = 'content' + identifier[0..-2] + '.html'
      end
      parent_path = File.dirname(path)

      # Notify
      Nanoc3::NotificationCenter.post(:file_created, path)

      # Write item
      FileUtils.mkdir_p(parent_path)
      File.open(path, 'w') do |io|
        io.write(YAML.dump(attributes.stringify_keys) + "\n")
        io.write("---\n")
        io.write(content)
      end
    end

    # Creates a new layout with the given content, attributes and identifier.
    def create_layout(content, attributes, identifier)
      # Determine path
      path = 'layouts' + identifier[0..-2] + '.html'
      parent_path = File.dirname(path)

      # Notify
      Nanoc3::NotificationCenter.post(:file_created, path)

      # Write layout
      FileUtils.mkdir_p(parent_path)
      File.open(path, 'w') do |io|
        io.write(YAML.dump(attributes.stringify_keys) + "\n")
        io.write("---\n")
        io.write(content)
      end
    end

  private

    # Returns a list of all files in +dir+, ignoring any unwanted files (files
    # that end with '~', '.orig', '.rej' or '.bak').
    #
    # +recursively+:: When +true+, finds files in +dir+ as well as its
    #                 subdirectories; when +false+, only searches +dir+
    #                 itself.
    def files(dir, recursively)
      glob = File.join([dir] + (recursively ? [ '**', '*' ] : [ '*' ]))
      Dir[glob].reject { |f| File.directory?(f) or f =~ /(~|\.orig|\.rej|\.bak)$/ }
    end

    # Parses the file named +filename+ and returns an array with its first
    # element a hash with the file's metadata, and with its second element the
    # file content itself.
    def parse_file(filename, kind)
      # Split file
      pieces = File.read(filename).split(/^(-{5}|-{3})/).compact
      if pieces.size < 3
        raise RuntimeError.new(
          "The file '#{filename}' does not seem to be a nanoc #{kind}"
        )
      end

      # Parse
      meta    = YAML.load(pieces[2]) || {}
      content = pieces[4..-1].join.strip

      [ meta, content ]
    end

  end

end