# encoding: utf-8
#
# kramdown-gist.rb - kramdown extension for gist tags
# Copyright (C) 2012 Matteo Panella <morpheus@level28.org>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

require 'kramdown-gist/version'

require 'kramdown'
require 'kramdown/parser/kramdown'

module Kramdown

  # @private
  class Element
    # Register :gist as a block-level element
    CATEGORY[:gist] = :block
  end

  module Parser

    # Standard Kramdown parser with support for embedding GitHub Gists
    # in the output.
    #
    # This class extends the default Kramdown syntax with a new block-level
    # element for embedding gists: `*{gist:<id>}`. The element is rendered
    # as a `<script>` tag pointing to `http://gist.github.com/<id>.js`.
    #
    # @author Matteo Panella
    class KramdownGist < ::Kramdown::Parser::Kramdown

     # Create a new gist-enabled Kramdown parser with the given `options`.
     def initialize(source, options)
        super
        @block_parsers.unshift(:gist)
      end

      # Regex for matching a gist tag
      # @private
      GIST_START = /^#{OPT_SPACE}\*\{gist:(\h+?)\}\n/

      # Do not use this method directly, it's used internally by Kramdown.
      # @api private
      def parse_gist
        @src.pos += @src.matched_size
        gist_id = @src[1]
        @tree.children << Element.new(:gist, gist_id)
      end
      define_parser(:gist, GIST_START)

    end

  end

  module Converter
    class Html

      # Convert a gist element into a `<script>` tag suitable for embedding.
      #
      # @return [String] an HTML fragment representing this element
      # @api private
      def convert_gist(el, indent)
        "#{' '*indent}<script src=\"http://gist.github.com/#{el.value}.js\"></script>\n"
      end

    end

    class Kramdown

      # Convert a gist element into the equivalent Kramdown "tag"
      #
      # @return [String] an Kramdown fragment representing this element
      # @api private
      def convert_gist(el, opts)
        "*{gist:#{el.value}}\n"
      end
    end

    class Latex

      # Convert a gist element into a LaTeX paragraph stating the Gist ID and
      # including the target hyperlink as metadata suitable for some output
      # formats (PDF).
      #
      # @return [String] a LaTeX fragment representing this element
      # @api private
      def convert_gist(el, opts)
        gist_id = el.value
        "See \\href{https://gist.github.com/#{gist_id}}{Gist #{gist_id}}.\n\n"
      end
    end
  end
end