require 'sanitize'
require 'cgi'

module Ag::Rendering
  class HTMLizer
    def self.HTMLize(mail)
      if mail.multipart?
        content_type = mime_split(mail.parts.first.content_type)

        if content_type == 'text/plain' || content_type == 'text/html'
          to_content(content_type, mail.parts.first.decoded, get_encoding(mail.parts.first))
        else
          # Nested multipart?
          if mail.parts.first.multipart?
            content_type = mime_split(mail.parts.first.parts.first.content_type)

            if content_type == 'text/plain' || content_type == 'text/html'
              to_content(content_type, mail.parts.first.parts.first.decoded, get_encoding(mail.parts.first.parts.first))
            else
              raise "Cannot find body: #{mail.message_id}"
            end
          # Specialty: Gnus/Emacs signed emails with no explicit multipart type
          elsif mime_split(mail.content_type) == 'multipart/signed'
            to_content('text/plain', mail.parts.first.decoded, get_encoding(mail.parts.first))
          end
        end
      else
        # No Content-Type, assume plain text (git-send-email)
        if mail.content_type.nil?
          to_content('text/plain', mail.body.decoded, get_encoding(mail))
        else
          to_content(mime_split(mail.content_type), mail.body.decoded, get_encoding(mail))
        end
      end
    end

    def self.get_encoding(part)
      part.content_type_parameters['charset'] if part.content_type_parameters
    end

    def self.to_content(content_type, content, _charset = nil)
      # content = content.force_encoding(charset) if charset

      if content_type == 'text/plain'
        escaped_content = CGI.escapeHTML(content)
        escaped_content.lines.map do |line|
          if line.start_with? '>'
            "<div class=\"ag-quote\">#{line.rstrip}</div>\n"
          else
            line
          end
        end.join.gsub("</div>\n<div class=\"ag-quote\">", "\n")
      elsif content_type == 'text/html'
        '<div class="ag-html-content">' + Sanitize.fragment(content, Sanitize::Config::BASIC) + '</div>'
      else
        '<div class="alert alert-danger" role="alert"><strong>Unsupported Content-Type</strong></div>'
      end
    end

    def self.mime_split(content_type)
      (content_type || '').split(';').first
    end
  end
end
# vim: ts=2 sts=2 et ft=ruby: