require "action_view"
require "htmlentities"

module Govspeak
  class AttachmentPresenter
    attr_reader :attachment
    include ActionView::Helpers::TagHelper
    include ActionView::Helpers::NumberHelper
    include ActionView::Helpers::TextHelper

    def initialize(attachment)
      @attachment = attachment
    end

    def id
      attachment[:id]
    end

    def url
      attachment[:url]
    end

    def title
      attachment[:title]
    end

    def file_extension
      # Note: this is a separate parameter rather than being calculated from the
      # filename because at the time of writing not all apps were using the effects
      # of this field.
      attachment[:file_extension]
    end

    def attachment_attributes
      attributes = []
      if file_extension == "html"
        attributes << content_tag(:span, 'HTML', class: 'type')
      elsif attachment[:external?]
        attributes << content_tag(:span, url, class: 'url')
      else
        attributes << content_tag(:span, humanized_content_type(file_extension), class: 'type') if file_extension
        attributes << content_tag(:span, number_to_human_size(attachment[:file_size]), class: 'file-size') if attachment[:file_size]
        attributes << content_tag(:span, pluralize(attachment[:number_of_pages], "page"), class: 'page-length') if attachment[:number_of_pages]
      end
      attributes.join(', ').html_safe
    end

    MS_WORD_DOCUMENT_HUMANIZED_CONTENT_TYPE = "MS Word Document".freeze
    MS_EXCEL_SPREADSHEET_HUMANIZED_CONTENT_TYPE = "MS Excel Spreadsheet".freeze
    MS_POWERPOINT_PRESENTATION_HUMANIZED_CONTENT_TYPE = "MS Powerpoint Presentation".freeze

    def file_abbr_tag(abbr, title)
      content_tag(:abbr, abbr, title: title)
    end

    def humanized_content_type(file_extension)
      file_extension_vs_humanized_content_type = {
        "chm"  => file_abbr_tag('CHM', 'Microsoft Compiled HTML Help'),
        "csv"  => file_abbr_tag('CSV', 'Comma-separated Values'),
        "diff" => file_abbr_tag('DIFF', 'Plain text differences'),
        "doc"  => MS_WORD_DOCUMENT_HUMANIZED_CONTENT_TYPE,
        "docx" => MS_WORD_DOCUMENT_HUMANIZED_CONTENT_TYPE,
        "dot"  => file_abbr_tag('DOT', 'MS Word Document Template'),
        "dxf"  => file_abbr_tag('DXF', 'AutoCAD Drawing Exchange Format'),
        "eps"  => file_abbr_tag('EPS', 'Encapsulated PostScript'),
        "gif"  => file_abbr_tag('GIF', 'Graphics Interchange Format'),
        "gml"  => file_abbr_tag('GML', 'Geography Markup Language'),
        "html" => file_abbr_tag('HTML', 'Hypertext Markup Language'),
        "ics" => file_abbr_tag('ICS', 'iCalendar file'),
        "jpg"  => "JPEG",
        "odp"  => file_abbr_tag('ODP', 'OpenDocument Presentation'),
        "ods"  => file_abbr_tag('ODS', 'OpenDocument Spreadsheet'),
        "odt"  => file_abbr_tag('ODT', 'OpenDocument Text document'),
        "pdf"  => file_abbr_tag('PDF', 'Portable Document Format'),
        "png"  => file_abbr_tag('PNG', 'Portable Network Graphic'),
        "ppt"  => MS_POWERPOINT_PRESENTATION_HUMANIZED_CONTENT_TYPE,
        "pptx" => MS_POWERPOINT_PRESENTATION_HUMANIZED_CONTENT_TYPE,
        "ps"   => file_abbr_tag('PS', 'PostScript'),
        "rdf"  => file_abbr_tag('RDF', 'Resource Description Framework'),
        "rtf"  => file_abbr_tag('RTF', 'Rich Text Format'),
        "sch"  => file_abbr_tag('SCH', 'XML based Schematic'),
        "txt"  => "Plain text",
        "wsdl" => file_abbr_tag('WSDL', 'Web Services Description Language'),
        "xls"  => MS_EXCEL_SPREADSHEET_HUMANIZED_CONTENT_TYPE,
        "xlsm" => file_abbr_tag('XLSM', 'MS Excel Macro-Enabled Workbook'),
        "xlsx" => MS_EXCEL_SPREADSHEET_HUMANIZED_CONTENT_TYPE,
        "xlt"  => file_abbr_tag('XLT', 'MS Excel Spreadsheet Template'),
        "xsd"  => file_abbr_tag('XSD', 'XML Schema'),
        "xslt" => file_abbr_tag('XSLT', 'Extensible Stylesheet Language Transformation'),
        "zip"  => file_abbr_tag('ZIP', 'Zip archive'),
      }
      file_extension_vs_humanized_content_type.fetch(file_extension.to_s.downcase, '')
    end

    def link(body, url, options = {})
      options_str = options.map { |k, v| %{#{encode(k)}="#{encode(v)}"} }.join(" ")
      %{<a href="#{encode(url)}" #{options_str}>#{body}</a>}
    end

  private

    def encode(text)
      HTMLEntities.new.encode(text)
    end
  end
end