require "cgi"

module BrowseHelper
  def printable_name(object, version = false)
    id = if object.id.is_a?(Array)
           object.id[0]
         else
           object.id
         end
    name = t "printable_name.with_id", :id => id.to_s
    name = t "printable_name.with_version", :id => name, :version => object.version.to_s if version

    # don't look at object tags if redacted, so as to avoid giving
    # away redacted version tag information.
    unless object.redacted?
      locale = I18n.locale.to_s

      locale = locale.sub(/-[^-]+/, "") while locale =~ /-[^-]+/ && !object.tags.include?("name:#{I18n.locale}")

      if object.tags.include? "name:#{locale}"
        name = t "printable_name.with_name_html", :name => content_tag(:bdi, object.tags["name:#{locale}"].to_s), :id => content_tag(:bdi, name)
      elsif object.tags.include? "name"
        name = t "printable_name.with_name_html", :name => content_tag(:bdi, object.tags["name"].to_s), :id => content_tag(:bdi, name)
      elsif object.tags.include? "ref"
        name = t "printable_name.with_name_html", :name => content_tag(:bdi, object.tags["ref"].to_s), :id => content_tag(:bdi, name)
      end
    end

    name
  end

  def link_class(type, object)
    classes = [type]

    if object.redacted?
      classes << "deleted"
    else
      classes += icon_tags(object).flatten.map { |t| h(t) }
      classes << "deleted" unless object.visible?
    end

    classes.join(" ")
  end

  def link_title(object)
    if object.redacted?
      ""
    else
      h(icon_tags(object).map { |k, v| k + "=" + v }.to_sentence)
    end
  end

  def link_follow(object)
    "nofollow" if object.tags.empty?
  end

  def format_key(key)
    if url = wiki_link("key", key)
      link_to h(key), url, :title => t("browse.tag_details.wiki_link.key", :key => key)
    else
      h(key)
    end
  end

  def format_value(key, value)
    if wp = wikipedia_link(key, value)
      link_to h(wp[:title]), wp[:url], :title => t("browse.tag_details.wikipedia_link", :page => wp[:title])
    elsif wdt = wikidata_links(key, value)
      # IMPORTANT: Note that wikidata_links() returns an array of hashes, unlike for example wikipedia_link(),
      # which just returns one such hash.
      wdt = wdt.map do |w|
        link_to(w[:title], w[:url], :title => t("browse.tag_details.wikidata_link", :page => w[:title].strip))
      end
      safe_join(wdt, ";")
    elsif url = wiki_link("tag", "#{key}=#{value}")
      link_to h(value), url, :title => t("browse.tag_details.wiki_link.tag", :key => key, :value => value)
    elsif url = telephone_link(key, value)
      link_to h(value), url, :title => t("browse.tag_details.telephone_link", :phone_number => value)
    else
      linkify h(value)
    end
  end

  def type_and_paginated_count(type, pages)
    if pages.page_count == 1
      t "browse.changeset.#{type}",
        :count => pages.item_count
    else
      t "browse.changeset.#{type}_paginated",
        :x => pages.current_page.first_item,
        :y => pages.current_page.last_item,
        :count => pages.item_count
    end
  end

  private

  ICON_TAGS = %w[aeroway amenity barrier building highway historic landuse leisure man_made natural railway shop tourism waterway].freeze

  def icon_tags(object)
    object.tags.find_all { |k, _v| ICON_TAGS.include? k }.sort
  end

  def wiki_link(type, lookup)
    locale = I18n.locale.to_s

    # update-wiki-pages does s/ /_/g on keys before saving them, we
    # have to replace spaces with underscore so we'll link
    # e.g. `source=Isle of Man Government aerial imagery (2001)' to
    # the correct page.
    lookup_us = lookup.tr(" ", "_")

    if page = WIKI_PAGES.dig(locale, type, lookup_us)
      url = "https://wiki.openstreetmap.org/wiki/#{page}?uselang=#{locale}"
    elsif page = WIKI_PAGES.dig("en", type, lookup_us)
      url = "https://wiki.openstreetmap.org/wiki/#{page}?uselang=#{locale}"
    end

    url
  end

  def wikipedia_link(key, value)
    # Some k/v's are wikipedia=http://en.wikipedia.org/wiki/Full%20URL
    return nil if value =~ %r{^https?://}

    if key == "wikipedia"
      # This regex should match Wikipedia language codes, everything
      # from de to zh-classical
      lang = if value =~ /^([a-z-]{2,12}):(.+)$/i
               # Value is <lang>:<title> so split it up
               # Note that value is always left as-is, see: https://trac.openstreetmap.org/ticket/4315
               Regexp.last_match(1)
             else
               # Value is <title> so default to English Wikipedia
               "en"
             end
    elsif key =~ /^wikipedia:(\S+)$/
      # Language is in the key, so assume value is the title
      lang = Regexp.last_match(1)
    else
      # Not a wikipedia key!
      return nil
    end

    if value =~ /^([^#]*)#(.*)/
      # Contains a reference to a section of the wikipedia article
      # Must break it up to correctly build the url
      value = Regexp.last_match(1)
      section = "#" + Regexp.last_match(2)
      encoded_section = "#" + CGI.escape(Regexp.last_match(2).gsub(/ +/, "_")).tr("%", ".")
    else
      section = ""
      encoded_section = ""
    end

    {
      :url => "https://#{lang}.wikipedia.org/wiki/#{value}?uselang=#{I18n.locale}#{encoded_section}",
      :title => value + section
    }
  end

  def wikidata_links(key, value)
    # The simple wikidata-tag (this is limited to only one value)
    if key == "wikidata" && value =~ /^[Qq][1-9][0-9]*$/
      return [{
        :url => "//www.wikidata.org/wiki/#{value}?uselang=#{I18n.locale}",
        :title => value
      }]
    # Key has to be one of the accepted wikidata-tags
    elsif key =~ /(architect|artist|brand|name:etymology|network|operator|subject):wikidata/ &&
          # Value has to be a semicolon-separated list of wikidata-IDs (whitespaces allowed before and after semicolons)
          value =~ /^[Qq][1-9][0-9]*(\s*;\s*[Qq][1-9][0-9]*)*$/
      # Splitting at every semicolon to get a separate hash for each wikidata-ID
      return value.split(";").map do |id|
        { :title => id, :url => "//www.wikidata.org/wiki/#{id.strip}?uselang=#{I18n.locale}" }
      end
    end
    nil
  end

  def telephone_link(_key, value)
    # does it look like a phone number? eg "+1 (234) 567-8901 " ?
    return nil unless value =~ %r{^\s*\+[\d\s\(\)/\.-]{6,25}\s*$}

    # remove all whitespace instead of encoding it http://tools.ietf.org/html/rfc3966#section-5.1.1
    # "+1 (234) 567-8901 " -> "+1(234)567-8901"
    value_no_whitespace = value.gsub(/\s+/, "")

    "tel:#{value_no_whitespace}"
  end
end