helpers do

  def items
    nr = 0
    @items = Dir[File.join(@dir, '*.json')].sort.collect do |file|
      item = JSON.parse(File.read(file))
      mention = mention(item['attributedTo'])
      following_path = File.join('public', 'following', mention + '.json')
      File.exists?(following_path) ? follow = 'unfollow' : follow = 'follow'
      nr += 1
      { :id => item['id'],
        :nr => nr,
        :parent => item['inReplyTo'],
        :file => file,
        :actor_url => item['attributedTo'],
        :mention => mention,
        :follow => follow,
        :content => item['content'],
        :attachment => item['attachment'],
        :indent => 2,
        :replies => []
      }
    end.compact
    @items.last[:nr] = @items.last[:nr] - 2 unless @items.empty?
  end

  def threads
    items
    @threads = []
    @items.each do |i|
      if i[:parent].nil? or @items.select{|it| it[:id] == i[:parent] }.empty?
        @threads << i
      else
        @items.select{|it| it[:id] == i[:parent] }.each do |it|
          i[:indent] = it[:indent] + 2
          it[:replies] << i
        end
      end
    end
  end

  def html item
    @item = item
    erb :item
  end

  def people
    File.read('cache/people.tsv').split("\n").collect {|l| l.chomp.split("\t")}
  end

  def mention actor
    person = people.select{|p| p[1] == actor} 
    if person.empty?
      mention = "#{fetch(actor)["preferredUsername"]}@#{URI(actor).host}"
      File.open('cache/people.tsv','a'){|f| f.puts "#{mention}\t#{actor}"}
      mention
    else
      person[0][0]
    end
  end

  def actor mention
    mention = mention.sub(/^@/, '').chomp
    actors = people.select{|p| p[0] == mention} 
    if actors.empty?
      user, server = mention.split("@")
      actor = fetch("https://#{server}/.well-known/webfinger?resource=acct:#{mention}",
          "application/jrd+json")["links"].select { |l|
        l["rel"] == "self"
      }[0]["href"]
      File.open('cache/people.tsv','a'){|f| f.puts "#{mention}\t#{actor}"}
      actor
    else
      actors[0][1]
    end
  end

  def fetch url, accept = 'application/ld+json; profile="https://www.w3.org/ns/activitystreams"'
    p url
    response = `/run/current-system/sw/bin/curl --fail-with-body -sSL -H 'Accept: #{accept}' #{url}`
    halt 400 unless $?.success?
    JSON.parse(response)
  end

  # https://github.com/mastodon/mastodon/blob/main/app/lib/request.rb
  def send_signed object, url

    keypair = OpenSSL::PKey::RSA.new(File.read('private.pem'))
    date = Time.now.utc.httpdate
    sha256 = OpenSSL::Digest::SHA256.new
    body = object.to_json
    digest = "SHA-256=" + sha256.base64digest(body)
    host = URI.parse(url).host
    inbox = fetch(url)["inbox"]
    request_uri = URI(inbox).request_uri

    signed_string = "(request-target): post #{request_uri}\nhost: #{host}\ndate: #{date}\ndigest: #{digest}\ncontent-type: application/activity+json"
    signature = Base64.strict_encode64(keypair.sign(OpenSSL::Digest.new('SHA256'), signed_string))
    signed_header = 'keyId="' + ACTOR + '#main-key",algorithm="rsa-sha256",headers="(request-target) host date digest content-type",signature="' + signature + '"'

    p url
    #puts `/run/current-system/sw/bin/curl --fail-with-body -sSL -X POST -H 'Content-Type: application/activity+json' -H 'Host: #{host}' -H 'Date: #{date}' -H 'Digest: #{digest}' -H 'Signature: #{signed_header}' -d '#{body}' #{inbox}`
    puts `/run/current-system/sw/bin/curl -iL -X POST -H 'Content-Type: application/activity+json' -H 'Host: #{host}' -H 'Date: #{date}' -H 'Digest: #{digest}' -H 'Signature: #{signed_header}' -d '#{body}' #{inbox}`
  end

end