# frozen_string_literal: true

require 'English'

helpers do
  def outbox(type, object, recipients, add_recipients = false)
    activity = {
      '@context' => 'https://www.w3.org/ns/activitystreams',
      'type' => type,
      'actor' => ACTOR,
      'object' => object
    }

    now = Time.now
    date = now.strftime('%Y-%m-%dT%H:%M:%S.%N')
    httpdate = now.utc.httpdate
    basename = "#{date}.json"
    activity_rel_path = File.join(type.downcase, basename)
    activity_path = File.join(OUTBOX_DIR, activity_rel_path)
    activity['id'] = File.join(OUTBOX_URL, activity_rel_path)
    activity['published'] = httpdate
    # assumes that recipient collections have been expanded by sender
    # put all recipients into 'to', avoid 'cc' 'bto' 'bcc' 'audience' !!
    activity['to'] = recipients if add_recipients

    # save object
    if activity['object'] && activity['object']['type'] && !activity['object']['id']

      object = activity['object']
      object['@context'] = 'https://www.w3.org/ns/activitystreams'
      object_rel_path = File.join activity['object']['type'].downcase, basename
      object_path = File.join OUTBOX_DIR, object_rel_path
      object['id'] = File.join OUTBOX_URL, object_rel_path
      object['published'] = httpdate
      FileUtils.mkdir_p File.dirname(object_path)
      File.open(object_path, 'w+') { |f| f.puts object.to_json }
    end
    # save activity
    FileUtils.mkdir_p File.dirname(activity_path)
    File.open(activity_path, 'w+') { |f| f.puts activity.to_json }
    update_collection OUTBOX, activity['id'] if %w[Create Announce].include?(type)

    # send
    # https://github.com/mastodon/mastodon/blob/main/app/lib/request.rb
    keypair = OpenSSL::PKey::RSA.new(File.read('private.pem'))
    body = activity.to_json
    sha256 = OpenSSL::Digest.new('SHA256')
    digest = "SHA-256=#{sha256.base64digest(body)}"

    inboxes = []
    recipients.uniq.each do |url|
      next if [ACTOR, 'https://www.w3.org/ns/activitystreams#Public'].include? url

      actor = fetch url
      next unless actor

      if actor['endpoints'] and actor['endpoints']['sharedInbox']
        inboxes << actor['endpoints']['sharedInbox']
      elsif actor['inbox']
        inboxes << actor['inbox']
      end
    end
    inboxes.compact.uniq.each do |inbox|
      uri = URI(inbox)
      string = "(request-target): post #{uri.request_uri}\nhost: #{uri.host}\ndate: #{httpdate}\ndigest: #{digest}\ncontent-type: application/activity+json"
      signature = Base64.strict_encode64(keypair.sign(OpenSSL::Digest.new('SHA256'), string))
      signed_header = "keyId=\"#{ACTOR}#main-key\",algorithm=\"rsa-sha256\",headers=\"(request-target) host date digest content-type\",signature=\"#{signature}\""

      curl(
        "-X POST -H 'Content-Type: application/activity+json' -H 'Host: #{uri.host}' -H 'Date: #{httpdate}' -H 'Digest: #{digest}' -H 'Signature: #{signed_header}' -d '#{body}'", inbox
      )
    end
    activity
  end

  def update_collection(path, objects, delete = false)
    objects = [objects] unless objects.is_a? Array
    File.open(path, 'r+') do |f|
      f.flock(File::LOCK_EX)
      json = f.read
      collection = JSON.parse(json)
      objects.each do |object|
        id = object['id'] || object
        if delete
          collection['orderedItems'].delete_if { |o| o['id'] == id or o == id }
        else
          ids = collection['orderedItems'].collect { |i| i['id'] }
          collection['orderedItems'] << object unless ids.include?(id) or collection['orderedItems'].include?(id)
        end
      end
      collection['totalItems'] = collection['orderedItems'].size
      f.rewind
      f.puts collection.to_json
      f.truncate(f.pos)
    end
  end

  def fetch(url, accept = 'application/activity+json')
    uri = URI(url)
    httpdate = Time.now.utc.httpdate
    keypair = OpenSSL::PKey::RSA.new(File.read('private.pem'))
    string = "(request-target): get #{uri.request_uri}\nhost: #{uri.host}\ndate: #{httpdate}"
    signature = Base64.strict_encode64(keypair.sign(OpenSSL::Digest.new('SHA256'), string))
    signed_header = "keyId=\"#{ACTOR}#main-key\",algorithm=\"rsa-sha256\",headers=\"(request-target) host date\",signature=\"#{signature}\""

    response = curl(
      "-H 'Accept: #{accept}' -H 'Host: #{uri.host}' -H 'Date: #{httpdate}' -H 'Signature: #{signed_header}' ", url
    )
    response ? JSON.parse(response) : nil
  end

  def curl(ext, url)
    p url
    # p "/run/current-system/sw/bin/curl --fail-with-body -sSL #{ext} #{url}"
    response = `/run/current-system/sw/bin/curl --fail-with-body -sSL #{ext} #{url}`
    if $CHILD_STATUS.success?
      response
    else
      p response
      nil
    end
  end

  def mention(actor)
    person = people.select { |p| p[1] == actor }
    if person.empty?
      a = fetch(actor)
      return nil unless a

      mention = "#{a['preferredUsername']}@#{URI(actor).host}"
      cache mention, actor, a
      mention
    else
      person[0][0]
    end
  end

  def actor(mention)
    mention = mention.sub(/^@/, '').chomp
    actors = people.select { |p| p[0] == mention }
    if actors.empty?
      _, server = mention.split('@')
      a = fetch("https://#{server}/.well-known/webfinger?resource=acct:#{mention}", 'application/jrd+json')
      return nil unless a

      actor = a['links'].select do |l|
        l['rel'] == 'self'
      end[0]['href']
      cache mention, actor, a
      actor
    else
      actors[0][1]
    end
  end

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

  def cache(mention, actor, a)
    sharedInbox = a['endpoints']['sharedInbox'] if a['endpoints'] && a['endpoints']['sharedInbox']
    File.open('private/people.tsv', 'a') { |f| f.puts "#{mention}\t#{actor}\t#{sharedInbox}" }
  end
end