# frozen_string_literal: true

before '/inbox' do
  request.body.rewind # in case someone already read it
  @body = request.body.read
  unless @body.empty?
    @activity = JSON.parse @body
    @object = @activity['object']
    @object = fetch(@object) if @object.is_a?(String) && @object.match(/^http/)
    halt 400 unless @object
  end
end

# client-server
post '/outbox' do
  protected!
  # send_signed @activity
end

# server-server
post '/inbox' do
  verify!
  # file = File.join INBOX, "#{SecureRandom.uuid}.json"
  # File.open(file, 'w+') { |f| f.puts @activity.to_json }
  type = @activity['type'].downcase.to_sym
  respond_to?(type) ? send(type) : p("Unknown activity: #{type}")
end

# public
get '/.well-known/webfinger' do
  if request['resource'] == "acct:#{ACCOUNT}"
    send_file('./public/webfinger',
              type: 'application/jrd+json')
  else
    halt(404)
  end
end

get '/outbox' do
  ordered_collection(OUTBOX).to_json
end

get '/inbox' do
  # protected!
  ordered_collection(File.join(INBOX, 'note')).to_json
end

['/following', '/followers'].each do |path|
  get path do
    ordered_collection(File.join(PUBLIC_DIR, path)).to_json
  end
end

get '/tags/:tag' do |tag|
  ordered_collection(File.join(TAGS, tag)).to_json
end

helpers do
  # https://github.com/mastodon/mastodon/blob/main/app/controllers/concerns/signature_verification.rb
  def verify!
    # digest
    sha256 = OpenSSL::Digest.new('SHA256')
    digest = "SHA-256=#{sha256.base64digest(@body)}"
    halt 403 unless digest == request.env['HTTP_DIGEST']

    # signature
    signature_params = {}
    request.env['HTTP_SIGNATURE'].split(',').each do |pair|
      k, v = pair.split('=')
      signature_params[k] = v.gsub('"', '')
    end

    key_id = signature_params['keyId']
    headers = signature_params['headers']
    signature = Base64.decode64(signature_params['signature'])

    actor = fetch key_id
    halt 403 unless actor

    key = OpenSSL::PKey::RSA.new(actor['publicKey']['publicKeyPem'])

    comparison = headers.split(' ').map do |signed_params_name|
      if signed_params_name == '(request-target)'
        '(request-target): post /inbox'
      elsif signed_params_name == 'content-type'
        "#{signed_params_name}: #{request.env['CONTENT_TYPE']}"
      else
        "#{signed_params_name}: #{request.env["HTTP_#{signed_params_name.upcase}"]}"
      end
    end.join("\n")

    halt 403 unless key.verify(OpenSSL::Digest.new('SHA256'), signature, comparison)
  end

  def create
    return unless @object
    return if object_exists?

    File.open(object_file, 'w+') { |f| f.puts @object.to_json }
    return unless @object['inReplyTo']

    @object = fetch @object['inReplyTo']
    create if @object
  end

  def delete
    Dir['inbox/*/*.json'].each do |file|
      FileUtils.rm file if JSON.parse(File.read(file))['id'] == @object['id']
    end
  end

  def update
    delete
    create
  end

  def announce
    create
  end

  def accept
    return unless @object['type'] == 'Follow'

    File.open(File.join(FOLLOWING, "#{mention(@object['object'])}.json"), 'w+') { |f| f.puts @object.to_json }
  end

  def undo
    return unless @object['type'] == 'Follow'

    Dir[File.join(FOLLOWERS, '*.json')].each do |follower|
      FileUtils.rm follower if JSON.parse(File.read(follower))['actor'] == @object['actor']
    end
  end

  def follow
    File.open(File.join(FOLLOWERS, "#{mention(@activity['actor'])}.json"), 'w+') { |f| f.puts @body }
    accept = { '@context' => 'https://www.w3.org/ns/activitystreams',
               'id' => File.join("#{SOCIAL_URL}#accepts", SecureRandom.uuid),
               'type' => 'Accept',
               'actor' => ACTOR,
               'object' => @activity,
               'to' => [@activity['actor']] }
    send_signed accept
  end

  # when "Like"
  # when "Move"
  # when "Add"
  # when "Remove"
  # when "Block"

  def inbox
    Dir[File.join(INBOX, '*', '*.json')].collect do |file|
      JSON.parse(File.read(file))
    end.sort_by { |o| o['published'] }
  end

  def object_exists?
    !inbox.select { |o| o['id'] == @object['id'] }.empty?
  end

  def object_file
    dir = File.join 'inbox', @object['type'].downcase
    FileUtils.mkdir_p dir
    File.join dir, "#{Time.now.strftime('%Y-%m-%dT%H:%M:%S.%N')}.json"
  end

  def ordered_collection(dir)
    posts = Dir[File.join(dir, '*.json')].collect { |f| JSON.parse(File.read(f)) }.sort_by { |o| o['published'] }
    {
      '@context' => 'https://www.w3.org/ns/activitystreams',
      'summary' => "#{USER} #{dir}",
      'type' => 'OrderedCollection',
      'totalItems' => posts.size,
      'orderedItems' => posts
    }
  end
end